Quantitative analysis of arbutin and hydroquinone in strawberry tree (Arbutus unedo L., Ericaceae) leaves by gas chromatography-mass spectrometry

Abstract

Phenolic glycoside arbutin and hydroquinone, its metabolite with uroantiseptic activity, occurs naturally in the leaves of various medicinal plants and spices. In this study, an extraction procedure coupled with gas chromatography-mass spectrometry (GC-MS) method has been developed to determine content of arbutin and hydroquinone in strawberry tree (Arbutus unedo L.) leaves. The method showed good linearity (R²>0.9987) in tested concentration range (0.5-200 µg mL^-1), as well as good precision (RSD<5 %), analytical recovery (>96 %), and sensitivity (limit of detection=0.009 and 0.004 µg mL^-1 for arbutin and hydroquinone, respectively). Results obtained by validated GC-MS method corresponded well to those obtained by high performance liquid chromatography (HPLC) method. The proposed method was applied for determining arbutin and hydroquinone content in methanolic leaf extracts. The amount of arbutin in the leaves collected on the island of Koločep (6.81 mg g^-1 dry weight) was found to be higher in comparison to the amount of arbutin in the leaves collected on the island of Mali Lošinj (2.75 mg g^-1 dry weight). Hydroquinone was not detected in any samples. Analytical features of the proposed GC-MS method demonstrated that arbutin and hydroquinone could be determined alternatively by gas chromatography. Due to the wide concentration range, the method is also suitable for analysis of arbutin and hydroquinone in leaves of plants other than strawberry tree.