In this study, protective effect of rice with Phellinus linteus mycelium (PLMR) against hydrogen peroxide-induced oxidative stress in mouse hippocampal neuronal HT22 cell line through MTS assay and western blot.
MTS assay with HT22 cell showed that PLMR extract did not influence the cell viability at a concentration range from 1 ㎎/㎖ to 5 ㎎/㎖. However, at concentrations over 10 ㎎/㎖, PLMR extract resulted in increases in cell death. Cell viability of the HT22 was significantly decreased by H2O2 treatment, and the decrease in cell viability was efficiently restored by treatment of PLMR extract in a dose-dependent manner at a dose range from 0.1 to 1 mg/ml.
Cells treated with H2O2 showed increase in the expression of Bax, a pro-apoptotic protein, which was decreased by treatment of PLMR extract. On the other hand, cells treated with H2O2 resulted in decrease in the expression of Bcl-2, an anti-apoptotic protein, which was restored by the treatment of PLMR extract. In addition, the treatment of PLMR extract reduced the expressions of cleaved caspase-3 and PARP, which were enhanced by H2O2 treatment. The results may suggest that the treatment of PLMR extract would suppress the H2O2-induced apoptosis of HT22 cells.
We also investigated quality characteristics of porridge with substitutions of glutinous rice with 25, 50, 75 and 100% PLMR. Proximate compositions of PLMR were as following: moisture 13.05%, crude ash 0.88%, crude lipid 1.13%, crude protein 6.29% and carbohydrate 78.65%. Glutinous rice had moisture 13.99%, crude ash 0.32%, crude lipid 0.66%, crude protein 7.85% and carbohydrate 77.18%. Water absorption of PLMR increased with increasing soaking time up to 6 hours, while that of glutinous rice increased only up to 30 minutes of soaking. pH of porridge decreased as increased addition of PLMR. Viscosity of porridge was lowest in the control showing 914.77 cp, and it increased as increased PLMR addition. Spreadability of porridge decreased as increased PLMR contents. In color, lightness was highest in 50% PLMR. Redness was highest in 75% PLMR, and yellowness was lowest in control. In textural characteristics, hardness and fracturability were increased as increased PLMR contents, whereas springiness, cohesiveness and resilience decreased as PLMR increased. In consumer acceptance test, flavor, appearance, viscosity, delicate taste and overall acceptability were not significantly different among samples. From the results, adding 25~50% PLMR would be suggested to be optimal for porridge recipe.