Kenneth R. Markham

Separation and Quantification of Flavonoids A. Marston and K. Hostettmann Spectroscopic Techniques Applied to Flavonoids T. Fossen and O.M. Andersen Molecular Biology and Biotechnology of Flavonoid Biosynthesis K.M. Davies and K.E. Schwinn Flavonoids in Foods J.A.M. Kyle and G.G. Duthie Flavonoids in Wine V. Cheynier Dietary Flavonoids and Health - Broadening the Perspective M. Clifford and J.E. Brown Isoflavonoids and Human Health H. Wiseman Flavonoid Functions in Plants K.S. Gould and C. Lister Flavonoid-Protein Interactions O. Dangles and C. Dufour The Anthocyanins O.M. Andersen and M.Jordheim Flavans and Proanthocyanidins D. Ferreira, D. Slade, and J.P.J. Marais Flavones and Flavonols K.M. Valant-Vetschera and E. Wollenweber Flavone and Flavonol O-Glycosides C.A. Williams C-Glycosylflavonoids M. Jay, M.R. Viricel, and J.F. Gonnet Flavanones and Dihydroflavonols R.J. Grayer and N.C. Veitch Chalcones, Dihydrochalcones, and Aurones N.C. Veitch and R.J. Grayer Bi-, Tri-, Tetra-, Penta-, and Hexaflavonoids D. Ferreira, D. Slade, and J.P.J. Marais Appendix - Checklist for Isoflavonoids O.M. Andersen Index

Bee-collected pollen ("bee pollen") is promoted as a health food with a wide range of nutritional and therapeutic properties. The objective of the current study is to evaluate the contribution made through the free radical scavenging capability of bee-collected floval pollens by their flavonoid/phenolics constituents, and to determine whether this capability is affected by aging. The free radical scavenging effectiveness of a bee pollen (EC(50)) as measured by the DPPH method is shown to be determined by the nature and levels of the constituent floral pollens, which can be assayed via their phenolics profiles by HPLC. Each pure floral pollen has been found to possess a consistent EC(50) value, irrespective of its geographic origin or date of collection, and the EC(50) value is determined to a large extent (ca. 50%) by the nature and the levels of the pollen's flavonoids and phenolic acids. Non-phenolic antioxidants, possibly proteins, account for the balance of the activity. Pollen aging over 3 years is demonstrated to reduce the free radical scavenging activity by up to 50% in the most active floral pollens, which tend to contain the highest levels of flavonoids/phenolic acids. It is suggested that the freshness of a bee pollen may be determined from its free radical scavenging capacity relative to that of fresh bee pollen containing the same floral pollen mix.