Stability indicating RP-HPLC method for the simultaneous determination of multi-flavonoid compounds in herbal extracts, besides green analytics

A stability-indicating RP-HPLC method was developed and validated for the simultaneous quantification of five flavonoids, viz., epigallocatechin gallate (EGCG), silibinin (SL), naringenin (NG), genistein (GT), and apigenin (AG), in herbal extracts. Chromatographic separation was achieved on a C18 column using 0.1 M ammonium acetate and methanol at 40:60% v/v. The method demonstrated acceptable resolution, linearity (r²: 0.9905-0.9969), precision (<2% RSD), recovery (82.09-99.62%), and sensitivity (LOD: 0.068-1.516 μg/mL; LOQ: 0.20-4.59 μg/mL). The method successfully quantified these flavonoids in the aqueous extracts of Phyllanthus emblica L., Brassica oleracea L., Camellia sinensis (L.). Kuntze, Moringa oleifera L., Syzygium cumini (L.) Skeels, and Allium cepa L. Results revealed that EGCG was the major constituent found in all extracts, whilst AG, GT, and SL were found as minor constituents. The method identified six degradation products with a mass balance of >98%. The method demonstrated acceptable green chemistry by the AGREES and GAPI tools.