Diversity of Bioactive Compounds in Microalgae: Key Classes and Functional Applications

Abstract

Microalgae offer a sustainable and versatile source of bioactive compounds. Their rapid growth, efficient CO₂ utilization, and adaptability make them a promising alternative to traditional production methods. Key compounds, such as proteins, polyunsaturated fatty acids (PUFAs), polyphenols, phytosterols, pigments, and mycosporine-like amino acids (MAAs), hold significant commercial value and are widely utilized in food, nutraceuticals, cosmetics, and pharmaceuticals, driving innovation across multiple industries. Their antiviral and enzyme-producing capabilities further enhance industrial and medical applications. Additionally, microalgae-based biostimulants and plant elicitor peptides (PEPs) contribute to sustainable agriculture by enhancing plant growth and resilience to environmental stressors. The GRAS status of several species facilitates market integration, but challenges in scaling and cost reduction remain. Advances in biotechnology and metabolic engineering will optimize production, driving growth in the global microalgae industry. With increasing consumer demand for natural, eco-friendly products, microalgae will play a vital role in health, food security, and environmental sustainability.

Keywords: biomass; carbon dioxide utilization; cosmeceuticals; food supplements; pharmaceuticals.

Figure 1

Sustainability advantages of microalgae for bioactive molecule production. Microalgae offer a renewable, eco-friendly source for bioactive compounds by utilizing sunlight, water, and CO₂ efficiently. They require minimal land and can grow in saline or brackish water. Microalgae contribute to carbon sequestration, can treat wastewater, and offer scalable production systems for various applications. Additionally, they reduce dependence on fossil fuels, supporting sustainable and greener alternatives.

Figure 2

Important categories of bioactive compounds from microalgae, such as proteins, polyunsaturated fatty acids (PUFAs), polyphenols, phytosterols, pigments. Emerging compounds encompass mycosporine-like amino acids (MAAs), which act as UV-absorbing compounds, biostimulants that promote plant growth, plant elicitor peptides (PEPs) that trigger plant defenses, antivirals with potential to inhibit viral replication, and industrial and analytical enzymes that are used in manufacturing and research.

Figure 3

Representative chemical structures of phytosterols derived from microalgae. (a) The steroid skeleton. Sterols are based on the cyclopenta[a]phenanthrene carbon skeleton (rings A, B, C, and D), typically bearing methyl groups at positions C-10 and C-13, and often an alkyl substituent (R) at C-17. (b) Ergosterol, a sterol found in several microalgae species and known for its anticancer activity. (c) Fucosterol, a phytosterol commonly isolated from brown algae, associated with antioxidant, anti-inflammatory, and cholesterol-lowering effects.

Figure 4

The structure of chlorophyll a (a), β-carotene (b), and different types of phycobilins: phycocyanobilin (c), phycoerythrobilin (d), phycourobilin (e), and phycoviolobilin (f).

Figure 5

Ribbon model of the structure of PBPs. (a) The structure of Thermosynechococcus elongatus allophycocyanin (PDB code 2V8A). (b) The structure of Limnospira platensis Cphycocyanin (PDB code 1HA7). (c) The structure of C-phycoerythrin from marine cyanobacterium Phormidium sp. A09DM (PDB code 5NB3). The bound phycobilins are shown in a ball and stick representation.

Figure 5

Ribbon model of the structure of PBPs. (a) The structure of Thermosynechococcus elongatus allophycocyanin (PDB code 2V8A). (b) The structure of Limnospira platensis Cphycocyanin (PDB code 1HA7). (c) The structure of C-phycoerythrin from marine cyanobacterium Phormidium sp. A09DM (PDB code 5NB3). The bound phycobilins are shown in a ball and stick representation.

Figure 6

Some of the most commonly identified mycosporine-like amino acids (MAAs) in cyanobacteria and microalgae, along with their respective absorption maxima (λ_max, determined in distilled water).

Figure 7

Graphical representation of antiviral algal compounds and their mechanism. (A) Viral envelope proteins bind to the host’s membrane receptors in the first step of infection uninterrupted, in the absence of antiviral compounds. (B) Algal polysaccharides have been observed to increase the host’s immune response, which in turn helps reduce the strain caused by infection. (C) Algal polysaccharides can also prevent infection by neutralizing their positive charge. (D) They can also bind to either host or viral proteins thus preventing the interaction between the two. (E) Algal polysaccharides can prevent viral conformational changes and inhibit adsorption. (F) Lectins bind in a specific manner to glycosylated proteins, either on the viral envelope or the host’s cell membrane, occupying the binding site and preventing interaction.

Figure 8

Ribbon model of the structures of antiviral lectins. (a) Lectin from Microcystis aeruginosa PCC7806 (Microvirin or MVN) (PDB code: 2YHH, crystal structure of MVN bound to mannobiose). (b) Lectin from Microcystis viridis NIES-102 (MVL) (PDB code: 1ZHS, crystal structure of MVL bound to Man3GlcNAc2). (c) Lectin from Nostoc ellipsosporum (CV-N) (PDB code: 3GXY, crystal structure of CV-N bound to a synthetic hexamannoside).