Comparison of polyphenol and volatile compounds and in vitro antioxidant, anti-inflammatory, antidiabetic, anti-ageing, and anticancer activities of dry tea leaves

In the study, the polyphenol profile, volatile compounds, antioxidant, anti-inflammatory, antidiabetic, anti-ageing, and anticancer properties of tea methanolic extracts were analysed. Five types of tea were investigated: green, black, red, blue (oolong), and white. The highest phenolics content (30.68 g/100 g) was found in green tea, while the lowest (23.38 g/100 g)was observed in oolong tea. Using the GC-MS Arrow-HS method, 117 volatile compounds were identified based on MS spectra and retention indices. White tea demonstrated the highest antioxidant activity, while green tea exhibited the strongest inhibition of COX-1 and COX-2 enzymes (up to 77 %). Oolong and white teas showed the most potent α-amylase inhibition (up to 96.9 %). White and blue teas displayed the strongest anticancer activity, with significant cytotoxic effects on lung cancer cells. The dual role of tea polyphenols in oxidative stress and anticancer therapy is highlighted by ROS regulation in cancer cells.