Study of free radical scavenging activity of extracts of leaves of Bergenia by HPTLC-DPPH· method

Leaves of Siberian plant Bergenia crassifolia (L). Fritsch showed antimicrobial, immunostimulating and adaptogen activities [1]. Prominent feature of Bergenia is simultaneous presence both green (young), and black (wintered) leaves on one plant. The aim of this study was to assess the antioxidant properties of green and black Bergenia leaves. Total phenols were estimated according to the Folin-Ciocalteu method. The qualitative- quantitative analysis made by HPTLC plates with toluene-ethyl acetate-formic acid-methanol 3:3:0.8:0.2 v/v/v/v as mobile phase. Free radical scavenging activity of methanol extracts of bergenia leaves was examined using HPTLC-DPPH · method [2]. HPTLC-densitometry and post chromatographic derivatization of plates in HPTLC-DPPH · method were developed and validated. The ID 50 values (the dose of the compounds required to scavenge 50% of DPPH · ) were calculated (Table). Content and free radical scavenging activity of phenol compounds of bergenia leaves: Sample Total phenols, % % Arbutin Gallic acid Hydroquinone inhibition of DPPH · contents, % ID 50 , nmol contents, % ID 50 , nmol contents, % ID 50 , nmol Green leaves 4.95±0.25 62 7.00±0.60 0.879 0.10±0.01 0.488 not detected 1.227 Black leaves 3.25±0.16 65 not detected 0.50±0.04 1.00±0.08 No significant association between the total phenolic content and DPPH · radical scavenging for green and black leaves extracts of Bergenia was observed. The components arbutin, gallic acid, bergenin and insignificant amount of ellagic acids were identified in green leaves using authentic standards. In black leaves gallic acid, hydroquinone, bergenin and insignificant amount of ellagic acid were detected. All compounds excluding coumarin bergenin were capable to scavenge DPPH · radicals. The radical sceving activity of green leaves extract is due to the high concentration of arbutin and that of black leaves extract to the high concentration of gallic acid. References: [1] Popov SV. et al. (2005) Phytother. Res. 19: 1052–1056. [2] Pozharitskaya ON. et al. (2007) J Sep Sci. 30; in press.