Donator acceptor map of psittacofulvins and anthocyanins: are they good antioxidant substances?

Psittacofulvins represent an unusual class of pigments (noncarotenoid lipochromes), which are found only in the red, orange, and yellow plumage of parrots. Anthocyanins are flavonoids, and they are one of the primary types of colorants found in plants. Blue butterflies acquire blue and UV hues on their wings, owing to the presence of flavonoids. It is assumed that these natural pigments are valuable antioxidants because they are able to scavenge free radicals. The aim of this investigation is to rationalize the scavenging activity of psittacofulvins and anthocyanins, in terms of the one electron transfer mechanism, taking into account that to prevent oxidative stress, substances must either donate or accept electrons. Density functional approximation calculations are used to obtain ionization potentials, electron affinities, electrodonating, and electroaccepting power indexes. Taking these values, a donator acceptor map (DAM) was constructed, indicating that anthocyanins are good electron donors, whereas psittacofulvins are good electron acceptors. Anthocyanins and vitamins are antioxidants, whereas psittacofulvins and carotenoids are antireductants (oxidants). In terms of solvent effects, animal pigments (carotenoids, psittacofulvins, and anthocyanins) are much better electron acceptors in water than in either the gas phase or benzene. Solvent effects do not alter the electron donor capacity of vitamins, but anthocyanins become effective electron acceptors in water, rather than effective electron donors. The information presented here may also be valuable for the design and analysis of further experiments.