Purple Sweet Potato Extract extends lifespan by activating autophagy pathway in male Drosophila melanogaster

Purple sweet potato is a nutritive food rich in anthocyanins that possess antioxidant effects. Drosophila melanogaster owns short growth cycle, fast reproduction, less chromosomes, more mutants, small individuals, therefore, which is an appropriate genetic model organism. To investigate the anti-aging activity of Purple Sweet Potato Extract (PSPE) in male Drosophila melanogaster and explore the underlying mechanism. PSPE-induced longevity was associated with improvements in climbing ability and tolerance to stressors such as paraquat and hydrogen peroxide (H2O2). Furthermore, PSPE supplementation increased the activity of superoxide dismutase (SOD) and catalase (CAT), as well as expression of SOD and CAT genes, but decreased malondialdehyde (MDA) content. Meanwhile, PSPE decreased the intestinal stem cells (ISCs) proliferation and improved intestinal homeostasis, which was measured by Smurf assay and colony-forming units (CFUs) measurement in aging flies. Additionally, PSPE markedly inhibited the expression of upstream genes AKT-1, PI3K and mTOR and elevated the downstream gene 4E-BP, which further activated the expression of autophagy-related genes (Atg1, Atg5, Atg8a and Atg8b). Moreover, the production of lysosomes increased, indicating that the autophagy pathway was activated. The results provided direct evidence of PSPE anti-aging effects on an organism level, indicating PSPE could be developed for use in effective anti-aging products.