Isolation and Identification of Two Antibacterial Agents from Chromolaena odorata L. Active against Four Diarrheal Strains

Abstract

Chromolaena odorata L (Asteraceae) is a bad invasive plant, found in the humid tropics and sub-tropics worldwide. It is used against dysentery, diarrhea, malaria, wound healing, headache and toothache in traditional medicine. In the pre- sent study, we investigated the antibacterial activities of different leaves extracts of Chromolaena odorata L. (cyclo- hexane, dichloromethane, ethyl acetate and butanol) against four clinical diarrheal strains (Klebsiella oxytoca, Salmo- nella enterica, Shigella sonnei and Vibrio cholera). We demonstrated that C. odorata leaves extracts show an antibacte- rial activity between 0.156 and 1.25 mg/mL. Bioassay-guided chromatography by bioautography with iodonitrotetra- zolium-based colorimetric assay allowed the isolation and identification of two active compounds. After the combina- tion of RP-HPLC, mass spectrometry analysis, 1D and 2D-NMR spectroscopy, we isolated and characterized two active molecules corresponding to 3’,4’,5,6,7-Pentamethoxyflavone (Sinensetin) and 4’,5,6,7-Tetramethoxyflavone (Scutel- lareintetramethyl ether).