Effects of Agitation on β-glucan Production and Antioxidant Activity in Lentinus polychrous Mycelial Extract from Thailand

Lentinus polychrous Lév. is a widely cultivated mushroom in Thailand. Submerged mycelial mushroom cultivation under agitation conditions can enhance mycelial biomass production. This study was carried out to investigate the effects of agitation on mycelial biomass and bioactive compound production in L. polychrous. Mycelia were cultivated in potato dextrose broth at agitation speeds of 0, 50, 100 and 150 rpm for 7 days at 35 ± 2°C, followed by extraction with water and 70% ethanol. The extracts were then analyzed for bioactive compounds and antioxidant activity. Results showed that mycelial biomass increased significantly at higher agitation speeds. High levels of β-glucan (11.22 ± 1.63% w/w), ABTS radical cation scavenging activity (42.11 ± 2.36 mg trolox eq per g extract), and ferric reducing antioxidant power (11.75 ± 4.09 mg trolox eq per g extract) were observed in the alcoholic extract of mycelia cultivated under optimal conditions at 100 rpm. The mycelial extract from the scaled-up cultivation was evaluated for cytotoxicity against human embryonic kidney (HEK 293) cells and macrophage (RAW 264.7) proliferation using an MTT assay. Results showed that the alcoholic extract at a concentration of 0.11 mg mL-1 promoted Raw 264.7 cell proliferation, increasing by 1.32 times compared to the control, with low toxicity. These findings conclude that the β-glucan content in L. polychrous mycelium positively influences macrophage proliferation.