Free radical scavenging and antiproliferation of peptide from chicken feather meal

Abstract

A free radical is an atom or compound, which contains a lone pair electron reactive to cells and molecules in the human body. The free radical cannot be eliminated and plays an important role in many diseases such as coronary thrombosis, cancer, Alzheimer’s, and arthritis. The antioxidant system in the body is one of the mechanisms that respond to free radicals. In this research peptides from chicken feather meal protein hydrolysates with microbial proteases (Alcalase®, Flavourzyme® and Neutrase®) were prepared and their antioxidant activities determined. Peptide fractions derived from chicken feather meal hydrolyzed by 5% Neutrase®, shown the highest DPPH and ABTS radical scavenging activity with IC50 values of 16.45±0.23 and 9.34±0.08 µg/mL, respectively. Peptide fractions were fractionated using molecular weight cut-offs of 10, 5, 3 and 0.65 kDa membranes and their antioxidant properties further analyzed. Of the fractions, MW < 0.65 kDa (F5 fraction) exhibited high levels of free radical scavenging activities towards DPPH and ABTS with IC50 values of 1.72±0.04 and 0.42±0.02 µg/mL, respectively. The F52 fraction from Superdex® 75 column presented the highest scavenging activities on DPPH and ABTS radicals with IC50 values of 7.35±0.30 and 14.79±0.24 µg/mL, respectively. The F52 fraction was purified using RP-HPLC and separated into three fractions (F521, F522, and F523). All fractions exhibited very strong DPPH radical scavenging activities (32.01±2.17, 22.52±4.87 and 59.66±5.89 µg/mL), and all fractions were identified by mass spectrometry as Phe-Asp-Asp-Arg-Gly-Arg-X (FDDRGRX, 875 Da), Val-Thr-Leu-Ala-Val-Thr-Lys-His (VTLAVTKH, 868 Da) and Val-Ser-Glu-Ile-X-Ser-Ile-Pro-Ile-Ser (VSEIXSIPIS, 1,055 Da), respectively. Furthermore, the F52 fraction could protect hydroxyl radical-induced DNA damage as shown in pKS, pUC19, and pBR322. In addition, as concerns cancer, the F52 fraction possessed high antiproliferative activity in human SW620 colon cancer cell lines using an MTT assay with IC50 values of 26.37±2.87 µg/mL, and 0.5% of the F52 fraction (protein content as 0.31 µg/mL) could induce apoptosis as measured by an FITC Annexin V Apoptosis Detection Kit with PI using flow cytometry and increased caspase 3 and 8 activities in SW620 cells for 24 and 48 h. Hence, F52 fraction could be used as a new natural antioxidant and source of antiproliferative activities for drug development.