Evaluation of phytochemical, antimicrobial and time-killing assay of Camellia species

Tea (Camellia sinensis and C. assamica) possess antimicrobial property due to the presence of bioactive compounds. Qualitative analysis of phytochemicals of both tea species such as alkaloids, flavonoids, carbohydrates, saponins, tannins, steroids, terpenoids and cardiac glycosides was carried out. The antimicrobial activity of both plant species extracts were performed by well and disc agar diffusion methods. The most antimicrobial potential of plant extract was further selected to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against two most susceptible human pathogens. Phytochemicals and antimicrobial activity assays showed different results according to the type of the applied extract solvent. The methanol extract of C. sinensis shows more inhibitory effect than the other extracts of both tea species. The lowest concentration of C. sinensis was found at 0.048 mg/mL against Staphylococcus aureus. The MIC and MBC of S. aureus and Pseudomonas aeruginosa were ranged from 0.097 to 0.197 mg/mL and 0.19 to 0.39 mg/mL, respectively. Time-killing assay was performed against all tested pathogenic bacteria. After 6 h, P. aeruginosa showed no growth followed by Escherichia coli, Candida albicans, Klebsiella pneumoniae, S. aureus, Salmonella typhi, Listeria monocytogenes.