LC-HRMS-based metabolomics to evaluate the phytochemical profile and antioxidant capacity of Cosmos caudatus with different extraction methods and solvents

Cosmos caudatus, a medicinal plant used in traditional medicine, is also consumed as a vegetable. This study aimed to determine the total phenolics, total flavonoids, antioxidant activity, and metabolite profiles of C. caudatus extracts obtained using different extraction methods (direct and successive macerations) and solvents. In addition, metabolite profiles were analyzed using principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) to distinguish samples and correlate them with their antioxidant activity. The total phenolic and flavonoid content in C. caudatus varied from 97.03 to 472.60 mg gallic acid equivalent/g dried sample and 24.56–68.00 mg quercetin equivalent/g dried sample. Ethanol extracts obtained through direct maceration method showed the highest antioxidant capacity. PCA using LC-HRMS chromatogram data distinguished the samples with a total PC of 95.1% (positive ionization mode) and 98.5% (negative ionization mode). Using PLS-DA, we identified several compounds, such as isoquercitrin, quercetin-3-O-rutinoside, avicularin, rutin, quercitrin, and vitexin, which likely contribute to the antioxidant capacity of C. caudatus.