2.2. Tea samples and preparation
White tea (Silver needle, KWF Food Industries, China), was purchasedfrom the local market. Tea infusion was prepared by placing 2 g of tea leaves in 100 ml of distilled water at boiling temperature (100 _C) and brewing for 5 min. The sample (Silver needle white tea infusion) was filtered through Whatman filter paper No. 1 and the water extracts were freeze–dried. The concentrated extract was diluted appropriately with distilled water according to each specific assay and stored at _20 _C until further analysis.