Green tea polyphenols require the mitochondrial iron transporter, mitoferrin, for lifespan extension in Drosophila melanogaster.

Green tea has been found to increase the lifespan of various experimental animal models including the fruit fly, Drosophila melanogaster. High in polyphenolic content, green tea has been shown to reduce oxidative stress in part by its ability to bind free iron, a micronutrient that is both essential for and toxic to all living organisms. Due to green tea's iron-binding properties, we questioned whether green tea acts to increase the lifespan of the fruit fly by modulating iron regulators, specifically, mitoferrin, a mitochondrial iron transporter, and transferrin, found in the hemolymph of flies. Publicly available hypomorph mutants for these iron regulators were utilized to investigate the effect of green tea on lifespan and fertility. We identified that green tea could not increase the lifespan of mitoferrin mutants but did rescue the reduced male fertility phenotype. The effect of green tea on transferrin mutant lifespan and fertility were comparable to w1118 flies, as observed in our previous studies, in which green tea increased male fly lifespan and reduced male fertility. Expression levels in both w1118 flies and mutant flies, supplemented with green tea, showed an upregulation of mitoferrin but not transferrin. Total body and mitochondrial iron levels were significantly reduced by green tea supplementation in w1118 and mitoferrin mutants but not transferrin mutant flies. Our results demonstrate that green tea may act to increase the lifespan of Drosophila in part by the regulation of mitoferrin and reduction of mitochondrial iron.

Extension of Drosophila Lifespan by Rhodiola rosea Depends on Dietary Carbohydrate and Caloric Content in a Simplified Diet.

The root and rhizome extract of Rhodiola rosea has been extensively used in traditional medicine to improve physical and mental performance and to protect against stress. We, and others, have reported that R. rosea can extend lifespan in flies, worms, and yeast. We also previously found that the extract can act independently of dietary restriction (DR), a treatment that can extend lifespan in a range of model organisms. In flies, DR is implemented through a reduction in dietary yeast content. Here, we report that the ability of R. rosea extract to extend lifespan in flies is dependent on the carbohydrate and caloric content when supplemented with a simplified diet composed of yeast and sucrose. R. rosea extract elevated the sugar content in flies and down-regulated hexokinase expression, suggesting that it perturbs carbohydrate metabolism in flies. In our previous studies, bananas, barley malt, and corn syrup provided dietary carbohydrates, and R. rosea extract could extend lifespan with a range of caloric levels. We conclude that the lifespan-extending effect of R. rosea extract in flies is dependent on dietary carbohydrate and caloric contents coupled with an interaction with complex dietary components present in bananas, barley, or corn.

The impact of green tea polyphenols on development and reproduction in Drosophila melanogaster.

Although, green tea has numerous health benefits, adverse effects with excessive consumption have been reported. Using Drosophila melanogaster, a decrease in male fertility with green tea was evidenced. Here, the extent of green tea toxicity on development and reproduction was investigated. Drosophila melanogaster embryos and larvae were exposed to various doses of green tea polyphenols (GTP). Larvae exposed to 10 mg/mL GTP were slower to develop, emerged smaller, and exhibited a dramatic decline in the number of emerged offspring. GTP protected flies against desiccation but sensitized them to starvation and heat stress. Female offspring exhibited a decline in reproductive output and decreased survival while males were unaffected. GTP had a negative impact on reproductive organs in both males and females (e.g., atrophic testes in males, absence of mature eggs in females). Collectively, the data show that high doses of GTP adversely affect development and reproduction of Drosophila melanogaster.

Extension of Drosophila lifespan by cinnamon through a sex-specific dependence on the insulin receptor substrate chico.

Cinnamon is a spice commonly used worldwide to flavor desserts, fruits, cereals, breads, and meats. Numerous health benefits have been attributed to its consumption, including the recent suggestion that it may decrease blood glucose levels in people with diabetes. Insulin signaling is an integral pathway regulating the lifespan of laboratory organisms, such as worms, flies, and mice. We posited that if cinnamon truly improved the clinical signs of diabetes in people that it would also act on insulin signaling in laboratory organisms and increase lifespan. We found that cinnamon did extend lifespan in the fruit fly, Drosophila melanogaster. However, it had no effect on the expression levels of the 3 aging-related Drosophila insulin-like peptides nor did it alter sugar, fat, or soluble protein levels, as would be predicted. In addition, cinnamon exhibited no protective effects in males against oxidative challenges. However, in females it did confer a protective effect against paraquat, but sensitized them to iron. Cinnamon provided no protective effect against desiccation and starvation in females, but sensitized males to both. Interestingly, cinnamon protected both sexes against cold, sensitized both to heat, and elevated HSP70 expression levels. We also found that cinnamon required the insulin receptor substrate to extend lifespan in males, but not females. We conclude that cinnamon does not extend lifespan by improving stress tolerance in general, though it does act, at least in part, through insulin signaling.