A novel antioxidant and ACE inhibitory peptide from rice bran protein: Biochemical characterization and molecular docking study

•Rice bran protein was hydrolyzed using trypsin and the hydrolysates were isolated and purified.•A novel antioxidant and antihypertension peptide was obtained.•The amino acid sequences, Tyr-Ser-Lys was identified by Q-TOF-MS.•Molecular docking studies were firstly used to reveal the ACE inhibition of the peptide.

Rice bran protein was hydrolyzed using trypsin. The hydrolysate (RBPH) was then further separated by membrane bioreactor system, gel filtration and reversed phase high-performance liquid chromatography (RP-HPLC). A novel antioxidant and angiotensin I-converting enzyme (ACE) inhibitory peptide named as F2-a, which exhibited high DPPH free radicals scavenging activity, reducing power and ACE inhibitory activity (IC50 of 76 μM) was isolated. The amino acid sequence, Tyr-Ser-Lys (Mw: 395.0 Da), was identified by Quardrupole Time-of-flight Mass Spectrometer (Q-TOF-MS) with an electro-spray ionization (ESI) source. The molecular docking study revealed that the ACE inhibition of Tyr-Ser-Lys was mainly attributed to forming very strong hydrogen bonds with the active pockets of human ACE. These results indicate that rice bran is a potential source of bioactive peptides possessing antioxidant and ACE inhibitory activities.