A novel antifungal analog peptide derived from protaetiamycine

Identification, characterization and hypolipidemic effect of novel peptides in protein hydrolysate from Protaetia brevitarsis larvae

The proteins were mainly derived from Protaetia brevitarsis larval extracts obtained using two empty intestine methods (traditional static method: TSM or salt immersion stress method: SISM) and extraction solvents (water: W or 50 % water-ethanol: W:E), and the proteins were used as objects to investigate the effect of emptying intestine methods on hypolipidemic peptides. The results revealed that the F-2 fractions of protein hydrolysate had stronger in vitro hypolipidemic activity, with the peptides obtained by SISM possessing a stronger cholesterol micelle solubility inhibition rate, especially in SISM-W:E-P. Moreover, a total of 106 peptides were tentatively identified, among which SISM identified more peptides with an amino acid number < 8. Meanwhile, five novel peptides (YPPFH, YPGFGK, KYPF, SPLPGPR and VPPP) exhibited good hypolipidemic activity in vitro and in vivo, among which YPPFH, VPPP and KYPF had strong inhibitory activities on pancreatic lipase (PL) and cholesteryl esterase (CE), and KYPF, SPLPGPR and VPPP could significantly reduce the TG content in Caenorhabditis elegans. Thus, P. brevitarsis can be developed as a naturally derived hypolipidemic component for the development and application in functional foods.

Anti-Candida property of a lignan glycoside derived from Styrax japonica S. et Z. via membrane-active mechanisms

Styraxjaponoside C was investigated with respect to its antifungal activity and mechanisms of action. Devoid of hemolytic activity, Styraxjaponoside C demonstrated an antifungal effect against the human pathogenic yeast Candida albicans in an energy-independent manner. To characterize the mechanisms of the antifungal activity of Styraxjaponoside C, fluorescence analysis with membrane probe 1,6-diphenyl-1,3,5-hexatriene, and flow cytometric analysis on C. albicans were conducted. The results showed that Styraxjaponosdie C induced cytoplasmic membrane perturbation. The current study suggested that Styraxjaponoside C was active against C. albicans with membrane-active mechanisms.

Characterization and cDNA cloning of a cecropin-like antimicrobial peptide, papiliocin, from the swallowtail butterfly, Papilio xuthus

Cecropin is a well-studied antimicrobial peptide that is synthesized in fat body cells and hemocytes of insects in response to hypodermic injury or bacterial infection. A 503 bp cDNA encoding for a cecropin-like peptide was isolated by employing annealing control primer (ACP)-based differential display PCR and 5'-RACE with immunized Papilio xuthus larvae. The open reading frame of the isolated cDNA encoded for a 62-amino acid prepropeptide with a putative 22-residue signal peptide, a 2-residue propeptide, and a 38-residue mature peptide with a theoretical mass of 4060.89 Da. The deduced amino acid sequence of the peptide evidenced a significant degree of identity with other lepidopteran cecropins. This peptide was named papiliocin. RTPCR results revealed that the papiliocin transcript was detected at significant levels after injection with bacterial lipopolysaccharide (LPS). On the basis of the deduced amino acid sequence of papiliocin, a 38-mer mature peptide was chemically synthesized via the Fmoc method, and its antimicrobial activity was analyzed. The synthetic papiliocin peptide evidenced a broad spectrum of activity against fungi, Gram-positive and Gram-negative bacteria, and also evidenced no hemolytic activity against human red blood cells.