A cost-effective HPLC-DAD method for quality and stability assessment of antihypertensive herbal extracts in their recently co-formulated nutraceutical product

Abstract

Hypertension is a chronic public health crisis that results in worldwide morbidity and mortality. The use of herbal extracts as natural alternative for health promotion, prevention and treatment of diseases in humans is gaining popularity over the years. Hibiscus sabdariffa and Olea europaea herbs have received historical attention for their high nutritious and therapeutic values. In the present work, a novel and economic high performance liquid chromatographic (HPLC) method coupled with diode array detection (DAD) was developed for quality control and stability assessment of their co-formulated antihypertensive nutraceutical product (NW Roselle® capsules). The most abundant markers contributing to the therapeutic activity, namely, Delphinidin 3-sambubioside (DEL) and Oleuropein (OLE) were quantified simultaneously. Chromatographic separation was attained using an Inertsil C18, 250 × 4.6 mm, 5.0 µm column and a mobile phase consisted of acetonitrile - phosphate buffer, pH 3.0 ± 0.1 in a ratio of 30:70, v/v, pumped at a flow rate of 1.0 mL/min in an isocratic elution mode. The use of DAD permits proper wavelength selection for sensitive and selective quantitation of the separated markers as well as chromatographic peak purity assessment. Satisfactory separation was achieved within short analysis time without any interference from the matrix co-extracted constituents. The proposed method was validated in accordance to the ICH guidelines. Moreover, evaluating the stability of NW Roselle® capsules was performed under accelerated storage conditions in addition to shelf-life estimation. The developed method represents an efficient and economic analytical approach for the routine quality control and stability testing of a new combination nutraceutical product, with the aim of improving consumer’s wellbeing by tracking identity, strength and therapeutic effect throughout the shelf life.