Metabolic Profiling of Nine Species and Prediction of Their Antioxidant Properties Using Chemometrics.

species are well recognized for their medicinal and aromatic properties. The comprehensive metabolite profiles of nine species have been determined. The extracts of these species were also screened for antioxidant and free radical scavenging activities. Forty-seven hydrophilic and seventeen lipophilic compounds were identified and quantified from the selected species. Also, eleven phenolic compounds, riboflavin and eight carotenoids were present, and their composition and content varied among the various species. The different species exhibited a range of antioxidant potencies. Horse mint especially exhibited the strongest antioxidant capacities (1,1-diphenyl-2-picryl-hydrazyl (DPPH), hydrogen peroxide, and reducing power assay) among the nine species. A difference between different samples from the same species was not observed by multivariate analysis. A high correlation between metabolites involved in closely linked biosynthetic pathways has been indicated. The projection to latent structure method, using the partial least squares (PLS) method, was applied to predict antioxidant capacities based on the metabolite profiles of leaves. According to the PLS analysis, several carotenoid contents, such as -β-carotene, 9-β-carotene, 13-β-carotene and lutein, as well as phenolic compounds, showed a positive relationship in reducing the power of extracts. Horse mint is a good candidate because of its high antioxidant efficacy among the nine species included in the study.