Phytochemical profiles and antimicrobial activity of Citrus hystrix DC. (Kaffir Lime) leaves extract against selected bacterial gastroenteritis / Nur Fatin Nadira Muda

In the recent decade, search of complementary and alternative plant derived medicine has gained gradually interest among researchers due to side effects of the chemically synthesized drugs and antibiotic resistant bacteria. This study was carried out to determine the phytochemical compounds and antibacterial activity of methanolic leaves extract of Citrus hystrix (C. hystrix) on selected gastrointestinal pathogens (Staphylococcus aureus, Bacillus cereus, Salmonella typhimurium and Shigella flexneri) using the agar well diffusion method. The extract exhibited broad spectrum antimicrobial activity against the tested bacteria ranging from 11 to 18 mm. Predominantly, the maximum inhibition zone was observed against B. cereus (17.33±0.58 mm) followed by S. aureus (15.67±0.58 mm). The extract showed moderate antibacterial activity against S. flexneri (11.67±0.58 mm) followed by S. typhimurium (11.33±0.58 mm). The strongest minimum inhibitory concentration (MIC) value was observed against B. cereus with concentration 31.25 mg/ml. The extract also showed good patterns of inhibition against S. aureus and S. typhimurium with concentration 125 mg/ml. MIC values were maximized against S. flexneri with concentration 250 mg/ml. The most effective bactericidal activity of the extract was observed against B. cereus with minimum bactericidal concentration (MBC) at 125 mg/ml followed by S. aureus and S. flexneri with MBC at 250 mg/ml. S. typhimurium was the least sensitive to the extract with the MBC value at 500 mg/ml. Phytochemical screenings revealed the presence of alkaloid, flavonoid, terpenoid and tannin compounds. The results of the present study suggest this extract exhibited the strongest antibacterial activity against B. cereus with maximum inhibition zone and least MIC and MBC values.