Antiproliferative Constituents in the Plant 8. Seeds of Rhynchosia volubilis

The MeOH extract of the seeds of Rhynchosia volubilis (Leguminosae) showed antiproliferative activity against human gastric adenocarcinoma [MK-1, 50% growth inhibition (GI50): 25 μg/ml], human uterus carcinoma (HeLa, GI50: 30 μg/ml), and murine melanoma (B16F10, GI50: 8 μg/ml) cells. Bioactivity-guided fractionation resulted in the isolation of gallic acid methylester (1), gallic acid (2), 7-O-galloylcatechin (3), 1,6-di-O-galloylglucose (4), 1-O-galloylglucose (5), and trigalloylgallic acid (6), and their antiproliferative activity was estimated. All showed much stronger inhibition against B16F10 cell growth than against HeLa and MK-1 cell growth. Compound 2 and its tetramer (6) with a free carboxyl group showed higher activity than those which did not have a free carboxyl group. In relation to the gallic acid tetramer (6), two gallic acid dimers (ellagic acid and dehydrodigallic acid) and trimers (tergallic acid dilactone and flavogallonic acid dilactone) were tested for their activity, and compared with those of the isolates

Activity-Guided Fractionation of Green Tea Extract with Antiproliferative Activity against Human Stomach Cancer Cells

Epidemiological studies have suggested that the consumption of green tea provides protection against stomach cancer. Fractionation of green tea extract, guided by antiproliferative activity against human stomach cancer (MK-1) cells, has resulted in the isolation of six active flavan-3-ols, epicatechin (EC), epigallocatechin (EGC), epigallocatechin gallate (EGCg), gallocatechin (GC), epicatechin gallate (ECg), gallocatechin gallate (GCg), together with inactive glycosides of kaempferol and quercetin. Among the six active flavan-3-ols, EGCg and GCg showed the highest activity, EGC, GC, ECg followed next, and the activity of EC was lowest. These data suggest that the presence of the three adjacent hydroxyl groups (pyrogallol or galloyl group) in the molecule would be a key factor for enhancing the activity. Since reactive oxygen species play an important role in cell death induction, radical scavenging activity was evaluated using the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical. The order of scavenging activity was ECg?EGCg?EGC?GC?EC. The compounds having a galloyl moiety showed more potent activity. The contribution of the pyrogallol moiety in the B-ring to the scavenging activity seemed to be less than that of the galloyl moiety

Antiproliferative Activity of the Main Constituents from Phyllanthus emblica

Eighteen main compounds, including four norsesquiterpenoids (1?4) and 14 phenolic compounds (5?18) isolated previously from Phyllanthus emblica, together with a main constituent, proanthocyanidin polymers (19) identified at this time from the roots, were estimated for their antiproliferative activities against MK-1 (human gastric adenocarcinoma), HeLa (human uterine carcinoma), and B16F10 (murine melanoma) cells using an MTT method. All of the phenolic compounds including the major components 5?8 from the fruit juice, 8, 9, and 12 from the branches and leaves, and 19 from the roots showed stronger inhibition against B16F10 cell growth than against HeLa and MK-1 cell growth. Norsesquiterpenoid glycosides 3 and 4 from the roots exhibited significant antiproliferative activities, although their aglycon 1 and monoglucoside 2 showed no inhibitory activity against these tumor cells