Comparative Analysis of Phenolic Compounds in Cyanobacteria and Microalgae from Different Evolutionary Lineages

The study presents the results of an analysis of phenolic compounds in nine strains representing Cyanobacteria, Heterokontophyta, Chlorophyta, and Charophyta, using tandem mass spectrometry. Phenolic compounds were detected in all analyzed strains; however, their qualitative composition varied significantly. In total, 23 phenolic compounds were detected, including 18 phenolic acids, 3 flavonols, 1 hydroxycoumarin, and 1 other polyphenol. Several compounds were confirmed with authentic standards, while the remainder should be considered tentative identifications based on MS/MS spectra and comparison with literature data. For the first time, a compound of the hydroxycumarins class was detected in Edaphochlorella mirabilis (Chlorophyta). Among the studied strains, the highest yield of extractable substances and total content of phenolic compounds was observed in Edaphochlorella mirabilis (Chlorophyta). The greatest diversity of compounds was recorded in the cyanobacteria Roholtiella mixta (9 compounds) and Anagnostidinema pseudacutissimum (6 compounds), as well as in the green algae Edaphochlorella mirabilis and Coelastrella terrestris (6 compounds each). Only a single compound was detected in Klebsormidium flaccidum (Charophyta) and Vischeria magna (Heterokontophyta, Eustigmatophyceae). The taxonomic positions of all isolated strains were determined using molecular identification methods.