[HPTLC scanning determination of 6 flavonoids in 166 Rhododendron species]

This paper reports a quantitative determination in the contents of flavonoids in Rhododendron leaves by HPTLC scanning method. The methanol extract of each sample was spotted on a HPTLC silica gel plate (E. Merck F254) alongside with standard substances. Using the upper layer of petroleum ether (60-90 degrees C)-ether-formic acid (62:31:7) as developing solvent I, farrerol, kaempferol and quercetin were well separated. The spots were determined by a single wavelength (366 nm) TLC-scanner, Camag model 76510. The same plate was then further developed by developing solvent II:7 ml of the lower layer of chloroform-methanol-water (7:3:1) plus 0.5 ml of formic acid to separate polystachoside, quercitrin and hyperoside. The densitometric determination of each spot was also carried out with the same scanner. The contents of 6 flavonoids in the leaves of 166 Rhododendron species were thus determined.