Trichomoniasis is the most common nonviral sexually transmitted disease in humans, but treatment options are limited. Here, we report a resorufin-based drug sensitivity assay for high-throughput microplate-based screening under hypoxic conditions. A 5203-compound enamine kinase library and several specialized compound series were tested for the inhibition of Trichomonas growth at 10 μM with Z' values of >0.5. Hits were rescreened in serial dilution to establish an IC50 concentration. A series of 7-substituted 7-deazaadenosine analogues emerged as highly potent anti-T. vaginalis agents, with EC50 values in the low double digit nanomolar range. These analogues exhibited excellent selectivity indices. Follow-up medicinal chemistry efforts identified an optimal ribofuranose and C7 substituent. Several nucleosides rapidly cleared cultures of T. vaginalis at a concentrations of just 2 × EC50. Preliminary in vivo evaluation in a murine trichomoniasis model (Tritrichomonas foetus) revealed promising activity upon topical administration, validating purine nucleoside analogues as a new class of antitrichomonal agents.
Keywords: Trichomonas vaginalis; high-throughput screening; mouse model; nucleoside analog; tubercidin.