Abstract
The observation that stilbene 3 (5350150) blocks HIV replication through its impact on HIV mRNA processing prompted a program to develop non-cytotoxic analogues that maintain its mechanism of action. This initially involved replacement of the central double bond in 3 by an amide function and the quinoline motif by a 2-aminobenzothiazole subunit, as in 12jj (R' = Cl), 12pp (R = NO(2)), and 12vv (R = CF(3)). On the basis of the possible CF(3) ↔ NO(2) bioisostere relationship in 12vv and 12pp, compound 23 was prepared and also found to be active. In the final step, the thiazole compounds 28 (GPS488) (EC(50) = 1.66 μM) and 29 (GPS491) (EC(50) = 0.47 μM) were prepared and evaluated. Similar activity and cell viability values (therapeutic index (TI = CC(50)/EC(50)) values of 50-100) were observed in primary peripheral blood mononuclear cells. Furthermore, they remained active against a panel of HIV mutant strains displaying resistance to individual drugs used in antiretroviral therapy. It was determined that compound 29 suppressed expression of the HIV-1 structural protein Gag and altered HIV-1 RNA accumulation, decreasing the abundance of RNAs encoding the structural proteins while increasing levels of viral RNAs encoding the regulatory proteins, a pattern similar to that seen for compound 3.