Screening of antimicrobial peptides from hemolymph extract of tasar silkworm Antheraea mylitta against urinary tract and wound infecting multidrug-resistant bacteria

Antimicrobial peptides (AMPs) are an evolutionarily conserved component of the innate immune response and they were found among all classes of life forms. In the present study AMPs were extracted from the hemolymph of Antheraea mylitta and fractionated by High Performance Liquid Chromatography (HPLC). Antimicrobial activity was tested against three clinically isolated multidrug-resistant (MDR) bacteria, such as urinary tract infecting Escherichia coli, wound infecting Pseudomonas aeruginosa and Bacillus pumilus. Fraction I (comprised of three different peptides of varying mass) did not inhibit the growth of any of these clinical isolates, whereas, fraction III inhibited the growth of B. pumilus without affecting the growth of gram-negative isolates. Fraction II exhibited bactericidal effects against P. aeruginosa and E. coli, whereas, B. pumilus was not susceptible. Scanning electron microscopic study revealed that serious structural alterations of cell morphology and disruption of the outer membrane, that facilitates the release of cytoplasmic content through holes and channels in E. coli, treated with this isolated peptide. Our results indicate that the peptide from the isolated fraction could be used as potent alternative antimicrobial compounds for the treatment of MDR E. coli andP. aeruginosa infections

Identification of multifunctional peptides from human milk

Pharmaceutical industries have renewed interest in screening multifunctional bioactive peptides as a marketable product in health care applications. In this context, several animal and plant peptides with potential bioactivity have been reported. Milk proteins and peptides have received much attention as a source of health-enhancing components to be incorporated into nutraceuticals and functional foods. By using this source, 24 peptides have been fractionated and purified from human milk using RP-HPLC. Multifunctional roles including antimicrobial, antioxidant and growth stimulating activity have been evaluated in all 24 fractions. Nevertheless, only four fractions show multiple combined activities among them. Using a proteomic approach, two of these four peptides have been identified as lactoferrin derived peptide and kappa casein short chain peptide. Lactoferrin derived peptide (f8) is arginine-rich and kappa casein derived (f12) peptide is proline-rich. Both peptides (f8 and f12) showed antimicrobial activities against both Gram-positive and Gram-negative bacteria. Fraction 8 (f8) exhibits growth stimulating activity in 3T3 cell line and f12 shows higher free radical scavenging activity in comparison to other fractions. Finally, both peptides were in silico evaluated and some insights into their mechanism of action were provided. Thus, results indicate that these identified peptides have multiple biological activities which are valuable for the quick development of the neonate and may be considered as potential biotechnological products for nutraceutical industry