Anti-AIDS Agents. 60. † Substituted 3‘R,4‘R-Di-O-(−)-camphanoyl-2‘,2‘-dimethyldihydropyrano[2,3-f]chromone (DCP) Analogues as Potent Anti-HIV Agents

Synthesis of positional isomers is a commonly used technique in drug design. Accordingly, based on prior SAR studies of 3‘R,4‘R-di-O-(S)-camphanoyl-(+)-cis-khellactone (DCK, 1) analogues, a series of mono- and disubstituted chromone derivatives of 3‘R,4‘R-di-O-(−)-camphanoyl-2‘,2‘-dimethyldihydropyrano[2,3-f]chromone (DCP, 4) were designed and synthesized. Together with 1 and 4-methyl DCK (2), all newly synthesized DCP analogues (4−21) were screened for anti-HIV-1 activity against a non-drug-resistant strain in H9 lymphocytes and a multiple reverse transcriptase (RT) inhibitor-resistant strain in the MT4 cell line. Several DCP analogues (4, 5, 7, 8, 13, and 17) exhibited extremely high anti-HIV activity in the non-drug-resistant strain assay, with EC50 values ranging from 0.00032 to 0.0057 μM and remarkable therapeutic indexes (TI) ranging from 5.6 × 103 to 1.16 × 105, which were similar to those of 2 (EC50 0.0059 μM, TI > 6.6 × 103) and better than those of 1 (EC50 0.049 μM, TI > 328). Even more promisingly, some DCP analogues also showed activity against a multi-RT inhibitor-resistant strain, HIV-1 RTMDR1, whereas most DCK analogues did not. The most significant compound was 8, with an EC50 value of 0.06 μM and TI of 718 against the multi-RT inhibitor-resistant HIV-1 strain. Compounds 9 and 10 also showed good activity with an EC50 value of 0.14 μM, and TIs of 272 and >111, respectively. 2-Ethyl DCP (8) exhibited the best anti-HIV activity in both assays. Further development of 8-related compounds as clinical trial candidates is warranted.