. Conclusions
Our results show that for the eight purple basil varieties in this study, cultivar had a significant influence on total anthocyanin levels as well as individual anthocyanin concentrations. Analysis of individual anthocyanin levels revealed substantial variations in the profiles of the four predominant anthocyanins (labelled as anthocyanins A–D) among cultivars. Hierarchical cluster analysis based on the anthocyanin composition was used to place the cultivars into four groups, with the largest cluster characterised by relatively low concentrations of anthocyanins B and D, the next largest cluster containing varieties with moderate levels of anthocyanins B, C and D, and the remaining two clusters containing a single cultivar, one with high levels of anthocyanin C, and the other with high levels of anthocyanins B and D.
Cultivar also did not have a significant effect on total phenolic levels although it did influence the concentration of some individual phenolic acids including caftaric and chicoric acids. Hierarchical cluster analysis was used to place the cultivars into five classifications: the largest group was characterised by low caffeic, chicoric and rosmarinic acid levels; two groups contained two cultivars, one with very low gentisic acid levels and low caffeic and chicoric acid levels, and the other having low caftaric acid levels and high chicoric acid levels; and two groups with only a single cultivar, one with low gentisic acid levels, high rosmarinic acid levels, and very high caftaric, caffeic, and chicoric acid levels, and the other with high gentisic and rosmarinic acid levels and low caffeic acid levels. Comparing hierarchical cluster analysis results for phenolic acids and anthocyanins revealed that different relationships exist for the production of these secondary metabolites among cultivars. In some cultivars, high phenolic acid production correlated with low anthocyanin synthesis and vice versa. For other cultivars, however, phenolic acids and anthocyanin levels were uniformly low compared to other varieties. Finally, although total phenolic and anthocyanin concentrations correlated with measured FRAP antioxidant capacities, for some purple basil cultivars both the individual phenolic acid and anthocyanin composition was also found to be an important factor governing the antioxidant properties.