The increasing tendency of microbial infections, rapid emergence of drug-resistant to recent antibiotics and quick evolution through mutation are of great threats to control of microbial infection. It has generated the urgency to develop new class of antibiotics. Antimicrobial peptides (AMPs) are the most important and effective antibiotics to combat the increasing emergence of drug resistant bacteria. In plants, several molecules are responsible for defense having known function as antimicrobial peptides (AMPs). The plant species used in this study is Jatropha curcas L., the twigs of J. curcas are used for tooth brushing from the ancient times. A novel antimicrobial peptide isolated by RP-HPLC from Jatropha curcas L and molecular weight was determined in MALDI-ToF mass spectrometry, designated as Jc-AMP. It has excellent activity against S. mutans and S. epidermidis, human oral pathogenic bacteria. The MIC and MBC values of the Jc-AMP were 2 and 4 μg/mL, respectively. Jc-AMP showed antimicrobial activity by increasing the membrane permeability through the degradation of cell membrane of S. epidermidis and S. mutans.It also inhibits the biofilm formation of S. mutans and has no adverse effects on red blood cells. Jc-AMP showed a hydrophobic ratio of 64% and a boman index of -1.03 kcal/mol. Electron microscopy and membrane permeability assay (FACS) confirm the formation of pores or channels in the bacterial cell membrane through hydrophobic surface of the peptide.
Key words: Antibacterial peptides, Jatropha curcas,hydrophobic, membrane permeability.