Inhibition of HIV-1 protease and RNase H of HIV-1 reverse transcriptase activities by long chain phenols from the sarcotestas of Ginkgo biloba.

Nine long-chain phenols: four cardanols (1-4), two bilobols (5, 6) and three alkylsalicylic acids (7-9) [corrected] were isolated from the CH(2)Cl(2) extracts of the sarcotestas of Ginkgo biloba as HIV-1 protease (PR) inhibitors. From these phenols, the bilobols (IC (50), 2.6 - 5.8 microM) and alkylsalicylic acids (IC (50), 10.2 - 24.9 microM) exhibited dose-dependent potent inhibitory activities on HIV-1 PR, while the cardanols did not. On the other hand, only the alkylsalicylic acids (IC (50), 33.7 - 170.3 microM) inhibited the activities of RNase H of HIV-1 reverse transcriptase (RT), while all of the compounds failed to affect the RNA dependent DNA polymerase (RDDP) of HIV-1 RT. Therefore, we regard bilobols as a new class and selective inhibitors of HIV-1 PR; in addition, alkylsalicylic acids are elucidated as a new class of inhibitors against HIV-1 PR and RNase H of HIV-1 RT.