Determination of polyphenolics in extracts of Potentilla species by high-performance thin-layer chromatography photodensitometry method.

INTRODUCTION Separation of polyphenolics in different plant materials using high-performance thin-layer chromatography (HPTLC) represents an effective method for their detection and quantification. OBJECTIVE To develop a simple, specific, precise, sensitive and accurate method for the simultaneous quantification of tiliroside (TRS), methyl brevifolincarboxylate (MBR) and ellagic acid (EA) in a plant extract using the HPTLC-photodensitometry method. METHODOLOGY Aerial parts of the selected Potentilla species, P. anserina, P. erecta, P. grandiflora and P. nepalensis var. 'Miss Willmott', were extracted with methanol. After solvent evaporation, the methanolic extracts were diluted with water and successively partitioned between chloroform and then diethyl ether. The diethyl ether extracts from each sample were used for quantification. The analyses were performed on HPTLC precoated silica gel 60F(254) plates with toluene-ethyl formate-formic acid (6 : 4 : 1 v/v/v) as the mobile phase (distance of 7.5 cm). Densitometric detections of TRS, MBR and EA were performed at 320, 287 and 280 nm, respectively. The amounts of these compounds were calculated using the regression equations of the calibration curves, which were linear within a range of 0.05-0.5 microg/spot (R(2) = 0.9957) for TRS, 0.05-0.525 microg/spot (R(2) = 0.9965) for MBR and 0.0525-0.5 microg/spot (R(2) = 0.9998) for EA. RESULTS The amounts of marker compounds measured by the method developed are expressed in mg/g of dry extracts. TRS ranged from 20.3 +/- 0.3 mg/g for P. erecta herbs to 197.7 +/- 2.9 mg/g for P. grandiflora herbs; MBR ranged from 5.0 +/- 0.6 mg/g for P. erecta herbs to 68.5 +/- 3.4 mg/g for P. nepalensis flowers; and EA ranged from 24.0 +/- 0.6 mg/g for P. erecta herbs to 216.2 +/- 3.2 mg/g for P. anserina leaves. CONCLUSION The proposed method was found to be relatively simple, specific, precise, sensitive and accurate and may be used for the routine assay of simultaneous determination of TRS, MBR and EA in other extracts and phytomedicines containing Potentilla species.