Nguyen Van Thanh

Two New Triterpene Glycosides from the Vietnamese Sea CucumberHolothuria scabra

Two new triterpene glycosides, namely holothurin A3 (1) and A4 (2) were isolated from the methanol extract of the sea cucumber,Holothuria scabra, with their structures elucidated from the spectroscopic evidence (1D NMR, 2D NMR, ESI-MS and HRESI-MS). Compounds1 and2 were found to be strongly cytotoxic to both cancer cell lines, KB and Hep-G2, with 50% inhibitory concentrations (IC50) of 0.87 and 0.32 μg/mL (for compound 1) and of 1.12 and 0.57 μg/mL (for compound2), respectively.

Anti-inflammatory asterosaponins from the starfish Astropecten monacanthus.

Four new asterosaponins, astrosteriosides A-D (1-3 and 5), and two known compounds, psilasteroside (4) and marthasteroside B (6), were isolated from the MeOH extract of the edible Vietnamese starfish Astropecten monacanthus. Their structures were elucidated by chemical and spectroscopic methods including FTICRMS and 1D and 2D NMR experiments. The effects of the extracts and isolated compounds on pro-inflammatory cytokines were evaluated by measuring the production of IL-12 p40, IL-6, and TNF-α in LPS-stimulated bone marrow-derived dendritic cells. Compounds 1, 5, and 6 exhibited potent anti-inflammatory activity comparable to that of the positive control. Further studies are required to confirm efficacy in vivo and the mechanism of effects. Such potent anti-inflammatory activities render compounds 1, 5, and 6 important materials for further applications including complementary inflammation remedies and/or functional foods and nutraceuticals.

Cytotoxic triterpene saponins from Cercodemas anceps

Seven holostane-type triterpene saponins (1-7), including five new compounds namely cercodemasoides A-E (2-6), were isolated from the sea cucumber Cercodemas anceps. Their structures were elucidated on the basis of spectroscopic evidence including HR ESI MS, ESI MS/MS, 1D and 2D NMR. The cytotoxic effects of isolated compounds were evaluated by SRB method on five human cancer cell lines including Hep-G2 (hepatoma cancer), KB (epidermoid carcinoma), LNCaP (prostate cancer), MCF7 (breast cancer), and SK-Mel2 (melanoma). Compounds 1-7 showed potent cytotoxicity on five tested cancer cell lines with IC50 values ranging from 0.03 ± 0.01 to 7.36 ± 0.46 μM. With respect to the potent cytotoxicity of the isolated saponins, further studies are required to confirm efficacy in vivo and the mechanism of cytotoxic effects.

Cytotoxic triterpene diglycosides from the sea cucumber Stichopus horrens

Using various chromatographic separation techniques, eight triterpene diglycosides (1-8), including four new compounds namely stichorrenosides A-D (1-4), were isolated from a methanol extract of the Vietnamese sea cucumber S. horrens. Their structures were elucidated based on spectroscopic analyses, including HR ESI MS, 1D and 2D NMR. Their in vitro cytotoxic activity against five human cancer cell lines, Hep-G2 (hepatoma cancer), KB (epidermoid carcinoma), LNCaP (prostate cancer), MCF7 (breast cancer), and SK-Mel2 (melanoma), was evaluated using SRB methods. Stichorrenoside D (4), stichoposide A (5), and 3β-O-[β-d-xylopyranosyl-(1→2)-β-d-xylopyranosyl]-23S-acetoxyholost-7-ene (7) showed strong cytotoxicity on all five tested cancer cell lines, whereas significant effect was observed for stichorrenoside C (3) and stichoposide B (6).

Asterosaponins and glycosylated polyhydroxysteroids from the starfish Culcita novaeguineae and their cytotoxic activities

Using combined chromatographic methods, two asterosaponins (compounds 1 and 2), including a new compound novaeguinoside E (compound 1), and six glycosylated polyhydroxysteroids (compounds 3–8) were isolated from a methanol extract of the starfish Culcita novaeguineae. Their structures were determined on the basis of spectroscopic data (1H and 13C NMR, HSQC, HMBC, 1H–1H COSY, ROESY, and HRESI-MS) and by comparison with the literature values. The new compound 1 represents the third example of asterosaponins containing the 5α-cholesta-9(1l)-en-3β,6α,20,22-tetraol aglycone. Among isolated compounds, 4–7 exhibited moderate to weak cytotoxic activities against five human cancer cell lines such as Hep-G2 (hepatoma), KB (epidermoid carcinoma), LNCaP (prostate cancer), MCF7 (breast cancer), and SK-Mel2 (melanoma).

Steroid constituents from the soft coral Sinularia microspiculata

Abstract A methanol extract of the soft coral Sinularia microspiculata revealed five sterols, including two new compounds. Using combined chromatographic and spectroscopic experiments, the new compounds were found to be 7-oxogorgosterol (1) and 16α-hydroxysarcosterol (2). Their structures were determined on the basis of spectroscopic data (1H and 13C NMR, HSQC, HMBC, 1H-1H COSY, NOESY, and FT-ICR-MS) and by comparing obtained results to the values indicated in previous studies. Among the isolated compounds, 3 showed weak cytotoxic effects against HL-60 (IC50  =  89.02  ±  9.93 μM) cell line, whereas 5 was weakly active against HL-60 (IC50  =  82.80  ±  13.65 μM) and SK-Mel2 (IC50  =  72.32  ±  1.30 μM) cell lines.

Steroid Constituents from the Soft Coral Sinularia nanolobata

Six steroids (1-6), including the two new compounds 3β,4α-dihydroxyergosta-5,24(28)-diene (1) and 24(S),28-epoxyergost-5-ene-3β,4α-diol (2), were isolated from the methanol extract of the Vietnamese soft coral Sinularia nanolobata. Their structures were elucidated by spectroscopic methods including one and two dimensional (1D- and 2D)-NMR, Fourier transform ion cyclotron resonance (FT-ICR)-MS, and circular dichroism (CD). Compound 2 exhibited moderate cytotoxicity against the acute leukemia (HL-60) cell line with IC50 value of 33.53±4.25 µM and weak effect on the hepatoma cancer (HepG2) and colon adenocarcinoma (SW480) cell lines with IC50 values of 64.35±7.00 and 71.02±4.00 µM, respectively.

Chemical constituents from Kandelia candel with their inhibitory effects on pro-inflammatory cytokines production in LPS-stimulated bone marrow-derived dendritic cells (BMDCs)

Chemical investigation of Kandelia candel resulted in the isolation of 19 compounds (1-19), including one new sesquiterpene glycoside, kandelside (1), three megastigman glycoside compounds (7-9), 16 known phenolic compounds (2-6 and 10-19). Structures of the isolated compounds were elucidated based on spectral data comparison with reported values. Isolated compounds were also evaluated for their inhibitory effects on the production of pro-inflammatory cytokines interleukin (IL)-12 p40, IL-6, and tumor necrosis factor α (TNF-α) in lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells. Among these compounds, compound 9 exhibited strong inhibitory activity against IL-6 production (IC50=0.07 ± 0.05 μM) and moderate inhibitory activity against TNF-α production (IC50=49.86 ± 1.02 μM), but exhibited no activity on IL-12 p40 production. Compounds 5 and 6 significantly inhibited IL-12 p40, IL-6, and TNF-α production with IC50 values of 11.68 ± 0.38, 44.52 ± 1.08, and 28.73 ± 0.96 μM, respectively.

NF-κB inhibitory activity of polyoxygenated steroids from the Vietnamese soft coral Sarcophyton pauciplicatum.

Chromatographic purification of the methanolic extract from the soft coral Sarcophyton pauciplicatum led to the isolation of three polyhydroxylated steroids 1-3, including a new compound, sarcopanol A (1). Their structures were elucidated by spectroscopic analysis and by comparison of the spectroscopic data with those of similar compounds previously reported in literature. The anti-inflammatory effects of isolated compounds were evaluated using nuclear factor kappa B (NF-κB) luciferase and reverse transcription polymerase chain reaction (RT-PCR). The effect of isolated compounds on cell growth was evaluated by MTS assays. Compounds 1 and 2 significantly inhibited TNFα/INFγ-induced NF-κB transcriptional activity in human keratinocyte (HaCaT) cells in a dose-dependent manner, with EC50 values of 8.27±3.28 and 26.07±5.59 μM, respectively. Furthermore, the transcriptional inhibition of these compounds was confirmed by a decrease in cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and intercellular adhesion molecule-1 (ICAM-1) gene expression levels in HaCaT cells.

Cytotoxic Steroids from the Vietnamese Soft Coral Sinularia conferta

Twelve steroids, including five new compounds 1-5, were isolated and structurally elucidated from a methanol extract of the Vietnamese soft coral Sinularia conferta. Their cytotoxic effects against three human cancer cell lines, lung carcinoma (A-549), cervical adenocarcinoma (HeLa), and pancreatic epithelioid carcinoma (PANC-1), were evaluated using 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assays. Among isolated compounds, 10 exhibited potent cytotoxic effects on all three tested cell lines with IC50 values of 3.64±0.18, 19.34±0.42, and 1.78±0.69 µM, respectively.