Potential of Microalgae Extracts for Food and Feed Supplementation-A Promising Source of Antioxidant and Anti-Inflammatory Compounds.

Microalgae are known producers of antioxidant and anti-inflammatory compounds, making them natural alternatives to be used as food and feed functional ingredients. This study aimed to valorise biomass and exploit new applications and commercial value for four commercially available microalgae: Isochrysis galbana, Nannochloropsis sp., Tetraselmis sp., and Phaeodactylum tricornutum. For that, five extracts were obtained: acetone (A), ethanol (E), water (W), ethanol:water (EW). The antioxidant capacity (ABTS•+/DPPH•/•NO/O2•-/ORAC-FL) and anti-inflammatory capacity (HBRC/COX-2) of the extracts were screened. The general biochemical composition (carbohydrates, soluble proteins, and lipids) and the main groups of bioactive compounds (carotenoids, phenolic compounds, and peptides) of extracts were quantified. The results of antioxidant assays revealed the potential of some microalgae extracts: in ABTS•+, Nannochloropsis sp. E and Tetraselmis sp. A, E, and P; in DPPH•, Tetraselmis sp. A and E; in •NO, P. tricornutum E and EW; in O2•-, Tetraselmis sp. W; and in ORAC-FL, I. galbana EW and P. tricornutum EW. Concerning anti-inflammatory capacity, P. tricornutum EW and Tetraselmis sp. W showed a promising HBRC protective effect and COX-2 inhibition. Hence, Tetraselmis sp. and P. tricornutum extracts seem to have potential to be incorporated as feed and food functional ingredients and preservatives.

Cosmetic Potential of Pigments Extracts from the Marine Cyanobacterium Cyanobium sp.

The current mindset in the cosmetics market about sustainable ingredients had increased the search for new sources of natural active ingredients. Cyanobacteria are a great source of functional ingredients for cosmetics, as a producer of pigments with described bioactive potential (carotenoids and phycobiliproteins). This work aimed to evaluate the cosmetic potential of marine cyanobacterium Cyanobium sp. pigment-targeted extracts (carotenoids and phycobiliproteins), evaluating their in vitro safety through cytotoxicity assays, cosmetic-related enzyme inhibition, ingredient stability, and putative product (serum formulation). Results showed no cytotoxicity from the extracts in skin-related cell lines. Carotenoid extract showed anti-hyaluronidase capacity (IC50 = 108.74 ± 5.74 mg mL-1) and phycobiliprotein extract showed anti-hyaluronidase and anti-collagenase capacity (IC50 = 67.25 ± 1.18 and 582.82 ± 56.99 mg mL-1, respectively). Regarding ingredient and serum stability, both ingredients showed higher stability at low-temperature conditions, and it was possible to maintain the pigment content and bioactive capacity stable during the tested period, although in higher temperatures the product was degraded in a week. As a major conclusion, both extracts can be potential natural and sustainable ingredients for cosmetic uses, with relatively simple formulation and storage, and can be promising natural anti-aging ingredients due to their bioactive capacity.

Light Modulation for Bioactive Pigment Production in Synechocystis salina.

Cyanobacteria are microorganisms that are well-adapted to sudden changes in their environment, namely to light conditions. This has allowed them to develop mechanisms for photoprotection, which encompass alteration in pigment composition. Therefore, light modulation appears to be a suitable strategy to enhance the synthesis of specific pigments (e.g., phycocyanin) with commercial interest, in addition to conveying a more fundamental perspective on the mechanisms of acclimatization of cyanobacterium species. In this study, Synechocystis salina was accordingly cultivated in two light phase stages: (i) white LED, and (ii) shift to distinct light treatments, including white, green, and red LEDs. The type of LED lighting was combined with two intensities (50 and 150 µmolphotons·m-2·s-1). The effects on biomass production, photosynthetic efficiency, chlorophyll a (chl a) content, total carotenoids (and profile thereof), and phycobiliproteins (including phycocyanin, allophycocyanin, and phycoerythrin) were assessed. White light (under high intensity) led to higher biomass production, growth, and productivity; this is consistent with higher photosynthetic efficiency. However, chl a underwent a deeper impact under green light (high intensity); total carotenoids were influenced by white light (high intensity); whilst red treatment had a higher effect upon total and individual phycobiliproteins. Enhanced PC productivities were found under modulation with red light (low intensities), and could be achieved 7 days earlier than in white LED (over 22 days); this finding is quite interesting from a sustainability and economic point of view. Light modulation accordingly appears to be a useful tool for supplementary studies pertaining to optimization of pigment production with biotechnological interest.

Gloeothece sp. as a Nutraceutical Source-An Improved Method of Extraction of Carotenoids and Fatty Acids.

The nutraceutical potential of microalgae boomed with the exploitation of new species and sustainable extraction systems of bioactive compounds. Thus, a laboratory-made continuous pressurized solvent extraction system (CPSE) was built to optimize the extraction of antioxidant compounds, such as carotenoids and PUFA, from a scarcely studied prokaryotic microalga, Gloeothece sp. Following "green chemical principles" and using a GRAS solvent (ethanol), biomass amount, solvent flow-rate/pressure, temperature and solvent volume-including solvent recirculation-were sequentially optimized, with the carotenoids and PUFA content and antioxidant capacity being the objective functions. Gloeothece sp. bioactive compounds were best extracted at 60 °C and 180 bar. Recirculation of solvent in several cycles (C) led to an 11-fold extraction increase of ß-carotene (3C) and 7.4-fold extraction of C18:2 n6 t (5C) when compared to operation in open systems. To fully validate results CPSE, this system was compared to a conventional extraction method, ultrasound assisted extraction (UAE). CPSE proved superior in extraction yield, increasing total carotenoids extraction up 3-fold and total PUFA extraction by ca. 1.5-fold, with particular extraction increase of 18:3 n3 by 9.6-fold. Thus, CPSE proved to be an efficient and greener extraction method to obtain bioactive extract from Gloeothece sp. for nutraceutical purposes-with low levels of resources spent, while lowering costs of production and environmental impacts.

Evaluation of the antioxidant activity of cell extracts from microalgae.

A growing market for novel antioxidants obtained from non-expensive sources justifies educated screening of microalgae for their potential antioxidant features. Characterization of the antioxidant profile of 18 species of cyanobacteria (prokaryotic microalgae) and 23 species of (eukaryotic) microalgae is accordingly reported in this paper. The total antioxidant capacity, accounted for by both water- and lipid-soluble antioxidants, was evaluated by the (radical cation) ABTS method. For complementary characterization of cell extracts, a deoxyribose assay was carried out, as well as a bacteriophage P22/Salmonella-mediated approach. The microalga Scenedesmus obliquus strain M2-1 exhibited the highest (p > 0.05) total antioxidant capacity (149 ± 47 AAU) of intracellular extracts. Its scavenger activity correlated well with its protective effects against DNA oxidative damage induced by copper(II)-ascorbic acid; and against decay in bacteriophage infection capacity induced by H2O2. Finally, performance of an Ames test revealed no mutagenic effects of the said extract.