Evaluation of Antimicrobial, Antibiofilm, Antioxidant, and Ciprofloxacin‐Polysaccharide Checkerboard Interaction Effects of Polysaccharides Isolated From Lentinula edodes

There is considerable interest in polysaccharides isolated from medicinal mushrooms, such as Lentinula edodes . This study aims to isolate, characterize, and evaluate the bioactive properties of a water‐soluble polysaccharide from L. edodes . The polysaccharides are purified using DEAE‐Sephadex A‐25 and Sephadex G‐200 chromatography. GPC determines that the molecular weight of the purified polysaccharide (PP) is 238.4 kDa. HPLC identifies the monosaccharide composition, including glucose, glucuronic acid, galacturonic acid, arabinose, galactose, mannose, and fructose. FTIR and NMR analyses confirm structural features such as glycosidic linkages. The water‐soluble PP exhibits greater monosaccharide heterogeneity than previously reported. The IC50 of the DPPH radical scavenging assay for PP is measured 129.23 µg/mL. The minimum inhibitory concentrations are reported as follows: Escherichia coli ATCC 25922 (3.75 mg/mL), Klebsiella pneumoniae ATCC 13883 (7.5 mg/mL), Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 29213 (both 30 mg/mL). No antimicrobial activity is observed against Candida albicans PTCC 5027. The checkerboard Interaction effect of PP combined with ciprofloxacin (CIP) and the anti‐biofilm activity at MIC concentrations are assessed against the same bacterial strains. These findings indicate that the novel PP, in combination with CIP, showed additive effects against all strains except for K. pneumoniae ATCC 13883 which showed indifference.