Fast RP-HPLC Method for Analysis of Glucosinolates and Phenolics in Moringa stenopetala Leaf Powder Preparations

Abstract

Moringa stenopetala (M. stenopetala) leaf powder is extensively used as food, for preparation of nutraceuticals and herbal medicines in many developing countries. Glucosinolates and phenolics are known to be important bioactive constituents of these preparations. In this study, a selective and fast RP-HPLC method was developed and validated for simultaneous determination of intact glucosinolates and phenolics in M. stenopetala leaf powders. The developed method was linear with a coefficient of determination (r²) ≥ 0.998, precision ≤ 1.5%, and recovery values close to 100%. The method was also sensitive with detection and quantification limits below 1.5 µg/mL and 5 µg/mL, respectively. Besides the use of external standards, quantitative analysis of multicomponents by a single marker (QAMS) was developed and applied to commercial Moringa samples. The correlation coefficient (r ≥ 0.9993) between the QAMS and the external standard method proved the consistency and the strength of the relationship between the two methods. Rutin was used as single marker for the determination of five bioactive components in M. stenopetala leaf samples. Furthermore, a radar plot was used to differentiate samples collected from different geographical origin. Analysis results of the commercial samples revealed that rutin was found to be the constituent with the highest concentration (varying from 6.6 mg/g to 18.8 mg/g) among the phenolics while glucomoringin (0.2–4.2 mg/g) was the most common glucosinolate.