Synthesis, Structure–Activity Relationships, and Biological Studies of Chromenochalcones as Potential Antileishmanial Agents

Antileishmanial activities of a library of synthetic chalcone analogues have been examined. Among them, five compounds (<b>11</b>, <b>14</b>, <b>16</b>, <b>17</b>, <b>22</b>, and <b>24</b>) exhibited better activity than the marketed drug miltefosine in in vitro studies against the intracellular amastigotes form of Leishmania donovani. Three promising compounds, <b>16</b>, <b>17</b>, and <b>22</b>, were tested in a L. donovani/hamster model. Oral administration of chalcone <b>16</b>, at a concentration of 100 mg/kg of body weight per day for 5 consecutive days, resulted in >84% parasite inhibition at day 7 post-treatment and it retained the activity until day 28. The molecular and immunological studies revealed that compound <b>16</b> has a dual nature to act as a direct parasite killing agent and as a host immunostimulant. Pharmacokinetics and serum albumin binding studies also suggest that compound <b>16</b> has the potential to be a candidate for the treatment of the nonhealing form of leishmaniasis