Comparing various techniques for maximising the yield of bioactive compounds and antioxidants from Chaetomorpha linum (O.F. Müller) Kützing (1845)

Seaweeds are a rich source of bioactive compounds and antioxidants. However, the extraction of these compounds from Australian seaweed species including Chaetomorpha linum remain unknown to date. No study has reported the impact of different techniques on the yield of bioactive compounds. The current study aimed to compare the yield of bioactive compounds using four extraction techniques, such as microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), enzyme-assisted extraction (EAE), and conventional solvent extraction (CSE), for determining total polysaccharide content (TPS), total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of C. linum extracts. Antioxidant activity was determined using DPPH, ABTS, and ORAC assays. Result revealed that EAE yielded the highest overall extraction yield (28.9%), followed by UAE (26.1%), MAE (23.5%), and CSE (17.5%). EAE also resulted in a significantly (p < 0.05) higher total polysaccharide content than the other techniques, whereas no significant difference was observed in TPS between UAE and MAE. Further, both UAE and MAE extracts recorded significantly higher total phenolic content and total flavonoid content than other extraction methods. UAE and MAE exhibited significantly higher DPPH scavenging activity and ORAC values. The ABTS radical scavenging activity was significantly higher in the UAE extracts than in other methods. These findings compared the yield of the applied extraction methods in enhancing the recovery of bioactive compounds and antioxidants from C. linum. In conclusion, UAE and MAE were identified as the most suitable methods for maximising the phenolic and flavonoid compounds, whereas EAE was more effective for polysaccharides recovery.