Antibacterial and antileishmanial activity of 1,4-dihydropyridine derivatives

We have synthesized twenty-three 1,4-dihydropyridine derivatives (1,4-DHPs) by using a microwave-assisted one-pot multicomponent Hantzsch reaction and evaluated their antibacterial activity against a representative panel of cariogenic bacteria and their in vitro antileishmanial activity against Leishmania (L.) amazonensis promastigotes. Thirteen compounds were moderately active against Streptococcus sanguinis, Streptococcus mitis, and Lactobacillus paracasei. Compound 22 (diethyl 4-(3-methoxy-4-hydroxyphenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate) displayed moderate antibacterial activity against S. mitis and S. sanguinis, with a Minimum Inhibitory Concentration (MIC) of 500 µg/mL); compounds 8 (diethyl 4-(3-chlorophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate ) and 10 (diethyl 4-(3-nitrophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate) were moderately active against S. sanguinis (MIC = 500 µg/mL) and very active against L. amazonensis promastigotes (IC50 = 43.08 and 34.28 µM, respectively). Among the eight 1,4-DHPs that were active (IC50 < 50 µM) against L. amazonensis promastigotes, compound 13 (diethyl 4-(3,4,5-trimethoxyphenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate) gave the lowest IC50 (24.62 µM). On the basis of our results, asymmetric 1,4-DHPs derived from dimedone exhibit antileishmanial potential.