Conventional extraction methods for bioactive compounds from marine microalgae

Microalgae are valuable sources of organic metabolites: polyunsaturated fatty acids, proteins, pigments, essential acids, and phycobiliproteins with numerous physicochemical properties such as antibacterial, antifungal, antidiabetic, antiviral and anti-algae, antioxidant, antitumor, anti-inflammatory, and others. The most widely utilized method for extracting biologically active compounds from microalgae is hydrodistillation. The most used solvents for extraction are ethanol, ethyl acetate, acetone, and methanol. The principles and mechanisms of extraction were studied. It was found that in the process of microalgae extraction, proteins up to 91.0 %, phycocyanin up to 82.48 %, astaxanthin up to 3.4 %, lipids up to 96.2 %, chlorophyll up to 10.3 %, beta-carotene up to 14.6 %, essential fatty acids up to 30 %, carotenoids up to 7.5 %, docosahexaenoic acid up to 6.5 %, superoxide dismutase up to 3.2 %, phycobiliproteins up to 70 %, and oil up to 15 % are obtained. The process of cold pressing and steam distillation of microalgae was investigated. Steam distillation is used to extract vaporized bioactive metabolites from algae biomass. The advantages and disadvantages of the steam distillation method were discussed. The maceration process of microalgae was studied. Maceration is performed on a polarity basis with solvent, then heating and stirring are applied to increase solubility and extract the biocompounds from the microalgae sample. Studying affordable ways to grow microalgae and finding efficient methods are important for making sure that bioactive compounds from microalgae are economically viable and sustainable.

The development of efficient and ecofriendly extraction techniques will play a key role in enhancing yield while maintaining the biological activity of microalgae-derived compounds.