Synthesis and biological evaluation of ricinoleic acid-based lipoamino acid derivatives

Abstract

A series of novel ricinoleic acid based lipoamino acid derivatives were synthesized from (Z)-methyl-12-aminooctadec-9-enoate and different l-amino acids (glycine, alanine, phenyl alanine, valine, leucine, isoleucine, proline and tryptophan). The structures of all the prepared compounds were characterized by 1H NMR, 13C NMR and mass spectral studies. The title compounds were evaluated for their antimicrobial and anti-biofilm activities. Among all the derivatives, compound 7a (Z)-methyl-12-(2-aminoacetamido)octadec-9-enoate exhibited promising antibacterial activity (MIC, 3.9–7.8μg/mL) and compounds 7b (Z)-methyl 12-(2-aminopropanamido)octadec-9-enoate and 7g (Z)-methyl-12-(pyrrolidine-2-carboxamido)octadec-9-enoate exhibited moderate activity (MIC, 7.8–31.2μg/mL) selectively against four different Gram-positive bacterial strains such as Staphylococcus aureus MTCC 96, Bacillus subtilis MTCC 121, S. aureus MLS-16 MTCC 2940, Micrococcus luteus MTCC 2470. These compounds also exhibited excellent antifungal activity against studied fungal strains. Further, the compounds 7a, 7b and 7g were also screened for anti-biofilm activity. Among these lipoamino acid derivatives, compound 7a exhibited good anti-biofilm activity (IC50, 1.9–4.1μg/mL) against four Gram-positive bacterial strains.