IN VITRO AND IN VIVO BIOLOGICAL ACTIVITIES AND PHYTOCHEMICAL STUDIES OF POMEGRANATE PEEL POLYPHENOLS

INGLESE

This PhD project focuses on the chemical composition and antimicrobial potential of pomegranate peel extracts (PPEs) from seven Punica granatum varieties grown in Sardinia, Italy. The peel, rich in bioactive compounds like phenols, flavonoids, tannins, and anthocyanins, was evaluated for its antimicrobial effects against various pathogens, including Gram-positive and Gram-negative bacteria. The research employed Orthogonal projections to latent structures discriminant analysis (OPLS-DA) to characterize each variety based on its chemical profile. The PPEs exhibited antimicrobial activity, particularly against Staphylococcus aureus and Listeria monocytogenes, with varying efficacy against different bacterial strains. Notably, Mollar de Elche, Primosole, and Sassari 3 varieties demonstrated the highest antimicrobial activity, attributed to punicalagin, flavonoids, and chlorogenic acid content. Furthermore, the study explored the potential application of pomegranate peel extract as a sustainable antimicrobial source, valorizing agricultural waste in a circular economy framework. The findings suggest that these extracts could serve as natural alternatives to synthetic antimicrobials, highlighting their promising role in combating antibiotic resistance. In parallel, another investigation focused on pomegranate peel extracts specifically against Staphylococcus aureus, a significant human pathogen. Employing bioassay-guided fractionation, researchers isolated and identified the bioactive compounds responsible for antibacterial activity. Chemical analyses and chromatographic techniques further characterized these compounds, alongside safety assessments for potential pharmaceutical applications. The comprehensive analysis underscores the potential of pomegranate peel extracts as natural alternatives to traditional antibiotics, offering a sustainable approach in the fight against antibiotic-resistant pathogens. Additionally, a study explored the impact of ripening stages on the physicochemical and phytochemical composition of pomegranate peels and juice across different cultivars. This investigation provides valuable insights into optimizing pomegranate product quality and health benefits through understanding maturity-related changes.