Cytochrome P450-Dependent Metabolism of Caffeine in Drosophila melanogaster

Abstract

Caffeine (1, 3, 7-trimethylxanthine), an alkaloid produced by plants, has antioxidant and insecticide properties that can affect metabolism and cognition. In vertebrates, the metabolites derived from caffeine have been identified, and their functions have been characterized. However, the metabolites of caffeine in insects remain unknown. Thus, using radiolabelled caffeine, we have identified some of the primary caffeine metabolites produced in the body of Drosophila melanogaster males, including theobromine, paraxanthine and theophylline. In contrast to mammals, theobromine was the predominant metabolite (paraxanthine in humans; theophylline in monkeys; 1, 3, 7-trimethyluric acid in rodents). A transcriptomic screen of Drosophila flies exposed to caffeine revealed the coordinated variation of a large set of genes that encode xenobiotic-metabolizing proteins, including several cytochromes P450s (CYPs) that were highly overexpressed. Flies treated with metyrapone—an inhibitor of CYP enzymes—showed dramatically decreased caffeine metabolism, indicating that CYPs are involved in this process. Using interference RNA genetic silencing, we measured the metabolic and transcriptomic effect of three candidate CYPs. Silencing of CYP6d5 completely abolished theobromine synthesis, whereas CYP6a8 and CYP12d1 silencing induced different consequences on metabolism and gene expression. Therefore, we characterized several metabolic products and some enzymes potentially involved in the degradation of caffeine. In conclusion, this pioneer approach to caffeine metabolism in insects opens novel perspectives for the investigation of the physiological effects of caffeine metabolites. It also indicates that caffeine could be used as a biomarker to evaluate CYP phenotypes in Drosophila and other insects.

Comparative CYP‐omic analysis between the DDT‐susceptible and ‐resistant Drosophila melanogaster strains 91‐C and 91‐R

“…The over‐expressed Cyp6a8 we found in 91‐R is not known to metabolize DDT or confer resistance to DDT when expressed at high levels . The common induction of Cyp6a2 , Cyp6a8 , and Cyp6w1 in response to chemical challenge, and Cyp6a8 and Cyp6w1 up‐regulation in response to caffeine exposure may suggest their involvement in general detoxification or stress response pathways. Notably, a number of previous studies reported that multiple P450 genes such as Cyp6g1 and Cyp12d1 were over‐expressed in DDT‐resistant D. melanogaster strains, suggesting that Cyp6g1 and Cyp12d1 are globally associated with DDT resistance .…”

Caffeine effects on AdoR mRNA expression in Drosophila melanogaster

“…Moreover the metabolites of caffeine (theophylline, theobromine, paraxanthine) are also highly bioactive compounds that are capable of causing further effects [44]. This is especially relevant regarding theophylline, which is known to have a higher degree of affinity to AdoR in comparison to caffeine and its other metabolites [32].…”

Potential metabolism of pharmaceuticals in radish: Comparison of in vivo and in vitro exposure

“…The initial N-demethylation reaction (loss of one -CH3 group) is common in mammalians and insects, which is believed to be mediated by cytochrome P450 enzyme systems (i.e. CYP1A2 isoenzyme) (Berthou et al, 1991;Berthou et al, 1992;Coelho et al, 2015;Kot and Daniel, 2008). The N-demethylation reaction of antidiabetic agent metformin was also observed in Typha latifolia (Cui and Schröder, 2016).…”