Abstract: An antioxidant peptide named PDII was purified by sequential ultrafiltration and SP Sephadex C-25 and Sephadex G-25 chromatography from the protein hydrolysate prepared by sequential enzymatic hydrolysis of pine nut kernels (Pinus koraiensis Sieb. et Zucc.) with pepsin and trypsin. The molecular mass distribution of PDII was determined and its in vitro antioxidant and in vivo antifatigue effect were evaluated. The results showed that the molecular mass of PDII was distributed in the range of 500–1 100 Da, and that it had a strong antioxidant effect. PDII at all investigated doses could maintain normal blood glucose level, increase glycogen storage capacity and decrease serum urea nitrogen and malondialdehyde and blood lactate acid; there results were statistically significant compared with the blank group (P < 0.01), indicating that PDII had both antioxidant activity in vitro and anti-fatigue effect in vivo.

Key words: peptide derived from pine nut kernels, two-step enzymatic hydrolysis, isolation and purification, antioxidant activity, antifatigue effect