Radical scavenging was a primary function of antioxidants to
inhibit oxidative processes, and used extensively to evaluate reducing
substances. The DPPH radical-scavenging activity of the
peptide RVPSL is listed in Table 1. As the concentration of RVPSL
increased from 0.01 to 100 mM, the DPPH radical-scavenging
activity of RVPSL increased from 11.4 ± 4.1% to 34.2 ± 5.1%
(Table 1). Similarly, there was a report of the peptide YAEERYPIL
that possessed an ACE-inhibitory activity and the radicalscavenging
activity (Davalos and others 2004). Peptides of potato
were also reported to had both the ACE-inhibitory activity and
antioxidant property (Pihlanto and others 2008). Moreover, research
was carried out to study the structure–activity relationship
(SAR) of LLPHH, which was compared with other 28 structurally
related synthesized peptides. Results suggested that His and Pro played important roles in the antioxidant activity of the synthetic
peptides (Chen and others 1996). However, the SAR study of
antioxidative peptides has neither been fully defined nor is well
understood yet.