Pharmacological Properties of the Polysaccharides Isolated from the Medicinal Mushroom Phellinus rimosus (Berk) Pilat

Objectives: Phellinus rimosus is a less-explored wood-decaying macrofungus growing exclusively on jackfruit tree trunks in Kerala, India. This investigation focused on the antioxidant, anti-inflammatory, and antidiabetic potential of polysaccharides from this mushroom. Methods: Polysaccharides were isolated from the mushroom by hot water extraction and ethanol precipitation. TLC, HPLC, and Sephadex G-100 chromatography were employed for characterization and determination of molecular weight. Total Antioxidant Capacity and Total Reducing Power assays evaluated the antioxidant potential. Inhibition of inflammatory mediators such as Cyclooxygenase, Lipoxygenase, and Inducible Nitric Oxide Synthase was used to study anti-inflammatory potential. Antidiabetic activity was measured through yeast glucose uptake and alpha-amylase inhibition assays. Findings: We isolated and characterized a high molecular weight (120,000 Da) Polysaccharide-protein complex (PPC-Pr) from P. rimosus. TLC analysis showed glucose as the only monomeric unit, indicating it to be a glucan. HPLC analysis revealed aspartic acid, glutamic acid, glycine, alanine, and serine as the major amino acids in PPC-Pr. In both antioxidant assays, the compound showed significant dose-dependent activity. Previous reports have revealed the profound ability of PPC-Pr to act as free radical scavengers. This study showed the ability of PPC-Pr as a reducing agent to neutralize the free radicals in the in vitro system. In murine macrophage RAW 264.7 cells, it significantly inhibited Cyclooxygenase (51.82%), Lipoxygenase (52.30%), and Inducible Nitric Oxide Synthase (48.78%) production at a dose of 100 µg/ml. PPC-Pr has been reported to possess significant anti-inflammatory activity in animal models. This investigation supports the previous research through the in vitro anti-inflammatory activity of the compound. While PPC-Pr did not enhance glucose uptake, it exhibited 61.57% alpha-amylase inhibition at 1000 µg/ml. Novelty: This study revealed that PPC-Pr possesses significant antioxidant, anti-inflammatory, and antidiabetic potential in a dose-related manner. The antioxidant activity of PPC-Pr might be responsible for its profound anti-inflammatory and antidiabetic effects. Keywords: Phellinus, Mushrooms, Polysaccharides, Anti-oxidant, Anti-inflammatory