Cationic peptides from peptic hydrolysates of rice endosperm protein exhibit antimicrobial, LPS-neutralizing, and angiogenic activities

• Published in: Peptides (New York, N.Y. : 1980) Vol. 97; pp. 70 - 78
• Main Authors: Taniguchi, Masayuki, Kawabe, Junya, Toyoda, Ryu, Namae, Toshiki, Ochiai, Akihito, Saitoh, Eiichi, Tanaka, Takaaki
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2017
• Subjects: Angiogenic peptides; Angiogenic Proteins - chemistry; Angiogenic Proteins - pharmacology; Animals; Anti-Infective Agents - chemistry; Anti-Infective Agents - pharmacology; Antifungal Agents - pharmacology; Antimicrobial Cationic Peptides - chemical synthesis; Antimicrobial Cationic Peptides - chemistry; Antimicrobial peptides; Bacteria - drug effects; Endosperm - chemistry; Fungi - drug effects; Hemolysis - drug effects; Human Umbilical Vein Endothelial Cells; Humans; Hydrolysates of rice endosperm proteins; Hydrolysis; Inhibitory Concentration 50; Lipopolysaccharides; LPS-neutralizing peptides; Multi-functional cationic peptides; Oryza - chemistry; Plant Proteins - chemistry; Multi-functional cationic peptides; Hydrolysates of rice endosperm proteins; Angiogenic peptides; LPS-neutralizing peptides; Antimicrobial peptides
• ISSN: 0196-9781; 1873-5169
• DOI: 10.1016/j.peptides.2017.09.019

•Peptides were fractionated from hydrolysates of rice endosperm protein by autofocusing.•Cationic peptides were purified by RP-HPLC and then identified by MALDI-TOF MS.•Of identified peptides, five cationic peptides exhibited dual or multiple functions.•Five peptides exhibited angiogenic and LPS-neutralizing activities.•Fractions obtained from hydrolysates of rice endosperm protein contain non-toxic cationic peptides with multiple functions. In this study, we hydrolyzed rice endosperm protein (REP) with pepsin and generated 20 fractions containing multifunctional cationic peptides with varying isoelectric point (pI) values using ampholyte-free isoelectric focusing (autofocusing). Subsequently, we determined antimicrobial activities of each fraction against the pathogens Prophyromonas gingivalis, Propionibacterium acnes, Streptocossus mutans, and Candida albicans. Fractions 18, 19, and 20 had pI values greater than 12 and exhibited antimicrobial activity against P. gingivalis, P. acnes, and C. albicans, but not against S. mutans. In further experiments, we purified and identified cationic peptides from fractions 18, 19, and 20 using reversed-phase high-performance liquid chromatography and matrix-assisted laser/desorption ionization–time-of-flight mass spectroscopy. We also chemically synthesized five identified peptides (RSVSKSR, RRVIEPR, ERFQPMFRRPG, RVRQNIDNPNRADTYNPRAG, and VVRRVIEPRGLL) with pI values greater than 10.5 and evaluated antimicrobial, lipopolysaccharide (LPS)-neutralizing, and angiogenic activities. Among these synthetic peptides, only VVRRVIEPRGLL exhibited antimicrobial activity against P. gingivalis, with an IC50 value of 87μM. However, all five cationic peptides exhibited LPS-neutralizing and angiogenic activities with little or no hemolytic activity against mammalian red blood cells at functional concentrations. These present data show dual or multiple functions of the five identified cationic peptides with little or no hemolytic activity. Therefore, fractions containing cationic peptides from REP hydrolysates have the potential to be used as dietary supplements and functional ingredients in food products.