Chemical profiling of Egyptian propolis and determination of its xanthine oxidase inhibitory properties using UPLC–MS/MS and chemometrics

Abstract

In the current study, propolis samples from various geographical localities in Egypt were investigated by chemical profiling and xanthine oxidase (XO) inhibitory and radical scavenging activity testing. Metabolic fingerprints were attained using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS), UHPLC-MS analysis in an untargeted holistic perspective followed by the subsequent annotation of 65 compounds in total. Variation in chemical profiles of samples was assessed by principle component analysis and orthogonal projection to latent structures discriminant analysis which was able to successfully classify Egyptian propolis samples into two main types (orange and blue) and one subtype (green or mixed) and rapidly screen type-specific markers. Further, propolis extracts were assessed for their antioxidant and xanthine oxidase inhibitory effects through in vitro assays coupled to orthogonal projection to latent structures in order to relate metabolite profiles to biological effects in Egyptian propolis and pick out the potential biomarkers pinocembrin, kaempferide, coumaroyl acetyl glycerol, galangin, palmitic acid and pinobanksin as likely mediators of antioxidant and XO inhibitory activity. To the best of our knowledge, this is the first comprehensive profiling of Egyptian propolis secondary metabolites that can present a chemical-based evidence for its efficacious consistency regarding its potential XO inhibitory activity.