Li an Shi

Alkaloids and other constituents from Tribulus terrestris

Three new compounds, terrestribisamide, 25R-spirost-4-en-3,12-dione and tribulusterine, together with 10 known compounds, N-p-coumaroyltyramine, terrestriamide, hecogenin, aurantiamide acetate, xanthosine, fatty acid ester, ferulic acid, vanillin, p-hydroxybenzoic acid and β-sitosterol, were isolated and characterized from dried fruits of Tribulus terrestris. Structures of these compounds were determined by spectral analysis.

Cardiac glycosides from Antiaris toxicaria with potent cardiotonic activity.

An ethanolic extract of Antiaris toxicaria trunk bark showed potent in vitro cardiotonic effect on isolated guinea pig atria. Bioassay-guided fractionation of the extract led to identification of nine new cardiac glycosides (1-9, named antiarosides A-I), antiarotoxinin A (10), and 18 known compounds. Their structures were established using MS and NMR spectroscopic studies, including homonuclear and heteronuclear correlation experiments. The ability of these cardiotonic compounds to produce positive inotropic action and their safety indexes were examined in comparison with those of ouabain, a classical inhibitor of Na(+)/K(+)-ATPase. Malayoside (23) was nearly equipotent and had a similar safety index to ouabain in guinea pig atria. However, the maximal positive inotropic effect and safety index of 23 in papillary muscle were better than those of ouabain. An electrophysiological recording showed that 23 inhibited the sodium pump current in a concentration-dependent manner.

Antiplatelet principles from the root of Petasites formosanus

Abstract Three bakkenolide-type compounds, bakkenolides-G, -H and deisobutyryl bakkenolide-H were isolated from the roots of Petasites formosanus . The structures were characterized by spectral methods. Bakkenolide-G and -H showed inhibitory activity against platelet activation factor (PAF), whereas deisobutyryl bakkenolide-H and ferulic acid showed inhibitory activity against arachidonic acid (AA) and collagen (Col)-induced aggregation of washed rabbit platelets.

Phenylalkynes from Artemisia capillaris

Eight new phenylalkynes, capillaridins A-H, together with three known compounds, capillin, capillene and O-methoxycapillene, were isolated and identified from the aerial parts of Artemisia capillaris.

Cytotoxic phenanthroindolizidine alkaloids from the roots of Ficus septica.

Activity-monitored fractionation of the CHCl3 solubles of the MeOH extract of the roots of Ficus septica using cytotoxicity assay led to the isolation of twenty phenanthroindolizidine alkaloids, including ten new ficuseptines E-N and ten known compounds. The cytotoxic effects of some of the isolates were tested on gastric adenocarcinoma (NUGC) and nasopharyngeal carcinoma (HONE-1) cell lines and the results demonstrated that, with the exception of dehydrotylophorine, all the tested compounds displayed pronounced cytotoxic activity with significant cell growth inhibitory effects. In addition, 13a R-antofine was found to be highly effective with ED(50) values of < 0.1 microg/mL against L-1210, P-388, A-549 and HCT-8 cell lines in another assay.

Cytotoxic cardiac glycosides and coumarins from Antiaris toxicaria

Eight new cardiac glycosides/aglycones (antiaritoxiosides A-G, 1-7, and antiarotoxinin B, 8), two new coumarins (anticarins A-B, 41-42), and two new flavanones (antiarones L-K, 43-44) were isolated from trunk bark of Antiaris toxicaria together with 53 known compounds. The new structures were established by extensive analysis of spectroscopic data. Compound 1 (10-carboxy and 3α-hydroxy) and compounds 3-6 (10-hydroxy) contain unique substituents that are rarely found in cardiac glycosides. The cytotoxic effects of isolated compounds against ten human cancer cell lines, KB, KB-VIN, A549, MCF-7, U-87-MG, PC-3, 1A9, CAKI-1, HCT-9 and S-KMEL-2, were tested using the sulforhodamine B assay. Five compounds (12, 16, 20, 22, and 31) showed significant cytotoxicity against all ten cancer cell lines, with notable potency at the ng/mL level against some cell lines, which merits further development as clinical trial candidates.

A secoiridoid and other constituents of Gonocaryum calleryanum

Investigation of the leaves, branch, stem and root bark of Gonocaryum calleryanum resulted in the isolation of a new secoiridoid glycoside, gonocaryoside E, together with 14 known compounds. Their structures were elucidated by spectral analysis and chemical transformation. Gonocaryoside E was shown to be a derivative of kingiside in which the lactone ring was open, and with the 8-hydroxy group esterified with tiglic acid. Alkaline hydrolysis of these secoiridoids is discussed.

Severibuxine, a new quinolin-2,4-dione and other constituents from Severinia buxifolia

Abstract A new quinolin-2,4-dione alkaloid, severibuxine, together with 23 known compounds were isolated from the root bark of Severinia buxifolia . The structure of these compounds were determined by spectral and chemical methods. Most of them showed cytotoxic activity against P-388.