Classification of different edible plants based on total phenolic and in vitro antioxidant activities using principal component and hierarchical cluster analysis

An acetone-aqueous extracts of 16 edible plants was prepared; their Total Phenolic Content (TPC), 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH), 2,2?-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) radical scavenging (ABTS), Oxygen Radical Absorbance Capacity (ORAC) and Ferric Reducing Antioxidant Power (FRAP) were measured. Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were used to clarify the correlations between antioxidant assays and plant extracts. The first (PC1) and the second (PC2) principal components accounted for 91.60 % of the overall variability, whereas HCA classified samples into three main groups based on measured parameters. The 16 plants were classified into high, medium and low antioxidant activity groups based on according to TPC and the antioxidant activities results. Those in the high-antioxidant activity group were Punica granatum, Rheum officinale, Phyllanthus niruri and Melaleuca leucadendra. The plants in the medium-antioxidant activity group were Thymus vulgaris, Datura metel, Menthae arvensis, Parameria laevigata, Glycyrrhiza glabra, Curcuma xanthorrhiza and Zingiber officinale. The plants in the low-antioxidant activity group were Plantago major, Guazuma ulmifolia, Centella asiatica, Sericocalyx crispus and Piper nigrum. Positive relationships existed between TPC and the antioxidant activity of the extracts, indicating that the principal contributors to the antioxidant characteristics of the studied plants are phenolic compounds. Some of these plants may serve as valuable sources of natural antioxidants.