Anthocyanins and proanthocyanidins of Prunus mahaleb fruits as novel potential source of functional pigments

The phenolic characterisation of unknown or not traditionally-used plants are of great interest, due to the potential use as novel sources of bio-functional compounds. Anthocyanins are at the centre of the interest concerning the numerous bioactive effects, observed both in vitro and in vivo: inhibition of growth of human colon cancer cells (1); high antioxidant and anti-inflammatory activity (2,3); protection of neuronal cells from oxidative stress (4); regulation of adipocyte function, preventing thus the risks related to metabolic syndrome (5). Anthocyanins are important also because every days significantly quantity of them are ingested from vegetable sources (6). As described for other foods like dark chocolate, also the proanthocyanidin fraction is correlated to the total antioxidant capacity. P. mahaleb L. ('Mahaleb' or 'St. Lucy' cherry) is a woody species used as rootstock for sweet and sour cherry, only in well-drained soils, as the Apulia (Italy) soils. It produces highly pigmented small stone fruits, that have no importance for crop production, due to their astringent and sour taste. The astringent taste should be probably correlated with a high content on proanthocyanidins. These fruits had never been characterized for their chemical composition, except for the constituents of kernels (7), used finely ground for sweet breads and confectionery. A preliminary phenolic characterization of Prunus mahaleb fruits was done (8). Aim of this study was the chemical characterization of both anthocyanins and proantocyanidins, particularly concerning their qualitative characterization as well as the evaluation of the total antioxidant capacity.