Longevity-promoting efficacies of rutin in high fat diet fed Drosophila melanogaster.

Composition of diet significantly impacts lifespan in Drosophila melanogaster. Diet-composition becomes even more crucial while assessing a phytocompound for probable pro-longevity effects in flies. Rutin is a flavonol glycoside present in apple, buckwheat, black tea and green tea. Our previous study had reported hormetic efficacy of rutin to improve longevity and other physiological parameters in Drosophila melanogaster fed with standard diet. This study aimed to understand whether rutin could exhibit similar longevity promoting effects in flies fed with a high fat diet (HFD). In this study, wild type Canton-S males and females were reared on high fat diet (HFD) treated with or without rutin at different doses (100-800 µM) and assessed for survival, food intake, fecundity, locomotion, development, resistance to various forms of stresses and relative mRNA expression of specific genes associated with ageing, namely dFoxO, MnSod, Cat, dTsc1, dTsc2, Thor, dAtg1, dAtg5, dAtg7 and dTor. Rutin at only 400 µM significantly improved survival in males fed with HFD; while at 200 µM and 400 µM it significantly improved survival in females. Doses beyond 400 µM proved detrimental for both sexes. Rutin at 200 µM and 400 µM significantly reduced average food intake in both males and females fed with HFD. A significant reduction in number of eggs laid per female per day was observed in females treated with rutin at 400 µM. Rutin at 200 µM and 400 µM significantly improved climbing efficiency in males and females. A significant reduction in eclosion time was observed in larvae fed with HFD and treated with rutin at 400 µM. Rutin at 400 µM significantly improved resistance of males and females to different stresses namely heat shock, cold shock and starvation stresses. Interestingly, rutin at 400 µM significantly reduced survival of males and females exposed to oxidative stress. In males fed with HFD, rutin at 200 µM showed significantly increased relative expression of dFoxo, MnSod, Cat, dAtg1, dAtg5 and dAtg7; at 400 µM it significantly increased the relative expression of dFoxO, MnSod, Cat, dTsc1, dTsc2, Thor, dAtg1, dAtg5, dAtg7 while decreasing relative expression of dTor. Thus, data from this study collectively showed that rutin at 400 µM and to an extent 200 µM positively impacted lifespan and modulated other physiological parameters in males and females fed with HFD.