Identification and characterization of multifunctional cationic peptides derived from peptic hydrolysates of rice bran protein

- Peptides were fractionated from hydrolysates of rice bran protein by autofocusing.
- Cationic peptides were purified by RP-HPLC and then identified by MALDI-TOF MS.
- Of identified peptides, three cationic peptides exhibited multiple functions.
- Three peptides exhibited angiogenic, LPS-neutralizing, and antimicrobial activities.
- Multifunctional cationic peptides are expected to be used as ingredients in foods.

In this study, to prepare the fraction containing multifunctional cationic peptides, we first hydrolyzed rice bran protein (RBP) with pepsin. We separated the enzymatic hydrolysate of RBP into 20 fractions containing peptides with different isoelectric point (pI) values by ampholyte-free isoelectric focusing (autofocusing). Subsequently, we examined the antimicrobial activity of each fraction against four pathogens. In addition, we purified the cationic peptides from fractions exhibiting antimicrobial activity by reversed-phase high-performance liquid chromatography and identified them by matrix-assisted laser/desorption ionization-time-of-flight mass spectroscopy. Of five cationic peptides identified, we chemically synthesized three peptides with high pI values and evaluated their multiple functions, including antimicrobial, lipopolysaccharide-neutralizing and angiogenic activities. Our results demonstrated that the three identified cationic peptides exhibited multiple functions with little or no haemolytic activity. Fractions containing cationic peptides obtained from RBP hydrolysate have the potential to be used as dietary supplements and functional ingredients in food products.