In Vitro and In Silico Analyses of New Cinnamid and Rosmarinic Acid-Derived Compounds Biosynthesized in Escherichia coli as Leishmania amazonensis Arginase Inhibitors

Arginase is a metalloenzyme that plays a central role inLeishmaniainfections. Previously, rosmarinic and caffeic acids were described as antileishmanial agents and asLeishmania amazonensisarginase inhibitors. Here, we describe the inhibition of arginase inL. amazonensisby rosmarinic acid analogs (1–7) and new caffeic acid-derived amides (8–10). Caffeic acid esters and amides were produced by means of an engineered synthesis inE. coliand tested againstL. amazonensisarginase. New amides (8–10) were biosynthesized inE. colicultured with 2 mM of different combinations of feeding substrates. The most potent arginase inhibitors showed Ki(s) ranging from 2 to 5.7 μM. Compounds2–4and7inhibitedL. amazonensisarginase (L-ARG) through a noncompetitive mechanism whilst compound9showed a competitive inhibition. By applying an in silico protocol, we determined the binding mode of compound9. The competitive inhibitor of L-ARG targeted the key residues within the binding site of the enzyme, establishing a metal coordination bond with the metal ions and a series of hydrophobic and polar contacts supporting its micromolar inhibition of L-ARG. These results highlight that dihydroxycinnamic-derived compounds can be used as the basis for developing new drugs using a powerful tool based on the biosynthesis of arginase inhibitors.Keywords:arginase;Leishmania amazonensis;biosynthesis;natural products;molecular modeling