Study on the chemical constituents of the dried leaves of Camellia sinensisvar. assamica resulted in isolation of a new compound: 13-methyl lansic acid (2) and eleven known compounds: -sitosterol (1), lansionic acid (3), stigmasterol (4),(+)catechin (5), 21R-hydroxyonocera-8(2b),14-dien-3-one (6), lupeol (7), lupenone (8), (-)epigallocatechin gallate (9), (-)epicatechin gallate (10) and (-)epicatechin (11). Their structures were elucidated on the basis of UV, IR and NMR spectroscopic data.

The compounds with sufficient quantity were evaluated for their antioxidationand antibacterial activities. Compounds 5, 9, 10 and 11 exhibited stronger antioxidant activity (IC50 0.60, 0.23, 0.27 and 0.07 mM, respectively) than that of ascorbic acid (IC50 1.75 mM) and BHT (IC50 3.03 mM). These four compounds also showed the moderate activities to inhibit the growth of Staphylococcus aureus, Escherichia coli,
Bacillus cereus, Pseudomonas florescens and Salmonella typhimurium with MIC 16- 128 g/mL compared to those of gentamycin and vancomycin (0.5 g/mL).