In vitro and in silico studies of prenylated phenylpropanoids of green propolis and their derivatives against cariogenic bacteria

Artepillin C, drupanin, and plicatin B are prenylated phenylpanoids naturally occurring in Brazilian green propolis. In this study, these compounds and eleven derivatives were synthesized and evaluated for their in vitro antimicrobial activity against a representative panel of cariogenic bacteria in terms of their minimum inhibitory concentration (MIC) values. Plicatin B (2) and its hydrogenated derivative 8 (2’,3’,7,8-tetrahydro-plicatin B) were the most active compounds. Plicatin B (2) displayed strong activity against all bacteria tested (MIC = 31.2 μg/mL). On the other hand, compound 8 (2’,3’,7,8-tetrahydro-plicatin A) displayed strong activity against Streptococcus mutans, S. salivarius, S. sobrinus, Lactobacillus paracasei (MIC = 62.5 μg/mL) and S. mitis (MIC = 31.2 μg/mL) as well as a moderate activity against Enterococcus faecalis and S. sanguinis (MIC = 125 μg/mL). In silico studies showed that the complexes formed compound 2 and 8 has energy score values close to those of the native ligands of S. mitis, S. sanguinis, and S. mutans due to the formation of strong hydrogen bonds with the active sites of those bacteria. Moreover, all the estimated physicochemical parameters satisfy the drug-likeness criteria without violating the Lipinski, Veber, and Egan rules, so these compounds are not expected to cause problems with oral bioavailability and pharmacokinetic parameters. Compounds 2 and 8 also have suitable ADME-T parameters, as the online server pkCSM calculates. These results make compounds 2 and 8 good candidates as anticariogenic compounds.