Novel Trichomonacidal Spermicides

Abstract

Metronidazole, the U.S. Food and Drug Administration-approved drug against trichomoniasis, is nonspermicidal and thus cannot offer pregnancy protection when used vaginally. Furthermore, increasing resistance of Trichomonas vaginalis to 5-nitro-imidazoles is a cause for serious concern. On the other hand, the vaginal spermicide nonoxynol-9 (N-9) does not protect against sexually transmitted diseases and HIV in clinical situations but may in fact increase their incidence due to its nonspecific, surfactant action. We therefore designed dually active, nonsurfactant molecules that were capable of killing Trichomonas vaginalis (both metronidazole-susceptible and -resistant strains) and irreversibly inactivating 100% human sperm at doses that were noncytotoxic to human cervical epithelial (HeLa) cells and vaginal microflora (lactobacilli) in vitro. Anaerobic energy metabolism, cell motility, and defense against reactive oxygen species, which are key to survival of both sperm and Trichomonas in the host after intravaginal inoculation, depend crucially on availability of free thiols. Consequently, molecules were designed with carbodithioic acid moiety as the major pharmacophore, and chemical variations were incorporated to provide high excess of reactive thiols for interacting with accessible thiols on sperm and Trichomonas. We report here the in vitro activities, structureactivity relationships, and safety profiles of these spermicidal antitrichomonas agents, the most promising of which was more effective than N-9 (the OTC spermicide) in inactivating human sperm and more efficacious than metronidazole in killing Trichomonas vaginalis (including metronidazole-resistant strain). It also significantly reduced the available free thiols on human sperm and inhibited the cytoadherence of Trichomonas on HeLa cells. Experimentally in vitro, the new compounds appeared to be safer than N-9 for vaginal use.

N-Alkyl/aryl-4-(3-substituted-3-phenylpropyl)piperazine-1-carbothioamide as dual-action vaginal microbicides with reverse transcriptase inhibition

“…Compound 12 exhibited promising RT inhibitory activity at 72.30%. Another nine compounds (13e16, 20e22, 25,26) showed moderate activity (38.40e59.62%). The standard nonnucleoside reverse transcriptase inhibitor (NNRTI), Nevirapine (NVP) showed 99.6% inhibition.…”

“…Within hydroxyl compounds (17e21) the preferred groups in thiourea at N 4 of piperazine were phenethyl (21) and butyl (17) against MTZ susceptible and phenethyl (21) and cyclohexyl (19) against resistant strain. When trifluoromethylphenoxy (22e26) group was present at position-3 of propanamine chain then phenethyl group in thiourea at N 4 of piperazine (26) susceptible to resistant strains while these compounds lost activity by 2e4 times only. The results of antifungal activity of N-alkyl/aryl-4-(3-substituted-3-phenylpropyl)piperazine-1-carbothioamide (12e26, MIC 4.22e74.8 mM; Table 2) showed that the oxo derivatives (12e16) presented better activity profile than hydroxyl/4-trifluoromethylphenoxy derivatives (17e26).…”

“…Phenethyl 4-(3-phenyl-3-(4-(trifluoromethyl)phenoxy) propyl)-piperazine-1-carbothioamide (26) The title compound was synthesized from phenethyl 4-(3-hydroxy-3-phenylpropyl)piperazine-1-carbothioamide (21) Spermicidal activity was determined by MEC i.e., the minimum effective spermicidal concentration as previously described in standard procedure [21]. Briefly, the test compounds were dissolved in a minimum volume of DMSO and diluted with physiological saline (0.85% NaCl in distilled water) to make a 1.0% test solution.…”

“…The effect of compounds exhibiting potent spermicidal activity on Lactobacillus acidophilus was determined by following the method published earlier [26]. Spores of Lactobacillus jensenii (ATCC 25258, strain 62G) were grown in 6% Rogosa SL broth medium (Hi Media, India) containing 0.132% acetic acid at 37 C. Briefly, Rogosa SL broth medium was distributed in a 48-well plate (500m l/well).…”

A unique dithiocarbamate chemistry during design & synthesis of novel sperm-immobilizing agents

“…Piperazine (1) was protected selectively at one nitrogen (2) which on being reacted with carbon disulfide under alkaline conditions gave dithiocarbamate sodium salt (3). Compound (3) was reacted with alkyl halides to yield carbodithioic esters (4)(5)(6)(7)(8), which were deprotected with TFA to provide desired compounds (9)(10)(11)(12)(13), however, in the case of benzyl chloride an unusual N-benzyl product (14) was isolated in 20-30% yield (Scheme 1).…”