Antioxidant, Cytotoxic, Anti-Glycation, and Anti-Tyrosinase Compounds from the Leaves of Uvaria Siamensis.

A new oxidized heptene, 7-benzoyloxy-4-hydroxy-1-ethoxy-2E,4Z-heptadiene-1,6-dione, namely siamheptene A (1), together with eight known compounds (2-9), were isolated from the leaves of Uvaria siamensis. Their structures were elucidated by detailed analysis of spectroscopic (IR, 1D and 2D NMR) and mass spectrometric data. Compound 9 is reported for the first time from Uvaria genus. Siamheptene A was evaluated for cytotoxicity against HeLa (cervical cancer cells), A549 (lung cancer cells), and Vero cells using the MTT assay and screened for antibacterial activities. In addition, the isolated compounds (1-7, and 9) were investigated for their antioxidant (DPPH, FRAP and ABTS+ assays), anti-glycation, and anti-tyrosinase properties. Based on our results, compound 1 had mild cytotoxicity against Hela and A549 cancer cell lines, with IC50 ranging from 31.09 to 31.67 µg/mL. Compound 1 also showed antioxidant activities in all tasted assays. However, it showed no detectable activity (>128 µg/mL) against various bacterial strains, and it has no inhibitory effects on tyrosinase enzymes. Among of all tested compounds, chrysin (5), showcased highest anti-glycation and anti-tyrosinase activities. This comprehensive analysis provides highlighting the potential of 1 as a lead compound for further structural modification and development of cytotoxic or antioxidant agents.

Thermal Degradation Kinetics and pH-Rate Profiles of Iriflophenone 3,5-C-ß-d-diglucoside, Iriflophenone 3-C-ß-d-Glucoside and Mangiferin in Aquilaria crassna Leaf Extract.

The health benefits of the Aquilaria crassna Pierre ex Lecomte leaf extract (AE) make it very useful as an ingredient in food and pharmaceutical products. Iriflophenone 3,5-C-ß-d-diglucoside (1), iriflophenone 3-C-ß-d-glucoside (2) and mangiferin (3) are bioactive compounds of AE. We assessed the stability of AE by investigating the thermal degradation kinetics and shelf-life (t90%) of compounds 1, 2 and 3 using Arrhenius plot models and studied their pH-rate profiles. The results demonstrate that 1 and 2 were degraded, following a first-order kinetic reaction. The degradation of 3 followed first-order reaction kinetics when present in a solution and second-order reaction kinetics in the dried powder form of the extract. According to the first-order kinetic model, the predicted shelf-life (t90%) of the extract at 25 °C in dried form for compound 1 was 989 days with activation energy 129.86 kJ·mol-1, and for 2 it was 248 days with activation energy 110.57 kJ·mol-1, while in the extract solution, the predicted shelf-life of compounds 1-3 was 189, 13 and 75 days with activation energies 86.83, 51.49 and 65.28 kJ·mol-1, respectively. In addition, the pH-rate profiles of 1-3 indicated that they were stable in neutral to acidic environments.

Inhibitory efficiency of Andrographis paniculata extract on viral multiplication and nitric oxide production.

Andrographis paniculata (Burm. F.) Nees is a medicinal plant previously reported with broad-spectrum antivirals but the mode of inhibition remains elusive. The objective of this study was to identify the most active fraction from A. paniculata ethanol extract (APE, APE-2A, APE-2B and APE-2C) and dry powder extract (APSP) against influenza A (H3N2), representing RNA viruses, and herpes simplex virus-1 (HSV-1), representing DNA viruses. The results showed that the fractions APSP, APE, APE-2B, and APE-2C directly neutralized the HSV-1 and influenza A (H3N2) when incubated at room temperature for 60 min before infecting the cells. The results also showed that the additional APE-2A fraction also directly neutralized the influenza A (H3N2), but not the HSV-1. The APE, APE-2B and APE-2C inhibited the HSV-1 by more than 0.5 log when the fractions were introduced after infection. Similarly, the APSP and APE inhibited the influenza A (H3N2) more than 0.5 log after infection. Only 50 µg/mL APE-2C inhibited the viruses greater than 0.5 log. In addition, A. paniculata extracts were also evaluated for their interfering capacities against nitric oxide (NO) production in LPS-activated RAW 264.7 macrophages. As well, APE-2C potently inhibited NO production at the IC50 of 6.08 µg/mL. HPLC and LC-MS analysis indicated that the most actively antiviral fractions did not contain any andrographolide derivatives, whereas the andrographolide-rich fractions showed moderate activity.

Thermal Degradation Kinetics and pH-Rate Profile of Verbascoside and Stability Improvement by Solid Lipid Nanoparticles.

Thermal degradation of verbascoside (VB) in Acanthus ebracteatus Vahl (AE) always affects its health benefit. Here the temperature effect on VB in both AE extract and solid lipid nanoparticles (SLNs)-encapsulated AE extract was demonstrated using the Arrhenius plot. The reaction rate constants were calculated for shelf life and plotted to obtain pH-rate profiles. VB degradation was a first-order reaction. The reaction rate in a neutral to alkaline solution was faster than in an acidic solution. VB in AE extract-loaded SLNs was more stable than in uncapped AE extract. The shelf life of VB in SLNs was 153 days with activation energy (E a) of 76.16 kJ mol-1, whereas those of VB in AE extract and in AE extract solution were 75 days with E a = 78.03 kJ mol-1 and 12 days with E a = 49.24 kJ mol-1, respectively. Therefore, we anticipate that the AE extract-loaded SLNs will be beneficial for product development.

Extract of Aquilaria crassna leaves and mangiferin are vasodilators while showing no cytotoxicity.

The leaves of Aquilaria spp. promote "physiological balance", and are "cardiotonic and provide blood nourishment". In Asia, these leaves are increasingly consumed as tea and claimed to provide benefits to cardiovascular function, albeit without any scientific proof. Therefore, this study sought to evaluate the action of Aquilaria crassna leaf aqueous extract (AE) on vascular function and vascular smooth muscle cytotoxicity. AE and a main constituent, mangiferin were investigated for their vasorelaxation of rat mesenteric arteries and aortae in vitro. Acute cytotoxicity of AE (0.1-1000 µg/ml) and mangiferin (0.1-100 µM) on rat enzymatically isolated vascular smooth muscle cells was assayed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. AE dilated rat mesenteric arteries (EC50∼107 µg/ml, Emax∼95%) more than aorta (EC50∼265 µg/ml, Emax∼76%, p < 0.05). AE-induced vasodilation in mesenteric artery was reduced by endothelial removal (EC50∼202 µg/ml, p < 0.05), incubation with endothelial nitric oxide synthase (eNOS) (100 µM, L-NAME) (EC50∼309 µg/ml, p < 0.05), and partly reduced by L-type Ca2+ channel blockade at higher concentrations. Likewise, mangiferin (1-100 µM) dilated the mesenteric artery more potently than the aorta. However, its maximum relaxation was less than with AE (41% in the mesenteric artery and <10% in the aorta). Isolated vascular smooth muscle cells incubated in AE or mangiferin for 1 h showed no cytotoxicity. Thus, AE is a vasorelaxant while being free of acute cytotoxicity towards vascular smooth muscle, thus potentially ameliorating human vascular dysfunction.