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In this study, the antibiotic enhancement and quorum sensing (QS) inhibition of allylpyrocatechol (APC) and methyl gallate (MG) isolated from leaves of Piper betle (betel) and leaf shoots of Anacardium occidentale (cashew), respectively, were compared. When applied with streptomycin and tested against Staphylococcus aureus and Pseudomonas aeruginosa, the effect of APC was additive while that of MG was synergistic. In terms of QS inhibition against Chromobacterium violaceum, both compounds were equally effective with violacein inhibition observed at concentrations of 60 μg/mL. We successfully increased the purity of APC in the methanol betel leaf extract from 13.2% to 31.5% w/w through solvent partitioning. This study is the first to document the anti-QS activity of APC, which is comparable to that of MG.

In our previous work, we have demonstrated that at equal volume, green tea extract (GT) exhibited a higher inhibition efficiency (IE) than commercial calcium nitrite corrosion inhibitor, on corrosion of steel reinforcing bar (rebar) embedded in mortar (75–80 vs. 14–24%). GT behaved as a mixed-type corrosion inhibitor which increased rebar polarization resistance (Rp); indicating that it formed a protective layer on rebar surface. In this paper, the formation of a protective layer was confirmed with visual inspection and microscopic examinations. In presence of this layer, rebar corrosion was reduced. This is evidenced by a reduced rebar weight loss and further indicated by a similar chloride permeability between control and GT concrete, and a similar corrosion rate (CR) between control reinforced mortar and reinforced mortar incorporating solely the residual solid of GT. The similarities ruled out the plausible higher IE of GT due to an improved physical barrier of mortar/concrete against corrosion. Analyses with energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), and Fourier-transform infrared spectroscopy (FTIR) suggested that the layer was enriched with calcium, specifically the calcium carbonate polymorphs. Although the formation of protective layer and increase in Rp were influenced by the magnitude of antioxidant activity, in this study GT has shown a better IE than CI. This should encourage more studies on the IE of sustainable ‘green’ corrosion inhibitors in concrete.

Objectives Metabolic syndrome (MetS), a multiplex risk factor for cardiovascular disease and type 2 diabetes, is increasingly prevalent worldwide. Ellagitannin geraniin, a polyphenol found in the rind of rambutan (Nephelium lappaceum), has demonstrated therapeutic effects against metabolism dysfunction. The aim of this study was to characterize the metabolic effects and possible mechanism of geraniin in rats with MetS induced by a high-fat diet (HFD). Methods MetS was induced in Sprague Dawley rats on an HFD, followed by a daily oral gavage of geraniin (25 mg/kg) for 4 wk. The outcomes of geraniin-treated rats were compared with those of untreated rats on either a control diet or an HFD and with rats with MetS treated with metformin on a daily basis (200 mg/kg). Results The supplementation of geraniin ameliorated multiple metabolic abnormalities caused by HFD, including hypertension, impaired glucose and lipid metabolism, ectopic fat deposition in the visceral fat and liver, and disturbed antioxidant mechanism and inflammatory response. The benefits conferred by geraniin were comparable to metformin. Transcriptomic analysis revealed a profound influence of geraniin on the hepatic expression profiles. The lipid and steroid metabolic processes that were aberrantly activated by HFD were suppressed by geraniin. Based on the differential transcriptomes, geraniin also exerted a significant modulatory effect on the expression of mitochondrial genes, potentially influencing the mitochondrial activity and leading to the observed beneficial effects. Conclusion Geraniin supplementation mitigated metabolic anomalies of MetS in rats, making it an attractive drug candidate for further investigation.

Zingiberaceae is a family that consists of many edible ginger plants. Etlingera pubescens (B.L.Burtt & R.M.Sm.) R.M.Sm. was studied for its antioxidant properties. Preliminary screening of the methanol extracts of its leaves, stems, rhizomes showed that the fresh leaves had the highest antioxidant activity, with total phenolic content (TPC), ascorbic acid equivalent antioxidant capacity (AEAC), and oxygen radical absorbance capacity (ORAC) values of 1020 ± 20 mg GAE/100 g, 1130 ± 30 mg AAE/100 g, and 140 ± 30 µmol TE/g, respectively. Subsequently, a diarylheptanoid, etlingerin, was isolated from the leaf methanol extract. When contrasted with curcumin (a well-known diarylheptanoid), etlingerin showed comparable free radical scavenging properties. However, using a cell-based antioxidant assay, etlingerin showed significantly better protective effects (with cellular antioxidant activity values as high as 84 ± 4%) than curcumin at all concentrations tested. In the cytoprotective study, only etlingerin could protect cells that were challenged with hydrogen peroxide. These effects might be explained by etlingerin's high lipophilicity and good free radical scavenging properties. Etlingerin was also found to be significantly less cytotoxic than curcumin (up to 10-fold, as determined using a MTT cell viability assay), thus suggesting its safety. The work showed that etlingerin has better antioxidant properties, hence highlighting its potential as a functional food component that could reduce the risks of oxidative stress-related diseases.

The present study exploits the potential of spent coffee grounds (SCGs) as a supplementary substrate for cultivating Pleurotus species. Increased levels of SCG in mixed substrate resulted in retardation of mycelial growth rate in a concentration-dependent manner. Subsequently, fruitification was inhibited when concentrations of SCG in the mixed substrate exceeded 30% (w/w) due to the relatively high phenolic and caffeine concentrations in SCG. Partial reductions in phenolic content and caffeine have been observed whenever SCG was present in the substrate; trace amounts of caffeine were also detected in fruiting bodies grown on all SCG-containing substrate mixtures. This finding suggests that Pleurotus spp. can reduce the levels of caffeine and phenolic compounds in SCG via bioaccumulation and biodegradation, respectively. Next, the supplementation of up to 20% (w/w) SCG did not significantly affect the proximate compositions, mineral contents, and fatty acid profiles in basidiocarps of both Pleurotus species compared to standard formulations.

Graphical abstract The effective high-calorie diet for metabolic syndrome induction is different between Sprague Dawley rats of different developmental stages. The post-weaning rats on high-fat diet for 8 weeks developed all phenotypes of metabolic syndrome while the adult rats on high-fat-high-sucrose diet merely became obese and hypertensive. The post-weaning rats on high-fat diet is a better and less time-consuming model for metabolic syndrome research., The present study aimed to examine the effects of the types of high-calorie diets (high-fat and high-fat-high-sucrose diets) and two different developmental stages (post-weaning and young adult) on the induction of metabolic syndrome. Male, post-weaning and adult (3- and 8-week old, respectively) Sprague Dawley rats were given control, high-fat (60% kcal), and high-fat-high-sucrose (60% kcal fat + 30% sucrose water) diets for eight weeks (n = 6 to 7 per group). Physical, biochemical, and transcriptional changes as well as liver histology were noted. Post-weaning rats had higher weight gain, abdominal fat mass, fasting glucose, high density lipoprotein cholesterol, faster hypertension onset, but lower circulating advanced glycation end products compared to adult rats. This is accompanied by upregulation of peroxisome proliferator-activated receptor (PPAR) α and γ in the liver and receptor for advanced glycation end products (RAGE) in the visceral adipose tissue. Post-weaning rats on high-fat diet manifested all phenotypes of metabolic syndrome and increased hepatic steatosis, which are linked to increased hepatic and adipocyte PPARγ expression. Adult rats on high-fat-high-sucrose diet merely became obese and hypertensive within the same treatment duration. Thus, it is more effective and less time-consuming to induce metabolic syndrome in male post-weaning rats with high-fat diet compared to young adult rats. As male rats were selectively included into the study, the results may not be generalisable to all post-weaning rats and further investigation on female rats is required.

Aims The aim of this study was to investigate the antimicrobial activities of Etlingera pubescens, and to isolate and identify the antimicrobial compound. Methods and results The crude extracts of E. pubescens were obtained through methanol extraction, and evaluated for antimicrobial activities. From this extract, 1,7-bis(3,4-dihydroxyphenyl)heptan-3-yl acetate (etlingerin) was isolated. When compared to curcumin (a compound with a similar chemical structure), etlingerin showed twofold lower minimum inhibitory concentration values while also being bactericidal. Through time kill assay, etlingerin showed rapid killing effects (as fast as 60 min) against the Gram-positive bacteria (Staphylococcus aureus ATCC 43300 and Bacillus subtilis ATCC 8188). Further assessment revealed that etlingerin caused leakage of intracellular materials, therefore suggesting alteration in membrane permeability as its antimicrobial mechanism. Cytotoxicity study demonstrated that etlingerin exhibited approximately 5- to 12-fold higher IC50 values against several cell lines, as compared to curcumin. Conclusions Etlingerin isolated from E. pubescens showed better antibacterial and cytotoxic activities when compared to curcumin. Etlingerin could be safe for human use, though further cytotoxicity study using animal models is needed. Significance and impact of the study Etlingerin has a potential to be used in treating bacterial infections due to its good antimicrobial activity, while having potentially low cytotoxicity.

Ursolic acid (UA) is a pentacyclic triterpene of the ursane type. As a common chemical constituent among species of the family Lamiaceae, UA possesses a broad spectrum of pharmacological properties. This overview focuses on the anticancer properties of UA against breast cancer (BC) and colorectal cancer (CRC) that are most common among women and men, respectively. In vitro studies have shown that UA inhibited the growth of BC and CRC cell lines through various molecular targets and signaling pathways. There are several in vivo studies on the cytotoxic activity of UA against BC and CRC. UA also inhibits the growth of other types of cancer. Studies on structural modifications of UA have shown that the -OH groups at C3 and at C28 are critical factors influencing the cytotoxic activity of UA and its derivatives. Some needs for future research are suggested. Sources of information were from ScienceDirect, Google Scholar and PubMed.

The present study aimed to outline the physiological and metabolic disparity between chow- and purified ingredient-based high-fat diets and their efficacy in the induction of metabolic syndrome (MetS). Male, 3-week-old Sprague Dawley rats were randomly assigned to chow-based control diet, chow-based high-fat diet, purified control diet, and purified high-fat diet for 12 weeks. Physical and biochemical changes were documented. Chow-based diets, irrespective of the lipid content, resulted in significantly lower weight gain and organ weight compared to purified ingredient-based diets. Circulating insulin, total proteins, albumin, and certain lipid components like the triglycerides, total cholesterol, and high-density lipoprotein-cholesterol were also lower in the chow-based diet groups. Both chow- and purified high-fat diets induced central obesity, hypertension, and hyperglycaemia, but the latter was associated with earlier onset of the metabolic aberrations and additionally, dyslipidaemia. In conclusion, purified high-fat diet is a better diet for MetS induction in rats. PRACTICAL APPLICATIONS: Modeling metabolic syndrome is commonly accomplished with the use of chow- or purified ingredient diets enriched with carbohydrates and/or lipids, but the differences and associated drawbacks are unclear. This study highlights that chow- or modified chow-based diets have a tendency to introduce unwanted metabolic changes which are inconsistent with the progression of metabolic syndrome. Thus, the use of these diets in metabolic disease study should be avoided. On the other hand, purified high-fat diet which can effectively induce the features of metabolic syndrome is highly recommended.

Commelinaceae is a family of herbaceous flowering plants with many species used in ethnobotany, particularly in South America. However, thus far reports of their bioactivity are few and far between. The primary aim of this study was to quantify the antioxidant and antibacterial activity of five Commelinaceae methanolic leaf extracts. The antioxidant content was evaluated by the total phenolic content (TPC), total tannin content (TTC), and total flavonoid content (TFC) assays. The antioxidant activities measured were DPPH free radical scavenging (FRS), ferric reducing power (FRP), and ferrous ion chelating (FIC), of the five plants, the methanolic leaf extract of Tradescantia zebrina showed the highest antioxidant content and activity, and exhibited antibacterial activity against six species of Gram-positive and two species of Gram-negative bacteria in a range of 5–10 mg/mL based on the broth microdilution method.

Anthocyanins, a popular choice for natural food colorants, are unstable at low acidity or neutral pH. Thus, anthocyanins that are less affected by pH, such as those with multiple acylated groups, are highly desirable. One such source is from the leaves of Rhoeo spathacea (Swartz) Stearn, an herbal plant traditionally decocted and consumed orally. This study tests the stability of the purple-red colour of R. spathacea extract from pH 1.0 to 11.5 stored under refrigerated and room temperature conditions, in the presence and absence of light over a period of 60 days. The colour stability was also monitored in a solid food model (jelly) and a liquid food model (barley water) for a month. The colour was found to be remarkably stable in acidic pH, and completely stable in the food models. The primary anthocyanin in R. spathacea leaves was isolated and identified by NMR to be rhoeonin.

Natural antioxidants with multiple polar atoms and electron-rich bonds are potential mixed-type corrosion inhibitors and ‘green’ alternatives to commercial inorganic corrosion inhibitors. Green tea is one of the richest sources of natural antioxidants. Therefore, this paper compares the corrosion inhibition efficiency (IE) of green tea extract (GT) against commercial calcium nitrite corrosion inhibitor (CI), on steel reinforcing bars (rebars) embedded in mortar. Rebar corrosion was accelerated with impressed current and cyclic wetting-drying, and corrosion development was measured with linear polarization resistance. Selected CI dosages encompassed four chloride-to-nitrite ratios, and the IE of CI and GT were compared at: 1) similar concentration and 2) equal volume. At similar concentration, CI and GT demonstrated a similar IE (51–70%). However, at equal volume, GT exhibited a higher IE than CI (75–80% vs. 14–24%), due to a significant increase in rebar polarization resistance and reduction in iron oxidation rate (anodic slope). Meanwhile, oxygen reduction rate (cathodic slope) and open circuit potential did not change significantly. The changes in anodic and cathodic slope without a significant open circuit potential change suggested that GT was a mixed-type corrosion inhibitor as hypothesized, which formed a protective layer on rebar surface and increased the polarization resistance of the rebars. Based on liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry analyses, it is hypothesized that (-)-epigallocatechin gallate, (-)-epicatechin gallate, and catechin or (-)-epicatechin are responsible for the anti-corrosion activity of GT as a mixed-type corrosion inhibitor.

The clinical value of tocotrienols is increasingly appreciated because of the unique therapeutic effects that are not shared by tocopherols. However, their effect on metabolic syndrome is not well-established. This study aimed to investigate the effects of a tocotrienol-rich fraction (TRF) from palm oil in high-fat-diet-treated rats. Male, post-weaning Sprague Dawley rats were provided high-fat (60% kcal) diet for eight weeks followed by a TRF (60 mg/kg) treatment for another four weeks. Physical, metabolic, and histological changes were compared to those on control and high-fat diets respectively. High-fat feeding for eight weeks induced all hallmarks of metabolic syndrome. The TRF reversed systolic and diastolic hypertension, hypercholesterolemia, hepatic steatosis, impaired antioxidant defense, and myeloperoxidase hyperactivity triggered by the high-fat diet. It also conferred an inhibitory effect on protein glycation to reduce glycated hemoglobin A1c and advanced glycation end products (AGE). This was accompanied by the suppression of the receptor for advanced glycation end product (RAGE) expression in the liver. The treatment effects on visceral adiposity, glycemic control, triglyceride level, as well as peroxisome proliferator-activated receptor α and γ expression were negligible. To conclude, treatment with a TRF exhibited protective effects on the cardiovascular and liver health in addition to the amelioration of plasma redox imbalance and AGE-RAGE activation. Further investigation as a therapy for metabolic syndrome is therefore worthwhile.

The decoction and infusion of Rhoeo spathacea (Swartz) Stearn leaves have been recognized as a functional food particularly in South America, but has not yet gained international popularity as a beverage. The primary aim of this study was to establish the viability of R. spathacea aqueous leaf extracts as a beverage, in terms of its antioxidant activity and antibacterial activity. The antioxidant contents of aqueous and methanol leaf extracts were evaluated by the total phenolic content (TPC) and total flavonoid content (TFC) assays. The antioxidant activities measured were DPPH radical scavenging activity (FRS), ferric reducing power (FRP) and ferrous ion chelating (FIC) activity. The aqueous leaf extracts in the forms of decoction and infusion, were found to have comparable TPC and antioxidant activity with other herbal teas previously reported by our research group. Both decoction and infusion also exhibited antibacterial activity against six species of Gram positive and four species of Gram negative bacteria, notably methicillin-resistant Staphylococcus aureus and Neisseria gonorrhoeae. A total of four different known phenolic compounds were identified by HPLC and MS, three of which have not been previously reported to be found in this plant. Both the decoction and infusion of the leaves R. spathacea have potential to be popularized into a common beverage.

Background For generations, the rhizomes of Drynaria ferns have been used as traditional medicine in Asia. Despite this, the bioactivities of Drynaria rhizomes and leaves have rarely been studied scientifically. Methods This study evaluates the antioxidant properties of the methanolic extracts of the fertile fronds and rhizomes from three species in this genus: Drynaria quercifolia, Drynaria rigidula and Drynaria sparsisora. The phenolic and flavonoid contents of the samples were respectively quantified with the total phenolic content (TPC) and total flavonoid content (TFC) assays, while the antioxidant activities were determined via measuring the DPPH radical scavenging activity (FRS), ferric reducing power (FRP), ferrous ion chelating (FIC) activity and lipid peroxidation inhibition (LPI). The tyrosinase inhibition activity of all three species was also reported. Results The fertile fronds of D. quercifolia were found to exhibit the highest overall TPC (2939 ± 469 mg GAE/100 g) and antioxidant activity amongst all the samples, and the fertile fronds of D. quercifolia and D. rigidula exhibited superior TPC and FRP compared to their rhizomes, despite only the latter being widely used in traditional medicine. The fronds of D. quercifolia had high tyrosinase inhibition activity (56.6 ± 5.0 %), but most of the Drynaria extracts showed unexpected tyrosinase enhancement instead, particularly for D. sparsisora’s fronds. Conclusion The high bioactivity of the fertile fronds in the fern species indicate that there is value in further research on the fronds of ferns which are commonly used mostly, or only, for their rhizomes.