Abstract

Recently, drug resistance due to excessive use of antibiotics has become a severe problem, and alternative antibiotics’ development has become an urgent problem. Epoxy hyptolide is a compound of the synthesis of hyptolide through the reaction using meta-chloroperoxybenzoic acid (mCPBA) oxidizer, potentially developed as a natural antibiotic. This study aimed to investigate the relationship between hyptolide and its epoxide structure on the antibacterial activity against Gram-positive and Gram-negative bacteria. The results indicated that epoxy hyptolide was a successful synthesis of hyptolide from the isolation of the leaves of Hyptis pectinata (L.) Poit using the mCPBA. The chemical characterization of hyptolide and its epoxidation revealed a melting point of 86.9°C–87.8°C and 79°C–80°C, respectively. The Fourier-transform infrared spectrum of epoxy hyptolide showed the presence of a lactone ring on wavenumbers 1,250 cm−1 and 814 cm−1. On the other hand, a detailed 1H nuclear magnetic resonance spectrum of a chemical shift of 3.5 ppm indicated the presence of an oxygen ring due to the transformation of C=C olefin double bond into an epoxide form. Furthermore, the test of the antibacterial activity of hyptolide and epoxy hyptolide was carried out by disk diffusion method. The results revealed that hyptolide and epoxy hyptolide have a border antimicrobial spectrum in a dose-dependent manner. The maximum inhibition zone (IZ) of hyptolide was observed in Bacillus subtilis and the IZ was found to be 28.00 mm in comparison with amoxicillin as the control had 7.58 mm IZ. Interestingly, the most effective antibacterial activity in Salmonella typhi caused by the presence of epoxy hyptolide with the maximum IZ was 21.80 mm, compared to amoxicillin that had 6.320 mm IZ. It can be concluded that Gram-negative bacteria was more susceptible to epoxy hyptolide in comparison to hyptolide. The cell wall structure of the Gram-positive and Gram-negative bacteria could be the main reason for the bacteria’s susceptibility.

Key words: Hyptis pectinata (L.) Poit, mCPBA Epoxidation, Hyptolide, Gram positive-negative bacteria