Physico-chemical, antioxidant and intestinal absorption properties of whale shark type-II collagen based on its solubility with acid and pepsin

Type-II collagens (CIIs) were isolated from whale shark (WS) cartilage; and examined for their physico-functional and structural properties. The protein and ash content of WS cartilage were in the range of 8.02% and 23.39%, respectively. Pepsin soluble collagen (PSC) had high hydroxyproline content than acid soluble collagen (ASC). Fourier transform infrared (FTIR) spectra of ASC and PSC were similar and suggesting that pepsin hydrolysis did not affect the secondary structure of collagen, especially triple-helical structure. SEM microstructure depicted a homogenous, more compact, fibrillary and single-layered sheet like structure with coarse structural integrity. Low content of glycoprotein was observed in PSC than ASC due to the removal of some telopepdies by pepsin digestion. Denaturation temperature (Td) of PSC (34.02 °C) was quite higher than ASC. The antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl radicals and the reducing power of PSC was greater than that of ASC. Similar intestinal absorptive behavior was observed for PSC and ASC in an in vitro gut sac model. These results suggested that CIIs isolated from WS cartilage could be the suitable biomaterial for commercial applications as alternative to mammalian collagen.