Structure-Reactivity Relationships on Substrates and Inhibitors of the Lysine Deacylase Sirtuin 2 from Schistosoma Mansoni (SmSirt2)

The standard drug for treatment of the neglected disease Schistosomiasis is Praziquantel, and the possible emergence of resistance to this treatment makes the research on novel therapeutic agents necessary and urgent. To this end, the targeting of Schistosoma mansoni epigenetic enzymes, which regulate the parasitic life cycle, emerged as promising approach. Due to strong effects of human Sirtuin inhibitors on parasite survival and reproduction, Schistosoma sirtuins were postulated as potential therapeutic targets. In vitro testing of synthetic substrates of SmSirt2 and kinetic experiments on a myristoylated peptide newly demonstrated lysine long chain deacylation as an intrinsic SmSirt2 activity in addition to the known deacetylation. Focused in vitro screening of the GSK Kinetobox library and structure-activity relationships (SAR) of identified hits, led to the first SmSirt2 inhibitors with activity in the low micromolar range. Several SmSirt2 inhibitors showed potency against both larval schistosomes (viability) and adult worms (pairing, egg laying) in culture without general toxicity to human cancer cells.