Chemical constituents from the leaves of Sindora siamensis var. maritima and their antimicrobial and α-glucosidase inhibitory activities.

Two new glycosides, sindosides A-B (1-2), along with 11 previously identified metabolites (3-13), were isolated from an ethanolic extract of the leaves of Sindora siamensis var. maritima. The structures of the purified phytochemicals were elucidated by interpreting their spectroscopic data (IR, NMR, and HRMS). The absolute configuration of compound 1 was established by experimental and calculated ECD spectra. The antimicrobial results revealed that compound 8 selectively inhibited C. albicans fungal with a MIC value of 64 µg/mL, whereas 11 presented a weak inhibition toward E. faecalis, S. aureus, and B. cereus bacterial strains with the same MIC value of 128 µg/mL. Interestingly, compounds 1, 2, 8, 9, and 11 showed α-glucosidase inhibitory activity with IC50 values ranging from 14.42 ± 0.21 to 30.62 ± 0.18 µM, which were more active than the positive control (acarbose, with an IC50 value of 46.78 ± 1.37 µM). Enzyme kinetic analysis revealed that compounds 1, 2, and 11 behaved as uncompetitive inhibitors with Ki values of 8.60 ± 1.04, 5.16 ± 0.73, and 7.17 ± 0.98 µM, respectively.

Glycoside constituents from Miliusa sinensis leaves and their anti-inflammatory and acetylcholine protective effects.

Repeated column chromatography resulted in the isolation of two new glycosides, miliusides A-B (1 and 7), along with six known metabolites (2-6, and 8) from the leaves of Miliusa sinensis Finet and Gagnep. The structures of the purified phytochemicals were elucidated by interpreting their spectroscopic data (NMR, HRMS), as well as comparison with the previous literature. The biological evaluation of acetylcholinesterase (AChE) inhibitory effects and anti-inflammatory activity by measuring nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 mouse macrophage cells, were also conducted. Among them, compounds 5 and 7 exhibited significant AChE inhibitory activities (IC50 = 53.36 ± 4.20 and 88.50 ± 8.79 µM, respectively), compared with the positive control (Galanthamine, IC50 = 1.65 ± 0.15 µM). Only the MeOH extract showed suppression effects on NO production in LPS-induced RAW264.7 cells (IC50 = 38.18 ± 3.25 µg/mL) comparable to that of the positive control, l-NMMA (IC50 = 2.21 ± 0.56 µg/mL).

Dendrodoristerol, a cytotoxic C20 steroid from the Vietnamese nudibranch mollusk Dendrodoris fumata.

Using various chromatographic separations, four steroids including one new C20 steroid namely dendrodoristerol (1), were isolated from the Vietnamese nudibranch mollusk Dendrodoris fumata. The structure elucidation was confirmed by combination of spectroscopic experiments including 1D and 2D NMR, HR QTOF MS, and CD. Compound 1 was found to exhibit significant in vitro cytotoxic activity against six human cancer cell lines as HL-60, KB, LU-1, MCF-7, LNCaP, and HepG2. In addition, 1 induced HL-60 cancer cell death by apoptosis and necrosis.

Wedtrilosides A and B, two new diterpenoid glycosides from the leaves of Wedelia trilobata (L.) Hitchc. with α-amylase and α-glucosidase inhibitory activities.

In the ongoing research to find new diabetes constituents from the genus Wedelia, the chemical constituent of Wedelia trilobata leaves, a Vietnamese medicinal plant species used to treat type 2 diabetes mellitus, was selected for detailed investigation. From a methanolic extract, two new ent-kaurane diterpenoids, wedtrilosides A and B (1 and 2), along with five known metabolites (3-7), were isolated from W. trilobata. The chemical structures of (1-7) were assigned via spectroscopic techniques (IR, 1D, 2D NMR and HR-QTOF-MS data) and chemical methods. The isolates were evaluated for α-amylase and α-glucosidase inhibitory activities compared to the clinical drug acarbose. Among them, compounds 4, 6, and 7 showed the most potent against α-glucosidase enzyme with IC50 values of 27.54 ±â€¯1.12, 173.78 ±â€¯2.37, and 190.40 ±â€¯2.01 µg/mL. While moderate inhibitory effect against α-amylase was observed with compounds 6 and 7 (with IC50 = 181.97 ±â€¯2.62 and 52.08 ±â€¯0.56 µg/mL, respectively). The results suggested that the antidiabetic properties from the leaves of W. trilobata are not simply a result of each isolated compound, but are due to other factors such as the accessibility of polyphenolic groups to α-amylase and α-glucosidase activities.

α-Amylase and α-Glucosidase Inhibitory Activities of Chemical Constituents from Wedelia chinensis (Osbeck.) Merr. Leaves.

As part of an ongoing search for new natural products from medicinal plants to treat type 2 diabetes, two new compounds, a megastigmane sesquiterpenoid sulfonic acid (1) and a new cyclohexylethanoid derivative (2), and seven related known compounds (3-9) were isolated from the leaves of Wedelia chinensis (Osbeck.) Merr. The structures of the compounds were conducted via interpretation of their spectroscopic data (1D and 2D NMR, IR, and MS), and the absolute configurations of compound 1 were determined by the modified Mosher's method. The MeOH extract of W. chinensis was found to inhibit α-amylase and α-glucosidase inhibitory activities as well as by the compounds isolated from this extract. Furthermore, compound 7 showed the strongest effect with IC50 values of 112.8 ± 15.1 µg/mL (against α-amylase) and 785.9 ± 12.7 µg/mL (against α-glucosidase). Compounds 1, 8, and 9 showed moderate α-amylase and α-glucosidase inhibitory effects. Other compounds showed weak or did not show any effect on both enzymes. The results suggested that the antidiabetic properties from the leaves of W. chinensis are not simply a result of each isolated compound but are due to other components such as the accessibility of polyphenolic groups to α-amylase and α-glucosidase activities.

ytotoxic Constituents of Mallotus microcarpus.

A new 3-methoxybenzensulfonic acid 4-0-0-D-glucopyranoside (1), and ten known compounds (2-11) were isolated from the methanolic extract of the stems of Mallotus microcarpus. The cytotoxicity of the isolated compounds was evaluated by the MTT method. 3-Methoxybenzensulfonic acid 4-Ο-ß-D- glucopyranoside (1) and methyl salicylate 2-rutinoside (5) showed strong cytotoxicity against EGFR-TKI-resistant human lung cancer A549 cells in comparison with camptothecin. Compound 1, leonuriside A (2), 3,4'-dihydroxypropiophenone 3-Ο-glucoside (6) and (lR,2S)-hovetrichoside A (10) inhibited the growth of human breast cancer MCF-7 cell line with IC50 values in the range of 0.48-1.78 µM. This is the first report on the chemical composition and cytotoxic activity of M microcarpus.

Calcium and Vitamin D Deficiency in Vietnamese: Recommendations for an Intervention Strategy.

In recent years, reports have described various roles of vitamin D in human health. Vitamin D deficiency has emerged as a significant public health problem throughout the world. Even in the Vietnamese context, it has been reported to be present in a majority of the population in spite of the wide availability of sunlight. Vitamin D and calcium are essential nutrients for bone health. The proposed health benefits of vitamin D and calcium have attracted increased interest from health care professionals, the media, and the public. The aim of this paper is to summarize the published data on vitamin D and calcium intake as well as on the prevalence of vitamin D deficiency in the Vietnamese population, and to provide recommendations for a proper strategy to control calcium and vitamin D deficiency in this population. The national authorities should adopt policies aimed at improving vitamin D and calcium status by using measures such as dietary recommendations, food fortification, vitamin D supplementation, and judicious sun exposure.

A New Cytotoxic Gymnomitrane Sesquiterpene from Ganoderma lucidum Fruiting Bodies.

A new gymnomitrane-type sesquiterpenoid, gymnomitrane-3α,5α,9ß,15-tetrol (1), was isolated from the fruiting body of Ganoderma lucidum. Its structure was elucidated using spectroscopic methods. This compound significantly inhibited the growth of epidermal growth factor receptor-tyrosine kinase inhibitor EGFR-TKI-resistant human lung cancer A549 and human prostate cancer PC3 cell lines.