Reduction of membrane fluidity by antibacterial sophoraflavanone G isolated from Sophora exigua.
Sophoraflavanone G (5,7,2',4'-tetrahydroxy-8-lavandulylflavanone) has been referred as a phytochemical with the intensive antibacterial activity. To elucidate the pharmacological mechanism underlying an antibacterial action, sophoraflavanone G was isolated from Sophora exigua, thereafter its effect on membrane fluidity was studied using model membranes and compared with less active naringenin lacking 8-lavandulyl and 2'-hydroxyl groups. Highly purified sophoraflavanone G of 0.05-5 microg/ml, corresponding to the minimum growth inhibitory concentrations against various bacteria, significantly increased fluorescence polarization of the liposomes prepared from 1,2-dipalmitoyl-L-alpha-phosphatidylcholine and 1-palmitoyl-2-oleoyl-L-alpha-phosphatidylcholine. Such increases were found in both liposomes measured with two fluorescent probes to indicate an alteration of membrane fluidity in hydrophilic and hydrophobic regions, suggesting that sophoraflavanone G reduces the fluidity of outer and inner layers of membranes. Although naringenin also showed the membrane effect, it needed concentrations over 2.5 microg/ml to induce a significant reduction of membrane fluidity. Sophoraflavanone G is considered to exert an antibacterial effect by reducing the fluidity of cellular membranes.
Tsuchiya
H
H
Department of Dental Pharmacology, Asahi University School of Dentistry, Gifu, Japan. hiro@dent.asahi-u.ac.jp
Iinuma
M
M
D015060:1,2-Dipalmitoylphosphatidylcholine; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D007887:Fabaceae; D044950:Flavanones; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D008081:Liposomes; D008560:Membrane Fluidity / Q000187:drug effects*; D010713:Phosphatidylcholines; D010946:Plants, Medicinal; D013785:Thailand
D000900:Anti-Bacterial Agents; D044950:Flavanones; D005419:Flavonoids; D008081:Liposomes; D010713:Phosphatidylcholines; D015060:1,2-Dipalmitoylphosphatidylcholine; C064849:vexibinol; C028694:1-palmitoyl-2-oleoylphosphatidylcholine