Erythrocyte antioxidant protection of rose hips (Rosa spp.)

Rose hips are popular in health promoting products as the fruits contain high content of bioactive compounds. The aim of this study was to investigate whether health benefits are attributable to ascorbic acid, phenols, or other rose-hip-derived compounds. Freeze-dried powder of rose hips was preextracted with metaphosphoric acid and the sample was then sequentially eluted on a C18 column. The degree of amelioration of oxidative damage was determined in an erythrocyte in vitro bioassay by comparing the effects of a reducing agent on erythrocytes alone or on erythrocytes pretreated with berry extracts. The maximum protection against oxidative stress, 59.4 ± 4.0% (mean standard deviation), was achieved when incubating the cells with the first eluted meta-phosphoric extract. Removal of ascorbic acid from this extract increased the protection against oxidative stress to 67.9 ± 1.9% . The protection from the 20% and 100% methanol extracts was 20.8 ± 8.2% and 5.0 ± 3.2% , respectively. Antioxidant uptake was confirmed by measurement of catechin by HPLC-ESI-MS in the 20% methanol extract. The fact that all sequentially eluted extracts studied contributed to protective effects on the erythrocytes indicates that rose hips contain a promising level of clinically relevant antioxidant protection. © Copyright 2012 C. Widén et al.

Attenuation of muscle wasting in murine C2C12myotubes by epigallocatechin-3-gallate

Background: Loss of muscle protein is a common feature of wasting diseases where currently treatment is limited. This study investigates the potential of epigallocatechin-3-gallate (EGCg), the most abundant catechin in green tea, to reverse the increased protein degradation and rescue the decreased protein synthesis which leads to muscle atrophy. Methods: Studies were conducted in vitro using murine C2C12myotubes. Increased protein degradation and reduced rates of protein synthesis were induced by serum starvation and tumour necrosis factor-α (TNF-α). Results: EGCg effectively attenuated the depression of protein synthesis and increase in protein degradation in murine myotubes at concentrations as low as 10 μM. Serum starvation increased expression of the proteasome 20S and 19S subunits, as well as the proteasome ‘chymotrypsin-like’ enzyme activity, and these were all attenuated down to basal values in the presence of EGCg. Serum starvation did not increase expression of the ubiquitin ligases MuRF1 and MAFbx, but EGCg reduced their expression below basal levels, possibly due to an increased expression of phospho Akt (pAkt) and phospho forkhead box O3a (pFoxO3a). Attenuation of protein degradation by EGCg was increased in the presence of ZnSO4, suggesting an EGCg-Zn2+complex may be the active species. Conclusion: The ability of EGCg to attenuate depressed protein synthesis and increase protein degradation in the myotubule model system suggests that it may be effective in preserving skeletal muscle mass in catabolic conditions.