Juan Yang et al., J.Chem.Soc.Pak., Vol. 40, No. 01, 2018 158 Identification and Quantitative Evaluation of Major Sweet Ingredients in Sweet Tea (Lithocarpus polystachyus Rehd.) Based Upon Location, Harvesting Time, Leaf Age Juan Yang, Yuyi Huang, Zhi Yang, Chao Zhou and Xujia Hu* Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming 650500, P.R. China.
[email protected]* (Received on 11th April 2016, accepted in revised form 13th September 2017) Summary: Lithocarpus polystachyus Rehd. (Sweet Tea) is a traditional sweet tea plant. Flavonoids are the essential sweet active constituents of Sweet Tea, and they have direct relationship with the sweet tonic beverage and traditional herb. In this work, the chemical components of the sweeteners isolated from Sweet Tea were identified as 3-hydroxy phlorizin (1), phlorizin (2), kaempferol-3-O-β-D-glucoside (3) and trilobatin (4) by ESI•-MS and NMR analyses. Quantitative analysis of the flavonoid compounds in Sweet Tea from Yunnan province of China indicated their content was influenced by harvesting time and leaf age. Phlorizin and trilobatin were identified as principal flavonoids in Sweet Tea. The highest concentration of trilobatin was in April, and the highest concentration of phlorizin was in November. The flavonoids content was the highest in young leaves and decreased at mature stage. Moreover, considerable variations of flavonoids content in Sweet Tea from three locations (Yunnan, Hunan, Jiangxi) were observed. It was concluded that the quality of Sweet Tea is greatly influenced by harvesting time, location and leaf age. Therefore, the artificial cultivation of Sweet Tea is necessary to ensure its optimal quality and suitability for specific applications.