title: Age-induced diminution of free radical scavenging capacity in bee pollens and the contribution of constituent flavonoids.
abstract: 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.
authors.affiliation: Laboratory of Pharmacognosy, Faculty of Pharmacy, University of Coimbra, 3000-295 Coimbra, Portugal. mgcampos@ff.uc.pt
authors.forename: Maria G
authors.initials: MG
authors.lastname: Campos
authors.forename: Rosemary F
authors.initials: RF
authors.lastname: Webby
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Markham
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Mitchell
authors.forename: Antonio P
authors.initials: AP
authors.lastname: Da Cunha
mesh_terms: D000818:Animals; D001516:Bees; D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry; D016166:Free Radical Scavengers / Q000032:analysis*; D010636:Phenols / Q000032:analysis / Q000737:chemistry; D011058:Pollen / Q000737:chemistry*; D013997:Time Factors
chemical_list: D005419:Flavonoids; D016166:Free Radical Scavengers; D010636:Phenols