Isolation of polysaccharides from Malva aegyptiaca and evaluation of their antioxidant and antibacterial properties

This study investigated the antioxidant and antibacterial properties of crude water-soluble polysaccharides extracted from the mallow (Malva aegyptiaca) by precipitation with cetylpyridinium chloride (P1) or ethanol (P2). The Polysaccharides fractions were characterized by FTIR spectroscopy, a monosaccharide composition, and antioxidant and antibacterial activities. P1 showed the highest total sugars (81.2%) and sulfated groups (2.9%) contents but with the lowest total proteins content (8.7%). The infrared spectroscopic spectra exhibited the typical bands and peak characteristic of polysaccharides. Monosaccharides analysis revealed the dominance of galactose (40.3-43.7%) and glucuronic acid (25.9-30.9%). Interestingly, P1 displayed an important antioxidant activity as evaluated by the (Fe2+) chelating activity (IC50 = 1.15 mg/ml), (Fe3+) reducing power (EC50 = 1.22 mg/ml), β-carotene bleaching inhibition capacity (IC50 = 1.56 mg/ml) and DPPH-radical scavenging activity (IC50 = 1.94 mg/ml). Furthermore, P1 at 10 mg/ml was highly active than P2 against several bacterial strains and especially the Gram-positive bacteria, where the inhibition rate ranged between 84.2 and 90.3%. Obtained results suggest that M. aegyptiaca polysaccharides precipitated by cetylpyridinium chloride could be used as a naural antioxidant and antibacterial agent.