African Journal of Biotechnology Vol. 3 (10), pp. 555-559, October 2004           
ISSN 1684–5315 © 2004 Academic Journals

Full Length Research Paper

In vitro activity of three selected South African medicinal plants against human immunodeficiency virus type 1 reverse transcriptase

Pascal Obong Bessong^{1, 2*}, Chikwelu Larry Obi², Eunice Igumbor², Marie-Line Andreola³, Simon Litvak³

¹Center for Global Health, Division of Infectious Diseases and International Health, University of Virginia, P.O Box  801379 Charlottesville, VA 22908, USA.

²Department of Microbiology, Faculty of Natural and Applied Sciences, University of Venda for Science and Technology. PMB X5050 Thohoyandou 0950, Limpopo Province, South Africa.  ³REGER, UMR-5097 CNRS, Université Victor Segalen, Bordeaux 2, Rue Leo Saignat 33076 Bordeaux, France.

*Corresponding author. E-Mail: pb4j@virginia.edu. Tel: +1 434 924 9672 ,Fax: +1 434 977 5323

Accepted 10 August, 2004

Crude extracts of three ethnobotanically selected medicinal plants were screened for activity against two functions of human immunodeficiency type 1 reverse transcriptase. Inhibition of the RNA-dependent DNA polymerase activity was evaluated by measuring the degree of incorporation of methyl-3H thymidine triphosphate using polyadenylic acid.oligodeoxythymidylic acid as a template primer. Ribonuclease H activity was evaluated by measuring the extent of degradation of a radiolabelled RNA in an RNA/DNA hybrid by reverse transcriptase in the presence of test substance. The methanol extract of the leaves of Terminalia sericea (Combretaceae) was found to strongly inhibit the polymerase (IC₅₀ = 7.2 µg/ml) and the ribonuclease H (IC₅₀ = 8.1 µg/ml) activities. Isolation and characterization of a possible active molecule is warranted.

Key words: HIV-1 reverse transcriptase; inhibition; crude extracts; medicinal plants; Terminalia sericea; South Africa.