Trinh Nam Trung

The antimicrobial activity of compounds from the leaf and stem of Vitis amurensis against two oral pathogens

Nine compounds isolated from the leaf and stem of Vitis amurensis Rupr. (Vitaceae) were evaluated for their antimicrobial activity against two oral pathogens, Streptococcus mutans and Streptococcus sanguis, which are associated with caries and periodontal disease, respectively. The results of several antimicrobial tests, including MIC, MBC, and TBAI, showed that three compounds inhibited the growth of the test bacteria at concentrations ranging from 12.5 to 50 microg/mL. Among these compounds, compound 5, trans-epsilon-viniferin, displayed the strongest activity against S. mutans and S. sanguis with MIC values of 25 and 12.5 microg/mL, respectively. This is the first report on the antimicrobial activity of stilbenes and oligostilbenes isolated from the leaf and stem of V. amurensis. Thus, this result suggests that natural antimicrobial compounds derived from V. amurensis may benefit oral health as plaque-control agents for the prevention of dental caries and periodontal disease.

The selected flavonol glycoside derived from Sophorae Flos improves glucose uptake and inhibits adipocyte differentiation via activation AMPK in 3T3-L1 cells

Among nine flavonols (1-9) obtained from Sophorae Flos, we first isolated compounds 4, 5, 8, and 9. These isolates (1-9) were evaluated for the phosphorylation of AMPK and ACC. Administered at 10 μM, 9 possessed high potent activity. Compound 9 displayed a dose-dependent stimulation of glucose uptake in 3T3-L1 cells, and this increase was obviously attenuated by compound C, an AMPK inhibitor. In addition, 9 also phosphorylated AMPK and its downstream substrate ACC in 3T3-L1 cells in a time- and dose-dependent manner. Moreover, we discovered that compound C inhibits 9-stimulated ACC phosphorylation and motivated the 9-inhibited C/EBPα and PPARγ, and FAS gene expression, significantly. These results revealed the role of the AMPK downstream signaling pathway in 9-improved glucose metabolism in 3T3-L1 cells and 9-inhibited adipocyte differentiation. Differentiation was investigated by Oil Red O staining activity after 9 administration (0-20 μM) in 6 days. Compound 9 decreased mean droplet size in a dose-dependent manner. The results revealed that 9 blocked adipogenic conversion in 3T3-L1 cells together with several significant downregulating adipocyte-specific transcription factors, including PPARγ, C/EBPα, and SREBP1. It also reduced FAS gene expression in a dose-dependent manner, which is crucial for adipogenesis in vitro.

Selected compounds derived from Moutan Cortex stimulated glucose uptake and glycogen synthesis via AMPK activation in human HepG2 cells

AIM OF THE STUDY To evaluate the effect of selected compounds derived from Moutan Cortex on glucose uptake and glycogen synthesis associated with AMPK activation in insulin-resistant human HepG2 cell. MATERIALS AND METHODS The effect of isolated compounds (1-16) on glucose uptake and glycogen synthesis was performed using HepG2 cells. The western blot was used to determine the expression of AMPK and its downstream substrates, ACC, p-ACC, and p-GSK-3beta. RESULTS The effects of the 16 compounds from Moutan Cortex on glucose metabolism in HepG2 cells under high glucose conditions were evaluated. Compounds 2, 3, and 6 displayed highly potent effects on the stimulation of glucose uptake and glycogen synthesis in human HepG2 cells under high glucose conditions. Compounds 2, 3, and 6 phosphorylate AMPK (AMP-activated protein kinase), and resulted in increased phosphorylation of GSK-3beta and suppression of lipogenic expression (ACC and FAS) in a dose-dependent manner. Compounds 2, 3, and 6 also demonstrated interesting, strong eNOS phosphorylation in human umbilical vein endothelial cells (HUVECs). Compounds 1, 4, 5-12, and 14 displayed considerable effects on hepatic glucose production, AMPK activation, and phosphorylation of GSK-3beta in HepG2 cells under high glucose conditions. CONCLUSIONS These effects may indicate that the activation of AMPK by the active compounds from Moutan Cortex has considerable potential for reversing the metabolic abnormalities associated with type-2 diabetes.

Adlay Seed Extract (Coix lachryma-jobi L.) Decreased Adipocyte Differentiation and Increased Glucose Uptake in 3T3-L1 Cells

The aim of the present study was to investigate effects of the ethyl acetate fraction of an ethanol extract of Coix lachryma-jobi (ECLJ) on glucose uptake and adipocyte differentiation in 3T3-L1 cells. ECLJ phosphorylated AMP-activated protein kinase (AMPK) and its downstream substrate acetyl-coenzymeA carboxylase in 3T3-L1 cells in a time- and dose-dependent manner. Moreover, we discovered that compound C inhibits ECLJ-stimulated ACC phosphorylation. In addition, ECLJ exhibited a dose-dependent stimulation of glucose uptake in 3T3-L1 cells, and this increase was obviously attenuated by compound C. ECLJ also caused a decrease in the expression levels of adipogenesis factors such as fatty acid synthase, sterol-regulatory-element-binding protein-1c, peroxisome proliferator-activated receptor γ, and CAATT/enhancer binding protein α in a dose-dependent manner. Differentiation was examined by Oil red O staining activity after ECLJ treatment for 6 days. ECLJ decreased mean droplet size. These results suggest a possible role for AMPK in the process of adipose differentiation and that ECLJ targeted for adipocyte functions could be effective in improving the symptoms of metabolic syndrome.

Induction of Cell Cycle Arrest and Apoptosis by Physcion, an Anthraquinone Isolated From Rhubarb (Rhizomes of Rheum tanguticum ), in MDA-MB-231 Human Breast Cancer Cells

Background: Physcion is an anthraquinone from rhubarb (rhizomes of Rheum tanguticum) and has been reported to have anti-inflammatory, hepatoprotective, antifungal, and anti-cancer activities. However, the growth inhibitory activity against human cancer cells and the underlying molecular mechanisms have been poorly determined. This study was designed to investigate the anti-proliferative activity of physcion by induction of cell cycle arrest and apoptosis in human MDA-MB-231 triple negative breast cancer cell line. Methods: MDA-MB-231 cells were treated with physcion, and the anti-proliferative activity was evaluated by the sulforhodamine B assay. The mechanisms of action for the growth inhibitory activity of physcion were evaluated by flow cytometry for cell cycle distribution, and by Western blot for the assessment of potential target proteins. Results: Physcion showed a significant anti-proliferative activity against MDA-MB-231 human breast cancer cells. Flow cytometric analysis indicated that physcion markedly induced the accumulation of cells in the G0/G1 phase and the increase of cell population in the sub-G1 phase. The G0/G1 cell cycle arrest by physcion was associated with the down-regulation of Cyclin D1, Cyclin A, CDK4, CDK2, c-Myc and phosphorylated Rb protein expressions. The increase of sub-G1 peak by physcion was closely correlated with the induction of apoptosis, which was confirmed by the induction of cleaved poly-(adenosine diphosphate ribose) polymerase, activation of Caspases, and suppression of Bid and Bcl-2 expression. Conclusions: The induction of G0/G1 cell cycle arrest and apoptosis might be one of the plausible mechanisms of actions for the anti-proliferative activity of physcion in human breast cancer cells.

Chemical-based Species Classification of Rhubarb Using Simultaneous Determination of Five Bioactive Substances by HPLC and LDA Analysis

INTRODUCTION Rhubarb is a traditional Chinese medicine derived from the rhizome of three species: Rheum tanguticum, Rheum palmatum and Rheum officinale. There are several species that are often misidentified as rhubarb. Taxonomical identification of these various species can be challenging. We have developed an HPLC-based species classification to identify rhubarb. OBJECTIVE The objective of this study was to develop a simple HPLC method for the simultaneous determination of bioactive compounds and identification of medicinal rhubarb rhizome and non-medicinal species. METHODOLOGY Quantitative analysis was performed on a C₁₈-column using 0.05 M aqueous phosphoric acid and acetonitrile as the mobile phase under gradient conditions with ultraviolet detection at 280 nm. The method was validated with respect to linearity, accuracy, precision, and recovery. Statistical analysis was used to classify different groups of species. RESULTS All calibration curves showed good linearity (r ≥ 0.9995). The method showed good repeatability with intra- and inter-day standard deviations of less than 1.13% and 1.32%, respectively. The accuracy and recovery of all marker compounds were in the ranges of 98.0 to 102.6% and 99.21 to 102.04%, respectively. Seventeen peaks were selected, and 39 known and 57 unknown samples were classified into five species based on linear discriminant analysis with an accuracy of 100%. CONCLUSION A chemical-based species classification method of rhubarb using simultaneous determination of bioactive compounds by HPLC was developed with 39 known samples of five different species and successfully applied to identify 57 unknown samples collected from Korea and China.

Inhibitory activity of Plantago major L. on angiotensin I-converting enzyme

Eight compounds were isolated from methanol extract of Plantago major L. leaves and investigated for their ability to inhibit angiotensin I-converting enzyme activity. Among them, compound 1 showed the most potent inhibition with rate of 28.06 ± 0.21% at a concentration of 100 μM. Compounds 2 and 8 exhibited weak activities. These results suggest that compound 1 might contribute to the ability of P. major to inhibit the activity of angiotensin I- converting enzyme.

A new flavan-3-ol and the anti-inflammatory effect of flavonoids from the fruit peels of Wisteria floribunda

A new flavan-3-ol, (+)-afzelechin 5-O-β-d-glucopyranoside (2), together with 13 known flavonoids (1, 3–14), was isolated from the fruit peels of Wisteria floribunda. Their structures were assigned by detailed interpretation of NMR, MS, and CD spectroscopic data, as well as by comparing with published reports. The in vitro anti-inflammatory activity of the isolated compounds (1–14) was examined. Among them, compounds 3, 6, and 9 produced highest inhibitory effects on tumor necrosis factor alpha (TNF-α)-induced nuclear factor kappa-B activation in HepG2 cells with IC50 values of 14.1, 16.5, and 11.9 μM, respectively. With the exception of compound 6, the compounds significantly inhibited the accumulation of pro-inflammatory inducible nitric oxide synthase and cyclooxygenase-2 proteins in TNF-α-stimulated HepG2 cells at a concentration as low as 0.1 μM.

Sterols and triterpene from Trichosanthes kirilowii

By various chromatographic methods, two sterols and one triterpene, 22 E ,24 Z -stigmasta-7,22,24(28)-triene-3 β -ol, ergosta-6,22-diene-3 β ,5 α ,8 α -triol, and 3 β -hydroxymultiflora-8-ene-17-oic acid were isolated from the roots of Trichosanthes kirilowii MAXIM. Their structures were elucidated by spectroscopic methods and in comparison with the reported data. To our best knowledge, compound 1 was isolated from the nature for the first time. Compounds 2 and 3 were reported from Trichosanthes genus for the first time.