Nguyen Thi Hoang Anh

Naphthylisoquinoline alkaloids from Ancistrocladus cochinchinensis

Abstract From the leaves of Ancistrocladus cochinchinensis, besides the already known ancistrocladinine, the new naturally occurring alkaloids, 6-O-methylhamateine, hamatinine, 6-O-methylhamatinine, 6-O-demethyl-7-epi-ancistrobrevine D, 7-epi- ancistrobrevine D and 6-O-demethyl-8-O-methyl-7-epi-ancistrobrevine D have been isolated and their structures elucidated from spectroscopic data and chemical degradation.

Tetralones from Ancistrocladus cochinchinensis

Abstract From leaves of Ancistrocladus cochinchinensis , along with plumbagin, (+)-isoshinanolone, 3,3′-biplumbagin, 8,8′-biplumbagin, lupeol and betulin, three new tetralones have been isolated. Their structures were established as (2R∗, 4S∗)-4,5- dihydroxy-2-methyltetralone , (2R∗,4R∗)-4,5- dihydroxy-2-methyltetralone and (3R∗,4S∗)-3,4,8- trihydroxy-3-methyltetralone , respectively, by NMR spectroscopic data.

Study on chemical constituents and cytotoxic activities of Salacia chinensis growing in Vietnam.

Two new triterpenoids, named 7α,21α-dihydroxyfriedelane-3-one (1) and 7α,29-dihydroxyfriedelane- 3-one (2) have been isolated from the ethyl acetate extract of the stems of Salacia chinensis besides the known triterpenoid 21α,30-dihydroxyfriedelane-3-one (3). The structures of the isolated compounds were elucidated on the basis of spectral analysis. Eight triterpenoids from this plant have been tested against the four cancer cell lines Hep-G2, LU, KB, and MCF-7. The new compound 1 showed good activity against all four tested cell lines. Graphical Abstract Study on Chemical Constituents and Cytotoxic Activities of Salacia chinensis Growing in Vietnam

Neolignans and a sesquiterpene from Caryodaphnosis tonkinensis

Abstract In addition to various eupomatenoids 2-(4-hydroxyphenyl)-5-(2-oxopropyl)-3-methylbenzo[ b ]furan and (2 R ,3 R )-2,3-dihydro-2-(4-hydroxyphenyl)-3-methyl-5-[( E )-1-propenyl]benzo[ b ]furan, three hitherto unknown constituents have been isolated from Caryodaphnosis tonkinensis . Their structures were elucidated by spectral methods as erythro -1-(3,4-methylenedioxyphenyl)-2-{4-[( E )-1-propenyl]phenoxy}propan-1-ol, 2-(4-hydroxyphenyl)-3-methylbenzo[ b ] furan-5-carbaldehyde and 1,2,3,3a,4,5,6,7,8,8a-decahydro-7-(1-hydroxy-1-methylethyl)-1,4-dimethylazulene-3a,8a-diol.

Neolignans from Caryodaphnopsis baviensis

Besides the eupomatenoids 1, 3, 5 and 6, 5-(erythro-1,2-dihydroxypropyl)-2-(4-hydroxyphenyl)-3-methylbenzo[b]furan, 5-(erythro-1,2-dihydroxypropyl)-2-(4-hydroxy-3-methoxyphenyl)-3-methylbenzo[b]furan, (2R,3R)-2,3-dihydro-2-(4-hydroxyphenyl)-3-methyl-5-[(E)-1-propenyl]benzo[b]furan, erythro-1-(3,4-methylenedioxyphenyl)-2-{4-[(E)-1-propenyl]phenoxy}propan-1-ol, (+)-sesamin, isolinderanolide and icariside D1, two new neolignans have been isolated from Caryodaphnopsis baviensis. Their structures were elucidated as 3-methyl-2-(3,4-methylenedioxyphenyl)-5-[(E)-3-oxo-1-propenyl]benzo[b]furan and 4-hydroxy-α-{4-[(E)-1-propenyl]phenoxy}propiophenone.

Spirally oriented Au microelectrode array sensor for detection of Hg (II)

A simple and reproducible carbon microelectrode array (CMA), designed to eliminate diffusive interference among the microelectrodes, has been fabricated and used as a frame to build a gold (Au) microelectrode array (GMA) sensor. To prepare the CMA initially, rather than use an uncontrollable large number of carbon fibers, only 60 carbon fibers of regular size were used to ensure manageable and reproducible arrangement for array construction. In addition, for efficient spatial arrangement of the microelectrode and easy sensor preparation, carbon fibers were oriented in a spiral fashion by rolling around a Cu wire. The distance between carbon fibers was carefully determined to avoid overlap among individual diffusion layers, one of the important factors governing steady-state current response and sensor-to-sensor reproducibility. After the preparation of a spirally arranged CMA, Au was electrochemically deposited on the surface of individual carbon electrodes to build a final GMA sensor. Then, the GMA sensor was used to measure Hg(2+) in a low concentration range. Simultaneously, multiple GMA sensors were independently prepared to examine reproducibility in sensor fabrication as well as electrochemical measurement (sensor-to-sensor reproducibility). Overall, highly sensitive detection of Hg(2+) was possible using the proposed GMA sensor due to efficient arrangement of microelectrodes and the sensor-to-sensor reproducibility was superior owing to simplicity in sensor fabrication.

A new hydrochalcone from Miliusa sinensis

A new dihydrochalcone 4′,6′-dihydroxy-2′,3′,4-trimethoxydihydrochalcone (1) along with nine known compounds, pashanone (2), dihydropashanone (3), pinostrobin (4), 5-hydroxy-7,4′-dimethoxyflavanone (5), 5-hydroxy-6,7-dimethoxyflavanone (6), 5-hydroxy-7,8-dimethoxyflavanone (7), 24-methylencycloartane-3β,21-diol (8), liriodenine (9) and 3,5-dihydroxy-7,3’,4’-trimethoxyflavone (10), were isolated from the extracts, exhibiting cytotoxic activity (n-hexane and ethyl acetate extracts) of Miliusa sinensis. The structure of (1) was elucidated by the analysis of spectral data (IR, HR-MS, EI-MS, 1D and 2D NMR).

Cytotoxic and antimicrobial aporphine alkaloids from Fissistigma poilanei (Annonaceae) collected in Vietnam.

Two new aporphine alkaloids: 8-hydroxy-9-methoxy-1,2-methylenedioxyaporphine (1) and 8-hydroxy-3,9-dimethoxy-1,2-methylenedioxyaporphine (2) were isolated from the ethyl acetate extract of Fissistigma poilanei along with five known compounds: oxocrebanine (3), kuafumine (4), (2R,3R)-3′,4′,5,7-tetrahydroxydihydroflavonol-3-O-α-L-rhamnopyranoside (5), (+)-catechin 3-O-α-L-rhamnopyranoside (6) and quercetine 3,7-dimethoxy-3′-O-α-L-rhamnopyranosyl-(1 → 2)-β-D-glucopyranoside (7). These two new aporphine alkaloids exhibited a moderate cytotoxic activity against four human cancer cell lines (KB, Hep-G2, MCF-7, LU) as well as antimicrobial activity against Lactobacillus fermentum, Enterococcus faecium, Staphylococcus aureus and Bacillus subtillis.

Two New Bis-styryl Compounds from Miliusa balansae

Two new compounds named miliubisstyryl A and miliubisstyryl B were isolated from leaves and branches of Miliusa balansae Fin. & Gagn. (Annonaceae) in addition to octacosanoic acid. Their structures were elucidated by spectroscopic methods, especially 2D NMR spectroscopy. The rare cyclobutane skeletons of these compounds are derived from a styryl compound which is also present in this plant.

Polar eupomatenoids from Caryodaphnosis tonkinensis

Abstract From the bark of Caryodaphnosis tonkinensis three new polar eupomatenoids were isolated, for which the structures 5-(erythro-1,2-dihydroxypropyl)-2-(4-hydroxyphenyl)-3-methylbenzo[b]furan, 5-(erythro-1,2-dihydroxypropyl)-3-methyl-2-(3,4-methylenedioxyphenyl)benzo[b]furan and 5-(erythro-1,2-dihydroxypropyl)-2-(4-hydroxy-3-methoxyphenyl)-3-methylbenzo[b]furan were determined by spectral methods.