Protective effects of L-theanine against bisphenol A-induced oxidative stress and gut microbiota disruption in Wistar rats
This study investigates the protective role of L-theanine (LTN), a bioactive amino acid found in green tea, against the harmful effects of Bisphenol A (BPA), a common environmental contaminant, on the intestine. BPA has been linked to oxidative stress, inflammation, and disturbances in gut microbiota composition. L-theanine, known for its well-documented antioxidant and anti-inflammatory properties, has the potential to mitigate the harmful effects of BPA on intestinal health, but this role had not been thoroughly explored before. The study was conducted on female Wistar albino rats, which were divided into three groups: control, BPA (50 mg/kg/day), and BPA + LTN (100 mg/kg/day). All groups were treated for 30 days. After treatment, oxidative stress and inflammatory responses in intestinal and colonic tissues were assessed by measuring malondialdehyde (MDA), glutathione (GSH) levels, and the activities of myeloperoxidase (MPO) and catalase (CAT). BPA exposure significantly increased MDA and MPO levels, while reducing GSH and CAT activities compared to the control group. L-theanine treatment led to significant changes in MDA, MPO, and GSH levels, with MDA and MPO levels being significantly reduced in the intestine and colon tissues of the BPA+LTN group, and GSH and CAT levels being significantly increased compared to the BPA group. Additionally, fecal microbiota composition was analyzed using 16S rRNA gene sequencing, revealing that BPA exposure led to reduced microbial stability and compositional shifts. In contrast, L-theanine treatment partially restored microbial richness and community structure. In conclusion, these findings indicate that L-theanine alleviates BPA-induced oxidative stress and microbiota dysbiosis, suggesting its potential as a protective dietary compound against environmental toxicant-related intestinal injury.