Duong Thi Dung

Macrocyclic bis-quinolizidine alkaloids from Xestospongia muta

Abstract A new stereoisomer Meso-araguspongine C together with nine reported macrocyclic bis-quinolizidine alkaloids araguspongines A, C, E, L, N−P, petrosin, and petrosin A were isolated from marine sponge Xestospongia muta. Stereochemistry of meso-araguspongine C (2) and araguspongines N-P (3−5) were established by their NMR data and conformational analyses. Both araguspongine C (1) and meso-araguspongine C (2) exhibited great cytotoxic activity towards HepG-2, HL-60, LU-1, MCF-7, and SK-Mel-2 human cancer cells (IC50 in the range of 0.43–1.02 μM). At a concentration of 20 μM, isolated compounds (1−10) also showed modest inhibitory effects (from 7.6 to 40.8%) on the NO production in LPS activated RAW264.7 macrophages.

HEPATOPROTECTIVE EFFECTS OF PHENOLIC GLYCOSIDES FROM THE METHANOL EXTRACT OF PHYSALIS ANGULATA

By various chromatographic separations, four phenol ic glycosides, methyl salicylate 2O triglycoside (1), icariside E5 (2), quercetin 3O-rutinoside ( 3), and isorhamnetin 3O-rutinoside (4) were isolated from the methanol extract of the wh ole plant of Physalis angulata. Their structures were determined by 1D-, 2D-NMR spectrosc opic analyses and by comparison with reported data. Compounds 3 exhibited significant hepatoprotective activity wi th an EC50 value of 17.08 μg/mL. This is the first report of 1-4 from Physalis angulata.

Oleanane-type Saponins from Glochidion hirsutum and Their Cytotoxic Activities

Five new oleanane‐type saponins, hirsutosides A – E, were isolated from the leaves of Glochidion hirsutum (Roxb.) Voigt. Their structures were elucidated as 21β‐benzoyloxy‐3β,16β,23,28‐tetrahydroxyolean‐12‐ene 3‐O‐β‐d‐glucopyranoside (1), 21β‐benzoyloxy‐3β,16β,23,28‐tetrahydroxyolean‐12‐ene 3‐O‐β‐d‐glucopyranosyl‐(1 → 3)‐β‐d‐glucopyranoside (2), 21β‐benzoyloxy‐3β,16β,23,28‐tetrahydroxyolean‐12‐ene 3‐O‐6‐acetyl‐[β‐d‐glucopyranosyl‐(1 → 3)]‐β‐d‐glucopyranoside (3), 21β‐benzoyloxy‐3β,16β,23,28‐tetrahydroxyolean‐12‐ene 3‐O‐β‐d‐glucopyranosyl‐(1 → 3)‐〈‐l‐arabinopyranoside (4), and 21β‐benzoyloxy‐3β,16β,23‐trihydroxyolean‐12‐ene‐28‐al 3‐O‐β‐d‐glucopyranosyl‐(1 → 3)‐α‐l‐arabinopyranoside (5). All isolated compounds were evaluated for cytotoxic activities on four human cancer cell lines, HepG‐2, A‐549, MCF‐7, and SW‐626 using the SRB assay. Compounds 1, 2, 4, and 5 showed significant cytotoxic activities against all human cancer cell lines with IC50 values ranging from 3.4 to 10.2 μm. Compound 3 containing acetyl group at glc C(6″) exhibited weak cytotoxic activity with IC50 values ranging from 47.0 to 54.4 μm.

Sterols from the sponge Haliclona varia.

Using combined chromatographic methods, four sterols, 3 β -hydroxycholest-5-en-7-one ( 1 ), 22( E )-3 β -hydroxycholesta-5,22-dien-7-one ( 2 ), 3 β ,7 α -dihydroxycholest-5-ene ( 3 ), and 3 β ,7 β -dihydroxycholest-5-ene ( 4 ) were isolated from the methanol extract of the sponge Haliclona varia . Their structures were elucidated by 1D and 2D-NMR spectroscopic methods as well as in comparison with the previous literature. Compounds 2-4 were reported from the genus Haliclona for the first time. Keywords. Haliclona varia , sponge, sterol.

Furanosesterterpenes from the marine sponge Ircinia echinata (Keller, 1889)

Four furanosesterterpene, (7 E ,12 E ,20 Z ,18 β )-variabilin ( 1 ), (12 E ,20 Z ,18 β )-8-hydroxyvariabilin ( 2 ), (7 E ,11 E ,3 β )-3,7,11-trimethyl-14-(furan-3-yl)tetradec-7,11-dienoic acid ( 3 ), and furoscalarol ( 4 ), and one sterol, 3 β -hydroxycholest-5-en-7-one ( 5 ) were isolated from the methanol extract of the sponge Ircinia echinata (Keller, 1889). Their structures were elucidated by 1D and 2D-NMR spectra and in comparison with those reported in the literature. Keywords . Sponge, Ircinia echinata , furanosesterterpene, sterol.

Iridoid glycosides from Morinda tomentosa and their endoplasmic reticulum stress modulation activity

Three iridoids 1 - 3 , asperulosidic acid, daphylloside, and asperuloside, were isolated from the methanol extract of the leaves of Morinda tomentosa . Their chemical structures were elucidated by 1D- and 2D-NMR spectra and in comparison with those reported in the literature. The effects of these compounds on the endoplasmic reticulum stress in XBP1-eGFP-transfected the 293 T cells were measured. Compound 3 significantly reduced the ER-stress both in DMSO-treated and thapsigargin-treated cells. Unlike this compound, compound 3 selectively reduced thapsigargin-induced ER-stress without any effect on the level of XBP1 splicing in DMSO-treated cells. These results suggested that compounds 2 and 3 can be suggested as new ER stress regulators.

Withanolide glucosides from the Rhizomes of Tacca chantrieri

By various chromatographic separations, three withanolide glucosides, chantriolides A-C were isolated from the rhizomes of Tacca chantrieri . Their structures were elucidated by 1D-, 2D-NMR, and MS spectra and in comparison with the reported data.

Sesquiterpenes from marine sponge Dysidea fragilis

By various chromatographic separations, three sesquiterpenes, furodysinin lactone ( 1 ), O -methyl furodysinin lactone ( 2 ) and O -methyl-9-oxofurodysinin lactone ( 3 ) were isolated from Vietnamese marine sponge Dysidea fragilis . Their structures were determined by 1D-, 2D-NMR spectra and in comparison with the reported data. Compound 3 was reported from sponge D. fragilis for the first time.

A new isomalabaricane from Vietnamese marine sponge Petrosia ingricans

A new isomalabaricane triterpene, nigricanic acid A ( 1 ), and two known compounds (24 S )-ergostane 3β,5α,6β,25-tetraol-25-monoacetate ( 2 ) and (24 S )-ergostane-1β,3β,5α,6β,25-pentaol-25-monoacetate ( 3 ), was isolated from Vietnamese marine sponge Petrosia nigricans . Their structures were determined on the basis of 1D and 2D-NMR spectra and HR-ESI-MS, and in comparison with the reported data. The cytotoxicity of all compounds were evaluated by MTT assay on four human cancer cell lines, including Hep-G2, KB, LU-1, and MCF-7. As the results, compound 1 exhibited moderate cytotoxic activity on the four human cancer cell lines with IC 50 values ranging of 15.47÷19.34 μg/mL.