Role of dietary flavonoids in oxidative stress and prevention of muscle atrophy

Functional foods for the prevention of disuse muscle atrophy (DMA) are expected to improve the quality of life (QoL) of bedridden people. Ubiquitin ligases targeting muscle protein degradation, atrogin-1 and muscle-specific ring finger protein (MuRF-1), are critical in the degradation of muscle protein, and oxidative stress induced by mitochondrial dysfunction seems to be involved in muscle atrophy. Dietary antioxidants that attenuate the oxidative stress in skeletal muscle are strong candidates as food ingredients for preventing DMA. The antioxidative flavonoid quercetin was found to prevent DMA by attenuating the induction of atrogin-1/MuRF-1 in mice undertaking the tail suspension test. Several studies revealed that dietary quercetin accumulates in skeletal muscle after metabolic conjugation during absorption. There are many arguments that antioxidant activity is essential for dietary flavonoids to exert their preventive effects, but modulation of the IGF-1 signaling pathway is definitively involved in the mechanism of prevention. Nevertheless, dietary flavonoids (including quercetin) may be potential food factors in the prevention of muscle atrophy. Dietary flavonoids are expected to prevent DMA by attenuating oxidative stress derived from mitochondrial dysfunction.