Production and purification of antioxidant and hypolipidemic peptides from Deccan mahseer (Tor khudree)

The current study aimed for the production and purification of antioxidant and hypolipidemic peptides from Deccan mahseer (Tor khudree) fish protein hydrolysate (FPH). FPH was produced by enzymatic hydrolysis using 2% flavourzyme at 60°C for 6 h. The FPH exhibited potential DPPH radical scavenging activity (9.79 μM TE/mg), ABTS radical scavenging activity (45.47 μM TE/mg), FRAP antioxidant activity (2.78 μM TE/mg), pancreatic lipase inhibition activity (30.70%), and cholesterol esterase inhibition activity (23.45%). SDS-PAGE revealed the degradation of high molecular proteins to low molecular peptides, indicating the hydrolysis of fish proteins. FTIR spectra suggest the presence of amide A, B, I, II, and III bands in FPH. Functional properties suggests that FPH have good solubility (>60%) at wide range of pH (2-12) with good emulsifying (emulsifying activity index: 25.15 - 59.44 m2/g; emulsion stability index: 18.59 – 53.23 min) and foaming (foam expansion: 123.88-105%; foam stability: 111.94 - 100%). Further ultrafiltration of FPH resulted in the production of three fractions with peptides in the range of > 3kDa (FPH-UF-1), 1-3 kDa (FPH-UF-2), and < 1kDa (FPH-UF-3). FPH-UF-3 exhibited superior DPPH radical scavenging activity (43.33 μM TE/mg), ABTS radical scavenging activity (151.37 μM TE/mg), FRAP antioxidant activity (3.56 μM TE/mg), pancreatic lipase inhibition activity (84.98%), and cholesterol esterase inhibition activity (76.80%). Subsequent purification of FPH-UF-3 using Sephadex G-15 gel filtration chromatography yielded 3 fractions: FPH-GF-1, FPH-GF-2, and FPH-GF-3. FPH-GF-2 showed significant DPPH radical scavenging activity (331.95 μM TE/mg), ABTS radical scavenging activity (109.76 μM TE/mg), FRAP antioxidant activity (115.75 μM TE/mg), pancreatic lipase inhibition activity (86.5%), and cholesterol esterase inhibition activity (92.05 %). Reverse-phase high-performance liquid chromatography of FPH-GF-2 resulted in the four fractions, namely, FPH-RH-1, FPH-RH-2, FPH-RH-3, and FPH-RH-4, among which FPH-RH-4 was found to have the highest DPPH radical scavenging activity (784.40 μM TE/mg), ABTS radical scavenging activity (258.50 μM TE/mg), FRAP antioxidant activity (289.97 μM TE/mg), pancreatic lipase inhibition activity (96.87 %), and cholesterol esterase inhibition activity (96.55 %). These results suggest that the purified peptides may comprise more low-molecular-weight and hydrophobic peptides, which possess significant antioxidant and hypolipidemic properties. Therefore, the purified antioxidant and hypolipidemic peptides from FPH can serve as a promising natural antioxidant with hypolipidemic potential, thereby enhancing their applications in the functional food and nutraceutical industries.