Evaluation of properties inhibiting tyrosinase by selected plant extracts
Elżbieta Studzińska-Sroka, Agata Frątczak, Wiesława Bylka
Katedra i Zakład Farmakognozji Uniwersytet Medyczny w Poznaniu
Introduction. Hyperpigmentation is an important esthetic problem, therefore, the search for compounds with the whitening action is necessary.
Aim. The aim of this work was to determine capability of tyrosinase activity inhibition by the extracts from elderberry flowers (Sambucus nigra), calendula flowers (Calendula officinalis), eyebright (Euphrasia officinalis), as well as by the following phenolic acids: chlorogenic, gallic, and caffeic. The total polyphenols content in the examined extracts was also determined.
Materials and methods. The experiment was carried out using the aqueous extracts from plants and selected phenolic acids. The ability to inhibit tyrosinase was measured by spectroscopic method using mushroom enzyme and L-DOPA. The total content of polyphenols was analysed using the Folin-Ciocalteau method and the obtained results were presented as equivalent of caffeic acid.
Results. From among the tested extracts (the concentration 125 mg dw/ml), the strongest inhibitory effect was observed for the elderberry extract, the weakest for calendulae and the eyebright extracts. The inhibitory action was 18%, 11% and 4%, respectively, more potent than hydrochinon solution (5 mg/ml) used as a control. The polyphenols content was the highest in the elderberry flowers (28,52 mg CAE/g dw), lower in the eyebright herb (20,49 mg CAE/g dw), and in the calendula flowers (13,44 mg CAE/g dw). The inhibitory activity of phenolic acids was in the range of 34-64%.
Conclusions. The results of the study proved potential whitening properties of the elderberry flowers, calendula flowers, and eyebright extracts as well as of the phenolic acids present in the selected plants.
Key words: plant extracts, phenolic acids, polyphenols, tyrosinase inhibition