Salicylidene acylhydrazide compounds have been shown to inhibit bacterial pathogens, including Chlamydia and Neisseria gonorrhoeae. If such compounds could also target HIV-1, their potential use as topical microbicides to prevent sexually transmitted infections would be considerable. We determined the in vitro anti-HIV-1 activity, cytotoxicity and mechanism of action of several salicylidene acylhydrazides.
Inhibitory activity was assessed using TZMbl cells and primary peripheral blood mononuclear cells (PBMCs) as targets for HIV-1 infection. Anti-viral activity was measured against cell-free and cell-associated virus and in vaginal fluid and semen simulants. Since the anti-bacterial activity of salicylidene acylhydrazides is reversible by Fe2+, we determined whether Fe2+ and other cations could reverse the anti-HIV-1 activity of the compounds. We also employed real-time PCR to determine the stage affected in the HIV-1 replication cycle.
We identified four compounds with 50% HIV-1 inhibitory concentrations of 1 to 7 μM. In vitro toxicity varied but was generally limited. Activity was similar against three R5 clade B primary isolates and whether targets for virus replication were TZMbl cells or PBMCs. Compounds inhibited cell-free and cell-associated virus and were active in vaginal fluid and semen simulants. Fe2+, but not other cations, reversed the anti-HIV-1 effect. Finally, inhibitory effect of the compounds occurred at a post-integration step.
We identified salicylidene acylhydrazides with in vitro anti-HIV-1 activity in the μM range. The activity of these compounds against other sexually transmitted pathogens makes them potential candidates to formulate for use as a broad-spectrum topical genital microbicide.