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The first rate-limiting enzyme of the serine synthesis pathway (SSP), phosphoglycerate dehydrogenase (PHGDH), is hyperactive in multiple tumors, which leads to the activation of SSP and promotes tumorigenesis. However, only a few inhibitors of PHGDH have been discovered to date, especially the covalent inhibitors of PHGDH. Here, we identified withangulatin A (WA), a natural small molecule, as a novel covalent inhibitor of PHGDH. Affinity-based protein profiling identified that WA could directly bind to PHGDH and inactivate the enzyme activity of PHGDH. Biolayer interferometry and LC–MS/MS analysis further demonstrated the selective covalent binding of WA to the cysteine 295 residue (Cys295) of PHGDH. With the covalent modification of Cys295, WA blocked the substrate-binding domain (SBD) of PHGDH and exerted an allosteric effect to induce PHGDH inactivation. Further studies revealed that with the inhibition of PHGDH mediated by WA, the glutathione synthesis was decreased and intracellular levels of reactive oxygen species (ROS) were elevated, leading to the inhibition of tumor proliferation. This study indicates WA as a novel PHGDH covalent inhibitor, which identifies Cys295 as a novel allosteric regulatory site of PHGDH and holds great potential in developing anti-tumor agents for targeting PHGDH., Graphical abstract WA is a novel covalent-allosteric inhibitor of phosphoglycerate dehydrogenase (PHGDH), and inhibits the serine synthesis pathway and proliferation of colon cancer cells with overexpression of PHGDH.Image 1

Taiwania cryptomerioides Hayata is an endangered relict plant belonging to Taxodiaceae, and it is also an endemic plant to China. The decay-resistant of Taiwania timber can provide highly quality wood for building and furniture. Plenty of regenerative of leaves of T. cryptomerioides also has been used as a resource for the discovery of new dimeric diterpenoids. In a search for structurally diverse dimeric diterpenoids and potent bioactive isolates, ten new heterodimeric diterpenoids, taiwaniadducts K-T (1-4, 6, 8-11, 14), along with five known ones (5, 7, 12, 13, 15), were isolated from the leaves of T. cryptomerioides. These new compounds were defined by comprehensive spectroscopic analyses, putative biosynthetic pathways, and the value of optical. Biologically, anti-multidrug resistance (MDR) activities of compounds were evaluated. Compounds 4 and 10 exerted a 9.18-fold potentiation effect on bortezmib (BTZ) susceptibility at a tested concentration (20 μM) better than the positive control verapamil. The research of the leaves of T. cryptomerioides not only added the new data to the structural diversity and activities of dimeric diterpenoids but also could provide support for the medical and industrial application of the leaves of this endangered relict plant.

Graphical abstract, Introduction Previously, we have reported a withanolide-type steroid, named tubocapsenolide A (TA), which shows potent anti-proliferative activity in several cancer cell lines. However, its inhibitory effect on the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) pathway and therapeutic potential on osteosarcoma have not been reported. Objectives In the present study, we aimed to investigate the effect and molecular mechanism of TA in osteosarcoma. Methods The biological functions of TA in U2OS cells were investigated using colony formation, 5-ethynyl-20-deoxyuridine (EDU) staining, and cell cycle/apoptosis assays. The interaction between TA and Src homology 2 phosphatase 2 (SHP-2) was detected by enzyme activity and validated by target-identification methods such as drug affinity responsive target stability (DARTS), cellular thermal shift assay (CETSA), and biolayer interferometry (BLI). The in vivo anti-tumor efficacy of TA was analyzed in the xenograft tumor model. Western blotting analysis was performed to detect the protein expression levels. Results TA exhibited antitumor activity against osteosarcoma both in vitro and in vivo by regulating the JAK/STAT3 signaling pathway. Mechanically, TA interacted with SHP-2 directly and activated its phosphatase activity. Importantly, protein tyrosine phosphatase (PTP) inhibitor, SHP-2 inhibitor, and SHP-2 siRNA could reverse the inhibitory effect of TA on the JAK/STAT3 signaling pathway and restored the TA-induced cell death. Conclusion TA activated the phosphatase activity of SHP-2, which resulted in the inhibition of the JAK/STAT3 pathway and contributed to the antitumor efficacy of TA. Collectively, these findings suggested that TA could serve as a novel therapeutic agent for the treatment of osteosarcoma.

Six new oligomeric neolignans including two trimeric neolignans (1 and 2) and four dimeric neolignans (3-6) were isolated from the leaves of Magnolia officinalis var. biloba. Their structures were determined based on HR-ESIMS and NMR data, as well as electronic circular dichroism (ECD) calculations. Compound 1 is formed from two obovatol moieties directly linked to an aromatic ring of the remaining obovatol moiety, which is an unprecedented type of linkage between monomers. All isolates were assessed for their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophage cells. Compounds 1 and 3 showed significantly inhibitory activities with IC50 values of 6.04 and 3.26 μmol·L-1, respectively.

(±)-Patulinervones A (

Four new highly oxidized sesquiterpene lactones, Argyoxynolides A–D, along with two known analogs were isolated from the leaves of Artemisia argyi H.Lev. & Vaniot. Their structures were characterized utilizing extensive spectroscopic methods. All isolates were evaluated for the LPS-induced nitric oxide (NO) production inhibitory activity and one compound exhibited activity with IC50 = 37.95 ± 4.39 μM.

On-demand therapy following effective tumor detection would considerably reduce the side effects of traditional chemotherapy. DT-diaphorase (DTD), whose level is strongly elevated in various tumors, is a cytosolic flavoenzyme that promotes intracellular reactive oxygen species (ROS) generation via the redox cycling of hydroquinones. Incorporation of the DTD-responsive substrate to the structures of the probe and prodrug may facilitate the tumor detection and therapy. Herein, we established an multifunctional drug delivery nanosystem (HTLAC) that rapidly responds to the DTD enzyme, leads to the early-stage precise detection and termination of tumors. Firstly, the synthesis of DTD-responsive withaferin A (DT-WA) and indocyanine green (DT-Cy5) was performed. In the presence of DTD, WA, which produces ROS in cells, was released from DT-WA, and the red fluorescence of DT-Cy5 was detected for tumor imaging. Additionally, these DTD enzyme reaction processes of DT-WA and DT-Cy5 induced ROS. The self-burst of ROS generation by the two enzyme reaction processes as well as the released WA then led to the apoptosis of tumor cells. To increase the bioavailability and tumor targeting of drugs, cell-penetrating peptide and hyaluronic acid functionalized liposomes were used to encapsulate the drugs. The detailed in vitro and in vivo assays showed that HTLAC achieved enhanced tumor detection and superior antitumor efficiency. According to above outcomes, results showed that HTLAC might provide an efficacious approach for the fabrication of enzyme-triggering nanosystems to detect tumor and induce the self-burst of ROS for an efficient tumor treatment. STATEMENT OF SIGNIFICANCE: We have fabricated a HTLAC nanosystem to address the need of bursting reactive oxygen species (ROS) generation within tumor site. Our goal uniquely aims at not only augmentation of ROS-inducing anticancer efficacy, but also to meet the challenges of tumor dynamic detection in the clinical practices. In this work, the DT-diaphorase responsive withaferin A (DT-WA) and indocyanine green (DT-Cy5) are synthesized, and observed more specifically toward DTD under physiological conditions. As the cell-penetrating peptide and hyaluronic acid functionalized liposome, the HTLAC not only induces antiproliferative activity by generating self-burst of ROS, but also effectively accumulate and restore its fluorescence at the tumor site because of the HA actively targeting tumor along with the prolonged presence in blood circulation. Besides, this enzyme-triggering nanosystem exhibited an effective tumor inhibition with a low systemic toxicity.

Fortuneicyclidins A (1) and B (2), a pair of epimeric pyrrolizidine alkaloids containing an unprecedented 7-azatetracyclo[5.4.3.0.02,8]tridecane core, were isolated from the seeds of Cephalotaxus fortunei, along with two biogenetically relative known analogues, 3 and 4. The structures were determined by multiple spectral techniques and chemical derivatization methods. Compound 1 showed inhibitory activity against α-glucosidase.

Nonalcoholic steatohepatitis (NASH) is a common clinical condition that can lead to advanced liver diseases. The mechanism of the diaease progression, which is lacking effective therapy, remains obsure. Therefore, there is a need to understand the pathogenic mechanisms responsible for disease development and progression in order to develop innovative therapies. To accomplish this goal, experimental animal models that recapitulate the human disease are necessary. Currently, an increasing number of studies have focused on natural constituents from medicinal plants which have been emerged as a new hope for NASH. This review summarized the pathogenesis of NASH, animal models commonly used, and the promising targets for therapeutics. We also reviewed the natural constituents as potential NASH therapeutic agents.

Eight new germacranolides, minusolides A–H (1–8), along with two known analogues, 9 and 10, were isolated from the whole plant of Carpesium minus. Their structures were elucidated by spectroscopic ...

The thioredoxin system plays an important role in cancer cells. Inhibiting thioredoxin reductase (TrxR) has emerged as an effective strategy to selectively target cancer cells. Withangulatin A (WA), a natural product extracted from the whole herb of Physalis angulata L. (Solanaceae), exhibits potent anticancer activity and other diverse pharmacological activities. To improve activity and targeting, we designed and prepared 41 semisynthetic analogues of WA. Biological evaluation indicated that the most promising compound 13a displayed the most significant effect on HT-29 cells (human colon cancer cells) (IC50 = 0.08 μM). A structure-activity relationship study indicated that α,β-unsaturated ketones and ester are necessary groups, allowing 13a to undergo Michael addition reactions with mercaptan and selenol. Liquid chromatography-mass spectrometry (LC-MS) analysis confirmed that 13a modified selenocysteine 498 (U) residues in the redox centers of TrxR, resulting in enzyme inhibition. Therefore, compound 13a acts as a novel TrxR inhibitor and may be a promising candidate for cancer intervention.

(±)-Melipatulinones A–C (1–3), three unique enantiomeric pairs of lignan–phloroglucinol hybrids along with the biogenetically related compound melipatulignan A (4), were isolated from the leaves of Melicope patulinervia. Melipatulinones A (1) and B (2) share a novel spiro[hydrobenzofuran-2,3′-furan] 5/5/6 tricyclic ring system, while melipatulinone C (3) features an unprecedented spiro[cyclopenta[b]hydrofuran-2,3′-furan] 5/5/5 tricyclic framework. Their structures were determined by spectroscopic methods, electronic circular dichroism (ECD) calculations, and X-ray diffraction. Compounds 1–3 exhibited a pancreatic lipase inhibitory effect.

Taxodisones A and B, C30-terpenes with an unprecedented tetracyclo[12.4.0.0.2,709,14]octodecane core, were isolated from the seeds of Taxodium distichum. Their structures, including their configurations, were unambiguously determined. Their biomimetic synthesis suggests that they stem from diterpenes and monoterpenes, and not from squalene or oxidosqualene. In addition, their bioactivities were also evaluated.

[Image: see text] Harringtonolide (HO, 1) is a bioactive diterpenoid tropone isolated from Cephalotaxus harringtonia with antiproliferation activity. Until now there have been no reports to elucidate its anticancer mechanism. Herein we report the synthesis of HO-derived probes (10, 11, and 12) to identify the possible target of HO. As a result, the application of a novel photoaffinity alkyne-tagged probe from HO (compound 12) showed direct engagement between HO and receptor for activated C kinase 1 (RACK1). Furthermore, HO could suppress the epithelial–mesenchymal transition (EMT) process and inhibit activation of the FAK/Src/STAT3 signaling pathway in A375 cells. This study provides a groundwork for HO as an effective antitumor agent that targets RACK1 to suppress cancer cell migration.

Five new spirocyclic polycyclic polyprenylated acylphloroglucinols, Hyperpatulones C-G (1–5), were obtained from the leaves of Hypericum patulum. Their structures were characterized by the comprehensive analysis of their IR, NMR, CD spectra and HRESIMS data. All the new compounds were evaluated for the α-glycosidase inhibitory activities. Among them, compounds 3–5 showed α-glucosidase inhibitory activities, with IC50 values of 14.06–37.69 μM.

Development of noninvasive bioimaging fluorescent probes for detecting particular enzyme activity is greatly recommendable for preclinical diagnosis of cancer. Given that the elevated β-gal activity is positively correlated with several tumors, developing a fluorescent probe for the sensing of β-gal is therefore highly desirable for cancer diagnosis. Herein, a new enzyme-activatable near-infrared (NIR) turn-on fluorescent probe (DMC-βgal) was developed for accurately detecting β-gal activity characterized by excellent selectivity, high sensitivity (LOD = 0.298 U/L), and low toxicity. More importantly, DMC-βgal qualifies remarkable NIR excitation (725 nm) and emission wavelength (770 nm), an ideal tool for restrained photodamage and suppressed autofluorescence. The above excellent performance of DMC-β-gal allowed for the accurate monitoring of endogenous β-gal in living cells. Moreover, the probe was successfully applied to detect intracellular β-gal activity in different types of cancer cells, verifying that SKOV-3 cells had a higher level of β-gal activity than those of A549, HCT-116, MCF-7, and HepG2 cells. Furthermore, DMC-βgal could real-time visualize endogenously β-gal in tumor-bearing nude mice with low auto-fluorescence interference. All results fully demonstrated that DMC-βgal has potential value as a promising strategy for diagnosis of β-gal-related diseases.

Two uncommon C37 heterodimeric diterpenoids, taicrypnacids A (1) and B (2), and a known labdane-type diterpenoid (3) were isolated from the leaves of Taiwania cryptomerioides. Several techniques, such as comprehensive spectroscopic analysis, chemical conversion, X-ray crystallography, and ECD data, were employed to define the structures. The two new compounds displayed cytotoxicity against human breast cancer (MCF-7), osteosarcoma (U-2 OS), and human colon carcinoma (HCT-116) cell lines, while the methyl ester 1a showed no activity. Compound 1 induced Ca2+-ROS pathway-mediated endoplasmic reticulum stress, and excessive stress led to cell death by activating apoptosis and autophagy.

Artemisianins A-D (1–4), four stereoisomers of sesquiterpenoid dimers, forming via [4+2] cycloaddition from a 1, 10-seco-guaianolide dienophile and a guaianolide diene, along with two biosynthetically related precurors 5 and 6, were isolated from the famous traditional Chinese medicine Artemisia argyi. The structures of 1–4, including their absolute configurations, were elucidated by extensive spectroscopic data and ECD/TDDFT calculation analysis. Compounds 1–4 exhibited cytotoxicity with IC50 values ranging from 7.2 to 23.3 μM. The accumulation of Ca2+ in cytoplasm and enlarged endoplasmic reticulum (ER) indicated that 1 mediated HT-29 cancer cell apoptosis through improvement of ER-stress, which was further proved by unfolded protein response (UPR) pathway on basis of the upregulation of IRE1α, p-PERK, ATF6, and CHOP.

Background. Pharbitis Semen, the seeds ofPharbitis nil, is widely used as a traditional purgative medicine in China, Korea, and Japan. This study investigated the laxative effects of a purified resin glycoside fraction obtained in our previous study from Pharbitis Semen in vivo and in vitro.Materials and Methods. After orally administering a purified resin glycoside fraction from Pharbitis Semen (RFP) to rats, the content of fecal water, AQP3, NF-κB, COX-2 expression, and the prostaglandin E2(PGE2) concentrations in the colon were examined. Moreover, human intestinal epithelial cells (HT-29) were used to investigate the mechanism of RFP decreasing the AQP3 expression.Results. Results obtained showed that treatment with RFP increased the feces excretion and fecal water content of rats in a dose-dependent manner. More interestingly, AQP3 expression was suppressed by RFP treatment both in the rat colons and in HT-29 cells, while the NF-κB pathway-mediated PGE2production was activated. Interestingly, pretreating rats with BAY-11-7082 (NF-κB inhibitor) or indomethacin (COX-2 inhibitor) and RFP neither induced diarrhea nor decreased the AQP3 expression in the colon.Conclusions. The purgative property of the purified resin glycoside fraction was attributed to NF-κB activation in the colon, which increased the COX-2-mediated secretion of PGE2. PGE2decreased AQP3 expression which inhibits water absorbed from the intestine to the blood vessel side, resulting in the laxative effect of RFP.

Five novel formyl-phloroglucinol-β-caryophyllene meroterpenoids, namely littordials A–E (1–5), were isolated from the leaves of Psidium littorale. Their structures were established by spectroscopic data and computational methods, and the structure of 1 was confirmed by X-ray crystallography. Littordials A–E feature unusual acyl phloroglucinol units, and 5 possesses a rare 6/7/9/4-fused tetracyclic ring system. Compounds 2, 3 and 5 exhibited cytotoxic activities on two cancer cell lines (MDA-MB-231 and B16) with IC50 values from 6.6 ± 1.5 to 9.2 ± 1.7 μM.

Withangulatin A (WA) has been reported to exhibit potent antitumor activity. However, its possible mechanism and direct proteomic targets remain unknown. Herein we report the subcellular localization of WA by designing and synthesizing its fluorescent analogues with coumarin moieties. Furthermore, sarco/endoplasmic reticulum calcium-ATPase (SERCA)2 was identified as the potential target of WA for its antitumor activity by chemical proteomics.

A pair of novel C23 terpenoid epimers, officinalins A (1) and B (2), together with a biogenetically related known diterpenoid (3), was isolated from the leaves of Salvia officinalis. The epimers feature an unprecedented carbon skeleton with a tetracycline-[9.6.0.03,8.012,16]-heptadecane core and a peroxide bridge. Their structures were unequivocally established by extensive spectroscopic analyses, including electronic circular dichroism (ECD) calculations and ROESY correlation analogy with model compounds for the configuration assignment. Possible biosynthetic pathways of 1 and 2 were proposed. Compound 1 exhibited potent NO inhibitory activity with an IC50 value of 2.02 ± 0.87 μM.

Five new prenylated acetophenones, melicoptelins A-E (1–5), along with one known congener (6) were isolated from the roots of Melicope ptelefolia. Among them, compounds 2a/2b, 3a/3b, and 4a/4b were obtained as inseparable interconverting mixtures of keto and enol tautomers. Their structures were elucidated on the basis of extensive spectroscopic methods, including 1D, 2D NMR and HRESIMS. Compouds 2a/2b, 4a/4b and 5 exhibit protein tyrosine phosphatase 1B (PTP1B) inhibitory activity with IC50 values of 34.4, 55.2 and 66.6 μM, respectively.

Six new Cephalotaxus alkaloids, including five cephalotaxine-type alkaloids, and one homoerythrina-type alkaloid, along with six known analogues, were isolated from the seeds of Cephalotaxus fortunei. Their structures were elucidated by combination of spectroscopic data analyses, time-dependent density functional theory (TDDFT) ECD calculation, and single-crystal X-ray diffraction. Cephalofortine B represents the first example of C-5 epi-cephalotaxine-type alkaloid. All isolated compounds were tested for cytotoxicities against HCT-116, A375, and SK-Mel-28 cell lines. Cephalofortine E showed moderate activity against HCT-116 cell line, with an IC50 value of 7.46 ± 0.77 μM.

Increasing evidence have reported that NLRP3 inflammasome has a crucial role in various kinds of immunological diseases including colitis. However, there have only a few drug candidates directly targeting inflammasomes for the therapy of colitis. Here, we first reported that Tubocapsanolide A (TA), a natural small molecule, as a novel inhibitor of NLRP3 inflammasome for the treatment of colitis. TA inhibited the activation of NLRP3 inflammasome and suppressed the secretion of IL-1β and IL-18 in macrophages. Moreover, the ASC oligomerization was inhibited by TA. The assembly of the NLRP3 inflammasome was also restrained by TA, while had little effects on potassium and chloride efflux. Biolayer interferometry analysis showed that TA could directly bind to NLRP3. Importantly, LC-MS/MS analysis further demonstrated that TA covalently bound to the cysteine 514 residue (Cys514) of NLRP3. In vivo experiments showed that TA remarkably ameliorated DSS-induced experimental colitis in mice. However, the protection of TA against DSS-induced experimental colitis was abrogated in NLRP3-deficient (Nlrp3-/-) mice. Taken together, this study indicates TA as a novel inhibitor of NLRP3, which identifies Cys514 as a novel regulatory site of NLRP3 and suggests TA as a promising candidate compound for the treatment of colitis.

Fortuneicyclidins A (

Background and purpose Liver fibrosis is one of the leading causes of morbidity and mortality worldwide but lacks any acceptable therapy. The transcription factor glioma-associated oncogene homologue 1 (GLI1) is a potentially important therapeutic target in liver fibrosis. This study investigates the anti-fibrotic activities and potential mechanisms of the phytochemical, physalin B. Experimental approach Two mouse models (CCl4 challenge and bile duct ligation) were used to assess antifibrotic effects of physalin B in vivo. Mouse primary hepatic stellate cells (pHSCs) and human HSC line LX-2 also served as in vitro liver fibrosis models. Liver fibrogenic genes, GLI1 and GLI1 downstream genes were examined using Western blot and quantitative real-time PCR (qRT-PCR). GLI1 acetylation and LAP2α-HDAC1 interaction were analysed by co-immunoprecipitation. Key results In vivo, physalin B administration attenuated hepatic histopathological injury and collagen accumulation and decreased expression of fibrogenic genes. Physalin B dose-dependently suppressed fibrotic marker expression in LX-2 cells and mouse pHSCs. Mechanistic studies showed that physalin B inhibited GLI activity by non-canonical Hedgehog signalling. Physalin B blocked formation of lamina-associated polypeptide 2α (LAP2α)/histone deacetylase 1 (HDAC1) complexes, thus inhibiting HDAC1-mediated GLI1 deacetylation. Physalin B up-regulated acetylation of GLI1, down-regulated expression of GLI1 and subsequently inhibited HSC activation. Conclusion and implications Physalin B exerted potent antifibrotic effects in vitro and in vivo by disrupting LAP2α/HDAC1 complexes, increasing GLI1 acetylation and inactivating GLI1. This indicates that the phytochemical physalin B may be a potential therapeutic candidate for the treatment of liver fibrosis.

Harringtonolide (HO), a natural product isolated from Cephalotaxus harringtonia, exhibits potent antiproliferative activity. However, little information has been reported on the systematic structure−activity relationship (SAR) of HO derivatives. Modifications on tropone, lactone, and allyl positions of HO (1) were carried out to provide 17 derivatives (2–13, 11a–11f). The in vitro antiproliferative activity against four cancer cell lines (HCT-116, A375, A549, and Huh-7) and one normal cell line (L-02) was tested. Amongst these novel derivatives, compound 6 exhibited comparable cell growth inhibitory activity to HO and displayed better selectivity index (SI = 56.5) between Huh-7 and L-02 cells. The SAR results revealed that the tropone and lactone moieties are essential for the cytotoxic activities, which provided useful suggestions for further structural optimization of HO.

Two new phthalide dimers (1 and 2) were obtained from the rhizomes of Ligusticum sinense Oliv., along with three known dimeric phthalides (3–5). Their structures were determined with the aid of the spectroscopic data, and their absolute configurations were elucidated based on the comparison of calculated and experimental electronic circular dichroism (ECD) spectra. All the compounds were evaluated in vitro for their inhibitory activities against NO production in LPS-treated RAW264.7 macrophages. Among them, compounds 1 and 3 showed potent NO prohibitive activity with IC50 values at 4.86 ± 0.29 μM and 4.87 ± 0.32 μM, respectively.