Screening of Microalgae for Bioactivity with Antiviral, Antibacterial, Anti-Inflammatory and Anti-Cancer Assays

Simple Summary Numerous biotechnological applications exist that have been obtained from marine organisms. Nonetheless, despite their diversity and potential for massive growth, marine microalgae have been less studied than other groups. The aim of the present study was to add new information about microalgae to the existing research that shows the bioactivity of marine microalgae in diverse assays conducted by our research group. First, we selected representative species from different algal groups available in our laboratory and then their biomass was harvested to perform several bioactivity tests. Several strains yielded positive results for antibacterial, antiviral and anti-inflammatory activities. These findings act as an essential indicator for future work targeting the structural characterization of the compounds responsible and their potential application in biomedicine.Abstract Marine microalgae are a rich reservoir of natural compounds, including bioactives. Nonetheless, these organisms remain fairly unexplored despite their potential biotechnological applications. Culture collections with diverse taxonomic groups and lifestyles are a good source to unlock this potential and discover new molecules for multiple applications such as the treatment of human pathologies or the production of aquaculture species. In the present work extracts from thirty-three strains (including twenty dinoflagellates, four diatoms and nine strains from seven other algal classes), cultivated under identical conditions, were examined for their antiviral, antibacterial, anti-inflammatory and anti-cancer activities. Among these, antiviral and anti-inflammatory activities were detected in a few strains while the antibacterial tests showed positive results in most assays. In turn, most trials did not show any anti-cancer activity. Significant differences were observed between species within the same class, in particular dinoflagellates, which were better represented in this study. These preliminary findings pave the way for an in-depth characterization of the extracts with highest signals in each test, the identification of the compounds responsible for the biological activities found and a further screening of the CCVIEO culture collection.