The RP-HPLC method for analysis of usnic acid as potential marker of herbal drugs-based formulations containing Usnea barbata

Abstract

The aim of this study was to develop and validate a sensitive RP-HPLC method for the determination of usnic acid, as a potential marker substance of the herbal product for oromucosal use being a complex mixture of plant extracts and an essential oil, including the extract of Usnea barbata. Analysis of usnic acid in the tested formulation was performed through an extraction with methanol, prior to injection onto the HPLC column (Zorbax Eclipse XDB-C18 600 Bar (4.6 mm×100 mm, 1.8 μm)). The employed gradient procedure of the solvents (phosphoric acid (pH 2.5) and acetonitrile), at flow rate of 0.1 mL min-1 allowed for the efficient and reproducible separation of usnic acid from the other compounds present in the investigated complex mixture. The established suitability, linearity, precision, accuracy and selectivity/specificity of this assay implied its applicability for the reliable examination in the stability study of the investigated multi-ingredient herbal preparation.

Keywords

• usnic acid
• marker substance
• method development
• method validation
• herbal product