Characterization of phenolic profile alterations in metal-polluted bee pollen via capillary electrophoresis

Abstract

Bee pollen is a conglomerate of plant pollens, and its nutritional contents include bioactive compounds with antioxidant/antiradical potentials. These potentials are conditioned by botanical origin. In Chile, the native flora is diverse and promising in terms of bioactive compounds, but many plants grow in metal-polluted areas. The associated bioaccumulation could negatively affect the antioxidant/antiradical abilities of bee pollen. To assess the relationship between the bioaccumulation of metals and the antioxidant activity of pollen, complete bee pollen was collected near and far from the Llaima Volcano, albeit in ranges that ensured the same botanical origins. Mellisopalynological analysis determined Escallonia rubra pollen was the most abundant native flora in complete bee pollen. Therefore, E. rubra pollen collected near and far from the Llaima Volcano was evaluated for the following: phenolic compounds via colorimetric assays; antioxidant activity via ferric reducing/antioxidant power assays; antiradical activity via 1,1-diphenyl-2-picrylhydrazyl radical assays; and metal contents via inductively coupled plasma optical emission spectrometry. Llaima samples had higher Cu and Fe but lower Mn contents and lower antioxidant and antiradical capacities than did the control samples. These results were supported by subsequent fortification assays in Llaima E. rubra samples. In fortified samples with significantly higher metal contents, antiradical and antioxidant abilities decreased. Moreover, shifts in migration times were found for naringenin, rutine, and caffeic acid after capillary electrophoresis (CE) analysis in fortified samples. In conclusion, the results indicated an inverse correlation between metal contents and antioxidant/ antiradical potentials in bee pollen.