Interspecific variability for antioxidant activity and phenolic content among Solanum species

Total antioxidant activity was evaluated in 40 tuber-bearing Solanum species. Accessions identified in a broad screen as having high antioxidant activity were fine screened via high performance liquid chromatography (HPLC) to determine specific phenolic compounds present. The objective of the study was to identify tuber-bearing Solanum species that are higher in antioxidants than in currently available cultivated varieties and breeding lines, and to investigate the variability for this trait among accessions within species and genotypes within accessions. The identified accessions will be used as a source of germplasm to develop potato cultivars containing increased levels of antioxidant compounds. In a broad screen for total antioxidant activity, the 40 tuber-bearing species showed a wider range of variability than cultivated varieties and breeding lines. Solanum pinnatisectum and S. jamesii accessions consistently ranked among the highest in antioxidant activity and phenolic content. Based on the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay, antioxidant activity in the wild species ranged from 48 to 824 mu g trolox eq/gfw. HPLC analysis revealed that the phenolic content of these species was primarily composed of chlorogenic and caffeic acids. Other phenolics identified were p-coumaric acid, rutin hydrate, vanillic acid, epicatechin, t-cinnamic acid, gallic acid, and salicylic acid. The highest phenolic content found among the accessions was five-fold higher than the highest of the cultivated genotypes.