Nguyen Hai Dang

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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). Compounds 1 and 2 were found to be strongly cytotoxic to both cancer cell lines, KB and Hep-G2, with 50%(More)
Two new flavonoid glycosides, (1, 2), and eleven known compounds, (3-13), were isolated from from a 70% EtOH extract of the leaves of Chromolaena odorata (Asteraceae). Their structures were elucidated by 1D and 2D NMR spectroscopic interpretation as well as by chemical studies. The newly isolated compounds were tested in vitro for their cytotoxic activities(More)
The primary component of amyloid deposits found in the brains of patients with Alzheimer's disease is the beta-amyloid protein, a derivative of a much larger precursor protein (beta PP). We have previously reported that overexpression of carboxyl (COOH)-terminal fragments of beta PP from an integrated DNA construct leads to degeneration of neuronally(More)
Two new benzopyrans 6-[1'-oxo-3'(R)-hydroxy-butyl]-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (1) and 6-[1'-oxo-3'(R)-methoxy-butyl]-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (2) were isolated from the leaves of Mallotus apelta Muell.-Arg., (Euphorbiaceae). Their chemical structures were elucidated by spectroscopic analyses, especially by 1 D-, 2D-NMR and(More)
Seven diterpenes, four polyacetylenes, a lipid glycerol, and two sterols were isolated from the methylene chloride fraction of the root of Aralia cordata. Their chemical structures were determined as (-)-pimara-8(14),15-dien-19-oic acid (2), pimaric acid (3), (-)-kaur-16-en-19-oic acid (4), 17-hydroxy-ent-kaur-15-en-19-oic acid (9),(More)
This study evaluated the cytotoxic activity of extracts from Caesalpinia sappan heartwood against multiple cancer cell lines using an MTT cell viability assay. The cell death though induction of apoptosis was as indicated by DNA fragmentation and caspase-3 enzyme activation. A methanol extract from C. sappan (MECS) showed cytotoxic activity against several(More)
In the course of screening plants used in folk medicine as memory enhancers, a 70% ethanolic extract of Stephania rotunda roots showed significant AChE inhibitory activity. Repeated column chromatography led to the isolation of a new protoberberine alkaloid, which we named stepharotudine (1), and seven known compounds (2-8). The chemical structures of the(More)
From the methanol extract of Dracaena cambodiana roots two unusual 22S-spirostane steroids (1beta,3beta,14alpha,20R,22S,25R)-spirost-5-ene-1,3,14-triol (1) and (lbeta,3beta,14alpha,15alpha,20R,22S,25R)-spirost-5-ene-tetrol (2) have been isolated, together with a known 22R-spirostane compound, namogenin B (3). Their structures were elucidated by(More)
An important role of apolipoprotein E in the amyloidogenesis of Alzheimer's disease is suggested by an accumulation of apolipoprotein E in beta-amyloid plaques and a genetic association between Alzheimer's disease and one of the allelic variants (APOE4) of apolipoprotein E. Overexpression of a C-terminal region of beta-amyloid precursor protein brings about(More)