rhamnetin and kaempferol-7-methyl-ether

The study is to develop an HPLC method for simultaneous determination of rhamnazin (1), rhamnocitrin (2), rhamnetin (3), rhamnazin-3-O-beta-D-glucopyranoside (4), rhamnazin-3-O-beta-D-xylopyranosyl-(1-->4)-beta-D-glucopyranoside (5), rhamnazin-3-O-beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranoside (6), and rhamnocitrin-3-O-beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranoside (7) in Nervilia fordii. The separation was performed on a Kromasil C18 column (250 mm x 4.6 mm, 5 microm) with 0.4% phosphoric acid-acetonitrile as the mobile phase in a gradient elution at a flow rate of 1.0 mL x min(-1). The detect wavelength was set at 256 nm, and the column temperature was set at 40 degrees C. There were good linear relationships between the logarithm values of concentrations and those of the peak areas of seven flavonoids (1-7) in the range of 0.55-70.00 microg x mL(-1) (r = 0.9997), 0.86-110.00 microg x mL(-1) (r = 0.9997), 0.39-50.00 microg x mL(-1) (r = 0.999 7), 0.55-70.00 microg x mL(-1) (r = 0.999 5), 1.33-170.00 microg x mL(-1) (r = 0.9998), 1.33-170.00 microg x mL(-1) (r = 0.9998), 0.16-20.00 microg x mL(-1) (r = 0.9995), respectively. The recoveries of the seven flavonoids were between 97.19%-99.45%, the relative standard deviations (RSDs) were between 0.91%-2.69%. The established method is rapid, accurate with high repeatability, which could provide scientific evidence for the quality control of Nervilia fordii.

Topics: Chromatography, High Pressure Liquid; Drugs, Chinese Herbal; Flavonoids; Kaempferols; Orchidaceae; Plant Leaves; Plants, Medicinal; Quality Control; Quercetin

Preliminary studies with the four extracts of Oxytropis falcate Bunge exhibited that the chloroform and ethyl acetate extracts showed stronger antibacterial activities against the nine tested Gram-positive and Gram-negative bacteria. The HPLC-scanned and bioassay-guided fractionation led to the isolation and identification of the main flavonoid compounds, i.e. rhamnocitrin, kaempferol, rhamnetin, 2',4'-dihydroxychalcone and 2',4',beta-trihydroxy-dihydrochalcon. Except 2',4',beta-trihydroxy-dihydrochalcon, four other compounds had good antibacterial activities. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of the four compounds ranged between 125 and 515 microg mL(-1). Staphylococcus aureus was the most susceptible to these compounds, with MIC and MBC values from 125 to 130 microg mL(-1). This is the first report of antibacterial activity in O. falcate Bunge. In this study, evidence to evaluate the biological functions of O. falcate Bunge is provided, which promote the rational use of this herb.

Topics: Anti-Bacterial Agents; Bacteria; Chalcone; Chromatography, High Pressure Liquid; Flavonoids; Kaempferols; Microbial Sensitivity Tests; Oxytropis; Plant Extracts; Quercetin