A TIBO derivative, R82913, is a potent inhibitor of HIV-1 reverse transcriptase with heteropolymer templates

R82913, (+)-S-4,5,6,7-tetrahydro-9-chloro-5-methyl-6-(3-methyl-2-butenyl)- imidazo[4,5,1-jk][1,4]-benzodiazepin-2(1H)-thione (a TIBO derivative), inhibited the replication of thirteen different strains of HIV-1 in CEM cells with a median IC50 of 0.15 microM. The concentration of compound that killed 50% of the cells was much higher (46 microM), indicating that R82913 has a high selectivity index. R82913 was 20-fold more potent than AZT-TP in the inhibition of HIV-1 Reverse Transcriptase in an assay using a naturally occurring template (ribosomal RNA) that more accurately resembles native viral RNA than a synthetic homopolymer. With this template, R82913 inhibited HIV-1 Reverse Transcriptase with an ID50 (0.01 microM) that is equal to, or lower than, the IC50 for this compound in all of our Cell Culture assays (0.01-0.65 microM). R82913 has no effect on the replication of HIV-2 in CEM cells and does not inhibit the Reverse Transcriptase from this virus.