Tannase-Converted Green Tea Extract with High (-)-Epicatechin Inhibits Skeletal Muscle Mass in Aged Mice

Abstract

The objective of this study was to investigate the effects of tannase-converted green tea extract on body composition, muscle oxidative stress-related factors, and differentiation-related factors. The mean bone-related parameters and body composition were determined by the live dual-energy X-ray absorptiometry (DEXA). Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were used to determine mRNA expression and protein levels, respectively. The results of total mass testing in the epicatechin control (EC) and middle concentration tannase-converted green tea extract (T-1) intake groups were not significantly different compared with those in the control group; however, the high-concentration tannase-converted green tea extract (T-2) group showed a significantly higher effect to the lean than that of all other groups (p<0.05). The results of the assay of muscle differentiation-related genes indicated that the expression levels in the EC and T-1 groups (p<0.05) and the expression levels in the T-2 group (p<0.01) were significantly different in the bicep femoris compared with that in the control group. The results of the SOD gene assay indicate that the expression levels in the EC and T-1 groups (p<0.05) and the expression level in the T-2 group (p<0.01) were significantly different in the bicep femoris compared with that in the control group. Additionally, SOD gene expression in the T-2 group was significantly increased (p<0.05) in the soleus compared with that in the control, EC and T-1 groups. Our results suggest that tannase-converted green tea extract prevents muscle loss and regulates the quantity and quality of muscle by the levels of antioxidant stress-related enzymes and muscle differentiation factors to a greater extent than the administration of epicatechin and middle dose green tea extract.