Inhibitory effect against polymerase and ribonuclease activities of HIV-reverse transcriptase of the aqueous leaf extract of Terminalia triflora

Dichloromethane, methanol and aqueous extracts from the leaves of Terminalia trifora were investigated for their inhibitory effect on polymerase and ribonuclease activities of HIV reverse transcriptase. The most potent activity was found in the aqueous extract, which inhibited both polymerase and ribonuclease activities of the enzyme with an IC50 of 1.6 mug/mL and 1.8 mug/mL respectively. The antiinfective activity of the extract was demonstrated in HLT4LacZ-IIIB cell culture with an IC50 of 1.0 mug/mL. The extract was submitted to a purification process by extractive and chromatographic methods. The activity remained in the hydrophillic fraction. Tannins present in this active purified fraction, as determined by TLC and HPLC methods, could account for the anti HIV-RT activity found in the aqueous extract. Copyright (C) 2002 John Wiley Sons, Ltd.