Reduced iron and cobalt levels in response to curcumin supplementation are not responsible for the prolonged larval development and do not affect the oxidative stress tolerance and polyamine status of D. melanogaster

Abstract

Recent reports indicated that the phytochemical curcumin possesses iron‐chelating activity. Here, by employing the fruit fly Drosophila melanogaster, we conducted feeding studies supplementing curcumin or, as a control, the iron chelator bathophenanthroline (BPA). First, the absorption and further metabolization of dietary curcuminoids were proved by metabolomics analyses. Next, we found that 0.2% dietary curcumin, similar to BPA, lowered the iron but also the cobalt content, and to a lesser extent affected the manganese and zinc status. Supplementation during larval stages was required and sufficient for both compounds to elicit these alterations in adult animals. However, curcumin‐induced retarded larval development was not attributable to the changed trace metal status. In addition, a reduction in the iron content of up to 70% by curcumin or BPA supplementation did not reduce heme‐dependent catalase activity and tolerance toward H2O2 in D. melanogaster. Moreover, polyamines were not influenced by curcumin treatment and decreased iron levels. This was confirmed for selected organs from 0.2% curcumin‐treated mice, except for the spleen. Here, elevated spermidine level and concomitant upregulation of genes involved in polyamine production were associated with a putatively anemia‐derived increased spleen mass. Our data underline that the metal‐chelating property of curcumin needs to be considered in feeding studies.

A comprehensive in-vitro/in-vivo screening toolbox for the elucidation of glucose homeostasis modulating properties of plant extracts (from roots) and its bioactives

“…Moreover, as the hen’s egg test, experiments can be carried out without serious ethical concerns and regulatory frameworks. Supplementation studies with D. melanogaster do not only cover most of the key features present in human carbohydrate metabolism but also many pharmacological aspects (e.g., bioavailability, biotransformation, role of gut microbiota, toxicity) ( Günther et al, 2021 ; Lüersen et al, 2024 ). Despite this, physiological differences between the fruit fly and humans should be mentioned.…”