Thirty-one Tocklai vegetative (TV) tea clones contained caffeine and total catechin 44.39 and 227.55 mg/g dry weight of leaves, respectively. The (-)-epigallocatechin gallate (EGCG) was the most abundant (109.60 mg/g) followed by -(-)-epigallocatechin (EGC, 44.54 mg/g), (-)-epicatechin gallate (ECG, 41.74 mg/g), (-)-epicatechin (EC, 27.42 mg/g) and +catechin (4.25 mg/g). Total catechins were highest in TV 20 (509.7 mg/g) and lowest in TV 6 (71.7 mg/g). The tea clones that contain high level of total catechin exhibited the strongest antimicrobial activity. Among caffeine and flavanol compounds, theaflavins (TF) present in black tea possess a similar antimicrobial potency as EC present in fresh leaves, and that the conversion of catechins to TF during fermentation in making black tea tends to alter their antimicrobial activities. The bioactive molecules other than catechins present in tea leaves may also contribute towards antimicrobial activity.
Keywords: Antimicrobial activity; Catechins; TV tea clones; Tea extract.