Blue is not enough: biological activities of C-phycocyanin extracts from Anabaena cylindrica

BACKGROUND Natural products are currently in the spotlight due to the increasing awareness of consumers. Among these products is phycocyanin (C-PC), a blue colorant that can be extracted from cyanobacteria - a poorly explored feedstock - and applied in several fields, due to its argued health benefits. Arthropira (previously called Spirulina) is the major source of C-PC nowadays, but within the scope of pursuing alternative sources, the cyanobacterium Anabaena cylindrica was used in the present study to extract this colorant. RESULTS The biological activities of two types of extracts (raw and purified, both in fresh and in lyophilized forms) were analysed. The raw extracts produce better results than their pure counterparts by presenting a higher antioxidant activity and better biocompatibility and antitumor activity. However, when compared to literature records, C-PC extracts from A. cylindrica produced less impressive results. This leads to a new hypothesis and a simple comparison between the antioxidant activities of C-PC extracts from different biomass sources. These second-stage results showed that different cyanobacteria species produced different C-PC extracts with different antioxidant profiles; these results highlight that, even when the extracts are blue, they may present differential compositions and, therefore, different biological activities. CONCLUSION This study proves that the direct link often made between biological activities and C-PC can be speculative, and thus, should be avoided. (c) 2021 Society of Chemical Industry (SCI).

Automated summary

The study analyzed the biological activities of phycocyanin extracted from Anabaena cylindrica, finding that raw extracts performed better than pure extracts, and different cyanobacteria species produced C-PC extracts with different antioxidant profiles.