Two flavonoids have been isolated from ethyl acetate extract of Kalanchoe millotii and identified as quercetin (1) and eriodictyol (2). Isolation was carried out by the combination of column chromatography on silica gel and preparative HPLC. The molecular structures of both compounds (1-2) were identified using spectroscopic data (UV, IR, MS and NMR). Antibacterial assays done on the ethyl acetate extract and compounds 1-2, were carried out on Streptococcus mutans and Pseudomonas aeruginosa. The extract showed MIC values at 0.125 and 0.25 mg/mL against S. mutans and P. aeruginosa respectively while the their MBC value was 0.25 for both bacteria. Compounds 1 and 2 have the same MIC and MBC values on both bacteria at 1 mg/mL. The ethyl acetate extract therefore is more active as antibacterials than the isolated compounds.

Keywords: Kalanchoe millotii, flavonoids, quercetin, eriodictyol, antibacterial.