Studies on flavan 3 ols and biological activity of Kangra tea Camellia sinensis LO Kuntze

Abstract

newline ABSTRACT newlineSeasonal variations of total polyphenols (TP) in the range: 205.518 to 113.719 g kg-1, 269.529 to 140.210 g kg-1 and 263.223 to 104.759 g kg-1 and total catechins (TC) in the range of 110.209 to 40.904 g kg-1, 174.774 to 31.069 g kg-1 and 162.619 to 82.673 g kg-1 in fresh shoots of Kangra local tea [Camellia sinensis (L) O Kuntze] cultivar collected at seven day intervals throughout the harvesting seasons during three consecutive years (2007, 2008 and 2009) were significant. The variations in the levels of TP and TC ranging between 258.025 to 98.391 g kg-1and 173.399 to 76.645 g kg-1 in bud; 283.011 to 125.101 g kg-1 and 183.058 to 88.111 g kg-1 in first leaf and 252.562 to 107.818 g kg-1and 159.179 to 85.875 g kg-1 in second leaf, respectively, during 2009 were also significant. Summer and rainy flush season s samples of fresh tea shoots, bud, first leaf, second leaf and powders obtained by lyophilizing their aqueous extracts invariably had higher levels of TP and TC compared to first and winter flush seasons. Stepwise regression analysis indicated that mechanisms that induced seasonal variations in the levels of phenolic constituents of tea shoots may include one or all the weather parameters which varied markedly across harvesting seasons over the years under investigation. newlineThe variations of flavan-3-ols (per cent) in tea powders obtained from fresh green tea shoots, bud, first leaf and second leaf were; (+)-catechin (C): 2.84 to 0.69; (and#8722;)-epicatechin (EC): 14.05 to 3.54; (and#8722;)-epigallocatechin (EGC): 36.01 to 17.62; (and#8722;)-epigallocatechin gallate (EGCG): 59.94 to 38.08 and (and#8722;)-epicatechin gallate (ECG): 24.38 to 10.96. The levels of flavan-3-ols were invariably higher in the samples of summer and rainy flush seasons and always varied in the order: EGCG gt EGC gt ECG gt EC gt C. newlineThose aqueous extracts of fresh tea shoots, bud, first leaf, second leaf and tea powder solutions which had higher concentrations of EGCG and ECG were potent 2, 2-diphenyl-1-picrylhydrazyl free radical scavangers, ferrous ion chelators and growth inhibitors of bacterial pathogens: L. monocytogenes (MTCC-839), P. auroginosa (MTCC-741), B. cereus (MTCC-1272), S. aureus (MTCC-96) and S. mutans (MTCC-890). Teas of summer and rainy flush seasons exhibited superior biological activity compared to first and winter flush. The growth inhibition was found to be bacteriostatic instead of bactericidal. newline newline newline