Hydrophobicity of whey protein hydrolysates enhances the protective effect against oxidative damage on PC 12 cells.

The relationship between hydrophobicity and the protective effect of whey protein hydrolysates (WPHs) against oxidative stress was studied. Whey protein was first hydrolysed by pepsin and trypsin to obtain WPHs. After absorbed by macroporous adsorption resin DA201-C, three fractions named as M20, M40, and M60 were eluted by various concentrations of ethanol. The hydrophobicity showed a trend of increase from M20 to M60. Antioxidant ability test in vitro indicated that all the three components of WPHs displayed reasonably good antioxidant ability. Moreover, with the increase of hydrophobicity, antioxidant ability of WPHs improved significantly. Then rat pheochromocytoma line 12 (PC12) cells oxidative model was built to evaluate the suppression of oxidative stress of three components on PC12 cells induced by H2O2. Morphological alterations, cell viability, apoptosis rate, and intracellular antioxidase system tests all indicated that WPHs exert significant protection on PC cells against H2O2-induced damage. Among them, M60 had the highest protective effect by increasing 19·3% cell survival and reducing 28·6% cell apoptosis. These results suggested hydrophobicity of WPHs was contributing to the antioxidant ability and the protective effect against oxidative damage.

Exopolysaccharide from Lactobacillus planterum LP6: antioxidation and the effect on oxidative stress.

An exopolysaccharide (EPS-3) was isolated from the culture of Lactobacillus planterum LP6 and purified by ion exchange and gel chromatography. The concentrations required to scavenge 50% of the initial radical for DPPH·, OH· and O2(·-) radicals were 1.38, 3.43 and 0.11 mg/mL, respectively. The reducing power (A700 nm) was 0.632 at 5mg/mL. The cell viability of PC12 was improved by 21.67% at 200 µg/mL of EPS-3. Compared with the H2O2 group, the total-antioxidant capacity, activities of superoxide dismutase and catalase were enhanced by 65.81%, 41.34% and 59.05%, respectively. Meanwhile, the level of malondialdehyde and lactate dehydrogenase were decreased by 52.80% and 30.24%. The result indicated that EPS-3 had a notable protective effect against oxidative damage on PC12 cells. The study might lay a theoretical foundation for the comprehensive utilization of lactic acid bacteria source which could result in its application in food systems.

Protective effect of whey protein hydrolysates on H2O2-induced PC12 cells oxidative stress via a mitochondria-mediated pathway.

Whey protein hydrolysates (WPHs) were prepared with pepsin and trypsin. A PC12 cell model was built to observe the protective effect of WPHs against H2O2-induced oxidative stress. The results indicated that WPHs reduced apoptosis by 14% and increased antioxidant enzyme activities. Flow cytometry was used to assess the accumulation of reactive oxygen species (ROS), Ca(2+) levels and the mitochondrial membrane potential (MMP). The results showed that WPHs suppressed ROS elevation and Ca(2+) levels and stabilised MMP by 16%. The anti-apoptosis/pro-apoptosis proteins Bcl-2/Bax and poly (ADP-ribose) polymerase (PARP) were investigated by Western-blot analysis, which indicated that WPHs increased the expression of Bcl-2 while inhibiting the expression of Bax and the degradation of PARP. WPHs also blocked Caspase-3 activation by 62%. The results demonstrate that WPHs can significantly protect PC12 cells against oxidative stress via a mitochondria-mediated pathway. These findings indicate the potential benefits of WPHs as valuable food antioxidative additives.