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Carotenoids are tetraterpenoids molecules present in all photosynthetic organisms, responsible for better light-harvesting and energy dissipation in photosynthesis. In cyanobacteria, the biosynthetic pathway of carotenoids is well described, and apart from the more common compounds (e.g., β-carotene, zeaxanthin, and echinenone), specific carotenoids can also be found, such as myxoxanthophyll. Moreover, cyanobacteria have a protein complex called orange carotenoid protein (OCP) as a mechanism of photoprotection. Although cyanobacteria are not the organism of choice for the industrial production of carotenoids, the optimisation of their production and the evaluation of their bioactive capacity demonstrate that these organisms may indeed be a potential candidate for future pigment production in a more environmentally friendly and sustainable approach of biorefinery. Carotenoids-rich extracts are described as antioxidant, anti-inflammatory, and anti-tumoral agents and are proposed for feed and cosmetical industries. Thus, several strategies for the optimisation of a cyanobacteria-based bioprocess for the obtention of pigments were described. This review aims to give an overview of carotenoids from cyanobacteria not only in terms of their chemistry but also in terms of their biotechnological applicability and the advances and the challenges in the production of such compounds.

Microalgae (including cyanobacteria) are the simplest and the most efficient photosynthetic organisms, probably because they have very quick responses and adaptations to environmental stimuli that are not found in any other group of living beings. From phycobiliproteins to carotenoids and to chlorophylls, these organisms have a large range of chromatic compounds related to the photosynthetic metabolism. These microalgae pigments are being exploited for different applications in a variety of industries, from food dyes to health products. Although they appear to have great potential for biotechnological purposes, the use of these products still faces great challenges, like the high cost of production and the instability of the isolated compounds. However, several studies have provided promising prospects for the use of microalgae as a source of pigments by a sustainable bioprocess. The increased demand for natural pigments by consumers and consequently by industry has encouraged the creation of new patents and stimulated the market for these compounds, which has “bloomed” in recent years. Thus, this chapter will cover fundamental aspects of the industrial application of microalgae-based pigments and their economical relevance, the bioprocess optimization for the production of those pigments (e.g., phycocyanin, β-carotene, astaxanthin, and xanthophylls), and highlight the main challenges and future prospects.

Bioactive lipidic compounds of microalgae, such as polyunsaturated fatty acids (PUFA) and carotenoids, can avoid or treat oxidation-associated conditions and diseases like inflammation or cancer. This study aimed to assess the bioactive potential of lipidic extracts obtained from Gloeothece sp.–using Generally Recognized as Safe (GRAS) solvents like ethanol, acetone, hexane:isopropanol (3:2) (HI) and ethyl lactate. The bioactive potential of extracts was assessed in terms of antioxidant (ABTS•+, DPPH•, •NO and O2•assays), anti-inflammatory (HRBC membrane stabilization and Cox-2 screening assay), and antitumor capacity (death by TUNEL, and anti-proliferative by BrdU incorporation assay in AGS cancer cells), while its composition was characterized in terms of carotenoids and fatty acids, by HPLC-DAD and GC-FID methods, respectively. Results revealed a chemopreventive potential of the HI extract owing to its ability to: (I) scavenge -NO• radical (IC50, 1258 ± 0.353 µg·mL−1), (II) inhibit 50% of COX-2 expression at 130.2 ± 7.4 µg·mL−1, (III) protect 61.6 ± 9.2% of lysosomes from heat damage, and (IV) induce AGS cell death by 4.2-fold and avoid its proliferation up to 40% in a concentration of 23.2 ± 1.9 µg·mL−1. Hence, Gloeothece sp. extracts, namely HI, were revealed to have the potential to be used for nutraceutical purposes.

Marine microalgae constitute a natural source of a variety of drugs for pharmaceutical, food and cosmetic applications—which encompass carotenoids, among others. A growing body of experimental evidence has confirmed that these compounds can play important roles in prevention (and even treatment) of human diseases and health conditions, e.g., cancer, cardiovascular problems, atherosclerosis, rheumatoid arthritis, muscular dystrophy, cataracts and some neurological disorders. The underlying features that may account for such favorable biological activities are their intrinsic antioxidant, anti-inflammatory and antitumoral features. In this invited review, the most important issues regarding synthesis of carotenoids by microalgae are described and discussed—from both physiological and processing points of view. Current gaps of knowledge, as well as technological opportunities in the near future relating to this growing field of interest, are also put forward in a critical manner.

Microalgae are well known for their biotechnological potential, namely with regard to bioactive lipidic components-especially carotenoids and polyunsaturated fatty acids (PUFA), well-known for therapeutic applications based on their antioxidant capacity. The aim of this work was to evaluate the influence of four distinct food-grade solvents upon extractability of specific lipidic components, and on the antioxidant capacity exhibited against both synthetic (2,2-diphenyl-1-picrylhydrazyl (DPPH(•)) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS(+•))) and biological reactive species (O₂(•)⁻ and (•)NO⁻). A eukaryotic microalga (Scenedesmus obliquus (M2-1)) and a prokaryotic one (Gloeothece sp.) were used as case studies. Concerning total antioxidant capacity, the hexane:isopropanol (3:2) and acetone extracts of Sc. obliquus (M2-1) were the most effective against DPPH(•) and ABTS(+•), respectively. Gloeothece sp. ethanol extracts were the most interesting scavengers of O₂(•)⁻, probably due the high content of linolenic acid. On the other hand, acetone and hexane:isopropanol (3:2) extracts were the most interesting ones in (•)NO⁻ assay. Acetone extract exhibited the best results for the ABTS assay, likely associated to its content of carotenoids, in both microalgae. Otherwise, ethanol stood out in PUFA extraction. Therefore, profiles of lipidic components extracted are critical for evaluating the antioxidant performance-which appears to hinge, in particular, on the balance between carotenoids and PUFAs.