ANTIBACTERIAL ACTIVITY OF AQUO-ALCOHOLIC EXTRACT OF CAMELLIA SINENSIS AGAINST ISOLATES OF CARBAPENEM RESISTANT ESCHERICHIA COLI AND FOOD BORNE PATHOGENS
An aquo-alcoholic (1:1) extract of Camellia sinensis (PTRC-31911-A), containing 17.95±0.02 µg of quercetin / mg of dried extract exhibited [Flavonoid/ Polyphenol: F/P (Quercetin %) ~ 0.26 (1.68%)], taken as standardized indicator. The bioactivity fingerprint profile of PTRC-31911-A includes IC50 ratio [DPPH/NOS] = 0.092 as functional standardized value having IC50 (DPPH Scavenging) = 30.332 ± 0.5 µg/ml and IC50 (Nitric Oxide Scavenging) = 326.723 ± 0.5 µg/ml respectively. The reducing ability and anti-lipid peroxidation equivalent (Extract: Standard) of PTRC-31911-A with respect to standard was estimated to be 10.09 (Ascorbic acid) and 1.96 (Quercetin) respectively. The results also showed that the Minimum Inhibitory Concentration (MIC) of PTRC-31911-A extract against New Delhi Metallo-beta-lactamase-1 (NDM-1) Escherichia coli was 500µg/ml. While the respective zones of inhibition against the food borne pathogens i.e., Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Vibrio parahemolyticus, Salmonella typhimurium, E. coli O157:H7 and Shigella sonnei were in the effective range of 12-23 mm. Efficacy in terms of MIC against selected food borne pathogens was found to be in the range of 100 – 350 µg/ml. This broad spectrum antimicrobial activity of PTRC-31911-A could most possibly be attributed to its high total contents of phenolic compounds, flavonoids such as quercetin (2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4Hchromen-4-one) as identified in this study. Further pre-clinical efficacy studies in animal system studies are warranted