In vitro anti-HIV-1 activity of salicylidene acylhydrazide compounds

Abstract

Introduction 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. Methods 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. Results 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. Conclusions 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.

Formulation of the Microbicide INP0341 for In Vivo Protection against a Vaginal Challenge by Chlamydia trachomatis

“…INP0341 has previously been shown by in vitro and in vivo experiments to be a promising antibacterial and antiviral agent with activity against common sexually transmitted pathogens [1] , [2] , [3] , [5] , [6] . In these reports this compound was used in a liquid form.…”

“…A group of salicylidene acylhydrazide (SA) compounds have exhibited promising microbicidal properties in a number of recent studies [1] , [2] , [3] . The mechanism of action of the SA compounds is not completely understood but directly or indirectly involves iron, in that iron can reverse the antimicrobial activity [4] .…”

“…The mechanism of action of the SA compounds is not completely understood but directly or indirectly involves iron, in that iron can reverse the antimicrobial activity [4] . Of the SA compounds INP0341 has been the most extensively studied, and along with other SA compounds has been shown in vitro to exhibit activity against a variety of sexually transmitted organisms, including Chlamydia trachomatis, herpes simplex virus and HIV-1 [1] , [2] , [3] , [4] , [5] . In the case of HIV, the compounds exhibited IC 50 values (50% inhibition of virus) as low as 1 µM, while at the same time showing promise from a toxicological point of view [1] .…”

“…Of the SA compounds INP0341 has been the most extensively studied, and along with other SA compounds has been shown in vitro to exhibit activity against a variety of sexually transmitted organisms, including Chlamydia trachomatis, herpes simplex virus and HIV-1 [1] , [2] , [3] , [4] , [5] . In the case of HIV, the compounds exhibited IC 50 values (50% inhibition of virus) as low as 1 µM, while at the same time showing promise from a toxicological point of view [1] . The compounds have also been shown to be effective in vivo , when tested as a non-formulated solution in a mouse model to protect against a vaginal challenge with C. trachomatis [6] .…”

Benzylidene Acylhydrazides Inhibit Chlamydial Growth in a Type III Secretion- and Iron Chelation-Independent Manner

“…Nevertheless, it was not certain if these compounds exert their antichlamydial effect through direct inhibition of the chlamydial T3SS since the effect can be reversed with iron (26). This uncertainty was further augmented by the observation that salicylidene acylhydrazides also inhibit the growth of human immunodeficiency virus 1 in an irondependent manner (27). Therefore, we wanted to investigate whether or not it would be possible to segregate the antichlamydial effect, T3SS inhibition, and iron chelation by modifying salicylidene acylhydrazides.…”