An antioxidant peptide derived from Ostrich (Struthio camelus) egg white protein hydrolysates

Abstract

Ostrich (Struthio camelus) egg white (OEW) proteinswere hydrolyzed using various proteases (α-chymotrypsin,<br><br>pepsin, trypsin and papain). Antioxidant activities of hydrolysates were evaluated using 1, 1-diphenyl-<br><br>2-picrylhydrazyl (DPPH) radical scavenging and iron chelating activity. The hydrolysate obtained by trypsin<br><br>exhibited the highest antioxidant activity. This hydrolysate was passed through an ultrafiltration membrane<br><br>with a 3 kDa-cut off, and the resulting filtrate was purified using reversed-phase high performance liquid<br><br>chromatography (RP-HPLC). Eight peptide fractions were separated and their antioxidant activities were tested.<br><br>The results showed that the F6 fraction possessed the highest antioxidant activity in the inhibition of linoleic acid<br><br>autoxidation (86.4% at 20 μg/ml), scavenging activity for DPPH radical (81% at 200 μg/ml) and 2, 2-azino-bis<br><br>(3-ethylbenzothiazoline-6-sulphonicacid) diammonium salt (ABTS) radical (37.6% at 90.9 μg/ml). In addition,<br><br>the iron chelating activity, hydroxyl radical scavenging and reducing power of the F6 fraction were 20% at<br><br>317.5 μg/ml, 28.6% at 163.9 μg/ml and 0.083 at 113.6 μg/ml, respectively. The peptide sequence was found to<br><br>be LTEQESGVPVMK (with a molecular mass of 1317.65 Da) using mass spectrometry. The results suggest that<br><br>the digestion of OEWproteins by trypsin protease could be exploited to produce natural antioxidants.