Extraction methods: Effects on the contents of bioactive compounds and anti-oxidant activity of Coriolosis aspera mycelia

Coriolosis aspera has been known as a medicinal mushroom commonly used in Vietnam, China, and certain regions in South Asia. It has many health-beneficial effects, namely anti-inflammatory, anti-cancerous, and anti-antioxidant. Despite these advantages, the rigid and durable cell walls of C. aspera pose challenges during chemical or mechanical extraction processes. We aimed to identify the optimal method for extracting bioactive compounds from C. aspera among hot-water extraction, ultrasound-assisted extraction, microwave-assisted extraction, ultrasound-assisted alkali extraction, and ultrasound-assisted liquid nitrogen extraction. Among these methods, a combination of liquid nitrogen treatment (with a material-to-nitrogen ratio of 1:6) and ultrasoundassisted extraction (15 min) proved to be the most effective. This method yielded the highest concentrations of polyphenols (4.69 ± 0.02 mg GAE/g dry weight), flavonoids (0.88 ± 0.01 mg QE/g dry weight), and triterpenoids (1.28 ± 0.01 mg OAE/g dry weight). Additionally, it exhibited a notable antioxidant activity of 3.48 ± 0.01 μg acid ascorbic/g Dry weight. The scanning electron microscope images indicated that ultrasound-assisted liquid nitrogen extraction was the only method able to effectively disrupt the cell walls of C. aspera. Our study contributes to the potential application of C. aspera in developing functional foods. It emphasizes the importance of effective extraction techniques in discovering medicinal properties of the mushroom.