title: Antibacterial effect of amentoflavone and its synergistic effect with antibiotics.
abstract: Selaginella tamariscina is a traditional herb used in medicine. Phytochemical amentoflavone, a biflavonoid class of flavonoids, was isolated from the plant of Selaginella tamariscina. In this study, the antibacterial effects and combination effects of amentoflavone and conventional antibiotics such as ampicillin, cefotaxime, and chloramphenicol were investigated. These results showed that amentoflavone had a considerable antibacterial effect and synergistic interaction with antibiotics against various bacterial strains (fractional inhibitory concentration index ≤ 0.5), except for Streptococcus mutans. To study the mechanism(s) involved in the synergistic activities between amentoflavone and antibiotics, we detected hydroxyl radical formation using 3'-(p-hydroxyphenyl) fluorescein and measured the NAD⁺/NADH ratio by NAD⁺ cycling assay. The results indicated that the formation of hydroxyl radical would be a cause of the synergistic effect and that this oxidative stress originated from a transient NADH depletion. This study suggests that amentoflavone synergizes with antibiotics and has potential as a therapeutic agent for antimicrobial chemotherapy.
authors.affiliation: School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Daegu 702-701, Republic of Korea.
authors.forename: Ji Hong
authors.initials: JH
authors.lastname: Hwang
authors.forename: Hyemin
authors.initials: H
authors.lastname: Choi
authors.forename: Eun-Rhan
authors.initials: ER
authors.lastname: Woo
authors.forename: Dong Gun
authors.initials: DG
authors.lastname: Lee
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D044946:Biflavonoids / Q000302:isolation & purification / Q000494:pharmacology*; D004357:Drug Synergism; D017665:Hydroxyl Radical / Q000378:metabolism / Q000633:toxicity; D010946:Plants, Medicinal / Q000737:chemistry; D032503:Selaginellaceae / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D044946:Biflavonoids; D017665:Hydroxyl Radical; C011164:amentoflavone