The protective role of phytate in the oxidative degradation of cereal beta-glucans.

This study investigated the role of phytate in the Fenton reaction induced oxidative degradation of cereal ß-glucan. Viscosity analysis showed that the degradation rate was high in the beginning of oxidation, which fitted to the second order kinetic model. Oat ß-glucan contained significant amount of residual phytate and after the residual phytate was removed, faster degradation was shown compared to the original oat ß-glucan. Adding the same amount of phytic acid (PA) to the phytate removed ß-glucan sample also retarded the degradation but not as efficiently as the residual phytate. Considerable retardation of viscosity loss was shown when the PA to iron ratio was high. The presence of ascorbic acid weakened the retardation effect of phytic acid. Thus, phytate can significantly improve the oxidative stability of ß-glucan when the ratio of phytic acid to transition metals and the presence of ascorbic acid are taken into consideration.

In vitro Antioxidant Activities of Sodium Zinc andSodium Iron Chlorophyllins from Pine Needles.

Chlorophyll was extracted from pine needles, and then sodium zinc chlorophyllin (SZC) and sodium iron chlorophyllin (SIC) were synthesised by saponification, purification and substitution reaction, using sodium copper chlorophyllin (SCC) as a control. Their crystalline structures were verified by atomic absorbance spectroscopy, UV-VIS spectroscopy and HPLC. Moreover, their antioxidant activities were evaluated and compared with that of ascorbic acid through four biochemical assays: DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, reducing power, inhibition of ß-carotene bleaching and O 2- scavenging activity. SZC had better antioxidant properties at a lower dosage than SIC and SCC in all assays. In the ß-carotene bleaching assay, EC 50 of SZC, SIC and SCC was 0.04, 0.38 and 0.90 mg/mL, respectively, much lower than that of ascorbic acid (4.0 mg/mL). SZC showed a better result (p<0.05) than ascorbic acid in the O 2- scavenging activity assay. The results obtained from reducing power determination were also excellent: the absorbance values were all about 1.0 at 0.5 mg/mL, about half of that of ascorbic acid. In the investigation of DPPH radical scavenging activity, all chlorophyllins had lower activities than ascorbic acid. These results demonstrated the potential bioactivities of chlorophyll derivatives and supported their possible role in human health protection and disease prevention.