Biomedical subjects

Ya-Ching Shen

Publications and source records attributed to Ya-Ching Shen.

45 records · Page 3Linked to original sources

PubMed2003

New taxane diterpenoids from Taiwanese Taxus sumatrana.

Two new taxane diterpenoids, tasumatrols A (1) and B (2), have been isolated from extracts of the leaves and twigs of Taiwanese Taxus sumatrana. Tasumatrol A is a rare 5/6/6 taxene system, having a novel gamma-lactone at C-10 and C-19. The structures of compounds 1 and 2 were determined on the basis of two dimensional (2D)-NMR techniques, including correlation spectroscopy (COSY), 1H-detected heteronuclear multiple quantum coherence (HMQC) and heteronuclear multiple bond connectivity (HMBC) experiments.

Bridged-Ring Compounds↗

PubMed2002

Juncenolide A, a new briarane from the Taiwanese Gorgonian Junceella juncea.

Fractionation of the acetone extract of Junceella juncea collected in Taiwan resulted in the isolation of a new briarane, designated juncenolide A (1). The structure of 1 was determined on the basis of 2D NMR techniques, including COSY, HSQC, HMBC, and NOESY experiments, and was also confirmed by X-ray crystallographic analysis.

Animals↗

PubMed2002

Suberosols A-D, four new sesquiterpenes with beta-caryophyllene skeletons from a Taiwanese gorgonian coral Subergorgia suberosa.

Four new beta-caryophyllene-derived sesquiterpenes alcohols, suberosols A (1), B (2), C (3), and D (4), along with two known beta-caryophyllene-derived sesqueterpene ketones, buddledins C (5) and D (6), were isolated from a Taiwanese gorgonian coral Subergorgia suberosa. The structures of 1-4 were determined on the basis of extensive spectroscopic analyses. Cytotoxicity of these compounds toward various cancer cell lines is also described.

Animals↗

PubMed2002

New vibsane diterpenes and lupane triterpenes from Viburnum odoratissimum.

Bioassay-directed fractionation of the methanolic extract of the leaves and flowers of Viburnum odoratissimum resulted in the isolation of two new diterpenes, vibsanol A (1) and vibsanol B (2), together with two new triterpenoids, 6beta-hydroxylup-20(29)-en-3-oxo-27,28-dioic acid (3) and 6alpha-hydroxylup-20(29)-en-3-oxo-27,28-dioic acid (4). In addition, the known terpenoids vibsanins B and E, and 6alpha-hydroxylup-20(29)-en-3-oxo-28-oic acid, were also isolated. The structures of the new compounds were established by chemical and spectroscopic means. Vibsanol A (1) and compound 3 exhibited significant cytotoxicity against human gastric (NUGC) tumor cells.

Antineoplastic Agents, Phytogenic↗

PubMed2002

New taxane diterpenoids from the leaves and twigs of Taxus sumatrana.

Two new taxoids, taxumairol Q (1) and 13-O-acetyl wallifoliol (2), have been isolated from the leaves and twigs of Taxus sumatrana. Taxuspine F and wallifoliol (10) have been isolated for the first time from the yew T. sumatrana. Seventeen known taxoid diterpenoids have also been isolated. The new derivatives, 9,13-diacetyltaxumairol W (3), 10,13-dibenzoyltaxacustin (4), 7,13-diacetylwallifoliol (5), 7,13-dibenzoylwallifoliol (6), and 7,9-dibenzoyltaxumairol P (7), have been prepared by acylation of a crude mixture of taxoids. All structures were established primarily on the basis of 1D and 2D NMR techniques, including DEPT, COSY, and HMBC experiments, as well as chemical correlation with known compounds. Wallifoliol (10) exhibited significant cytotoxicities against both Hepa 59 T/VGH (human liver carcinoma) and KB (human oral epidermoid carcinoma) tumor cells. Taxuspine F and compound 5 possessed moderate activity against Hepa cells only, while 3, 6, 7, and 10-deacetylbaccatin III showed only marginal activity against Hepa cells.

Antineoplastic Agents, Phytogenic↗

PubMed2002

Taxumairols X--Z, new taxoids from Taiwanese Taxus mairei.

In addition to 19-dydroxybaccatin III, 1beta-hydroxy-5 alpha-deacetylbaccatin I, taxayuntin G and 13-O-deacetyltaxumairol Z (4), three new taxane diterpenoids, taxumairols X (1), Y (2), Z (3) have been isolated from extracts of the Formosan Taxus mairei (LEMEE & LEVL.) S. Y. HU. Compounds 1-2 belong to the 11(15-->1)-abeo-taxane system, having a tetrahydrofuran ring at C-2, C-3, C-4 and C-20. The new compound 3 and 4, which was misidentified previously are derivatives of 11(15-->1)-abeo-taxane with an intact oxirane system. The structures of compounds 1-4 were elucidated on the basis of extensive two dimensional (2D)-NMR analysis.

Magnetic Resonance Spectroscopy↗

PubMed2002

A novel cytotoxic C-methylated biflavone, taiwanhomoflavone-B from the twigs of Cephalotaxus wilsoniana.

A novel C-methylated biflavone, taiwanhomoflavone-B (1), together with known compounds, 7,4',7"-tri-O-methylamentoflavone, 6-C-methylnaringenin and apigenin-7-O-beta-glucoside were isolated from an ethanolic extract of Cephalotaxus wilsoniana. The structure of 1 was elucidated on the basis of spectroscopic analysis. Taiwanhomoflavone-B is cytotoxic with ED(50) values of 3.8 and 3.5 microg/ml, against KB oral epidermoid carcinoma and Hepa-3B hepatoma cells, respectively.

Cell Survival↗

PubMed2002

New taxane diterpenoids from the roots of Taiwanese Taxus mairei.

Five new taxane diterpenoids, taxumairols G (1), H (2), I (3), J (4), and L (5) were isolated from extracts of the roots of Taiwanese Taxus mairei (LEMEE & LEVL.) S. Y. Hu. Compounds 1-4 belong to the new 11(15-->1)-abeo-taxene system, having a tetrahydrofuran ring along carbons C-2, C-3, C-4 and C-20. Compounds 3 and 4 contain an isopropenyl group at C-1 while compounds 1 and 2 are attached with a benzoxyl group at C-15. The structures of compounds 1-5 were determined on the basis of two-dimensional (2D)-NMR techniques including correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond correlation (HMBC), and nuclear Overhauser effect spectroscopy (NOESY) experiments.

Bridged-Ring Compounds↗

PubMed1999

Synthesis and Biological Evaluation of 1-Deoxypaclitaxel Analogues.

The naturally occurring taxoid baccatin VI has been converted to various 1-deoxypaclitaxel derivatives by selective deacylation followed by attachment of the C-13 side chain. The bioactivities of the resulting analogues were determined in both tubulin polymerization and cytotoxicity assays, and several analogues with activity comparable to that of paclitaxel were discovered. It thus appears that the 1-hydroxyl group is not necessary for the activity of paclitaxel.

Journal Article↗