engleski

Medicinal plants as sources of resveratrol and its derivatives

Stilbene polyphenols are subject of numerous researches as antioxidant, cardioprotective and antitumour properties of resveratrol have already been proved. The aim of this study was to determine the polyphenolic composition and antioxidant properties of ten medicinal plants traditionally used in Croatian folk medicine. Antioxidant capacity of ethanolic plant extracts was determined as percentage of inhibition of stable α , α -diphenyl-β -picrylhydrazyl radical (DPPH). Total phenols (TP) were determined by Folin-Ciocalteu method. Stilbene polyphenols were analyzed by HPLC-RP. Significant differences in TP concentrations and antioxidant properties of analyzed plant extracts were confirmed, as expected. The total phenolic contents ranged from 508 to 1646 mg gallic acid equivalents (GAE)/100 g of dry plant material (Vitis idaeae folium > Mirtilli folium >Fragariae folium > Helichrysi flos >Teucrii montani herba > Menthae folium > Salviae folium > Poligonii herba >Symphity folium >Urticae folium). All plant extracts exhibited excellent capability of free radical scavenging. When DPPH was compared at equal concentration value of TP (100 mg GAE/L of plant extract), it ranged from 49.24 to 91.03 %. Vitis idaeae folium, Mirtilli folium, Fragariae folium and Salviae folium extracts showed the best DPPH results. HPLC separation indicated the differences in the polyphenolic composition of plant extracts. While Helichrysi flos and Menthae folium extracts were rich in flavonoid quercetin, stilbene glucosides (isorhapontin, piceid and/or astringin) were found in Salviae folium, Fragariae folium and Teucrii montani herba extracts. As these plants are well-known in phytomedicine their medicinal properties may be related to the presence of these resveratrol derivatives.

Polyphenols; stilbenes; medicinal plants

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