Introduction: Collagen is an extracellular matrix macromolecule (~300 kDa), constituted of three α peptide chains with a triple-helix construction and repetitive proline-rich Gly-X-Y sequences where X and Y most commonly represent proline and hydroxyproline, respectively. Collagen and its derivatives have been extensively applied in the food, cosmetics, medicine and pharmaceutical industries and the total demand from all over the world for collagen has amplified over the years. Collagen has excellent biocompatibility, limited immunogenicity, high antioxidant activity and coagulation function, and is considered a promising biomimetic scaffold. Normally, the content of type I collagen in the skin of babies and youngsters is negatively associated with age. After middle age, dermal fibroblasts function and collagen synthesize diminish annually; meanwhile, the firmness and constancy of collagen filaments intensify.
Methods: Acid-soluble, Pepsin-Soluble Collagen and Collagen Hydrolysate Preparation
Fresh swim bladder of Caspian white fish Caspian kutum was carefully cleaned and the unnecessary tissue was removed. The swim bladder was cut into small pieces. Swim bladder samples were extracted by acetic acid and pepsin, then again acid soluble collagen (ASC) and pepsin soluble collagen (PSC) were hydrolyzed enzymatically (by pepsin).
DPPH radical scavenging activity
The hydroxyl radical scavenging activity was determined by using DPPH (0.2%) in ethanol. The absorbance of the mixture was determined at 517 nm (As).The sample replaced with deionized water was set as the control group (Ac), and the DPPH exchanged with ethanol was established as the blank group (Ab). The DPPH radical scavenging activity of the samples was calculated as follows:
PPH radical scavenging activity (%) = [1- (As-Ab)]/Ac × 100%
Results: All samples including (ASC), (PSC), (ASCH), and (PSCH) had a DPPH radical scavenging activity superior to 50%. The highest scavenging activity (81.4%) was for (PSCH, Pepsin Soluble Collagen Hydrolysate).
Conclusion: Nowadays, marine collagen or collagen active peptides have attracted broad attention in pharmaceutical, cosmeceutical and skin care industry due to their antioxidative, and anti-aging activities. During skin aging, it is desirable to neutralize ROS, which are implicated in skin damage. So the radical scavenging activity is a significant property for the cosmeceutical products expected at the inhibition of photaging and skin damage against UV radiation. At a distinct low concentration, the radical scavenging activity of PSC was higher than that of ASC, and the radical scavenging activity of (PSCH) was highest. The highest scavenging activity (81.4 %) for (PSCH) was superior to those reported for peptide fractions of Carp Fish Byproduct ranging from 61.8, 65.9, 72.7 attributed to >30 kDa, 10-30 kDa and 3-10 kDa. But the highest scavenging activity (81.4%) for (PSCH) from Caspian White Fish was close but lower than (87%) for <3 kDa at 1 mg/mL, for common carp. Once more, our findings for PSC hydrolysate but not peptide fraction, were superior to those obtained with byproducts of different fish species (maximum DPPH˙ scavenging activity of 81% for <3 kDa fraction at 5 mg/mL) also were superior to 71.15% DPPH scavenging activity obtained with polypeptide fraction (molecular weight of 3 kDa) from swim bladder of Acipenser schrencki. In general, the worthy results attained could be associated with the existence of electron/hydrogen-donor polypeptides in the PSCH from swim bladder of Caspian White Fish, which interrupt radical chain reactions thanks to their proficiency to rejoin with free radicals.