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[Objective]To establish a method for the simultaneous determination of hyperin, quercetin and farrerol in Rhododendron dauricum by HPLC, and to discuss the effects of Rhododendron dauricum extract and its three main components on the relaxation of rat tracheal smooth muscle and the mechanism. [Method] The contents of hypericin, quercetin and farrerol in Rhododendron dauricum were determined by HPLC and the methodology was investigated. Rat tracheal rings were obtained by in vivo air tube perfusion method, and fixed in a Mack’s bath. The tracheal rings were pre-incubated with chlorphenamine, indometacin, glibenclamide, L-nitroarginine methyl ester (L-NAME), nifedipine and propranolol. After the tension of the tracheal ring stabilized, 60 mmol/ L KCl solution was added to shrink the tracheal ring. The relaxation experiment of tracheal ring by Rhododendron dauricum was conducted to observe the changes of tracheal smooth muscle tension in rats. [Result] The investigation results of the HPLC determination method for three main components in Rhododendron dauricum showed that the linear relationship between the three components was good in the range of 2-80 μg / mL. The average recovery rates were 100. 3% (RSD = 2. 63%) of hypericin, 102. 7% (RSD= 2. 89%) of quercetin and 102. 1% (RSD= 2. 36%) of farrerol. The diastolic effects of the extract and the three main components of Rhododendron dauricum in the incubated tissue of indometacin, glibenclamide and propranolol were not significantly different from those in the unincubated group. The diastolic effects of Rhododendron dauricum and hypericin in the tissues incubated with chlorphenamine, L-NAME and nifedipine were significantly different from those in the unincubated tissues. This phenomenon may be achieved through inhibition of histamine H1 receptors, nitric oxide synthase pathways, and calcium channel mediated calcium influx. [Conclusion] The established method is simple, accurate, and can quickly determine the content of hypericin, quercetin and farrerol in Rhododendron dauricum, providing an effective analytical means for quality evaluation and control. In addition, these three components are related to the effect of diastolic trachea of Rhododendron dauricum L., and can be used as a theoretical basis for the development of bronchodilators. [ABSTRACT FROM AUTHOR]

Farrerol is a flavonoid found in plants with a wide range of pharmacological effects, including protection and enhancement of nerve cell function, as well as antioxidant and antibacterial properties, among others. Neurodegenerative diseases are irreversible neurological disorders resulting from the loss of neuronal cells in the brain and spinal cord. In this experiment, we investigated the neuroprotective and antioxidant effects of farrerol on glutamate-induced HT22 cells. Our results showed that farrerol inhibited reactive oxygen species expression, apoptosis, mitochondrial damage, and the activation of caspases 3 and 9 in HT22 cells induced by glutamate. Additionally, farrerol potentially regulated the Nrf2/heme oxygenase-1 (HO-1) signaling pathway, as it attenuated the nuclear translocation of Nrf2 and promoted the expression of HO-1. These findings suggest that farrerol has potential as a new therapeutic option The mechanism of farrerol inhibiting cell apoptosis. [ABSTRACT FROM AUTHOR]

Farrerol (FA) is a traditional Chinese herbal medicine known for its anti-inflammatory and anti-oxidative properties in various diseases. Ferroptosis is an iron-dependent oxidative stressinduced cell death. It is characterized by lipid peroxidation and glutathione depletion and is involved in neuronal injury. However, the role of FA in inhibiting ferroptosis in hypoxic-ischemic encephalopathy (HIE) and its underlying mechanisms are not yet completely elucidated. This study aimed to investigate whether FA could mediate ferroptosis and explore its function and molecular mechanism in HIE. A neonatal rat model of HIE was used, and rats were treated with FA, ML385 (a specific inhibitor of nuclear factor erythroid 2-related factor 2 [Nrf2]), or a combination of both. Neurological deficits, infarction volume, brain water content, pathological changes, and iron ion accumulation in the brain tissues were measured using the Zea-Longa scoring system and triphenyl tetrazolium chloride (TTC), hematoxylin-eosin (HE), and Perls' staining. The expression levels of GSH-Px, MDA, SOD, and ROS in brain tissues were also evaluated. Western blot analysis was performed to analyze the expression of the Nrf2 pathway and ferroptosisrelated proteins. The results showed that FA administration significantly reduced neuronal damage, infarct volume, cerebral edema, and iron ion accumulation and inhibited MDA and ROS levels while promoting GSH-Px and SOD levels. FA also increased the expression levels of glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11 (SLC7A11), Nrf2, and HO-1. Moreover, the combination of ML385 and FA in HIE abolished the FA protective effects. Therefore, the study concludes that FA exerts a neuroprotective effect after HIE by inhibiting oxidative stress and ferroptosis via the Nrf2 signaling pathway. [ABSTRACT FROM AUTHOR]

Obstructive uropathy is a clinical condition that can lead to chronic kidney disease. However, treatments that can prevent the progression of renal injury and fibrosis are limited. Farrerol (FA) is a natural flavone with potent antioxidant and anti-inflammatory properties. Here, we investigated the effect of FA on renal injury and fibrosis in a mouse model of unilateral ureteral obstruction (UUO). Mice underwent a sham or UUO operation and received intraperitoneal injections of FA (20 mg/kg) daily for 8 consecutive days. Histochemistry, immunohistochemistry and immunofluorescence staining, TdT-mediated dUTP nick end labeling assay, Western blotting, gene expression analysis, and biochemical tests were performed. FA attenuated renal dysfunction (p < 0.05) and ameliorated renal tubular injury (p < 0.01) and interstitial fibrosis (p < 0.001) in UUO mice. FA alleviated 4-hydroxynonenal expression (p < 0.001) and malondialdehyde levels (p < 0.01) by regulating pro-oxidant and antioxidant enzymes. Apoptosis in the kidneys of UUO mice was inhibited by FA (p < 0.001), and this action was accompanied by decreased expression of cleaved caspase-3 (p < 0.01). Moreover, FA alleviated pro-inflammatory cytokine production (p < 0.001) and macrophage infiltration (p < 0.01) in the kidneys of UUO mice. These results suggest that FA ameliorates renal injury and fibrosis in the UUO model by inhibiting oxidative stress, apoptosis, and inflammation.

Cardiovascular disease has become the primary disease that threatens human health and is considered the leading cause of death. Cardiac remodeling, which is associated with cardiovascular disease, mainly manifests as cardiac hypertrophy, fibrosis, inflammation, and oxidative stress. Farrerol plays an important role in treating conditions such as inflammation, endothelial injury and tumors, and we speculated that Farrerol may also play an important role in mitigating cardiac hypertrophy and remodeling. We established a model of myocardial remodeling using Angiotensin II (Ang II) with concurrent intraperitoneal injection of Farrerol as an intervention. We used cardiac ultrasound, immunohistochemistry, Immunofluorescence, Wheat Germ Agglutinin, Dihydroethidium, Western Blot, qPCR and other methods to detect the role of Farrerol in cardiac remodeling. The results showed that Farrerol inhibited Ang II-induced cardiac hypertrophy; decreased the ratio of heart weight to tibia length in mice; reduced inflammation, fibrosis, and oxidative stress; and reduced the size of cardiomyocytes in vivo. Farrerol inhibited Ang II-induced cardiomyocyte hypertrophy, levels of oxidative stress, and the proliferation and migration of fibroblast in vitro. Our results revealed that Farrerol could inhibit Ang II-induced cardiac remodeling. Farrerol may therefore be a candidate drug for the treatment of myocardial remodeling. [ABSTRACT FROM AUTHOR]

The inhibition of intimal hyperplasia (IH) is an effective strategy to improve the long-term outcome of endovascular therapy and prevent restenosis. Farrerol, a naturally occurring dihydroflavone with a variety of bioactivities, exerts inhibitory effects against balloon injury-induced IH in rats. In the present study, bioinformatics analysis, in combination with in vitro experimental validation, was performed to elucidate the underlying inhibitory mechanisms. The protein–protein interaction (PPI) network was assessed to identify farrerol-related protein targets in the context of IH, based on which biological functions and pathway enrichment were analyzed. The proliferation and cell cycle distribution of vascular smooth muscle cells (VSMCs) were investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2 H -tetrazolium bromide and 5-ethynyl-2-deoxyuridine incorporation assays and flow cytometric analysis, respectively. The level of pro-inflammatory cytokines in the cell culture medium was estimated using an enzyme-linked immunosorbent assay (ELISA). Protein expression in A7r5 cells was determined by western blotting. Forty-six IH-related targets of farrerol were identified, and the PI3K/Akt/mTOR pathway was highly enriched among the 43 predicted pathways (P <.05). In serum (10% fetal bovine serum)-induced A7r5 cells, farrerol inhibited proliferation through non-cytotoxic effects, induced cell cycle arrest in the G0/G1 phase, and suppressed the activation of the PI3K/Akt/mTOR pathway. In H2O2 (300 µM)-induced A7r5 cells, farrerol reduced the release of IL-1 β and TNF- α and reversed the suppressive effect on the PI3K/Akt/mTOR pathway in response to H2O2 stimulation. In conclusion, farrerol inhibits the proliferation of VSMCs and protects VSMCs from oxidative injury via the bidirectional modulation of the PI3K/Akt/mTOR signaling pathway, which might contribute to the suppression of neointima formation. [ABSTRACT FROM AUTHOR]

Farrerol is an herbal compound extracted from rhododendron. Here, our study is to investigate biological effects of farrerol on lung adenocarcinoma (LAC) cells. Human LAC cell lines and xenograft mouse model were utilized to define the effects of farrerol on tumor growth. Our findings indicated that farrerol significantly reduced LAC cell viability as well as the colony‐forming capacity. Flow cytometry analysis demonstrated that farrerol contributed to cell apoptosis and G0/G1 phase cell cycle arrest. Mechanistically, farrerol treatment upregulated proapoptotic molecules (Bak, Bid, cleaved caspase‐3 and cleaved caspase‐9) and senescence markers (p16 and p2), but downregulated antiapoptosis genes (Bcl‐2 and Bcl‐XL) and cell cycle‐associated genes (CyclinD1 and CDK4); meanwhile, the phosphorylation of retinoblastoma (Rb) protein was attenuated upon pretreatment of LAC cells with farrerol in comparison to untreated control. Further studies indicated that farrerol elevated reactive oxygen species levels, activating mitochondrial apoptotic pathway and causing cell apoptosis. However, exposure to farrerol did not result in significant apoptosis in normal lung epithelial cells, suggesting a tumor‐specific effect of farrerol on LAC cells. In animal model, farrerol showed a significant inhibitory effect on LAC xenograft tumor growth. And gene expressions in tumor tissues, as mentioned above, were in line with the in vitro results. Taken together, these results suggested that farrerol caused LAC cell apoptosis by activating mitochondrial apoptotic pathway, whereas farrerol treatment had no notable effect on normal lung epithelial cells. Farrerol might be an effective therapeutic drug for LAC. [ABSTRACT FROM AUTHOR]

Tendinopathy is mainly characterized by local pain, functional limitation and decreased athletic ability, which seriously affects the quality of life of patients and the career of athletes. Farrerol (FA), one of the main active compounds extracted from Rhododendron and plants in the Rhododendron family, has a wide range of pharmacological activities, such as immunomodulatory, anti-inflammatory and antiviral effects. However, the effect of FA on tendinopathy is unclear. Here, we investigated the pharmacological effect and mechanism of FA in tendon injury through collagenase-induced tendinopathy in vivo and RSL3-induced tenocytes injury in vitro. The results showed that FA alleviated the infiltration of inflammatory cells, promoted tenogenesis and improved mechanical properties of the Achilles tendon in rats. In addition, ferroptosis inducer RSL3 inhibits the tenogenesis in vitro and in vivo, which accelerates the progression of tendinopathy. Moreover, FA effectively inhibited iron accumulation and alleviated ferroptosis in the Achilles tendon. Using in vitro experiments, we found that FA antagonized ferroptosis by reducing lipid peroxidation and iron accumulation in tenocytes. Finally, we found that glutathione peroxidase 4 silencing could block the protective effect of FA on ferroptosis of tenocytes. Therefore, the results of this study suggest that FA can relieve collagenase-induced tendinopathy by inhibiting ferroptosis, and reveal that FA may be a potentially effective drug for the treatment of tendinopathy in the future. [ABSTRACT FROM AUTHOR]

Myocardial ischemia/reperfusion (I/R) injury is associated with high mortality and morbidity, however, it has no curative treatment. Farrerol (FA), an active compound extracted from rhododendron, has antibacterial, anti-inflammatory, and antioxidant activities, but its effect and mechanism of FA in I/R injury remain unclear. Here, we found that FA alleviated myocardial I/R in vivo , and decreased the secretion of myocardial injury factors (CK-MB, LDH, troponin-1, and NT-proBNP) while inhibiting the release of inflammatory factors (IL-1β, IL-6, and TNF-α). FA could also alleviate excessive oxidative stress by elevating the level of antioxidant enzymes and reducing oxidation products; and decreased reduced the expression of apoptosis-associated proteins (cleaved caspase-3, Bax, and Bcl-2). However, inhibiting the autophagic pathway or knocking out the Nrf2 gene did not eliminate the myocardial protective effect of FA, but interestingly, macrophage clearance and Nlrp3 deficiency effectively blocked the myocardial protective effect of FA. In addition, FA suppressed NLRP3 inflammasome activation by interfering with NLRP3 and NEK7. In conclusion, these results support drug-targeted macrophage therapy for myocardial I/R and indicate that FA may be used as an immunomodulator in clinical therapy for myocardial I/R. [ABSTRACT FROM AUTHOR]

Myocardial ischemia/reperfusion (I/R) injury is associated with high mortality and morbidity, however, it has no curative treatment. Farrerol (FA), an active compound extracted from rhododendron, has antibacterial, anti-inflammatory, and antioxidant activities, but its effect and mechanism of FA in I/R injury remain unclear. Here, we found that FA alleviated myocardial I/R in vivo, and decreased the secretion of myocardial injury factors (CK-MB, LDH, troponin-1, and NT-proBNP) while inhibiting the release of inflammatory factors (IL-1β, IL-6, and TNF-α). FA could also alleviate excessive oxidative stress by elevating the level of antioxidant enzymes and reducing oxidation products; and decreased reduced the expression of apoptosis-associated proteins (cleaved caspase-3, Bax, and Bcl-2). However, inhibiting the autophagic pathway or knocking out the Nrf2 gene did not eliminate the myocardial protective effect of FA, but interestingly, macrophage clearance and Nlrp3 deficiency effectively blocked the myocardial protective effect of FA. In addition, FA suppressed NLRP3 inflammasome activation by interfering with NLRP3 and NEK7. In conclusion, these results support drug-targeted macrophage therapy for myocardial I/R and indicate that FA may be used as an immunomodulator in clinical therapy for myocardial I/R.

This study evaluated the anti‐inflammatory activity against lipopolysaccharide (LPS)‐mediated mouse macrophages (in vitro) and assessed the protective effect of farrerol on arthritis caused by complete freund adjuvant (CFA) in rats. For the evaluation of the pharmacological effect of farrerol on the activity of nitric oxide (NO) and cyclooxygenase, pro‐inflammatory cytokines including interleukin‐6 (IL‐6), tumor necrosis factor‐α (TNF‐α), and interleukin‐1β, RAW 264.7 cells were used. A 0.1 ml CFA was injected subcutaneously for the induction of arthritis. The paw volume, body weight and arthritic score were estimated at regular intervals. Pro‐inflammatory cytokines, inflammatory mediators, and antioxidant parameters were also estimated. Farrerol suppressed NO production and COX‐catalyzed prostaglandin (PGE2) in RAW 264.7. Farrerol also downregulated the p‐p65, p‐IκBα expression and upregulated the PPAR‐γ expression in RAW 264.7 cells. Treatment of farrerol increased body weight substantially, and reduced paw edema and arthritic score. Farrerol treatment also significantly improved the level of hemoglobin (Hb), count of red blood cells (RBC), and decreased the rate of erythrocyte sedimentation (ESR), white blood cell (WBC) parameters, while the generation of pro‐inflammatory cytokines inhibited. Together, farrerol also suppressed the pro‐inflammatory cytokines TNF‐α, IL‐6, and IL‐1β. Obtained results directed that the farrerol exerted its therapeutic effect against CFA‐induced arthritic rats through anti‐inflammatory mechanism by regulation of the PPAR‐γ. Practical applications: Increase the arthritis disease worldwide day‐by‐day. The current research study showed the anti‐arthritic effect of farrerol (flavonoid phytoconstituent) of Rhododendron dauricum Linn. In this study, farrerol considerably inhibited the NF‐κB to show the anti‐arthritic effect. The finding showed the potential effect against acute and chronic inflammation via inhibition of inflammatory mediators and oxidative stress. The result suggests the anti‐inflammatory and antioxidant effect of farrerol. On the basis of result, we can say that farrerol can be the beneficial drug to treat the arthritis. [ABSTRACT FROM AUTHOR]

Farrerol, an important bioactive constituent of rhododendron, exhibits broad activities such as anti-oxidative and anti-inflammatory effects. Recent studies showed that farrerol possesses neuroprotective activity, however, the mechanism has not been reported. The aim of the present study was to investigate the protective effect of farrerol on β-amyloid (Aβ)-induced mouse microglial BV-2 cells and the underlying mechanism. BV-2 cells were pretreated with farrerol for 1 h and then subjected to Aβ. MTT assay was performed to measure the mitochondrial metabolic activity in BV-2 cells. The production of reactive oxygen species (ROS) and malondialdehyde (MDA) and superoxide dismutase (SOD) activity were detected to reflect oxidative stress status. The secretion and mRNA levels of interleukin (IL)-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) were measured by ELISA and qRT-PCR. The expressions of NF-E2-related factor (Nrf2), heme oxygenase-1 (HO-1), NAD (P) H: quinone oxidoreductase 1 (NQO1), and Kelch-like ECH-associated protein 1 (Keap1) were measured by western blot. Our results showed that farrerol improved mitochondrial metabolic activity in Aβ-induced BV-2 cells. Aβ induced the production of ROS and MDA, and inhibited the SOD activity and the expression of SOD1 and SOD2 mRNA, while the effects were attenuated by farrerol. Farrerol also inhibited the induction effect of Aβ on IL-6, IL-1β, and TNF-α. In addition, farrerol enhanced the activation of Nrf2/Keap1 pathway in Aβ-induced BV-2 cells. Knockdown of Nrf2 by small interfere RNA (siRNA) targeting Nrf2 (si-Nrf2) abolished the protective effect of farrerol on Aβ-induced BV-2 cells. In conclusion, farrerol attenuated Aβ-induced oxidative stress and inflammation in BV-2 cells through enhancing the activation of Nrf2/Keap1 pathway. The findings indicated that farrerol could be considered as a therapeutic approach for the treatment of Alzheimer’s disease (AD).

A dummy molecularly imprinted polymer (d-MIP) was developed for extraction and cleanup of farrerol from Rhododendron aganniphum. The d-MIP was prepared by precipitation polymerization using quercetin as the dummy template, 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, and acetonitrile as the porogen. The d-MIP was characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy. Dynamic curves, adsorption isotherms, and Scatchard plots showed the d-MIP had good affinity, capacity, and selectivity for the target compound. The prepared d-MIP was used as a sorbent in solid-phase extraction cartridges and successfully applied to specific extraction and purification of farrerol from real samples. High recoveries were obtained for four spiked levels of farrerol in Rhododendron aganniphum using d-MIP solid-phase extraction coupled with high-performance liquid chromatography. The linear range was 1–100 µg mL−1, the limit of detection was 2.23 mg kg−1, the farrerol recovery range was 85.7%–104.1%, and the relative standard deviations (n = 3) were all less than 2.2% for real samples. The proposed method provides a simple, rapid, and environmentally friendly approach to the analysis of farrerol in complex herbal products.

Excessive bone resorption caused by upregulated osteoclast activity is a key factor in osteoporosis pathogenesis. Farrerol is a typical natural flavanone and exhibits various pharmacological actions. However, the role and mechanism of action of farrerol in osteoclast differentiation regulation remain unclear. This study aimed to evaluate the effects and mechanism of farrerol on the inhibition of osteoclastogenesis. Tartrate-resistant acid phosphatase staining, F-actin staining, and the pit formation assay were performed to examine the differentiation and functions of osteoclasts in vitro. The expression of proteins associated with the nuclear factor kappa B and mitogen-activated protein kinase signaling pathways was analyzed by western blotting. Dual X-ray absorptiometry, microcomputed tomography, and histopathological and immunohistochemical analyses were performed to determine the therapeutic effect of farrerol in vivo bone loss prevention. The effects of farrerol on osteoblastic bone formation were assessed using alkaline phosphatase, alizarin red S staining, and calcein-alizarin red S double labeling. Farrerol inhibited osteoclastogenesis and bone resorption in osteoclasts by suppressing nuclear factor kappa B signaling rather than mitogen-activated protein kinase signaling in vitro. Farrerol protected mice against ovariectomy-induced bone loss by inhibiting osteoclast-mediated bone resorption, instead of promoting osteoblast-mediated bone formation in vivo. The findings of the current study revealed that farrerol is a potential therapeutic agent for osteoporosis., Competing Interests: Declaration of competing interest The author reports no conflicts of interest in this work., (Copyright © 2024 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Farrerol, a dihydroflavone isolated from Rhododendron dauricum L., can inhibit vascular smooth muscle cell (VSMC) proliferation and exert a protective effect on H2O2-induced vascular endothelial cells injury. In this study, we investigated the effects of farrerol on VSMC phenotypic modulation and balloon injury-induced vascular neointimal formation and explored the underlying mechanisms. Serum-starved rat thoracic aorta SMCs (RASMCs) were first pretreated with farrerol (3, 10, and 30 μM, respectively), U0126 (a MEK kinase inhibitor), and SB203580 (a p38 kinase inhibitor), and followed by treatment with serum (10% FBS). The expression of several VSMC-specific markers, including α-SMA, SM22α, and OPN, were analyzed by western blot. Phosphorylation of extracellular signal-regulated protein kinase 1/2 (ERK 1/2) and p38 mitogen-activated protein kinase (MAPK) was also investigated. Farrerol inhibited the serum-induced transition of RASMCs from the contractile to the synthetic phenotype, and this was associated with a decrease in α-SMA and SM22α expression, and an increase in OPN expression. Farrerol also inhibited serum-induced phosphorylation of ERK1/2 and p38MAPK in RASMCs. Moreover, U0126 and SB203580 both inhibited the serum-induced phenotypic transition of RASMCs. These findings indicate that farrerol can maintain the contractile phenotype of VSMCs partly via inactivating the ERK1/2 and p38 MAPK signaling pathways. Using a rat model of carotid artery balloon injury, inhibition of VSMC phenotypic transition and suppression of neointimal formation were confirmed in vivo following the perivascular application of farrerol. Our results suggested that farrerol could be a promising lead compound for the treatment of vascular proliferative diseases. [ABSTRACT FROM AUTHOR]

Directly modulating the choice between homologous recombination (HR) and non-homologous end joining (NHEJ) - two independent pathways for repairing DNA double-strand breaks (DSBs) - has the potential to improve the efficiency of gene targeting by CRISPR/Cas9. Here, we have developed a rapid and easy-to-score screening approach for identifying small molecules that affect the choice between the two DSB repair pathways. Using this tool, we identified a small molecule, farrerol, that promotes HR but does not affect NHEJ. Further mechanistic studies indicate that farrerol functions through stimulating the recruitment of RAD51 to DSB sites. Importantly, we demonstrated that farrerol effectively promotes precise targeted integration in human cells, mouse cells and mouse embryos at multiple genomic loci. In addition, treating cells with farrerol did not have any obvious negative effect on genomic stability. Moreover, farrerol significantly improved the knock-in efficiency in blastocysts, and the subsequently generated knock-in mice retained the capacity for germline transmission.

Cisplatin is a chemotherapy drug that is often used in clinical practice, but its frequent use often leads to nephrotoxicity. Therefore, we urgently need a drug that reduces the nephrotoxicity induced by cisplatin. Farrerol reportedly has antioxidant potential, but its renal protective effects and potential mechanisms remain unclear. In this study, we used both cell and mouse models to determine the mechanism of farrerol in cisplatin-induced nephrotoxicity. The in vitro experiments revealed that farrerol improved cisplatin-induced nephrotoxicity and reactive oxygen species (ROS) production via nuclear factor erythrocyte 2-related factor 2 (Nrf2) activation. Moreover, farrerol effectively activated Nrf2 and subsequently increased the expression of Nrf2-targeted antioxidant enzymes, including heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase-1 (NQO1), but inhibited Kelch-like ECH-associated protein 1 (Keap1) and NADPH oxidase type 4 (NOX4). Furthermore, farrerol attenuated the phosphorylation of C-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38 mitogen-activated protein kinase (p38); the activation of phosphorylated nuclear factor-κB (p-NF-κB) and nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3); and the expression of phosphorylated p53 (p-p53), Bax, and cleaved caspase-3. In vivo, farrerol significantly improved cisplatin-induced renal damage, as demonstrated by the recovery of blood urea nitrogen (BUN), serum creatinine (SCr), kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and pathological damage. Moreover, farrerol inhibited inflammatory and apoptotic protein expression in vivo. Notably, farrerol exerted slight protection in Nrf2-knockout mice compared with wild-type mice. These findings indicate that farrerol can effectively activate Nrf2 and can serve as a therapeutic target in the treatment of acute kidney injury (AKI).

Purpose: To investigate the effect of farrerol on diabetic hepatopathy in a rat model of type 2 diabetes mellitus (T2DM). Methods: Adult male Wistar rats (n = 40) were randomly assigned to four groups of ten rats each: normal control, diabetic control, farrerol control and treatment groups. With the exception of normal control and farrerol control groups, the rats were fed high-fat diet (HFD) for four weeks, and thereafter injected streptozotocin (STZ) at a dose of 30 mg/kg body weight intraperitoneally (i.p.) for induction of T2DM. Rats in farrerol control and treatment groups received 50 mg/kg farrerol orally/day. Serum levels of triacylglycerol (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and lowdensity lipoprotein cholesterol (LDL-C) were determined. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels were assessed in liver homogenate while mRNA and protein expressions of glucose transporter 2 (GLUT2) were assayed in liver using real-time quantitative polymerase chain reaction (qRT-PCR) and Western blotting, respectively. Expression levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were also determined using qRT-PCR. Results: Diabetes mellitus (DM) led to significant reductions in rat body weight and SOD activity, while increasing fasting blood glucose (FBG) and MDA levels (p < 0.05). However, treatment with farrerol significantly reversed the effect of DM on these parameters (p < 0.05). The mRNA expressions of TNF- α and IL-1β were significantly higher in diabetic control group than in normal control group, but were significantly reduced after farrerol treatment (p < 0.05). Treatment with farrerol also significantly reversed the effect of DM on rat lipid profile (p < 0.05). The expression of GLUT2 protein was significantly downregulated in the liver of diabetic control rats, when compared with normal control rats, but was significantly upregulated after treatment with farrerol (p < 0.05). Conclusion: The results of this study show that farrerol alleviates STZ-induced hyperglycemia and dyslipidemia via reduction in oxidative stress and inflammation, and upregulation of GLUT2 protein expression. Thus, farrerol has antidiabetic and hepatoprotective potentials for clinical use in humans. [ABSTRACT FROM AUTHOR]

Cisplatin is a chemotherapy drug that is often used in clinical practice, but its frequent use often leads to nephrotoxicity. Therefore, we urgently need a drug that reduces the nephrotoxicity induced by cisplatin. Farrerol reportedly has antioxidant potential, but its renal protective effects and potential mechanisms remain unclear. In this study, we used both cell and mouse models to determine the mechanism of farrerol in cisplatin-induced nephrotoxicity. The in vitro experiments revealed that farrerol improved cisplatin-induced nephrotoxicity and reactive oxygen species (ROS) production via nuclear factor erythrocyte 2-related factor 2 (Nrf2) activation. Moreover, farrerol effectively activated Nrf2 and subsequently increased the expression of Nrf2-targeted antioxidant enzymes, including heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase-1 (NQO1), but inhibited Kelch-like ECH-associated protein 1 (Keap1) and NADPH oxidase type 4 (NOX4). Furthermore, farrerol attenuated the phosphorylation of C-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38 mitogen-activated protein kinase (p38); the activation of phosphorylated nuclear factor-κB (p-NF-κB) and nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3); and the expression of phosphorylated p53 (p-p53), Bax, and cleaved caspase-3. In vivo , farrerol significantly improved cisplatin-induced renal damage, as demonstrated by the recovery of blood urea nitrogen (BUN), serum creatinine (SCr), kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and pathological damage. Moreover, farrerol inhibited inflammatory and apoptotic protein expression in vivo. Notably, farrerol exerted slight protection in Nrf2-knockout mice compared with wild-type mice. These findings indicate that farrerol can effectively activate Nrf2 and can serve as a therapeutic target in the treatment of acute kidney injury (AKI). [ABSTRACT FROM AUTHOR]

Farrerol (FA) is a flavanone isolated from the Chinese herbal medicine “Man-shan-hong” (Rhododendron dauricum L.). In the present study, FA decreased the viability of SKOV3 cells in a dose- and time-dependent manner, and it induced G2/M cell cycle arrest and cell apoptosis. Cell cycle distribution analysis via flow cytometry showed that FA decreased G1 populations and increased G2/M populations in SKOV3 cells. Additionally, Western blotting confirmed an increase in the expression level of proteins involved in the cell cycle, e.g., CDK and cyclins. FA-induced apoptosis in SKOV3 cells was also investigated using a TUNEL assay, and increased expression levels of proapoptotic factors, including Caspase-3 and poly ADP ribose polymerase (PARP), through the Extracellular signal-regulated kinase (ERK)/MAPK pathway were investigated. Proinflammatory cytokines (e.g., IL-6, TNF-α, and IL-1) have been identified as a driver of the pathological mechanisms underlying involuntary weight loss and impaired physical function, i.e., cachexia, during cancer; in the present study, we showed that farrerol attenuates TNF-α-induced lipolysis and increases adipogenic differentiation in 3T3-L1 cells. Thus, farrerol could potentially be used as an anticancer agent or anticachetic drug.

• A Fe 3 O 4 @SiO 2 -GO@MIPs was fabricated for recognition of four flavonoids. • LC–MS/MS based on MIPs was developed for determination of four flavonoids in Rhododendrons. • The method exhibited good performance to extract four flavonoids in real samples. Herein, a novel magnetic molecularly imprinted polymer doped with reticular graphene oxide (Fe 3 O 4 @SiO 2 -GO@MIPs) was synthesized for the selective recognition and extraction of 4 flavonoids (farrerol, taxifolin, kaempferol, and hyperin) from Rhododendrons species. The Fe 3 O 4 @SiO 2 -GO@MIPs with lamellar membranes showed outstanding adsorption capacity. The 3D cavities complementary to the "shape" of farrerol were "imprinted" on the polymer framework after removal of farrerol template. Competitive binding assays showed that the polymer has a higher selectivity for farrerol compared with other analogues and references. The Fe 3 O 4 @SiO 2 -GO@MIPs as solid-phase extraction adsorbents combined with liquid chromatography-tandem quadrupole mass spectrometry (LC–MS/MS) was used for selective determination of four flavonoids from Rhododendrons samples. The limits of detection (LOD) were 0.07, 0.08, 0.06, and 0.08 μg L−1 for farrerol, taxifolin, kaempferol, and hyperin, respectively. These results suggest that the prepared Fe 3 O 4 @SiO 2 -GO@MIPs have the potential applicability to extract, purify, and enrich flavonoids from herbs, supplements, and other natural products. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the relaxation effect of farrerol on rat aortic vascular smooth muscle cells (VSMCs) and its underlying mechanism. VSMCs were cultured primarily and were used to examine the relaxation effect of farrerol. Cells surface and length were measured by dynamic observation, or by rhodamine-phalloidin labeling and hematoxylin-eosin staining. Cells contractive activity were tested using collagen gel contraction assay. The [Ca2+] in was measured with molecular probe fluo-4-AM. The mRNA and protein expression of regulatory proteins for contraction were measured. In addition, rat aortic VSMCs were transfected with lentivirus-mediated α 1D -adrenoceptor gene-shRNA, then the effect of farrerol were detected by the above experimental methods. The results revealed that 10 μΜ AngⅡ promoted cell contraction, increased [Ca2+] in and enhanced collagen contraction in rat aortic VSMCs. 10 μΜ AngⅡ not only increased expression of myosin light chain kinase (MLCK) and smooth muscle protein 22α (SM22α), but also increased phosphorylation level of myosin light chain (MLC) and myosin phosphatase target subunit 1 (MYPT1). The above effects induced by AngⅡ could be significantly inhibited by farrerol in a concentration dependent manner. When the cells were transfected with lentivirus mediated α 1D -adrenoceptor gene-shRNA, the effects of farrerol on changes induced by AngⅡ in rat aortic VSMCs were markedly reversed. In conclusion, farrerol could produce relaxtion effect in rat aortic VSMCs precontracted by 10 μΜ AngⅡ, which was involved in downregulation expression of MLCK and SM22α, and inhibition phosphorylation level of MYPT1 and MLC via activating α 1D -adrenoceptor gene. [ABSTRACT FROM AUTHOR]

Farrerol was found to possess neuroprotective effect; however, the mechanism remains unknown. The aim of the present study was to explore the effect of farrerol on MPP+ -induced inflammation in mouse microglial BV-2 cells and to elaborate the underlying mechanism. MTT assay was performed to measure the cell viability. The pro-inflammatory mediators and cytokines including interleukin (IL)-6, IL-1β, and tumor necrosis factor-α (TNF-α); inducible nitric oxide synthase; and cyclooxygenase 2 were measured. The expression of p-p65, p-IκBα, toll-like receptor 4 (TLR4), and myeloid differentiation primary response 88 were analyzed by western blot. We found that farrerol treatment improved cell viability in MPP+ -induced BV-2 cells. MPP+ -induced upregulation of IL-6, IL-1β, and TNF-α was inhibited by farrerol treatment. Farrerol treatment also attenuated MPP+ -induced expression of inducible nitric oxide synthase and cyclooxygenase 2 as well as the activation of NF-κB in BV-2 cells. MPP+ -induced TLR4 signaling was markedly diminished by farrerol treatment. Knockdown of TLR4 attenuated MPP+ -induced inflammatory response in BV-2 cells. In conclusion, farrerol treatment attenuated MPP+ -induced inflammatory response by inhibiting the TLR4 signaling pathway in BV-2 cells. The results indicated that farrerol could be used as a therapeutic agent for preventing or alleviating the neuroinflammation-related diseases, such as Parkinson's disease. [ABSTRACT FROM AUTHOR]

Highlights • Farrerol attenuated Aβ-induced viability inhibition in BV-2 cells. • Farrerol inhibited Aβ-induced oxidative stress. • Farrerol inhibited Aβ-induced inflammation. • Farrerol regulated the Nrf2/Keap1 pathway in activated BV-2 cells. Abstract Farrerol, an important bioactive constituent of rhododendron, exhibits broad activities such as anti-oxidative and anti-inflammatory effects. Recent studies showed that farrerol possesses neuroprotective activity, however, the mechanism has not been reported. The aim of the present study was to investigate the protective effect of farrerol on β-amyloid (Aβ)-induced mouse microglial BV-2 cells and the underlying mechanism. BV-2 cells were pretreated with farrerol for 1 h and then subjected to Aβ. MTT assay was performed to measure the mitochondrial metabolic activity in BV-2 cells. The production of reactive oxygen species (ROS) and malondialdehyde (MDA) and superoxide dismutase (SOD) activity were detected to reflect oxidative stress status. The secretion and mRNA levels of interleukin (IL)-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) were measured by ELISA and qRT-PCR. The expressions of NF-E2-related factor (Nrf2), heme oxygenase-1 (HO-1), NAD (P) H: quinone oxidoreductase 1 (NQO1), and Kelch-like ECH-associated protein 1 (Keap1) were measured by western blot. Our results showed that farrerol improved mitochondrial metabolic activity in Aβ-induced BV-2 cells. Aβ induced the production of ROS and MDA, and inhibited the SOD activity and the expression of SOD1 and SOD2 mRNA, while the effects were attenuated by farrerol. Farrerol also inhibited the induction effect of Aβ on IL-6, IL-1β, and TNF-α. In addition, farrerol enhanced the activation of Nrf2/Keap1 pathway in Aβ-induced BV-2 cells. Knockdown of Nrf2 by small interfere RNA (siRNA) targeting Nrf2 (si-Nrf2) abolished the protective effect of farrerol on Aβ-induced BV-2 cells. In conclusion, farrerol attenuated Aβ-induced oxidative stress and inflammation in BV-2 cells through enhancing the activation of Nrf2/Keap1 pathway. The findings indicated that farrerol could be considered as a therapeutic approach for the treatment of Alzheimer's disease (AD). [ABSTRACT FROM AUTHOR]

A dummy molecularly imprinted polymer (d-MIP) was developed for extraction and cleanup of farrerol from Rhododendron aganniphum. The d-MIP was prepared by precipitation polymerization using quercetin as the dummy template, 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, and acetonitrile as the porogen. The d-MIP was characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy. Dynamic curves, adsorption isotherms, and Scatchard plots showed the d-MIP had good affinity, capacity, and selectivity for the target compound. The prepared d-MIP was used as a sorbent in solid-phase extraction cartridges and successfully applied to specific extraction and purification of farrerol from real samples. High recoveries were obtained for four spiked levels of farrerol in Rhododendron aganniphum using d-MIP solid-phase extraction coupled with high-performance liquid chromatography. The linear range was 1-100 µg mL−1, the limit of detection was 2.23 mg kg−1, the farrerol recovery range was 85.7%-104.1%, and the relative standard deviations (n = 3) were all less than 2.2% for real samples. The proposed method provides a simple, rapid, and environmentally friendly approach to the analysis of farrerol in complex herbal products. [ABSTRACT FROM AUTHOR]

Farrerol is a flavonoid found in plants with a wide range of pharmacological effects, including protection and enhancement of nerve cell function, as well as antioxidant and antibacterial properties, among others. Neurodegenerative diseases are irreversible neurological disorders resulting from the loss of neuronal cells in the brain and spinal cord. In this experiment, we investigated the neuroprotective and antioxidant effects of farrerol on glutamate-induced HT22 cells. Our results showed that farrerol inhibited reactive oxygen species expression, apoptosis, mitochondrial damage, and the activation of caspases 3 and 9 in HT22 cells induced by glutamate. Additionally, farrerol potentially regulated the Nrf2/heme oxygenase-1 (HO-1) signaling pathway, as it attenuated the nuclear translocation of Nrf2 and promoted the expression of HO-1. These findings suggest that farrerol has potential as a new therapeutic option., (© The Author(s) 2023. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)

Farrerol is a 2,3-dihydro-flavonoid isolated from rhododendron. In this study, a sensitive and selective ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the determination of farrerol in rat plasma. Liquid-liquid extraction by was used for sample preparation. Chromatographic separation was achieved on an Agilent UHPLC XDB-C18 column (2.1 × 100 mm, 1.8 μm) with water and methanol (30:70, v/v) as the mobile phase. An electrospray source was applied and operated in negative ion mode; selection reaction monitoring was used for quantification using target fragment ions m/z 299 → 179 for farrerol and m/z 267 → 252 for internal standard. Calibration plots were linear in the range of 2.88-1440 ng/mL for farrerol in rat plasma. Intra- and inter-day precisions were <11.6%, and the accuracy ranged from −13.9 to 11.9%. The UHPLC-MS/MS method was successfully applied in pharmacokinetics and bioavailability studies of farrerol in rats. [ABSTRACT FROM AUTHOR]

Farrerol, isolated from Rhododendron dauricum L., has been proven to be an important multifunctional physiologically active component, but its vasoactive mechanism is not clear. The present study was performed to observe the vasoactive effects of farrerol on rat aorta and to investigate the possible underlying mechanisms. Isolated aortic rings of rat were mounted in an organ bath system and the myogenic effects stimulated by farrerol were studied. Intracellular Ca2+ ([Ca2+]in) was measured by molecular probe fluo-4-AM and the activities of L-type voltage-gated Ca2+ channels (LVGC) were studied with whole-cell patch clamp in cultured vascular smooth muscle cells (VSMCs). The results showed that farrerol significantly induced dose-dependent relaxation on aortic rings, while this vasorelaxation was not affected by NG-nitro-l-arginine methylester ester or endothelium denudation. In endothelium-denuded aortas, farrerol also reduced Ca2+-induced contraction on the basis of the stable contraction induced by KCl or phenylephrine (PE) in Ca2+-free solution. Moreover, after incubation with verapamil, farrerol can induce relaxation in endothelium-denuded aortas precontracted by PE, and this effect can be enhanced by ruthenium red, but not by heparin. With laser scanning confocal microscopy method, the farrerol-induced decline of [Ca2+]in in cultured VSMCs was observed. Furthermore, we found that farrerol could suppress Ca2+ influx via LVGC by patch clamp technology. These findings suggested that farrerol can regulate the vascular tension and could be developed as a practicable vasorelaxation drug.

Although farrerol, a characteristically bioactive constituent of Rhododendron dauricum L., exhibits extensive biological and pharmacological activities (e.g., anti-oxidant, anti-immunogenic, and anti-angiogenic) as well as a high drug development potential, its metabolism remains underexplored. Herein, we employed ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry coupled with multiple data post-processing techniques to rapidly identify farrerol metabolites produced in vivo (in rat blood, bile, urine and feces) and in vitro (in rat liver microsomes). As a result, 42 in vivo metabolites and 15 in vitro metabolites were detected, and farrerol shown to mainly undergo oxidation, reduction, (de)methylation, glucose conjugation, glucuronide conjugation, sulfate conjugation, N-acetylation and N-acetylcysteine conjugation. Thus, this work elaborates the metabolic pathways of farrerol and reveals the potential pharmacodynamics forms of farrerol.

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Farrerol, a type of 2, 3-dihydro-flavonoid, is obtained from Rhododendron. Previous studies have shown that Farrerol performs multiple biological activities, such as anti-inflammatory, antibacterial, and antioxidant activity. In this study, we aim to investigate the effect of Farrerol on colonic inflammation and explore its potential mechanisms. We found that the effect of Farrerol was evaluated via the 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis model in mice and found that Farrerol has a protective effect on TNBS-induced colitis. Farrerol administration significantly improved the weight change, clinical scores, colon length, and intestinal epithelium barrier damage and markedly decreased the inflammatory cytokines production in TNBS-induced mice. The protective effect of Farrerol was also observed in LPS-induced RAW264.7 cells. We found that Farrerol observably reduced the production of inflammatory mediators including IL-1β, IL-6, TNF-α, COX-2, and iNOS in LPS-induced RAW264.7 cells via suppressing AKT, ERK1/2, JNK1/2, and NF-κB p65 phosphorylation. In conclusion, the study found that Farrerol has a beneficial effect on TNBS-induced colitis and might be a natural therapeutic agent for IBD treatment.

Farrerol has been proved to have an anti-inflammatory effect. However, the effects of farrerol on mastitis have not been investigated. This study was aimed to investigate the effect and mechanism of farrerol in lipopolysaccharide (LPS)-induced mouse mastitis and LPS-induced inflammatory response of mouse mammary epithelial cells (mMECs). In vivo, LPS were injected to the tetrad pair of nipples for establishing mouse mastitis, and then tested the effect of farrerol on histopathological changes, inflammatory response and activation degree of protein kinase B (AKT), nuclear factor-kappa B p65 (NF-κB p65), p38, extracellular regulated protein kinase (ERK1/2). In vitro, the mMECs were incubated by farrerol for 1 h following by stimulating with LPS, and then the inflammatory response and the related signaling pathways were detected. The in vivo results found that farrerol could improve pathological injury of mammary gland, attenuate the activity of myeloperoxidase (MPO), inhibit the production of pro-inflammatory mediators and the phosphorylation of AKT, NF-κB p65, p38 and ERK1/2. The in vitro results also found farrerol inhibited inflammatory response and the related signaling pathways. Collectively, this study revealed that farrerol inhibits the further development of LPS-induced mastitis by inhibiting inflammatory response via down regulating phosphorylation of AKT, NF-κB p65, p38, and ERK1/2. These findings suggest that farrerol may be used as an anti-inflammatory drug for mastitis.

Cardiovascular disease has become the primary disease that threatens human health and is considered the leading cause of death. Cardiac remodeling, which is associated with cardiovascular disease, mainly manifests as cardiac hypertrophy, fibrosis, inflammation, and oxidative stress. Farrerol plays an important role in treating conditions such as inflammation, endothelial injury and tumors, and we speculated that Farrerol may also play an important role in mitigating cardiac hypertrophy and remodeling. We established a model of myocardial remodeling using Angiotensin II (Ang II) with concurrent intraperitoneal injection of Farrerol as an intervention. We used cardiac ultrasound, immunohistochemistry, Immunofluorescence, Wheat Germ Agglutinin, Dihydroethidium, Western Blot, qPCR and other methods to detect the role of Farrerol in cardiac remodeling. The results showed that Farrerol inhibited Ang II-induced cardiac hypertrophy; decreased the ratio of heart weight to tibia length in mice; reduced inflammation, fibrosis, and oxidative stress; and reduced the size of cardiomyocytes in vivo . Farrerol inhibited Ang II-induced cardiomyocyte hypertrophy, levels of oxidative stress, and the proliferation and migration of fibroblast in vitro . Our results revealed that Farrerol could inhibit Ang II-induced cardiac remodeling. Farrerol may therefore be a candidate drug for the treatment of myocardial remodeling., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 He, Xu, Wang and Yu.)

Obstructive uropathy is a clinical condition that can lead to chronic kidney disease. However, treatments that can prevent the progression of renal injury and fibrosis are limited. Farrerol (FA) is a natural flavone with potent antioxidant and anti-inflammatory properties. Here, we investigated the effect of FA on renal injury and fibrosis in a mouse model of unilateral ureteral obstruction (UUO). Mice underwent a sham or UUO operation and received intraperitoneal injections of FA (20 mg/kg) daily for 8 consecutive days. Histochemistry, immunohistochemistry and immunofluorescence staining, TdT-mediated dUTP nick end labeling assay, Western blotting, gene expression analysis, and biochemical tests were performed. FA attenuated renal dysfunction (p < 0.05) and ameliorated renal tubular injury (p < 0.01) and interstitial fibrosis (p < 0.001) in UUO mice. FA alleviated 4-hydroxynonenal expression (p < 0.001) and malondialdehyde levels (p < 0.01) by regulating pro-oxidant and antioxidant enzymes. Apoptosis in the kidneys of UUO mice was inhibited by FA (p < 0.001), and this action was accompanied by decreased expression of cleaved caspase-3 (p < 0.01). Moreover, FA alleviated pro-inflammatory cytokine production (p < 0.001) and macrophage infiltration (p < 0.01) in the kidneys of UUO mice. These results suggest that FA ameliorates renal injury and fibrosis in the UUO model by inhibiting oxidative stress, apoptosis, and inflammation.

Background: Farrerol is one of traditional Chinese medicines, isolated from Rhododendron dauricum L. It has been reported that Farrerol exerts multiple biological activities. Angiogenesis is an important drug target for cancer and inflammation therapy, the effect of Farrerol on angiogenesis is unknown.Hypothesis/purpose: We aimed to investigate whether Farrerol may have inhibitory effects against angiogenesis.Study Design/methods: Two kinds of endothelial cells, named human umbilical vein endothelia cell and human micro vessel endothelial cells, were used to examine the effect and mechanism of Farrerol on angiogenesis. MTT assay was used to detect cell proliferation, wound healing assay and boyden's chamber assay were used to examine cell migration, Matrigel was used as basement membrane substratum in tube formation assay, Annexin V-FITC/PI dual staining assay and trypan blue staining were used to detect cell apoptosis, mouse aortic rings assay was performed as ex vivo assay, the expression of proteins involved in angiogenesis was tested using western blot, the binding of Farrerol to Stat3 was monitored by docking assay, molecular dynamics simulations and MM-GBSA method.Results: Farrerol showed an inhibitory effect on proliferation, migration and tube formation of human umbilical vein endothelia cell and human micro vessel endothelial cells in a concentration-dependent manner. Farrerol induced cell cycle arrest and increased the apoptotic percentage of endothelial cells. Farrerol also suppressed the formation of new micro vessels from mouse aortic rings. Moreover, Farrerol reduced the phosphorylation levels of Erk, Akt, mTOR, Jak2 and Stat3 as well as protein expression of Bcl-2 and Bcl-xl. Docking assay, molecular dynamics simulations and MM-GBSA method showed that Farrerol bound to domain of Stat3, Ser613,Gln635, Glu638 and Thr714 are the main residues in Farrerol binding sites with the binding free energy -7.3 ∼ -9.0kcal/mol.Conclusions: In this study, we demonstrated that Farrerol inhibited angiogenesis through down regulation of Akt/mTOR, Erk and Jak2/Stat3 signal pathway. The inhibitory effect of Farrerol on angiogenesis suggested that this compound may be helpful to the angiogenesis-related diseases treatment, such as cancer and inflammations. [ABSTRACT FROM AUTHOR]

Objectives Farrerol, a new type of 2,3-dihydro-flavonoid isolated from rhododendron, has been shown to have anti-bacterial and anti-inflammatory activities. In the present study, we investigated the anti-inflammatory effects of farrerol on the production of IL-6 and IL-8 in human gingival fibroblasts (HGFs) treated with lipopolysaccharide (LPS). Methods The cytotoxicity of farrerol was determined using the MTT assay. The production of IL-6 and IL-8 was measured using ELISA and qRT-PCR. The effects of farrerol on PI3K, Akt phosphorylation, and NF-κB activation were detected using western blotting analyses. Results These results showed that farrerol inhibited LPS-induced IL-6 and IL-8 production in a dose dependent manner. LPS-induced NF-κB activation was suppressed by farrerol. Furthermore, farrerol suppressed LPS-induced PI3K and Akt phosphorylation, which are upstream molecules of NF-κB. Conclusion These results indicated that farrerol attenuated IL-6 and IL-8 production by inhibition of PI3K and AKT phosphorylation, resulting in an inhibition of NF-κB activation. Farrerol may be a therapeutic agent for the treatment of periodontal disease. [ABSTRACT FROM AUTHOR]

Six known compounds: sideroxylin ( 1 ), 5-hydroxylmethyl-2-furancarboxaldehyde ( 2 ), C- 6, O -7-dimethyldenaromadendrin ( 3 ), 4-(hydroxymethyl)-5-hydroxy-2 H -pyran-2-one ( 4 ), 7-deoxy- trans -dihydronarciclasine or trans -dihydrolycoricidine ( 5 ) and farrerol ( 6 ) were isolated from Scadoxus pseudocaulus (Björnstad & Friis) Friis & Nordal (Amaryllidaceae), famous for the treatment of liver cancer, cardiovascular disease, microbial diseases and mental disorders in Western region of Cameroon. The flavanone named farrerol ( 6) was partially modified by esterification reactions to give six novel semi-synthetic flavanone derivatives named 4′,7-diparamethylbenzoylfarrerol ( 7 ), 4′,7-dibutyrylfarrerol ( 8 ), 4′-butyrylfarrerol ( 9 ), 4′-dodecanoylfarrerol ( 10 ), 7-octanoylfarrerol ( 11 ) and 4′-octanoylfarrerol ( 12 ). Structures of isolated constituents and derivatives were elucidated with the aid of their NMR and MS spectral data as well as with the reported data. The antimicrobial, antioxidant and butyrylcholinesterase inhibition activities of the extracts and their isolated compounds as well as the six novel semi-synthetic flavanone derivatives were evaluated. Ethyl acetate fraction (MIC = 64–512 μg/mL) and compounds 6 , 7 and 10 (MIC = 2–16 μg/mL) displayed good antibacterial and antifungal activities that varied among the microbial species. Compound 11 is the most potent antioxidant with IC 50 49.7 μM which is comparable to standard butylated hydroxyanisole having IC 50 value of 44.2 μM. Compounds 12 , 4 and 6 also have significant antioxidant activity with IC 50 value 56.5, 59.5 and 58.2 μM, respectively. Compound 7 showed excellent butyrylcholinesterase inhibition activity (IC 50 = 12.6 μM) when compared with standard eserine (IC 50 = 7.8 μM). The overall results of this study indicate that most active samples could be used as complementary medicine after due host toxicity testing. [ABSTRACT FROM AUTHOR]

Farrerol, a typical natural flavanone, is the major active component of Rhododendron dauricum L. The objective of this study was to evaluate the attenuation effect of farrerol against the aortic lesions in spontaneously hypertensive rats (SHR) for the first time. Twelve-week-old male SHR were orally administered with farrerol (50 mg/kg/day), verapamil (50 mg/kg/day, positive control), or vehicle for 8 weeks ( n =10 in each group). Age-matched Wistar-Kyoto rats (WKY) served as normal controls ( n =10). Our results revealed that farrerol significantly reduced the systolic blood pressure in SHR (from 177±4 mmHg to 158±5 mmHg) and also dramatically attenuated the aortic lesion, which is characterized by decreased media thickness, wall area, media-lumen ratio, nuclei size and an increased nuclei number ( P <0.05). Moreover, the levels of O 2 - along with NAD(P)H oxidase activity were reduced ( P <0.05), while the activity of endothelial nitric oxide synthase (eNOS) was elevated ( P <0.05) in aortic homogenates after the intervention of farrerol. Furthermore, farrerol upregulated the expression of eNOS in both of mRNA and protein levels, accompanied by the downregulated mRNA and protein expression of p22 phox ( P <0.05), an essential subunit for NADPH oxidase activity. Our findings indicated that farrerol has a significant protective effect against the aortic lesion in SHR, which may be related to the enhanced eNOS activity and reduced NAD(P)H oxidase activity. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the anti-inflammatory effects and the underlying molecular mechanism of farrerol on IL-1β-stimulated human osteoarthritis chondrocytes. Chondrocytes were pretreated with farrerol 1 h before IL-1β stimulation. The effects of farrerol on NO and PGE2 production were tested by Griess reagent and ELISA. The effects of farrerol on COX-2, iNOS, Akt, phosphorylated Akt, and NF-κB activation were measured by western blot analysis. The results showed that farrerol remarkably inhibited IL-1β-induced NO and PGE2 production, as well as COX-2 and iNOS expression. Farrerol also inhibited IL-1β-induced NF-κB activation. Furthermore, farrerol significantly inhibited IL-1β-induced phosphorylation of PI3K and Akt. In conclusion, these results indicated that farrerol inhibited IL-1β-induced inflammatory responses in osteoarthritis chondrocytes by blocking PI3K/Akt/NF-κB signaling pathway. [ABSTRACT FROM AUTHOR]

Farrerol, (S)-2,3-dihydro-5,7-dihydroxy-2-(4-hydroxyphenyl)-6,8-dimethyl-4-benzopyrone, isolated from rhododendron, has been shown to have antioxidative potential, but the molecular mechanism underlying this activity remains unclear. The inducible expression of heme oxygenase-1 (HO-1), a potent antioxidative and cytoprotective enzyme, is known to play an important role in cytoprotection in a variety of pathological models. In this study, we evaluated the antioxidative potential of farrerol against oxidative damage and investigated its antioxidative mechanism in RAW 264.7 cells. The molecular mechanism underlying the cytoprotective function of farrerol was determined by analyzing intracellular signaling pathways, transcriptional activation and the inhibitory effect of HO-1 on ROS production. Farrerol induced antioxidant enzymes mRNA expression, HO-1 protein expression and nuclear translocation of NF-E2-related factor 2 in RAW 264.7 macrophage cells. Farrerol down-regulated the expression of the Keap1 protein and the thiol reducing agents attenuated farrerol-induced HO-1 expression. Further investigation utilizing Western blotting and specific inhibitors of Akt, p38, JNK and ERK demonstrated that Akt, p38, and ERK axis of signaling pathway mediates HO-1 expression. Moreover, tert-butyl hydroperoxide (t-BHP)-induced oxidative damage was ameliorated by farrerol treatment in a dose-dependent manner, which was abolished by Akt, p38, ERK and HO-1 inhibitors (Snpp). It is hence likely that farrerol inactivated KEAP-1 or activated the Akt, p38 and ERK to facilitate the release of Nrf2 from Keap1 and subsequent reduced the intracellular production of reactive oxygen species via the induction of HO-1 expression. These results support the central role of HO-1 in the cytoprotective effect of farrerol. [ABSTRACT FROM AUTHOR]

Abstract: Endothelial tight junction is a crucial intracellular junctional structure that controls paracellular permeability across vascular endothelium. Oxidative stress-mediated elevation in endothelial permeability is associated with pathogenesis of several cardiovascular diseases. In the present research, the regulation of farrerol on occludin, a transmembrane proteins associated with endothelial tight junction, was investigated in hydrogen peroxide-induced human endothelium-derived EA.hy926 cells. Western blot analysis demonstrated that H2O2 exposure caused a significant decrease in occludin expression, but had little effect on ZO-1 expression, and the decrease of occludin expression was significantly attenuated by farrerol in a dose-dependent manner. Meanwhile, immunofluorescent staining assay also demonstrated that the loss of occludin expression induced by H2O2 exposure was restored by farrerol pretreatment. Further investigations showed that farrerol prevented H2O2-induced activation of extracellular signal-regulated kinase (ERK) 1/2 in a dose-dependent manner. The use of U0126, a specific inhibitor of MEK1/2, proved that H2O2-induced decrease of occludin in EA.hy926 cells was likely associated with activation of ERK1/2, which indicated that the regulation of farrerol on occludin expression in H2O2-induced EA.hy926 cells was likely related to the modulation of ERK1/2 activation. In conclusion, the present study demonstrates for the first time that farrerol has potential effects on oxidative stress-induced endothelial tight junction disruption and suggests that farrerol is a potential candidate for the intervention of endothelial permeability-associated cardiovascular diseases. [Copyright &y& Elsevier]

Abstract: Mastitis, defined as inflammation of the mammary gland, is an infectious disease with a major economic influence on dairy industry. Staphylococcus aureus is a common gram-positive pathogen that frequently causes subclinical, chronic infection of the mammary gland in dairy cows. Farrerol, a traditional Chinese medicine isolated from rhododendron, has been shown to have anti-bacterial activity. However, the effect of farrerol on S. aureus infection in mammary epithelium has not been studied in detail. The aim of this study was to investigate the effect of farrerol on the invasion of bovine mammary epithelial cells (bMEC) by S. aureus. The expression of antimicrobial peptide genes by bMEC were assessed in the presence or absence of S. aureus infection. Our results demonstrated that farrerol (4–16 μg/ml) reduced > 55% the internalization of S. aureus into bMEC. We also found that farrerol was able to down-regulate the mRNA expression of tracheal antimicrobial peptide (TAP) and bovine neutrophil β-defensin 5 (BNBD5) in bMEC infected with S. aureus. The Nitric oxide (NO) production of bMEC after S. aureus stimulation was decreased by farrerol treatment. Furthermore, farrerol treatment suppressed S. aureus-induced NF-κB activation in bMEC. These results demonstrated that farrerol modulated TAP and BNBD5 gene expression in mammary gland, enhances bMEC defense against S. aureus infection and could be useful in protection against bovine mastitis. [Copyright &y& Elsevier]

Vascular endothelium plays an important role in the physiological homeostasis of blood vessels. Endothelial injury is considered to be implicated in the pathogenesis of many cardiovascular diseases, including atherosclerosis. Farrerol, a flavonoid considered to be the major bioactive component in a traditional Chinese herb, 'Man-shan-hong', which is the dried leaves of Rhododendron dauricum L., displays many bioactive properties, including antibechic, antibacterial, anti-inflammatory, and the inhibition of vascular smooth muscle cell (VSMC) proliferation. In this study, the protective effects of farrerol on hydrogen peroxide (H2O2)-induced apoptosis in human endothelium-derived EA.hy926 cells were investigated. The results showed that farrerol significantly inhibited the loss of cell viability and enhanced superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in H2O2-induced EA.hy926 cells. Meanwhile, farrerol inhibited H2O2-induced elevation in the levels of intracellular malondialdehyde and reactive oxygen species, as well as cell apoptosis. Furthermore, real time RT-PCR and Western blot analysis showed that farrerol significantly decreased the expression of Bax mRNA, Bax, cleaved caspase-3, and phosph-p38 MAPK, while increasing the exporession of Bcl-2 mRNA and Bcl-2 in H2O2-induced EA.hy926 cells. These results are the first demonstration that farrerol has protective effects against H2O2-induced apoptosis in EA.hy926 cells, and suggests that farrerol is a potential candidate for the intervention of endothelial-injury-associated cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Abstract: Farrerol, a new type of 2,3-dihydro-flavonoid, has been isolated from the leaves of Rhododendron dauricum L. In the present study, we found that farrerol exerted potent immunosuppressive effects on murine T cells both in vitro and in vivo. In vitro, farrerol markedly suppressed concanavalin A (ConA)-induced lymphocyte proliferation, Th1 and Th2 cytokine production, cluster of differentiation 4-positive (CD4+) T cell populations, and the ratio of CD4+/cluster of differentiation 8-positive (CD8+) T cells. Moreover, farrerol significantly inhibited the T cell-mediated delayed-type hypersensitivity (DTH) reaction in vivo. In addition, we investigated signal transduction mechanisms to determine the effects of farrerol by Western blotting. The data revealed that farrerol could downregulate the activation of the nuclear factor κB (NF-қB) and nuclear factor of activated T cells 2 (NFAT2) signal transduction pathways. These findings suggested that farrerol has potential effects on the regulation of the immune system and could be developed as a practicable immunosuppressive compound. [Copyright &y& Elsevier]