Differential effect of green tea catechins on three endothelial cell clones isolated from rat adipose tissue and on human umbilical vein endothelial cells

Angiogenesis inhibition by a lichen compound olivetoric acid

Lichens have been used in folk medicine for centuries and are symbiotic organisms of fungi and algae that produce unique secondary metabolites. Olivetoric acid is one of these secondary metabolites. In the present study, the effect of olivetoric acid isolated from acetone extract of the lichen Pseudevernia furfuracea (var. ceratea) on angiogenesis was evaluated. It displayed potent anti-angiogenic activities in vitro: inhibited proliferation of rat adipose tissue endothelial cells (RATECs) and disrupted endothelial tube formation in a dose-dependent manner. Furthermore, dose-dependent depolymerization effects of olivetoric acid on F-actin stress fibers were observed. Decrease in the tube formation of RATECs by olivetoric acid might be explained by a disorganization of the actin cytoskeleton. These findings suggest that olivetoric acid is a new anti-angiogenic agent and can be developed as a new therapeutic agent for angiogenesis-related diseases.

Crude extracts of, and purified compounds from, Pterocarpus angolensis, and the essential oil of Lippia javanica: their in-vitro cytotoxicities and activities against selected bacteria and Entamoeba histolytica

In a recent study, various extracts of Pterocarpus angolensis were prepared and tested against bacteria. The acetone extract was found to be the most active against all the bacteria investigated, with minimum inhibitory concentrations varying from 0.0156 mg/ml against Staphylococcus aureus to 2 mg/ml against Enterobacter cloacae. Seven pure compounds were subsequently isolated from the ethanol extract of P. angolensis. Using several chromatographic and spectroscopic methods, the structures of five of these compounds - phthalate and four derivatives of epicatechin [(-)-epicatechin, epicatechin-3-O-galate, epicatechin (4beta-8)-epicatechin (B2), and a hexamer of epicatechin] - were successfully determined. The seven purified compounds were then further tested, in vitro, against Staphylococcus aureus and Entamoeba histolytica, and for their in-vitro cytotoxic activity. Although all seven were active against S. aureus, just one of the purified compounds from P. angolensis and piperitenone, a pure compound isolated from Lippia javanica essential oil, were found to have marked activity against Entamoeba histolytica, with median inhibitory concentrations (IC(50)) of 25 and 100 microg/ml, respectively. The other P. angolensis compounds were either weakly active or showed no activity against the amoebae when tested at concentrations up to 400 microg/ml. All seven compounds isolated from P. angolensis showed less toxicity against cultures of human (HCT-8) cells than piperitenone, with IC(50) of 175-375 microg/ml. The presence of epichatechin and derivatives (with strong antibacterial activities but generally weak activities against Entamoeba histolytica) in the stem bark of P. angolensis has thus been demonstrated. Further investigation of the activities of these compounds and their potential use in the treatment of bacterial diseases appears justified.