Antioxidant properties and qualitative analysis of phenolic constituents in Ephedra spp. by HPTLC together with injection port derivatization GC-MS.
Ephedra herb extracts are being extensively investigated in terms of their antioxidative, antimicrobial and antiproliferative properties, with phenolic components being the general carriers of these bioactivities. Here we describe a comprehensive set of analytical methods employed to determine and characterize both the antioxidative activity and the qualitative profile of phenolic acids and flavonoids present in several Ephedra species of different geographical origin. Spectrophotometric methods were used to determine the total phenolic content, total flavonoid content and antioxidative activity. Multi-development HPTLC enabled chemical fingerprinting which can be used for species differentiation. Individual spots of the thin-layer chromatogram were subjected to GC-MS with injection port derivatization for identification, which was based on both the detected mass spectra and recorded retention indices. The results were compared and complemented with GC-MS using offline derivatization.