Identifying antibacterial activity components of cosmos flower extracts

This study investigated whether the extracts from cosmos flowers exhibit antibacterial activities and identified which components were ascribed to the antibacterial effects. The antibacterial effects of extracts from white, pink, and violet cosmos flowers were observed for 24 h after inoculation with four kinds of bacteria, including Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli. Among the three fractions of cosmos flower extracts, the best antibacterial activity against the four bacteria was observed in the extracts isolated from the EtOAc layer. However, the extracts from the CHCl3 layer were also effective against S. aureus. Moreover, the first of white, second of pink, and first of violet silica gel fractions (Fr.) isolated from the EtOAc layer exhibited minimal inhibition at a concentration of 0.1 mg/mL. Comparison of NMR and High-Pressure Liquid Chromatography results between silica gel Fr. and apigenin suggested that the effective fractions can contain a component including apigenin moiety.