benzofurans and myricetin

A novel unusual trimmer chalcone, polyanthumin (1), together with five known compounds myricetin 3-O-(3″-O-galloyl)-α-l-rhamnopyranoside (2), sulfuretin (3), fustin (4), gallic acid (5), and ethyl gallate (6), was isolated from the dry stems of Memecylon polyanthum H.L. Li. Among them, compound 1 is a new chalcone trimmer with a novel cyclobutane skeleton in nature. Compounds 3 and 4 are flavonoids carrying a single 7-OH in A ring, which provided the first example of these class flavonoids from the family Melastomataceae. In addition, the antitumor activities for 2-4 were reported for the first time in this study. The antitumor effects of the isolated compounds 1-6 in vitro were assayed by the SRB method using human cancer K562 cells, with the inhibition rates ranging from 39.4% to 54.5% at 100 μg/ml. The IC50 values of compounds 1 and 3 for the inhibition of K562 cell proliferation were determined to be 45.4 and 30.5 μg/ml, respectively. To the best of our knowledge, compound 1 was the second sample as chalcone trimer. In addition, the antitumor activities for 2-4 were reported for the first time in this study.

Topics: Antineoplastic Agents; Benzofurans; Chalcone; Chalcones; Cyclobutanes; Drug Screening Assays, Antitumor; Drugs, Chinese Herbal; Electron Spin Resonance Spectroscopy; Flavonoids; Gallic Acid; Humans; K562 Cells; Melastomataceae; Molecular Structure; Plant Stems; Stereoisomerism

This study was intended to look for anti-HIV chemical constituents of aerial parts of Caragana rosea Turcz. Column chromatographic technique was used for the isolation and purification of constituents of Caragana rosea under the guide of anti-HIV assay. The structures were established on the basis of physical and chemical properties and spectroscopic data. Five compounds were obtained from the EtOAc fraction of aerial parts of Caragana rosea and identified as myricetin (1), mearnsetin (2), p-hydroxy cinnamic acid (3), cararosinol A (4) and cararosinol B (5). At the same time, one possible transformation route between cararosinol B and kobophenol A, another resveratrol tetramer isolated from this plant previously, was proposed. Compounds 4, 5 are new resveratrol tetramers, compounds 1 -3 were isolated from this plant for the first time. All compounds showed no activities in an in vitro assay against HIV-1.

Topics: Anti-HIV Agents; Benzofurans; Caragana; Coumaric Acids; Flavonoids; HIV-1; Molecular Structure; Plant Components, Aerial; Plants, Medicinal; Propionates; Stilbenes