Autophagy as a molecular target of quercetin underlying its protective effects in human diseases

Autophagy, known as a "self-eating" process, is associated with degradation of aged or damaged components and organelles. Generally, autophagy is a survival mechanism that provides energy during nutritional deprivation. This mechanism plays a remarkable role during the physiological condition by maintaining homeostasis and energy balance and several pathological conditions, particularly neurological disorders. Due to the critical role of autophagy in cancer, much attention has been made in the regulation of autophagy using both naturally occurring and synthetic drugs. Quercetin is a plant-derived chemical belonging to the family of flavonoids. Quercetin has valuable biological and therapeutic effects such as anti-tumor, antioxidant, anti-inflammatory, anti-diabetic, hepatoprotective, and cardioprotective. At the present review, we first provide an introduction about quercetin and autophagy with its related molecular pathways. We also describe how quercetin modulates autophagy mechanism to exert its therapeutic effects.