Microalgae as a source of α-tocopherol: phylogenetic and technological factors

Vitamin E is a group of compounds, among which the most bioavailable and valuable is α-tocopherol of natural origin. It is synthesised only by photosynthetic organisms. The review systematises current data on the α-tocopherol biosynthetic pathways in microalgae and cyanobacteria, examines the evolutionary aspects of this compound's synthesis, and analyses current understanding of α-tocopherol recycling pathways and their role in cellular antioxidant defence. A comparison with similar processes in higher plants is made, and data from animal organisms are included to more fully demonstrate the evolutionarily conserved and specialised mechanisms of α-tocopherol function. Vitamin E distribution patterns were found to reflect changes in lighting conditions, nitrogen content in the nutrient medium, and time of laboratory storage. The α-tocopherol content exhibits particular specificity among phylogenetically isolated microalgal taxonomic groups. In contrast, at lower taxonomic levels, e.g., between closely related species and even among strains of the same species, α-tocopherol content is somewhat variable. The results obtained open new possibilities for screening microalgae to obtain biomass with high natural α-tocopherol content.