Development and validation method for simultaneous quantification of phenolic compounds in natural extracts and nanosystems

Introduction: Sage and savoury (Salvia sp. and Satureja montana, respectively) are plants used in traditional medicine. The quality control of their herbal formulations is of paramount concern to guarantee the expected biological activity of their anti-oxidant compounds.

Objective: To establish a simple and effective high-performance liquid chromatographic (HPLC) method to evaluate simultaneously quercetin and rosmarinic acid, in a pure form, in natural extracts (sage and savoury), and encapsulated into chitosan nanoparticles.

Methods: Chromatography was performed on an RP C18 -column, in a gradient mode with a mobile phase comprising methanol:formic acid:water 92.5:2.5:5 (v/v) at a flow rate of 0.75 mL/min and at wavelength of 280 nm.

Results: The method was specific, linear in the range of 0.05-1 mg/mL (R(2) = 1.00), precise at the intraday and interday levels, accurate (recovery rate 90.5 ± 0.6%), and robust to changes in equipment conditions.

Conclusion: The method established was effective for quercetin and rosmarinic acid characterisation in natural extracts and in chitosan nanoparticles, allowing the loading capacity determination, the association efficiency as well as the in vitro release.