Two new flavones glycosides with antimicrobial activities from Clerodendrum formicarum Gürke (Lamiaceae)

Clerodendrum formicarum Gürke from the Lamiaceae family is a Cameroonian medicinal plant. The crude methanol, methanol residual and ethyl acetate extracts of leaves have been phytochemically studied using chromatography column to afford four compounds; two new flavones glycoside: clerodendronone 1a (3) and clerodendronone 1b (4) along with two known compounds: 5,7-dihydroxy-4′-methoxyflavone (1) and 5-hydroxy-7,4′-dimethoxyflavone (2). Compound structures have been elucidated on the basis of their spectroscopy data and with literature information. The anti-microbial activities of extracts and three isolated compounds were performed. The antibacterial activity was evaluated against four gram positive, five gram negative and three fungus. Clerodendronone 1b (4) showed good antibacterial activity against bacterial gram negative Shigella flexineri NR518 (MIC = 62.5 μg/ml) and moderate activity against Staphylococcus aureus NR46374 (MIC = 250 μ/ml). The ethyl acetate extract recorded good antibacterial activity against Staphylococcus aureus NR46003 (MIC = 125 µg/ml) and Staphylococcus aureus NR46374 (MIC = 125 μg/ml).