Asterriquinone (ARQ; 2,5-bis-[1'-(1", 1"-dimethyl-2"-propenyl)- indol-3'-yl]-3,6-dihydroxy-1,4-benzoquinone) and its three analogues [i.e., 3,6-dihydroxy-2-[2'-(1", 1"-dimethyl-2"-propenyl)-indol-3'-yl]-5-[1', 7'- (1",1"-dimethylpropano)-indol-3'-yl]-1,4-benzoquinone (B1-4), 3,6-dihydroxy-2-[2'-(1", 1"-dimethyl-2"-propenyl)-indol-3'-yl]-5-indol-3'-yl-1,4-benzoquinone (C1-1) and 3,6-dihydroxy-2,5-diindol-3'-yl-1,4-benzoquinone (D-1)] were found to be strong inhibitors of the activity of reverse transcriptase from human immunodeficiency virus type-1. Under the reaction conditions employed, the enzyme activity was inhibited by more than 70% in the presence of 10 microM each of these compounds. The mode of inhibition by these compounds was competitive with respect to the template.primer, (rA)n.(dT)12-18, and noncompetitive with respect to the triphosphate substrate, dTTP. The Ki values of HIV-1 reverse transcriptase were determined to be 2.3, 1.5, 0.1 and 0.3 microM for ARQ, B1-4, C1-1 and D-1, respectively.