HPLC Profiling of Catechins and Purine Alkaloids in Leaves of Oolong and Green Tea Cultivars

The contents of catechins and purine alkaloids in two or three leaves with a bud from the spring and autumn shoots of 10 oolong and 10 green tea cultivars (Camellia sinensis) were determined by high performance liquid chromatography. A visual pattern recognition was performed with the aid of the principal components analysis, orthogonal partial least squares discriminant analysis and other statistical methods. There were distinctive differences on the profiles between the two categories of cultivars. The catechin and purine alkaloid fingerprints of oolong teas appeared more abundant and diverse than those of green teas. They also differed significantly by the season the leaves were plucked. Among the chemical constituents, caffeine, theobromine, epicatechin gallate, catechin, epigallocatechin, and an unknown component were particularly prominent. They could be used as the major markers for differentiating the two teas. In addition, 7 unknown components and epigallocatechin appeared suitable for distinguishing the spring shoots from the autumn shoots of oolong teas.