Improved and Validated HPTLC Method for Quantification of Oenothein B and its Use for Analysis of Epilobium angustifolium L.

A selective and simplest possible high-performance TLC (HPTLC) method for quantification of oenothein B on the basis of the free gallic acid and total gallic acid content after acid hydrolysis has been developed and used for analysis of cultivated Epilobium angustifolium. HPTLC of aqueous extracts of E. angustifolium was performed on silica gel with benzene methanol acetic acid 90:16:8 (v/v), as mobile phase. Quantitative evaluation of the plate was performed at 570 nm after derivatization with 1% ethanolic FeCl3 solution. The method was validated for precision, repeatability, and accuracy. Average recovery of the active ingredient from the samples was in the range 95.43-104.57%. The calibration plots were linear in the range 440-2200 ng per band. The technique was used, for the first time, for estimation of the oenothein B content of cultivated E. angustifolium. The oenothein B content was highest at budding time (18.4-20.2 mg g(-1)) and decreased dramatically to 1.0 mg g(-1) after flowering.