Profiling, identification, and quantification of antioxidant components in Gnaphalium affine by HPLC-ECD-MS/MS

Gnaphalium affine is a plant with various active properties and has been approved for use as a traditional medicine and food ingredient. In this study, liquid chromatography with electrochemical detection was utilized to separate the antioxidant compounds of G. affine, in conjunction with liquid chromatography-triple quadrupole mass spectrometry for identification. The in vitro antioxidant activity of G. affine was evaluated using DPPH and ABTS radical scavenging capacity assays, as well as the ferric reducing antioxidant power assay. The results showed that a total of 25 antioxidant compounds were screened and identified, among which 14 compounds were quantitatively analyzed. G. affine was found to be rich in phenolic substances, with the total phenolic content ranging from 14.62 to 59.30 mg GAE/g DW, which exhibited high antioxidant potential. The antioxidant activities showed a strong positive correlation with the total phenolic content (r > 0.9). The predominant phenolic compounds in G. affine were 5-O-caffeoylquinic acid, 3-O-caffeoylquinic acid, ferulic acid, luteolin-7-O-glucoside, 3,5-O-dicaffeoylquinic acid, 1,5-O-dicaffeoylquinic acid, and luteolin, with 3,5-O-dicaffeoylquinic acid and 1,5-O-dicaffeoylquinic acid exhibiting the highest levels. Statistical analysis indicated that monosubstituted caffeoylquinic acids, disubstituted caffeoylquinic acids, and luteolin derivatives strongly correlated with the antioxidant potential. This study identified and quantified the major chemical constituents responsible for the antioxidant properties of G. affine, demonstrating its potential as a natural source of antioxidants for the use in foods, pharmaceuticals, and health products.