Four New Stilbene Derivatives Isolated from Gnetum latifolium var. funiculare Markgr. and Their Inhibition of NO Production in LPS-activated RAW264.7 Cells.

Gnetum latifolium var. funiculare Markgr. is a medicinal plant and widely distributed in mountainous areas of Vietnam. Phytochemical investigation on the trunks of this plant afforded eight stilbene derivatives (1-8) including for new compounds (1-4). Their structures were determined based on extensive analyses of HR-ESI-MS, 1D and 2D NMR spectra. Among the isolates, compounds 1-3 showed moderate NO production inhibition in LPS-activated RAW264.7 cells with the IC50 values ranging from 46.81 to 68.10 µM, compounds 4 and 6 showed weak effects with the IC50 values of 96.57 and 79.46 µM, respectively, compared to that of the positive control compound, dexamethasone (IC50 14.20 µM).

Cell Growth Inhibition of Saponin XII from Dipsacus japonicus Miq. on Acute Myeloid Leukemia Cells.

In previous studies, we isolated the known compound saponin XII from the roots of Dipsacus japonicus Miq. Here, we show that this compound reduced the number of acute myeloid leukemia OCI-AML3 cells as evaluated by a hemocytometer. Flow cytometry analyses demonstrated that the reported activity was associated with a significant increase of apoptosis and of cells in the G0/G1 phase of the cell cycle, with a decrease of cells in the S and G2/M phases. Thus, the inhibition of cell growth in OCI-AML3 cells was due to antiproliferative and pro-apoptotic effects. Interestingly, the bioactivity of saponin XII exerted its effect at a concentration as low as 1 µg/mL.

New nor-lignans from the leaves of styrax annamensis guillaumin.

Phytochemical study of the leaves of Styrax annamensis Guillaumin resulted in the isolation of a new natural product egonol-3''-sulphate (1), and two new derivatives egonol-3-methyl-D-galactopyranoside (2) and 7-methoxy-2-(3',4'-methylenedioxyphenyl)-benzofuran-5-carboxamide (3). Their chemical structures were -elucidated by spectroscopic data. Compounds 1 and 3 significantly established a great role for the chemotaxonomic aspect. Compound 1 showed cytotoxicity against four cancer cell lines KB, HepG2, Lu, and MCF7 with the IC50 values of 84.90-101.69 µg/mL, and exhibited acetylcholinesterase (AChE) inhibitory activity with the IC50 value of 97.08 µg/mL.

Identification and nitric oxide production inhibitory activity of phenolic derivatives from the trunks of Gnetum latifolium.

Phytochemical investigation of the trunks from Gnetum latifolium led to the isolation of a novel phenolic glucoside, 2E-2,4-di-(3,4-dihydroxyphenyl)but-2-en-1-yl-O-ß-D-glucopyranoside (1), along with five known stilbene derivatives (2-6). Their structures were determined mainly using high-resolution electrospray ionisation mass spectrometry and nuclear magnetic resonance spectroscopic analyses, followed by comparisons of observed spectral data with reported values. The novel compound 1 in G. latifolium was found to be useful as a chemotaxonomic marker. Biological evaluation revealed that compound 6 had remarkable inhibitory effects on nitric oxide production, with a half-maximal inhibitory concentration (IC50) value of 4.85 ± 0.20 µM, which was much higher than that of the positive control dexamethasone (IC50 = 14.20 ± 0.54 µM).

Oleanane-type triterpenoid sulphates, two new α-glucosidase inhibitors from Elaeocarpus hainanensis.

In connection with our interest in the phytochemical investigation of Elaeocarpus hainanensis Oliv. (Elaeocarpaceae) growing in Vietnam, two new sulphated oleanane triterpenes were obtained herein and structurally identified. Based on the combination of the extensive 1D-, 2D NMR and HR ESI MS spectroscopic data analysis, their chemical structures have been elucidated as 1α,3ß-dihydroxy-olean-18-ene 1-sulphate (1) and 1α,3ß-dihydroxy-olean-12-ene 1-sulphate (2). Notably, compounds 1 and 2 are corroborating the proposition that triterpenoid sulphates serve as chemosystematic markers of the Elaeocarpus genus. Additionally, all these two new compounds 1 and 2 strongly inhibited α-glucosidase in vitro with the respective IC50 values of 3.81 ± 0.33 µM and 21.27 ± 0.48 µM, which were significantly better than that obtained from positive control, acarbose (IC50 247.73 ± 11.85 µM).

Novel trans-caffeate hydrazide derivatives: synthesis, inhibition of nitric oxide (NO) production and molecular docking studies.

Eight new caffeyl hydrazide derivatives (4a-4h) were synthesised via a convenient esterification of caffeic acid with some substituted aryl acid hydrazides. The synthesised caffeyl derivatives were evaluated for their inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 macrophages. The fluorobenzoylhydrazide derivatives 4f, 4 g and 4h were found to be the most powerful anti-inflammatory compounds with IC50 values ranging from 11.90 to 24.17 µM, which were more potent than the reference compound L-NMMA (IC50 32.8 µM). Additionally, synthesised compounds have been rationalised by using molecular docking studies which were performed in order to understand insights on the action mechanism of newly synthesised inhibitors against inflammatory mediator (iNOS). Obtained data indicate that compounds 4f, 4h, 4a and 4 g were observed to effectively bind to iNOS receptor with dock score values of -11.62, -10.81, -10.78 and -10.51 kcal/mol, respectively.

Chemical constituents of Impatiens parvisepala and their α-glucosidase inhibition activity.

The first chemical study of the whole Impatiens parvisepala S. X. Yu & Y. T. Hou led to the isolation of a new triterpene saponin, named Iparvisepala-1 (6) along with ten known compounds, which cover three flavonoid glycosides (1-3), one dihydrochalcone glucoside (4), one triterpenoid saponin (5), one triterpene (7) and four miscellaneous compounds (8-11). Their structures were elucidated by MS, NMR spectroscopic analyses as well as by comparisons of spectra data with those of the related published literatures. Additionally, flavonoid glucoside 2 showed impressive effect on α-glucosidase inhibition with the IC50 value of 12.53 ± 0.39 µM, much better than that of the positive control acabose (IC50 = 197.53 ± 2.68 µM).

Sesquiterpenoids from Tithonia diversifolia (Hemsl.) A. Gray induce apoptosis and inhibit the cell cycle progression of acute myeloid leukemia cells.

Three sesquiterpene lactones (1-3) were isolated from the aerial part of Tithonia diversifolia (Hemsl.) A. Gray grown in the Hoa Binh province in Viet Nam. The structures of these three sesquiterpene lactones were identified as tagitinin A (1), 1ß-hydroxytirotundin 3-O-methyl ether (2), and tagitinin C (3) by analyzing spectroscopic data. For the first time, compound 2 was isolated from T. diversifolia growing in Viet Nam. Furthermore, contrary to existing literature, we determined that compound 1 was the major isolate. Compounds 1 and 3 significantly decreased numbers of acute myeloid leukemia OCI-AML3 cells by promoting apoptosis and causing cell cycle arrest at G0/G1 phase at concentrations as low as 2.5 µg/mL (compound 1) and 0.25 µg/mL (compound 3). Additionally, all three compounds showed cytotoxic activity against five human cancer cell lines (A549, T24, Huh-7, 8505, and SNU-1), with IC50 values ranging from 1.32 ± 0.14 to 46.34 ± 2.74 µM. Overall, our findings suggest that compounds 1 and 3 may be potential anti-cancer therapeutics and thus warrant further study.

Noncytotoxic 16,23-epoxycucurbitacin-type triterpenoids from Elaeocarpus hainanensis.

Phytochemical investigation of methanol extract from Elaeocarpus hainanensis Oliv. leaves and twigs led to the isolation and structural determination of three 16,23-epoxycucurbitacin-type triterpenoids, including a new hydroperoxide, 16α,23α-epoxy-3ß,20ß-dihydroxy-24α-hydroperoxy-10αH,23ßH-cucurbit-5,25-dien-11-one (elahainencin A, 1), and two known analogs (2 and 3). Their chemical structures were determined by the spectroscopic analyses, including 1 D-, 2 D NMR and HR ESI MS spectra. Compound 1 represents a cucurbitacin derivative incorporating a hydroperoxide. In addition, these isolated compounds have been found to be noncytotoxic when tested in vitro against five human cancer cell lines (A549, T24, 8505, Huh-7 and SNU-1) by using the SRB method.

Chemical constituents of Impatiens chapaensis Tard. and their α-glucosidase inhibition activities.

Sixteen compounds (1-16) were isolated from Impatiens chapaensis. Chemical structures were determined by spectroscopic analyses and comparisons with previously published data. This report is the first to identify compounds 1, 5-7, 10, 12-14, and 16 from the genus Impatiens. Seven chosen isolates (5, 7, 10, 11, 12, 15, and 16) were submitted for α-glucosidase inhibition assays with acarbose as the positive control (IC50 = 227.14 ± 13.71 µM). Flavonoid 5 exhibited a significant inhibitory effect (IC50 = 101.00 ± 9.01 µM).

New phenolics from Dianella ensifolia.

Phytochemical investigation and chromatographic separation of extracts from the aerial parts of Dianella ensifolia (L.) DC. (synonym Dianella nemorosa Lam. Ex. Schiler f.) led to the isolation of 10 compounds, the structures of which were determined by HR-ESI-MS and 1 D- and 2 D-NMR spectroscopies, and by comparisons with published studies. Among the isolated compounds were three flavans, a biflavan, a biflavone, a tetralone, a naphthalen glycoside, an aromatic compound, and two steroids. Six of these were known chemicals, while three were identified as new compounds: 7-acetyl-4R,8-dihydroxy-6-methyl-1-tetralone, 2(S),2',4'-dihydroxy-7-methoxyflavan, and diaensi-biflavan. 2(S),7,4'-dimethoxy flavan was obtained for the first time as a natural product.