Dinh Thi Thu Thuy

Cytotoxic and anti-inflammatory cembranoids from the Vietnamese soft coral Lobophytum laevigatum

Four new cembranoids, namely laevigatol A-D (1-4), and six known metabolites (5-10), were isolated from the Vietnamese soft coral Lobophytum laevigatum. The structures of these compounds were elucidated by extensive spectroscopic analyses, and the absolute stereochemistry of 1 was determined using the modified Moshers method. Compounds 5, and 7-10 exhibited cytotoxic activity against selected human cancer cell lines. Compounds 1, 2, 8, and 9 showed dose-dependent inhibitory effects on the TNFα-induced NF-κB transcriptional activity in Hep-G2 cells. Moreover, compounds 1, 2, 8, and 9 significantly inhibited the induction of COX-2 and iNOS mRNA dose-dependently, indicating that these compounds attenuated the synthesis of these transcripts at the transcriptional level.

Cytotoxic and antioxidant activities of diterpenes and sterols from the Vietnamese soft coral Lobophytum compactum.

Two new diterpenes, lobocompactols A (1) and B (2), and five known compounds (3-7) were isolated from the methanol extract of the soft coral Lobophytum compactum using combined chromatographic methods and identified based on NMR and MS data. Each compound was evaluated for cytotoxic activity against A549 (lung) and HL-60 (acute promyelocytic leukemia) human cancer cell lines. Among them, compound 5 exhibited strong cytotoxic activity against the A549 cell line with an IC(50) of 4.97 ± 0.06 μM. Compounds 3, 4, and 7 showed moderate activity with IC(50) values of 23.03 ± 0.76, 31.13 ± 0.08, and 36.45 ± 0.01 μM, respectively. The cytotoxicity of 5 on the A549 cells was comparable to that of the positive control, mitoxantrone (MX). All compounds exhibited moderate cytotoxicity against the HL-60 cell line, with IC(50) values ranging from 17.80 ± 1.43 to 59.06 ± 2.31 μM. Their antioxidant activity was also measured using oxygen radical absorbance capacity method, compounds 1 and 2 exhibiting moderate peroxyl radical scavenging activity of 1.4 and 1.3 μM Trolox equivalents, respectively, at a concentration of 5 μM.

Cytotoxic and PPARs transcriptional activities of sterols from the Vietnamese soft coral Lobophytum laevigatum

A new unusual sterol, named lobophytosterol (1), and five known metabolites (2-6) were isolated from the methanol extract of the soft coral Lobophytum laevigatum. Their chemical structures were elucidated by extensive spectroscopic analysis and comparison with those reported in the literature. The absolute stereochemistry of 1 was determined using a modified Moshers method. Compounds 1-3 showed cytotoxic activity against HCT-116 cells with IC(50) values of 3.2, 6.9 and 18.1 μM, respectively. Compound 1 additionally displayed cytotoxic effects on A549 and HL-60 cells with IC(50) values of 4.5 and 5.6 μM, respectively. Treatment of these cells with compound 1 resulted in an induction of apoptosis evident by chromatin condensation in treated cells. Besides, compounds 2, 4, and 6 significantly upregulated PPARs transcriptional activity dose-dependently in Hep-G2 cells. Taken together, these data suggest that compound 1 might inhibit the growth of the cancer cells by the induction of apoptosis, and compounds 2, 4, and 6 might act as specific agonists for PPARα, PPARδ, and PPARγ and may therefore regulate cellular glucose, lipid, and cholesterol metabolism.

Carotenoids from the soft coral Sarcophyton elegans.

By various chromatographic separations, three carotenoids were isolated from the soft coral Sarcophyton elegans. They were elucidated as peridinin ( 1 ), peridininol ( 2 ), and all-trans-peridininol-5,8-furanoxide ( 3 ) by spectroscopic methods and in comparison with reported data. This is the first report of 3 from soft corals.

Chemical Composition and α-Glucosidase Inhibitory Activity of Vietnamese Citrus Peels Essential Oils

Background. Inhibition of α-glucosidase is an important factor to control postprandial hyperglycemia in type 2 diabetes mellitus. Citrus essential oils (CEO) are among the most widely used essential oils, and some of them exhibited promising antidiabetic effect. However, the α-glucosidase inhibition of CEO has not been investigated so far. The present work aims to evaluate the α-glucosidase inhibition of essential oils from six Vietnamese Citrus peels. Methods. The chemical composition of essential oils obtained by hydrodistillation from six Citrus peels was analyzed by GC-MS. All essential oils were tested for their inhibitory activity on α-glucosidase using p-nitrophenyl-α-D-glucopyranoside as substrate. Results. In Buddha’s hand and lime peels, the major components were limonene (59.0–61.31%) and γ-terpinene (13.98–23.84%) while limonene (90.95–95.74%) was most abundant in pomelo, orange, tangerine, and calamondin peels. Among the essential oils, the Buddha’s hand oil showed the most significant α-glucosidase inhibitory effect with the IC50 value of 412.2 μg/mL. The combination of the Buddha’s hand essential oil and the antidiabetic drug acarbose increased the inhibitory effect. Conclusions. The results suggested the potential use of Buddha’s hand essential oil as an alternative in treatment of type 2 diabetes mellitus.

Norisoprenoid, phenolic and steroidal constituents from Mallotus luchenensis

A C 13 -norisoprenoid malloluchenoside ( 1 ), two phenolics gallic acid ( 2 ) and corillagin ( 3 ), and t wo steroids daucosterol ( 4 ) and stigmast-5-enee-3-O-(6-O-octadecanoyl- b -D-glucopyranoside) ( 5 ) were isolated from the MeOH extract of Mallotus luchenensis. Their structures were elucidated on the basis of spectral and physicochemical data. Among which, 1 was isolated for the first time from the nature. Key words : Mallotus luchenensis , norisoprenoid, phenolic, steroid, malloluchenoside.