High-performance thin-layer chromatography method for quantitative determination of oenothein B and quercetin glucuronide in aqueous extract of Epilobii angustifolii herba

A method was developed for separation and quantitative determination of oenothein B (OeB) and quercetin glucuronide (QG) in aqueous extract of Epilobii angustifolii herba by HPTLC-densitometry. The analyses were performed on HPTLC RP-18 WF254 plates with 25% MeCN in water (+50 mM H3PO4) as the mobile phase (distance of 8 cm) for OeB quantification and then with acetonitrile (distance of 4 cm) for QG quantification. OeB and QG were determined by densitometry at 270 and 350 nm, respectively. Their amounts were calculated using the regression equations of the calibration curves which were linear in a range of 1.14–2.28 μg spot−1 for OeB and of 0.0768–0.6912 μg spot−1 for QG. The amounts of OeB and QG in aqueous extract of Epilobii angustifolii herba measured by the method developed were 152.46 ± 4.92 and 22.07 ± 1.38 mg g−1, respectively. The method was found to be relatively simple, specific, precise and accurate for the quality control of Epilobium angustifolium extracts.