Caffeine standard

Background Caffeine and aspartame (ASP) are mostly used as a diet regimen to reduce overweight. The risk increase if used during critical life periods that may affect the development of fetal organs. Objective To evaluate the individual and combined effects of maternal exposure to caffeine and ASP during gestation and lactation on the kidneys' development of rats' offspring. Methods Pregnant rats were divided randomly into four groups; Group I (control group). Group II (ASP group): ASP was given at a dose of 40 mg of /kg/day. Group III (Caffeine group): caffeine was given at a dose of 80 mg/kg/day. Group IV (ASP & caffeine group); where previous doses of ASP and caffeine were given at the same time. All the treatments were given by oral gavage from the first day of pregnancy until postnatal day 30. Kidneys of rats' offspring were dissected and tested for detection of oxidative stress markers and for histopathological & immunohistochemical examination. Results This study showed a high significant increase in oxidative load (malondialdehyde) in renal tissues in group IV associated with decreased activities of total glutathione and antioxidant enzymes (superoxide dismutase and glutathione peroxidase). Histological and morphometric examination results showed delayed maturation of renal tissues in Group II and III, but more deleterious effects were observed in group IV with a lot of pathological changes in renal tissues. Conclusion The extensive use of caffeine and ASP should be controlled to avoid the risk of their toxicity.

While caffeine is one of the most important bioactive metabolites for tea as the most consumed non-alcohol beverage, its biosynthesis and catabolism in tea plants are still not fully understood. Here, we integrated purine alkaloid profiling and transcriptome analysis on shoot tips and roots fed with caffeine, theophylline, or theobromine to gain further understanding of caffeine biosynthesis and degradation. Shoot tips and roots easily took up and accumulated high concentrations of alkaloids, but roots showed much faster caffeine and theophylline degradation rates than shoot tips, which only degraded theophylline significantly but almost did not degrade caffeine. Clearly feedback inhibition on caffeine synthesis or inter-conversion between caffeine, theophylline, and theobromine, and 3-methylxanthine had been observed in alkaloids-fed shoot tips and roots, and these were also evidenced by significant repression ofTCSandMXMTgenes critical for caffeine biosynthesis. Among these responsively repressed genes, two highly expressed genesTCS-4andTCS-8were characterized for their enzyme activity. While we failed to detect TCS-4 activity, TCS-8 displayedN-methyltransferase activities towards multiple substrates, supporting the complex metabolic network in caffeine biosynthesis in tea plants since at least 13 TCS-likeN-methyltransferase genes may function redundantly. This study provides new insight into complex metabolic networks of purine alkaloids in tea plants.