Antioxidant potential of nature's ``something blue{''}: Something new in the marriage of biological activity and extraction methods applied to C-phycocyanin

Background: C-phycocyanin (C-PC), a blue-colored natural pigment, is Spirulina's most crucial photosynthetic protein, and it is associated with this cyanobacteria's bioactivity. Many recent studies aimed at optimizing C-PC extraction from Spirulina using different protocols; however, the correlation between the extraction method (both lab scale experimental methods and industrial methods) and the antioxidant activity of the extract has not been explored yet. Scope and approach: This review aimed to gather information regarding the most used C-PC extraction techniques from Spirulina in the last decade (2010-2020) and compare these biomolecules' antioxidant capacity with the extraction methodology applied. A density map was created by searching keywords related to C-PC extraction on Scopus, which guided the discussion on the C-PC extraction methods used and their impact on its bioactivity. Key findings and conclusions: The density map showed that the lowest density words represented factors that can influence, describe, or determine the success of C-PC extraction. In contrast, the most cited expressions were related to the methods. The compilation of literature on the influence of C-PC extraction on its antioxidant activity showed that ultrasound-assisted extraction (UAE) and solvent extraction using water or buffer were the most used methods to extract C-PC from Spirulina in the last decade. However, the UAE does not seem to protect C-PC's bioactivity. Additionally, most studies of the previous ten years used a single method to determine C-PC's antioxidant activity. We concluded that C-PC's antioxidant activity needs to be appraised by more than one method using assays of different mechanisms to evaluate the extraction influence in its bioactivity in a panoramic way. (AU)