Standardized alkali-treated Euglena gracilis β-glucan mitigates PM

Abstract

ETHNOPHARMACOLOGICAL RELEVANCE: Euglena gracilis has a history of traditional use in East Asia as a functional food with reported antioxidant and immunomodulatory benefits. This study investigates the pharmacological potential of its bioactive component, standardized alkali-treated β-glucan (AEGB), in mitigating systemic toxicity induced by environmental pollutants, providing a rationale to investigate its protective effects in the context of particulate matter (PM2.5)-induced injury. AIM OF THE STUDY: To evaluate the protective effects of standardized alkali-treated E. gracilis β-glucan (AEGB) against PM2.5-induced pulmonary and cerebral toxicity in BALB/c mice via the lung-brain axis. MATERIALS AND METHODS: AEGB was prepared and standardized to contain 93% (w/w) β-glucan. BALB/c mice were intranasally exposed to PM2.5 and orally administered AEGB (200/400 mg/kg). Efficacy was evaluated via BALF analysis, histopathology, and immunoblotting, focusing on MAPK, NF-κB, NRF2-HO-1, and CREB-BDNF-TrkB pathways. RESULTS: AEGB exhibited higher antioxidant activity than untreated β-glucan. In PM2.5-exposed mice, AEGB (400 mg/kg) reduced inflammatory cells in BALF by 69.5% and suppressed lung pro-inflammatory cytokines (IL-1β, IL-6). Histologically, it attenuated bronchial thickening and mucin production. In the brain, AEGB downregulated NF-κB by 72.1% and restored hippocampal neuronal area (+41.1%) and tight junction marker expression associated with blood-brain barrier integrity. At the molecular level, AEGB inhibited pulmonary MAPK/NF-κB and activated NRF2-HO-1, while enhancing the cerebral CREB-BDNF-TrkB neurotrophic pathway. CONCLUSIONS: AEGB mitigates PM2.5-induced damage in both lung and brain tissues, accompanied by anti-inflammatory and neuroprotective responses consistent with inter-organ inflammatory/oxidative pathways relevant to the lung-brain axis. These findings validate the potential of E. gracilis-derived β-glucan as a functional agent for preserving respiratory and neural health.

Key Findings

• Standardized alkali-treated Euglena gracilis β-glucan (AEGB) exhibited higher antioxidant activity than untreated β-glucan.
• AEGB reduced inflammatory cells in bronchoalveolar lavage fluid by 69.5% and suppressed lung pro-inflammatory cytokines IL-1β and IL-6 in PM2.5-exposed mice.
• AEGB activated the NRF2-HO-1 antioxidant pathway in the lung and enhanced neuroprotective CREB-BDNF-TrkB signaling in the brain, while inhibiting NF-κB and MAPK inflammatory pathways.

Clinical Significance

Citation

You Ye-Lim, Byun Ha-Jun, Jeon Jin-Younget al.. Standardized alkali-treated Euglena gracilis β-glucan mitigates PM Journal of ethnopharmacology. 2026-May-10.