title: Flavonoids from Sophora moorcroftiana and their synergistic antibacterial effects on MRSA.
abstract: Synergy is now a widely recognized approach that has direct applicability for new pharmaceuticals. The ethanolic extract of the aerial parts of the herb Sophora moorcroftiana showed significant antibacterial activity against drug-resistant Staphylococcus aureus, and its minimum inhibitory concentration (MIC) was 8 µg/mL. In a phytochemical study of the extract, five flavonoids were obtained. However, the isolates exhibited antibacterial activity in the range of 32-128 µg/mL, which was weaker than the extract. In combination with antibiotics, the antibacterially inactive compound genistein (1) and diosmetin (4) showed significant synergistic activity against drug-resistant S. aureus. In combination with norfloxacin, genistein (1) reduced the MIC to 16 µg/mL and showed synergy against strain SA1199B with a fractional inhibitory concentration index (FICI) of 0.38. With the antibiotics norfloxacin, streptomycin and ciprofloxacin, diosmetin (4) showed synergy against SA1199B, RN4220 and EMRSA-15, with FICI values of 0.38, 0.38 and 0.09, respectively. In an efflux experiment to elucidate a plausible mechanism for the observed synergy, genistein showed marginal inhibition of the NorA efflux protein.
authors: School of Pharmacy, Fudan University, Shanghai, 201203, China.
authors: Shuang-Ying
authors: SY
authors: Wang
authors: Zhong-Lin
authors: ZL
authors: Sun
authors: Tao
authors: T
authors: Liu
authors: Simon
authors: S
authors: Gibbons
authors: Wen-Ju
authors: WJ
authors: Zhang
authors: Mu
authors: M
authors: Qing
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004357:Drug Synergism; D005419:Flavonoids / Q000494:pharmacology*; D019833:Genistein / Q000494:pharmacology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D010936:Plant Extracts / Q000494:pharmacology*; D029909:Sophora / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D005419:Flavonoids; D010936:Plant Extracts; D019833:Genistein; C039602:diosmetin
keywords: Sophora moorcroftiana; antibacterial synergy; drug-resistant Staphylococcus aureus; efflux pump; flavonoid; isoflavonoid