Screen for Potential Candidate Alternatives of from Its Six Adulterants Based on Their Phenolic Compositions and Antioxidant Activities.

Daxueteng, the liana stem of , is a widely used Traditional Chinese Medicine facing the overflow of its commercial adulterants. A method for discriminating adulterants and screening potential candidate alternatives of was thus established. Total phenols and flavonoids of and its six adulterants and their abilities to scavenge DPPH and ABTS•+, to absorb peroxyl radicals (ORAC), and to inhibit AAPH-induced supercoiled plasmid DNA strand scission were comprehensively assessed. and , two of the six adulterants of , shared considerably higher antioxidant activities as well as phenolic contents and, therefore, were considered as potential candidate alternatives. Phenolic compositions of the two potential candidate alternatives and itself were further determined by UPLC-QTOF-MS/MS. Totally 38 phenolics, including four hydroxybenzoic acids, two tyrosols, two caffeoylquinic acids, seven flavanol or its oligomers, two lignans, three hydroxycinnamic acids, six stilbenes, seven anthraquinones, and five flavanones were determined from three species. Furthermore, contents of different phenolic categories were semi-quantified and the major antioxidant contributors of and the two potential candidate alternatives were subsequently determined. It is concluded that tyrosols and caffeoylquinic acids were unique categories making great antioxidant contributions in and thus were considered as effective biomarkers in distinguishing its potential candidate alternatives.