Objective: It was aimed at determining which polyphenolic compound(s) in pomegranate mesocarp extract (PME) is liable for the antioxidant, anti-glycation and anti-CD36 activities.
Methods: The PME was fractionated using liquid-liquid extraction method. The fractions were tested for their polyphenolic content, antioxidant potency, anti-glycation activity and anti-CD36 potential. The metabolite compositions of PME and derived fractions were investigated in an untargeted manner using metabolomics in relation to its antioxidant and anti-glycation activities.
Results: The ethyl acetate and n-butanol fractions of the pomegranate mesocarp demonstrated highest antioxidant and anti-glycation potencies. These fractions, represented by gallic and ellagic acids monomers, were enriched in tannins and phenolic acids. Orthogonal partial least squares discriminate analysis (OPLS-DA) modeling of ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) metabolite profiles from the different pomegranate mesocarp fractions indicated that gallic and ellagic acids were potential contributors to the antioxidant and anti-glycation effects of the pomegranate mesocarp. At cellular level, the polyphenolic-rich crude extract as well as the ethyl acetate, n-butanol and aqueous residual fractions suppressed the protein expression of CD36. The anti-CD36 activity of these extracts and fractions was attributed to the presence of punicalagin, the ellagitannins that occurred in equal amount in the different fractions.
Conclusion: This work demonstrated the protective effect of the non-edible part of the pomegranate fruit and showed that gallic and ellagic acids account for the antioxidant and anti-glycation activities while punicalagin is liable for the anti-CD36 activity of PME.