Neuroprotective activities of enzymatically hydrolyzed peptides from porcine hide gelatin

Central nervous system disorders, including cerebrovascular disease, neurodegenerative diseases and head trauma are the most common cause of severe disability in adults and share a number of pathophysiological features. The therapeutic strategy of neuroprotection has been well accepted as one of the promising approaches in treating such brain disorders, and searching for the effective neuroprotective agents is still an open-ended task for neurologists and neuro-pharmacologists. In this study, we report for the first time that the enzymatic hydrolysates from type-B porcine hide gelatin has potent neuroprotective activity against H(2)O(2)- or serum deprivation-induced injuries of cultured SH-SY5Y cells. The peptides used in this study were prepared from type-B porcine hide gelatin digested with pepsin and papain. The neuroprotective activity of the porcine hide gelatin hydrolysate (PHH) was evaluated using MTT reduction assay. From the pre-screening of PHH, we found that the whole porcine hide gelatin hydrolysate obtained from papain digestion (PHH-I) showed significant neuroprotective activities (P<0.05). After further separation of PPH-I through SP-Sephadex C-50 and Sephadex G-25, only the fraction with smaller molecular weight from Sephadex G-25 (PHH-Ic) demonstrated potent neuroprotective activities (P<0.01). The active fraction showed a molecular mass between 1,000-3,000Da in SDS-polyacrylamide gel electrophoresis, and was rich in Glycine, Proline and Hydroxyproline in amino acid composition, indicating that peptides with a spectrum of molecular sizes and certain amino acids are critical for the neuroprotective activities of gelatin peptides. The viability of cultured cells treated with gelatin peptides was significantly improved in a dose-dependent manner. Further studies are necessary to establish the neuroprotective activity of hydrolyzed peptides for the neurons in vivo.