Anti-HIV-1 protease- and HIV-1 integrase activities of Thai medicinal plants known as Hua-Khao-Yen

Ethanolic- and water extracts from five species of Thai medicinal plants known as Hua-Khao-Yen were tested for their inhibitory effects against HIV-1 protease (HIV-PR) and HIV-1 integrase (HIV-1 IN). The result revealed that the ethanolic (EtOH) extract of Smilax corbularia exhibited anti-HIV-1 IN activity with an IC50 value of 1.9 mu g/ml, followed by the water extract of Dioscorea birmanica (IC50 = 4.5 mu g/ml), the EtOH extract of Dioscorea birmanica (IC50 = 4.7 mu g/ml), the water extract of Smilax corbularia (IC50 = 5.4 mu g/ml), the EtOH extract of Smilax glabra (IC50 = 6.7 mu g/ml) and the water extract of Smilax glabra (IC50 = 8.5 mu g/ml). The extracts of Pygmaeopremna herbacea and Dioscorea membranacea were apparently inactive (IC50 > 100 mu g/ml). Interestingly, only the EtOH extract of Dioscorea membranacea showed appreciable activity (IC50 = 48 mu g/ml) against HIV-1 PR, while the other extracts possessed mild activity. This result strongly supported the basis for the use of Smilax corbularia and Dioscorea membranacea for AIDS treatment by Thai traditional doctors. (c) 2005 Elsevier Ireland Ltd. All rights reserved.