High pressure extraction of bioactive diterpenes from the macroalgae Bifurcaria bifurcata : an efficient and environmentally friendly approach.

The brown macroalgae Bifurcaria bifurcata have gained special attention due to their ability to biosynthesize linear diterpenes (rarely found in other species). However, the conventional extraction methods normally used to extract these compounds involve organic solvents and often high temperatures, leading to the degradation of thermo-labile compounds. In this context, the main objective of this work was to study and optimize for the first time the extraction of diterpenes from B. bifurcata through an environmentally friendly methodology, namely, high pressure extraction (HPE) using ethanol : water. This was compared with conventional Soxhlet extraction, using dichloromethane. Box-Behnken design was employed to evaluate the linear, quadratic, and interaction effects of 3 independent variables (pressure ( X 1 ), ethanol percentage ( X 2 ), and time of extraction ( X 3 )) on response variables (extraction yield and diterpenes content (mg g -1 of extract and mg kg -1 of dry weight)) and the optimal extraction conditions ( X 1 : 600 MPa; X 2 : 80%; X 3 : 5 min) were estimated by response surface methodology (RSM). B. bifurcata extract obtained under HPE optimal conditions showed a diterpenes content (612.2 mg g -1 of extract) 12.2 fold higher than that obtained by conventional extraction (50.1 mg g -1 of extract). The HPE extract, obtained under optimal conditions, showed antioxidant and antibacterial (against Staphylococcus aureus ) activities considerably higher than the Soxhlet extract, and also presented a promising synergic effect with antibiotics, improving the antibiotic efficacy against S. aureus . In conclusion, these results indicate that HPE is a promising methodology, compared to conventional methodologies to obtain linear diterpene rich extracts from B. bifurcata with great potential to be exploited in pharmaceutical or biomedical applications.