Characterization of Phytochemicals in Petals of Different Colours From Viola × wittrockiana Gams. and Their Correlation With Antioxidant Activity

A study to establish relationship between the petal colour, extraction solvent, phenolic, flavonoid, anthocyanin content and antioxidant activity in three varieties of Viola × wittrockiana (yellow, red and violet) is reported in this article. Identification and quantification of flavonoids and anthocyanins using HPLC-DAD-ESI-MS is also presented. The antioxidant activity was studied by four different analytical assays: the measurement of scavenging capacity against ABTS and DPPH free radicals, oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP). The violet petals were the most active in all solvents employed for extraction and also showed higher total phenolic, flavonoid and anthocyanin content in comparison with red and yellow ones. Fourteen constituents were identified by HPLC coupled with diode-array detection (DAD) and mass spectrometry (ESI-MS), ten of them were flavonoids and four anthocyanins. The major compounds found in violet pansy were rutin, violanthin and violanin. Aqueous extract of violet pansy can be regarded as a suitable candidate to serve as a radical scavenging agent that could be used in functional foods.