Objective: To identify bioactive compound in pigeon pea leaves (Cajanus cajan) that inhibits Salmonella thypi (S. thypi). Methods: The leaf sample was powdered and macerated with methanol and fractioned by liquid–liquid extraction using ethyl acetate. The fraction was chromatographed and the isolates were identified for major component with liquid chromatography-mass spec-trometry and the antibacterial activity was tested against S. thypi by Kirby–Bauer method. Results: Subfraction 1 from the ethyl acetate fraction formed a yellowish solid with m/z 272, identified as naringenin. The naringenin-rich fraction shows fairly well inhibitory toward S. thypi in comparison with chloramphenicol. Conclusions: Naringenin shows antibacterial activity and can be developed to treat typhoid.

Objective To identify bioactive compound in pigeon pea leaves (Cajanus cajan) that inhibits Salmonella thypi (S. thypi). Methods The leaf sample was powdered and macerated with methanol and fractioned by liquid–liquid extraction using ethyl acetate. The fraction was chromatographed and the isolates were identified for major component with liquid chromatography-mass spectrometry and the antibacterial activity was tested against S. thypi by Kirby–Bauer method. Results Subfraction 1 from the ethyl acetate fraction formed a yellowish solid with m/z 272, identified as naringenin. The naringenin-rich fraction shows fairly well inhibitory toward S. thypi in comparison with chloramphenicol. Conclusions Naringenin shows antibacterial activity and can be developed to treat typhoid.