Determination of tea polyphenols and caffeine in tea flowers (Camellia sinensis) and their hydroxyl radical scavenging and nitric oxide suppressing effects.

The native occurrence of tea polyphenols, namely, (-)-epicatechin, (+)-catechin, (-)-epigallocatechin 3-gallate, (-)-epicatechin, and (-)-epicatechin 3-gallate, and caffeine in tea flowers was assessed by an isocratic HPLC procedure. The levels of total catechins and caffeine were determined in tea flowers collected from 10 different species of Camellia sinensis. The results showed the levels of total catechin ranged from 10 to 38 mg/g, whereas the level of caffeine ranged from 3 to 8 mg/g. Levels of catechins and caffeine in tea leaves and various teas were also determined and ranged from 2 to 126 mg/g and from 23 to 49 mg/g, respectively. Both tea flower and tea leaf extracts exert their strong hydroxyl radical scavenging effects in the Fenton reaction system and nitric oxide suppressing effects in LPS-induced RAW 264.7 cells. Most tea flowers contain less caffeine, but comparable amounts of total catechins, compared to tea leaves and teas. The present study demonstrates that both tea flowers and tea leaves contain appreciable amounts of catechins and caffeine. It is likely that tea flowers might be useful for making alternative tea beverages.

Screen and genetic assessment of tea germplasms with elevated methylated catechin, (-)-epigallocatechin-3-O-(3-O-methyl)gallate.

The aim of this research was to identify tea varieties containing high levels of catechin methyl ester that could be used as important sources for genetic breeding and in the production of high quality tea. We examined 113 species that have been preserved in the Taitung Branch of the Tea Research and Extension Station of Taiwan (TTES). The average level of (-)-epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3''Me) was 0.45% for all varieties screened. Among them, 16 varieties with higher EGCG3''Me content (>0.8%) were considered good candidates for manufacturing partially fermented tea. Analysis of these tea varieties revealed that the EGCG3''Me content in leaves did not correlate with the caffeine content. Genetic assessments revealed that the lengths of their internal transcribed spacers (ITS) were in the range of 638-670 bp and that the sequence identities were in the range of 0.690-1. Two major groups were constructed by phylogenetic analysis, I and II, with a genetic distance of 0.08 based on the ITS1-5.8S-ITS2 sequences between the ribosomal genes. Our results provide genetic information about tea varieties with elevated EGCG3''Me content and indicate the need for a comprehensive genetic assessment of tea germplasms preserved in the TTES to better serve the future of tea breeding.