Chemical characterization and biological properties of polysaccharide isolated from prickly pear fruits Opuntia stricta (Haw.) Haw

During the last decades, polysaccharides have emerged as promising molecules with valuable pharmacological properties. Within this vein, this study aimed to characterize polysaccharides derived from the pulp of Opuntia stricta (Haw.) Haw (POS), with particular focus on their antioxidant and anti-inflammatory activities. The phytochemical composition of POS was evaluated through an extensive analytical assessment, including structural features and the identification of compounds using gas chromatography-mass spectrometry (GC-MS). The chemical composition analysis showed that POS encompasses 56.73% of polysaccharide, with glucose, mannofuranose, and rhamnose being the shift compounds detected by GC-MS. Fourier- transform infrared and proton nuclear magnetic resonance spectra confirmed the presence of critical functional groups. The antioxidant activity demonstrated that POS effectively scavenged DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2,2’- azino-bis(3-ethylbenzothiazoline-6-sulphonic) acid) radicals, exhibited significant reducing power, and inhibited the β-carotene bleaching assay. The in vivo test proved that pre-treatment with POS significantly reduced carrageenan-induced paw edema, lipid peroxidation, and protein oxidation in skin tissues, while improving antioxidant enzyme activities. These findings were further supported by hematological analyses, C-reactive protein levels, and histopathological examination of paw tissue, showing cellular infiltration reduction. In addition, in silico docking investigations against cyclooxygenase (COX)-1 and COX-2 targets were carried out, and significant results were obtained. All these results highlight the outstanding performance of POS as a promising natural antioxidant with anti-inflammatory features, warranting further clinical investigation.