(±)-trans-2-phenyl-2,3-dihydrobenzofurans as leishmanicidal agents: Synthesis, in vitro evaluation and SAR analysis

Leishmaniasis, a neglected tropical disease caused by parasites of the genus Leishmania, causes a serious burden of disease around the world, represents a threat to the life of millions of people, and therefore is a major public health problem. More effective and non-toxic new treatments are required, especially for visceral leishmaniasis, the most severe form of the disease. On the backdrop that dihydrobenzofurans have previously shown antileishmanial activity, we present here the synthesis of a set of seventy trans-2-phenyl-2,3-dihydrobenzofurans and evaluation of their in vitro activity against Leishmania donovani as well as a discussion of structure-activity relationships. Compounds 8m-o and 8r displayed the highest potency (IC₅₀ < 2 μmol/L) and interesting selectivity of the antileishmanial activity over cytotoxicity against mammalian cells (SI > 4.6). Nonetheless, structural optimization as further requirement was inferred from the high clearance of the most potent compound (8m) observed during determination in vitro of its metabolic stability. On the other hand, chiral separation of 8m and subsequent biological evaluation of its enantiomers demonstrated no effect of chirality on activity and cytotoxicity. Holistic analysis of in silico ADME-like properties and ligand efficiency metrics by a simple scoring function estimating druglikeness highlighted compounds 16c, 18 and 23 as promising candidates for further development. Overall, the potential of trans-2-phenyl-2,3-dihydrobenzofurans as leishmanicidal agents was confirmed.