Impact of the biomass pretreatment and simulated gastrointestinal digestion on the digestibility and antioxidant activity of microalgae Chlorella vulgaris and Tetraselmis chuii.

Chlorella vulgaris and Tetraselmis chuii are two microalgae species already marketed because of their richness in high-value and health-beneficial compounds. Previous studies have demonstrated the biological properties of compounds isolated from both microalgae, although data are not yet available on the impact that pre-treatment and gastrointestinal digestion could exert on these properties. The aim of the present study was to analyze the impact of the biomass pre-treatment (freeze/thaw cycles plus ultrasounds) and simulated gastrointestinal digestion in the bioaccessibility and in vitro antioxidant activity (ABTS, ORAC, Q-FRAP, Q-DPPH) of the released digests. The cell wall from microalgae were susceptible to the pre-treatment and the action of saliva and gastric enzymes, releasing bioactive peptides and phenolic compounds that contributed to the potent antioxidant activity of digests through their radical scavenging and iron reduction capacities. Our findings suggest the potential of these microalgae against oxidative stress-associated diseases at both, intestinal and systemic level.

Antimicrobial Activity of Arthrospira (Former Spirulina) and Dunaliella Related to Recognized Antimicrobial Bioactive Compounds.

With the increasing rate of the antimicrobial resistance phenomenon, natural products gain our attention as potential drug candidates. Apart from being used as nutraceuticals and for biotechnological purposes, microalgae and phytoplankton have well-recognized antimicrobial compounds and proved anti-infectious potential. In this review, we comprehensively outline the antimicrobial activity of one genus of cyanobacteria (Arthrospira, formerly Spirulina) and of eukaryotic microalgae (Dunaliella). Both, especially Arthrospira, are mostly used as nutraceuticals and as a source of antioxidants for health supplements, cancer therapy and cosmetics. Their diverse bioactive compounds provide other bioactivities and potential for various medical applications. Their antibacterial and antifungal activity vary in a broad range and are strain specific. There are strains of Arthrospira platensis with very potent activity and minimum inhibitory concentrations (MICs) as low as 2-15 µg/mL against bacterial fish pathogens including Bacillus and Vibrio spp. Arthrospira sp. has demonstrated an inhibition zone (IZ) of 50 mm against Staphylococcus aureus. Remarkable is the substantial amount of in vivo studies of Arthrospira showing it to be very promising for preventing vibriosis in shrimp and Helicobacter pylori infection and for wound healing. The innovative laser irradiation of the chlorophyll it releases can cause photodynamic destruction of bacteria. Dunaliella salina has exhibited MIC values lower than 300 µg/mL and an IZ value of 25.4 mm on different bacteria, while Dunaliella tertiolecta has demonstrated MIC values of 25 and 50 µg/mL against some Staphylococcus spp. These values fulfill the criteria for significant antimicrobial activity and sometimes are comparable or exceed the activity of the control antibiotics. The bioactive compounds which are responsible for that action are fatty acids including PUFAs, polysaccharides, glycosides, peptides, neophytadiene, etc. Cyanobacteria, such as Arthrospira, also particularly have antimicrobial flavonoids, terpenes, alkaloids, saponins, quinones and some unique-to-them compounds, such as phycobiliproteins, polyhydroxybutyrate, the peptide microcystin, etc. These metabolites can be optimized by using stress factors in a two-step process of fermentation in closed photobioreactors (PBRs).

The Ocean's Pharmacy: Health Discoveries in Marine Algae.

Non-communicable diseases (NCDs) represent a global health challenge, constituting a major cause of mortality and disease burden in the 21st century. Addressing the prevention and management of NCDs is crucial for improving global public health, emphasizing the need for comprehensive strategies, early interventions, and innovative therapeutic approaches to mitigate their far-reaching consequences. Marine organisms, mainly algae, produce diverse marine natural products with significant therapeutic potential. Harnessing the largely untapped potential of algae could revolutionize drug development and contribute to combating NCDs, marking a crucial step toward natural and targeted therapeutic approaches. This review examines bioactive extracts, compounds, and commercial products derived from macro- and microalgae, exploring their protective properties against oxidative stress, inflammation, cardiovascular, gastrointestinal, metabolic diseases, and cancer across in vitro, cell-based, in vivo, and clinical studies. Most research focuses on macroalgae, demonstrating antioxidant, anti-inflammatory, cardioprotective, gut health modulation, metabolic health promotion, and anti-cancer effects. Microalgae products also exhibit anti-inflammatory, cardioprotective, and anti-cancer properties. Although studies mainly investigated extracts and fractions, isolated compounds from algae have also been explored. Notably, polysaccharides, phlorotannins, carotenoids, and terpenes emerge as prominent compounds, collectively representing 42.4% of the investigated compounds.

Integrated Process for Schizochytrium Oil Extraction, Enzymatic Modification of Lipids and Concentration of DHA Fatty Acid Esters Using Alternative Methodologies.

Marine microalgae Schizochytrium sp. have a high content of docosahexaenoic acid (DHA), an omega-3 fatty acid that is attracting interest since it prevents certain neurodegenerative diseases. The obtention of a bioactive and purified DHA fatty acid ester using a whole-integrated process in which renewable sources and alternative methodologies are employed is the aim of this study. For this reason, lyophilized Schizochytrium biomass was used as an alternative to fish oil, and advanced extraction techniques as well as enzymatic modification were studied. Microalgal oil extraction was optimized via a surface-response method using pressurized liquid extraction (PLE) obtaining high oil yields (29.06 ± 0.12%) with a high concentration of DHA (51.15 ± 0.72%). Then, the enzymatic modification of Schizochytrium oil was developed by ethanolysis using immobilized Candida antarctica B lipase (Novozym® 435) at two reaction temperatures and different enzymatic loads. The best condition (40 °C and 200 mg of lipase) produced the highest yield of fatty acid ethyl ester (FAEE) (100%) after 8 h of a reaction attaining a cost-effective and alternative process. Finally, an enriched and purified fraction containing DHA-FAEE was obtained using open-column chromatography with a remarkably high concentration of 93.2 ± 1.3% DHA. The purified and bioactive molecules obtained in this study can be used as nutraceutical and active pharmaceutical intermediates of marine origin.

Fabrication of Microalgae Oil Vesicles for Drug Delivery Applications.

In this study, it is demonstrated that natural microalgae oils, which contain fatty acid components including docosahexaenoic acid (DHA), could be directly applied to fabricate vesicular structures in aqueous phase through a forced formation process. The microalgae oil vesicles had initial average diameters of 170- 230 nm with negative charges apparently caused by dissociation of the fatty acid components. The vesicles possessed excellent stability with lifetimes for at least 450 days. The formation of the vesicular structures with hydrophilic cores/regions was confirmed by the transmission electron microscopy (TEM) image and successful encapsulation of a hydrophilic material. For encapsulation of a hydrophobic material, lutein, the vesicle size was increased probably due to the insertion of lutein into the hydrophobic vesicular bilayer structures. The analysis of Fourier transform infrared (FTIR) spectroscopy suggested that the vesicular bilayer fluidity was decreased by encapsulating lutein. However, the lutein-encapsulating microalgae oil vesicles still possessed high stability and the vesicular structures could maintain intact even at an environmental temperature up to 60℃. Applicability of the microalgae oil vesicles as drug delivery carriers was also demonstrated by successful encapsulation of curcumin. However, when the loaded curcumin was increased to a certain amount, physical stability of the microalgae oil vesicles was significantly reduced. This is probably because the vesicular structures with only limited spaces for accommodating hydrophobic materials were strongly affected by encapsulating a large amount of curcumin. It is interesting to note that by adding egg L-α-phosphatidylcholine, the curcumin encapsulation-induced instability of the microalgae oil vesicles could be alleviated. The results indicated that vesicular structures could be fabricated from microalgae oils and the microalgae oil vesicles were capable of encapsulating hydrophilic or hydrophobic materials for drug delivery applications. The findings lay a background for further dosage form development of nutritional supplements encapsulated by natural microalgae oils.

Taguchi approach for assessing supercritical CO2 (sCO2) fluid extraction of polyhydroxyalkanoate (PHA) from Chlorella Vulgaris sp. microalgae.

This research explicitly investigates the utilization of Chlorella Vulgaris sp. microalgae as a renewable source for lipid production, focusing on its application in bioplastic manufacturing. This study employed the supercritical fluid extraction technique employing supercritical CO2 (sCO2) as a green technology to selectively extract and produce PHA's precursor utilizing CO2 solvent as a cleaner solvent compared to conventional extraction method. The study assessed the effects of three extraction parameters, namely temperature (40-60 °C), pressure (15-35 MPa), and solvent flow rate (4-8 ml/min). The pressure, flowrate, and temperature were found to be the most significant parameters affecting the sCO2 extraction. Through Taguchi optimization, the optimal parameters were determined as 60 °C, 35 MPa, and 4 ml/min with the highest lipid yield of 46.74 wt%; above-average findings were reported. Furthermore, the pretreatment process involved significant effects such as crumpled and exhaustive structure, facilitating the efficient extraction of total lipids from the microalgae matrix. This study investigated the microstructure of microalgae biomatrix before and after extraction using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Fourier-transform infrared spectroscopy (FTIR) was utilized to assess the potential of the extracted material as a precursor for biodegradable plastic production, with a focus on reduced heavy metal content through inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis. The lipid extracted from Chlorella Vulgaris sp. microalgae was analysed using gas chromatography-mass spectrometry (GC-MS), identifying key constituents, including oleic acid (C18H34O2), n-Hexadecanoic acid (C16H32O2), and octadecanoic acid (C18H36O2), essential for polyhydroxyalkanoate (PHA) formation.

Hydrothermal co-liquefaction of microalgae, sugarcane bagasse, brewer's spent grain, and sludge from a paper recycling mill: Modeling and evaluation of biocrude and biochar yield.

Biomass can be used as an energy source to thermochemical conversion processes to biocrude production. However, the supply and dependence on only one biomass for biocrude production can be an obstacle due to its seasonality, availability, and logistics costs. In this way, biomass waste and agroindustrial residues can be mixture and used as feedstock to the hydrothermal co-liquefaction (co-HTL) process as an alternative to obtaining biocrude. In this sense, the present paper analyzed the biocrude yield influence of the co-HTL from a quaternary unprecedented blend of different biomasses, such as sugarcane bagasse, brewer's spent grain (BSG), sludge from a paper recycling mill (PRM), and microalgae (Chlorella vulgaris). In this way, a simplex lattice design was employed and co-HTL experiments were carried out in a 2000 mL high-pressure stirred autoclave reactor under 275 °C for 60 min, considering 15% of feedstock/water ratio. Significant effects in each feedstock and their blends were analyzed aiming to increase biocrude and biochar yield. It was found that the addition of microalgae is only significant when considered more than 50% into the blend with BSG and PRM sludge to increase biocrude yield.

Bioactive substances of cyanobacteria and microalgae: Sources, metabolism, and anticancer mechanism insights.

Cyanobacteria and microalgae contain various phytochemicals, including bioactive components in the form of secondary metabolites, namely flavonoids, phenolic acids, terpenoids, and tannins, with remarkable anticancer effects. This review highlights the recent advances in bioactive compounds, with potential anticancer activity, produced by cyanobacteria and microalgae. Previous in vitro investigations showed that many of these bioactive compounds exhibit potent effects against different human cancer types, such as leukemia and breast cancers. Multiple mechanisms implicated in the antitumor effect of these compounds were elucidated, including their ability to target cellular, subcellular, and molecular checkpoints linked to cancer development and promotion. Recent findings have highlighted various mechanisms of action of bioactive compounds produced by cyanobacteria and microalgae, including induction of autophagy and apoptosis, inhibition of telomerase and protein kinases, as well as modulation of epigenetic modifications. In vivo investigations have demonstrated a potent anti-angiogenesis effect on solid tumors, as well as a reduction in tumor volume. Some of these compounds were examined in clinical investigations for certain types of cancers, making them potent candidates/scaffolds for antitumor drug development.

Advances in oligosaccharides production from algal sources and potential applications.

In recent years, algal-derived glycans and oligosaccharides have become increasingly important in health applications due to higher bioactivities than plant-derived oligosaccharides. The marine organisms have complex, and highly branched glycans and more reactive groups to elicit greater bioactivities. However, complex and large molecules have limited use in broad commercial applications due to dissolution limitations. In comparison to these, oligosaccharides show better solubility and retain their bioactivities, hence, offering better applications opportunity. Accordingly, efforts are being made to develop a cost-effective method for enzymatic extraction of oligosaccharides from algal polysaccharides and algal biomass. Yet detailed structural characterization of algal-derived glycans is required to produce and characterize the potential biomolecules for improved bioactivity and commercial applications. Some macroalgae and microalgae are being evaluated as in vivo biofactories for efficient clinical trials, which could be very helpful in understanding the therapeutic responses. This review discusses the recent advancements in the production of oligosaccharides from microalgae. It also discusses the bottlenecks of the oligosaccharides research, technological limitations, and probable solutions to these problems. Furthermore, it presents the emerging bioactivities of algal oligosaccharides and their promising potential for possible biotherapeutic application.

Oral Microalgae-Nano Integrated System against Radiation-Induced Injury.

The increasing applications of ionizing radiation in society raise the risk of radiation-induced intestinal and whole-body injury. Astaxanthin is a powerful antioxidant to reduce the reactive oxygen generated from radiation and the subsequent damage. However, the oral administration of astaxanthin remains challenging owing to its low solubility and poor bioavailability. Herein, we facilely construct an orally used microalgae-nano integrated system (SP@ASXnano) against radiation-induced intestinal and whole-body injury, combining natural microalgae Spirulina platensis (SP) with astaxanthin nanoparticles (ASXnano). SP and ASXnano show complementation in drug delivery to improve distribution in the intestine and blood. SP displays limited gastric drug loss, prolonged intestinal retention, constant ASXnano release, and progressive degradation. ASXnano improves drug solubility, gastric stability, cell uptake, and intestinal absorption. SP and ASXnano have synergy in many aspects such as anti-inflammation, microbiota protection, and fecal short-chain fatty acid up-regulation. In addition, the system is ensured with biosafety for long-term administration. The system organically combines the properties of microalgae and nanoparticles, which was expected to expand the medical application of SP as a versatile drug delivery platform.

Effective recovery of microalgal biomass using various types of emulsion polymers.

Microalgae biomass has been considered as one of the potential feedstocks in biofuel production. Yet, biomass harvesting poses a challenge to the overall production cost due to its low cell density. Flocculation has been marked as one of the promising processes in microalgae harvesting technology. In this study, the first screening of two anionic (A-230, and A-330E) and five cationic polymers (C-810E, C-810EL, C-810EB, C-810ELH, and C-810EMB) followed by gravity settling with the mixed microalgae concentration of 2.24 gTSS/L revealed that anionic polymers are less effective. Whereas all cationic polymers achieved above 90% harvesting efficiency. Therefore, the maximum mass recovery of 98.7% with 86.8 gTSS/L sediment content was achieved by adjusting pH to 6-0.6 mL/L (115.178 mg/gbiomass) of C-810E followed by 15-min settling. The cationic polymer addition followed by settling would enable cost-effective downstream processing of microalgal biomass.

Microalgae-derived polysaccharides: Potential building blocks for biomedical applications.

In recent years, the increasing concern about human health well-being has strongly boosted the search for natural alternatives that can be used in different fields, especially in biomedicine. This has put microalgae-based products in evidence since they contain many bioactive compounds, of which polysaccharides are attractive due to the diverse physicochemical properties and new or improved biological roles they play. Polysaccharides from microalgae, specially exopolysaccharides, are critically important for market purposes because they can be used as anti-inflammatory, immunomodulatory, anti-glycemic, antitumor, antioxidant, anticoagulant, antilipidemic, antiviral, antibacterial, and antifungal agents. Therefore, to obtain higher productivity and competitiveness of these naturally available compounds, the cultivation parameters and the extraction/purification processes must be better optimized in order to bring perspectives for the exploitation of products in commercial and clinical practice. In this sense, the objective of the present review is to elucidate the potential biomedical applications of microalgae-derived polysaccharides. A closer look is taken at the main polysaccharides produced by microalgae, methods of extraction, purification and structural determination, biological activities and their applications, and current status.

Osteogenic activities of four calcium-chelating microalgae peptides.

BACKGROUND: Adequate calcium intake is necessary to prevent osteoporosis, which poses significant public health challenges. The natural bioactive peptide calcium chelates have been regarded as superior calcium supplements. Microalgae peptides are regarded as potential candidates for protection from bone loss in osteoporosis. This study aimed to prepare microalgae calcium-chelating peptides from four microalgae proteins and assess their osteogenic activities in osteoporosis-like zebrafish. RESULTS: After in vitro gastrointestinal digestion, 4.42% Chlorella pyrenoidosa protein, 2.74% Nannochloropsis oceanica protein, 6.07% Arthospira platensis protein and 10.47% Dunaliella salina protein were retained. The calcium-chelating capacities of four microalgae protein hydrolysates (MPHs) ranged from 14.10 ± 7.16% to 34.11 ± 9.34%. CaCl2 addition increased the maximum absorption peaks, absorption intensities and particle sizes of MPHs. Calcium-chelating MPHs showed stronger osteogenic activities than MPHs in the osteoporosis-like zebrafish model, with significantly increased mineralized tissue area and integrated optical density. CONCLUSION: Microalgae proteins have favorable digestibilities. Among the four MPHs, Nannochloropsis oceanica protein hydrolysates showed the highest calcium-chelating capacity, which might be due to its high degree of hydrolysis after in vitro digestion and high content of Ser, Tyr, Thr, Asp and Glu. The absorption intensities and particle sizes of MPHs both increased after calcium addition. MPH treatment could reverse dexamethasone-induced osteoporosis of zebrafish, and MPHs-Ca chelates showed higher osteogenic activities in osteoporosis-like phenotype zebrafish. © 2022 Society of Chemical Industry.

Total Phenolic Levels, In Vitro Antioxidant Properties, and Fatty Acid Profile of Two Microalgae, Tetraselmis marina Strain IMA043 and Naviculoid Diatom Strain IMA053, Isolated from the North Adriatic Sea.

This work studied the potential biotechnological applications of a naviculoid diatom (IMA053) and a green microalga (Tetraselmis marina IMA043) isolated from the North Adriatic Sea. Water, methanol, and dichloromethane (DCM) extracts were prepared from microalgae biomass and evaluated for total phenolic content (TPC) and in vitro antioxidant properties. Biomass was profiled for fatty acid methyl esters (FAME) composition. The DCM extracts had the highest levels of total phenolics, with values of 40.58 and 86.14 mg GAE/g dry weight (DW in IMA053 and IMA043, respectively). The DCM extracts had a higher radical scavenging activity (RSA) than the water and methanol ones, especially those from IMA043, with RSAs of 99.65% toward 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) at 10 mg/mL, and of 103.43% against 2,2-diphenyl-1-picrylhydrazyl (DPPH) at 5 mg/mL. The DCM extract of IMA053 displayed relevant copper chelating properties (67.48% at 10 mg/mL), while the highest iron chelating activity was observed in the water extract of the same species (92.05% at 10 mg/mL). Both strains presented a high proportion of saturated (SFA) and monounsaturated (MUFA) fatty acids. The results suggested that these microalgae could be further explored as sources of natural antioxidants for the pharmaceutical and food industry and as feedstock for biofuel production.

Innovative method to grow the probiotic Lactobacillus reuteri in the omega3-rich microalga Isochrysis galbana.

Microalgae are natural sources of valuable bioactive compounds, such as polyunsaturated fatty acids (PUFAs), that show antioxidant, anti-inflammatory, anticancer and antimicrobial activities. The marine microalga Isochrysis galbana (I. galbana) is extremely rich in ω3 PUFAs, mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Probiotics are currently suggested as adjuvant therapy in the management of diseases associated with gut dysbiosis. The Lactobacillus reuteri (L. reuteri), one of the most widely used probiotics, has been shown to produce multiple beneficial effects on host health. The present study aimed to present an innovative method for growing the probiotic L. reuteri in the raw seaweed extracts from I. galbana as an alternative to the conventional medium, under conditions of oxygen deprivation (anaerobiosis). As a result, the microalga I. galbana was shown for the first time to be an excellent culture medium for growing L. reuteri. Furthermore, the gas-chromatography mass-spectrometry analysis showed that the microalga-derived ω3 PUFAs were still available after the fermentation by L. reuteri. Accordingly, the fermented compound (FC), obtained from the growth of L. reuteri in I. galbana in anaerobiosis, was able to significantly reduce the adhesiveness and invasiveness of the harmful adherent-invasive Escherichia coli to intestinal epithelial cells, due to a cooperative effect between L. reuteri and microalgae-released ω3 PUFAs. These findings open new perspectives in the use of unicellular microalgae as growth medium for probiotics and in the production of biofunctional compounds.

Bioprospecting of Microalgae Isolated from the Adriatic Sea: Characterization of Biomass, Pigment, Lipid and Fatty Acid Composition, and Antioxidant and Antimicrobial Activity.

Marine microalgae and cyanobacteria are sources of diverse bioactive compounds with potential biotechnological applications in food, feed, nutraceutical, pharmaceutical, cosmetic and biofuel industries. In this study, five microalgae, Nitzschia sp. S5, Nanofrustulum shiloi D1, Picochlorum sp. D3, Tetraselmis sp. Z3 and Tetraselmis sp. C6, and the cyanobacterium Euhalothece sp. C1 were isolated from the Adriatic Sea and characterized regarding their growth kinetics, biomass composition and specific products content (fatty acids, pigments, antioxidants, neutral and polar lipids). The strain Picochlorum sp. D3, showing the highest specific growth rate (0.009 h-1), had biomass productivity of 33.98 ± 0.02 mg L-1 day-1. Proteins were the most abundant macromolecule in the biomass (32.83-57.94%, g g-1). Nanofrustulum shiloi D1 contained significant amounts of neutral lipids (68.36%), while the biomass of Picochlorum sp. D3, Tetraselmis sp. Z3, Tetraselmis sp. C6 and Euhalothece sp. C1 was rich in glycolipids and phospholipids (75%). The lipids of all studied microalgae predominantly contained unsaturated fatty acids. Carotenoids were the most abundant pigments with the highest content of lutein and neoxanthin in representatives of Chlorophyta and fucoxanthin in strains belonging to the Bacillariophyta. All microalgal extracts showed antioxidant activity and antimicrobial activity against Gram-negative E. coli and S. typhimurium and Gram-positive S. aureus.

The Effect of Chilling on the Photosynthetic Apparatus of Microalga Lobosphaera incisa IPPAS C-2047.

Photosynthetic organisms have developed a set of mechanisms aimed at preventing photo-oxidative reactions in the photosynthetic apparatus (PSA) initiated by excessively absorbed light energy. Along with high irradiance, other stressors, e.g., chilling temperatures, can lead to the absorption of the excess of light energy and hence to photo-oxidative stress. Here, we studied induction of photoprotective mechanisms in response to chilling (0°C) at a low irradiance (50 µmol PAR photons m-2·s-1) in the cells of microalga Lobosphaera incisa IPPAS C-2047. After 4 days of incubation at a low temperature, L. incisa IPPAS C-2047 cells showed a notable decrease in the photochemical activity of photosystem II (PSII) and in the efficiency of photosynthetic electron transport, as well as a significant increase in the thermal dissipation of the absorbed light energy in the light-harvesting antenna. In contrast, most conventional markers of PSA acclimation to excess light energy [total chlorophyll and carotenoid content; violaxanthin cycle pigment content and de-epoxidation state; photosynthetic antenna, PSII, and photosystem I (PSI) ratio] remained virtually unchanged. The content of major unsaturated fatty acids also remained almost unaffected, except for arachidonic acid (increased by 40%) recently assumed to activate violaxanthin de-epoxidase by adjusting its lipid microenvironment. Significant changes (4-7-fold increase) were observed in the expression of the gene encoding protective protein LhcSR. Pre-conditioning at 5°C prior to the acclimation to 0°C augmented the PSA photochemical activity. Our data show that the mid-term (4-d) acclimation of L. incisa IPPAS C-2047 to a chilling temperature at a low irradiance triggers the PSA response resembling, in part, the response to high light but relying mostly on the LhcSR protein-dependent quenching of excitation in the photosynthetic antenna.

Microalgae as a Potential Functional Ingredient: Evaluation of the Phytochemical Profile, Antioxidant Activity and In-Vitro Enzymatic Inhibitory Effect of Different Species.

The functional food market has been in a state of constant expansion due to the increasing awareness of the impact of the diet on human health. In the search for new natural resources that could act as a functional ingredient for the food industry, microalgae represent a promising alternative, considering their high nutritional value and biosynthesis of numerous bioactive compounds with reported biological properties. In the present work, the phytochemical profile, antioxidant activity, and enzymatic inhibitory effect aiming at different metabolic disorders (Alzheimer's disease, Type 2 diabetes, and obesity) were evaluated for the species Porphyridium purpureum, Chlorella vulgaris, Arthorspira platensis, and Nannochloropsis oculata. All the species presented bioactive diversity and important antioxidant activity, demonstrating the potential to be used as functional ingredients. Particularly, P. purpureum and N. oculata exhibited higher carotenoid and polyphenol content, which was reflected in their superior biological effects. Moreover, the species P. purpureum exhibited remarkable enzymatic inhibition for all the analyses.

Thermo resistant antioxidants from photoautotrophic microorganisms: screening and characterization.

The demand for natural antioxidants to be used in food industry is increasing, as synthetic antioxidants are toxic and have high production costs. Specifically, food processing and preservation require antioxidants resistant to thermal sterilization processes. In this study, twenty-five strains among microalgae and cyanobacteria were screened as antioxidants producers. The species Enallax sp., Synechococcus bigranulatus and Galdieria sulphuraria showed the highest content of chlorophyll a and total carotenoids. In vitro stability and antioxidant activity of the ethanolic extracts were performed. The results revealed that pigments present in the extracts, obtained from the previously mentioned species, were stable at room temperature and exhibited in vitro free radical scavenging potential with IC50 values of 0.099 ± 0.001, 0.048 ± 0.001 and 0.13 ± 0.02 mg mL-1, respectively. Biocompatibility assay showed that the extracts were not toxic on immortalized cell lines. The antioxidant activity was also tested on a cell-based model by measuring intracellular ROS levels after sodium arsenite treatment. Noteworthy, extracts were able to exert the same protective effect, before and after the pasteurization process. Results clearly indicate the feasibility of obtaining biologically active and thermostable antioxidants from microalgae. Green solvents can be used to obtain thermo-resistant antioxidants from cyanobacteria and microalgae which can be used in the food industry. Thus, the substitution of synthetic pigments with natural ones is now practicable.

Insight into Potential Anticancer Activity of Algal Flavonoids: Current Status and Challenges.

Flavonoids are some of the most precious phytochemicals, believed to be found largely in terrestrial plants. With the advancement of phytochemical research and marine bioprospecting, flavonoids have also been reported by the research of microalgae and macroalgae. High growth rate with minimal nutritional and growth requirement, saving arable land and rich metabolic profile make microalgae an excellent repertoire of novel anticancer compounds, such as flavonoids. In addition, marine algae, especially seaweeds contain different types of flavonoids which are assumed to have unique chemical structures and bioactivities than their terrestrial counterparts. Flavonoids are not only good antioxidants but also have the abilities to kill cancer cells by inducing apoptosis and autophagy. However, the study of the anticancer properties of flavonoids is largely limited to terrestrial plants. This review offers an insight into the distribution of different classes of flavonoids in eukaryotic microalgae, cyanobacteria and seaweeds with their possible anticancer activities. In addition, extraction and purification methods of these flavonoids have been highlighted. Finally, prospects and challenges to use algal flavonoids as anticancer agents have been discussed.