Characterisation of floral anthocyanins and their antioxidant activity in Vanda hybrid (V. teres x V. hookeriana)

The major anthocyanins and the antioxidant activity of sequentially extracted anthocyanins were evaluated in anthocyanin-based coloured florets of a Vanda hybrid (V. teres x V. hookeriana). Anthocyanins of this Vanda hybrid are less common anthocyanins, the molecules of which showed a bathochromic shift effect and additional peaks of maximum photoabsorption when incubated in two different pH values of 1.0 and 4.5 because of the complexation of a copigment in a molecule. Based on high-performance liquid chromatograph-photodiode array detector (HPLC-PDA) separation, the floral anthocyanins from the Vanda hybrid were only derived from cyanidin. A liquid chromatography-mass spectrometry (LC-ESI-MSn) analysis disclosed 5 major types of cyanidin derivatives were conjugated with hexose sugars and some organic acids that affected the stability of anthocyanin molecules. The extracted anthocyanins from butterfly pea flowers had the lowest molecular change after long storage period showing the delta absorbance (∆Abs) valued at 0.07 followed by those of Vanda hybrid florets and red grape at 0.12 and 0.20, respectively, after 6 month storage at 25°C in the dark. Modification of conjugating residue patterns of Vanda hybrid anthocyanins was detected by delta E* (∆E*), which revealed that the saponified anthocyanins had the lowest change at 10.01, while the raw extracted anthocyanins had the highest change at 13.18. The radicalscavenging activity (RSA) of saponified anthocyanin samples was significantly higher than that of extracted and purified samples especially at higher concentrations.