Poplar-type propolis components as trapping agents to prevent the formation of advanced glycation end-products (AGEs)

Abstract

Propolis is a complex mixture used by bees to seal off hives, or use as a chemical weapon against intruders. Propolis is mainly composed of plant resins and beeswax so that its chemical composition, and consequently biological activity, varies with collection sites. Therefore propolis is generally classified as "poplar-type" in temperate zones vs "green Brazilian", "Clusia", "Macaranga" or Mediterranean-type in tropical zones [1]. The antiglycation potential of an organic poplar-type propolis sample had been already evaluated by our team. This study revealed that a DCM extract exhibited a strong anti-AGEs activity (IC50 28 µg/mL vs 90 µg/mL for the reference i.e. an EtOH extract of Styphnolobium japonicum) [2]. A bioassay-guided fractionation highlighted the major anti-AGEs components of this extract as pinobanksine derivatives and prenyl cafeate. The present workaims to show that the associated inhibition mechanism is directly related to their trapping ability of reactive dicarbonyl species such as methylglyoxal, an intermediate component in AGEs formation (Figure 1). Fig. 1. The Maillard reaction - Schematic formation of AGEs. Rapid identification of chemical markers is an important issue in propolis studies. A fast dereplication analysis of the propolis DCM extract, using a Laser Desorption Ionization (LDI) MS technique [3], allowed us to instantly identify 25 polyphenol derivatives previously identified by classical methods [2,4]. The results clearly show that LDI-MS represents a fast and powerful method to characterize propolis extracts and identify their origin.