Comparative in vitro effects of AZT and extracts of Ocimum gratissimum, Ficus polita, Clausena anisata, Alchornea cordifolia, and Elaeophorbia drupifera against HIV-1 and HIV-2 infections.

The effects of Ocimum gratissimum (GHX-2), Ficus polita (GHX-6), Clausena anisata (GHX-7), Alchornea cordifolia (GHX-26), Elaeophorbia drupifera (GHX-27), and AZT on in vitro HIV-1 and HIV-2 replication and cytopathicity were compared. All plant extracts inhibited HIV-1 strain HTLVIII(B) cytopathicity, the leaves of GHX-2 and the seeds of GHX-26 having high antiviral indices (110 and 90, respectively). Against HIV-2 strain GH1, the EC(50) values ranged from <0.005 to 0.075 mg/ml when treatment was started at 40min after virus adsorption, except for GHX-7 which showed only moderate activity and GHX-26 which had no activity. When treatment was delayed for 2h, the plant extracts, unlike AZT, were still very effective against HIV-2. Likewise, only the plant extracts were able to attain EC(90) values when high multiplicity of infection (MOI) with HIV-1 strain GH3 was used when treatment was delayed for 2h. In Molt-4 cocultures with Molt-4/HIV, early cytopathic effect (CPE) of cell fusion was unaffected by AZT but was completely inhibited by all plants at noncytotoxic concentrations. In addition, GHX-27 was selectively toxic to Molt-4/HIV cells. The plant extracts also inhibited HIV-1 reverse transcriptase (RT) activity at EC(50) values of <0.01-0.03 mg/ml. HIV-1 proviral DNA copying as determined in a polymerase chain reaction, was completely inhibited by GHX-2 and GHX-6 at 0.011 and 0.015 mg/ml, respectively. GHX-26 and GHX-27 showed only very moderate activity.