Evaluating the Probiotic Potential of Lactic Acid Bacteria Implicated in Natural Fermentation of Table Olives, cv. Cobrançosa.

The probiotic features of Lactiplantibacillus (L.) pentosus and L. paraplantarum strains, endogenous in Cobrançosa table olives from northeast Portugal, were assessed in terms of functional properties and health benefits. Fourteen lactic acid bacteria strains were compared with Lacticaseibacillus casei from a commercial brand of probiotic yoghurt and L. pentosus B281 from Greek probiotic table olives, in attempts to select strains with higher probiotic performances than those references. For functional properties, the i53 and i106 strains, respectively, exhibited: 22.2 ± 2.2% and 23.0 ± 2.2% for Caco-2 cell adhesion capacity; 21.6 ± 7.8% and 21.5 ± 1.4% for hydrophobicity; 93.0 ± 3.0% and 88.5 ± 4.5% for autoaggregation ability by 24 h of incubation; and ability to co-aggregate with selected pathogens-from 29 to 40% to Gram+ (e.g., Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212); and from 16 to 44% for Gram- (e.g., Escherichia coli ATCC 25922 and Salmonella enteritidis ATCC 25928). The strains proved to be resistant (i.e., halo zone ≤14 mm) to some antibiotics (e.g., vancomycin, ofloxacin, and streptomycin), but susceptible (i.e., halo zone ≥ 20 mm) to others (e.g., ampicillin and cephalothin). The strains exhibited health-beneficial enzymatic activity (such as acid phosphatase and naphthol-AS-BI-phosphohydrolase), but not health-harmful enzymatic activity (such as ß-glucuronidase and N-acetyl-ß-glucosaminidase). Additionally, the antioxidant activity and cholesterol assimilation features, respectively, of the strains were 19.6 ± 2.8% and 77.5 ± 0.5% for i53, and 19.6 ± 1.8% and 72.2 ± 0.9% for i106. This study indicated that the addition of L. pentosus strains i53 and/or i106 to Cobrançosa table olives is likely to enhance the added value of the final product, in view of the associated potential benefits upon human health.

Effects of Temperature, pH, and NaCl Concentration on Biomass and Bioactive Compound Production by Synechocystis salina.

Synechocystis salina is a cyanobacterium that has biotechnological potential thanks to its ability to synthesize several bioactive compounds of interest. Therefore, this study aimed to find optimal conditions, in terms of temperature (15-25 °C), pH (6.5-9.5), and NaCl concentration (10-40 g·L-1), using as objective functions the productivities of biomass, total carotenoids, total PBPs, phycocyanin (PC), allophycocyanin (APC), phycoerythrin (PE), and antioxidants (AOXs) capacity of Synechocystis salina (S. salina) strain LEGE 06155, based in factorial design resorting to Box-Behnken. The model predicted higher biomass productivities under a temperature of 25 °C, a pH of 7.5, and low NaCl concentrations (10 g·L-1). Maximum productivities in terms of bioactive compounds were attained at lower NaCl concentrations (10 g·L-1) (except for PE), with the best temperature and pH in terms of carotenoids and total and individual PBPs ranging from 23-25 °C to 7.5-9.5, respectively. PE was the only pigment for which the best productivity was reached at a lower temperature (15 °C) and pH (6.5) and a higher concentration of NaCl (≈25 g·L-1). AOX productivities, determined in both ethanolic and aqueous extracts, were positively influenced by lower temperatures (15-19 °C) and higher salinities (≈15-25 g·L-1). However, ethanolic AOXs were better recovered at a higher pH (pH ≈ 9.5), while aqueous AOXs were favored by a pH of 8. The model showed that biomass production can be enhanced by 175% (compared to non-optimized conditions), total carotenoids by 91%, PC by 13%, APC by 50%, PE by 130%, and total PBPs by 39%; for AOX productivities, only water extracts exhibited a (marginal) improvement of 1.4%. This study provided insightful information for the eventual upgrading of Synechocystis salina biomass in the biotechnological market.

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.

Karlodinium veneficum: Growth optimization, metabolite characterization and biotechnological potential survey.

AIM OF THIS STUDY: The major aim of this work was to consistently optimize the production of biomass of the dinoflagellate Karlodinium veneficum and evaluate its extracts biotechnological potential application towards food, nutraceutical or/and pharmaceutical industries. METHODS AND RESULTS: A successful approach of biomass production of K. veneficum CCMP 2936 was optimized along with the chemical characterization of its metabolite profile. Several temperatures (12, 16, 20, 25, 30°C), L1 nutrient concentrations (0.5×, 2×, 2.5×, 3×) and NaCl concentrations (20, 25, 30, 40 g L-1 ) were tested. The growth rate was maximum at 16°C, 2× nutrient concentration and 40 g L-1 of NaCl; hence, these conditions were chosen for bulk production of biomass. Methanolic extracts were prepared, and pigments, lipids and phenolic compounds were assessed; complemented by antioxidant and anti-inflammatory capacities, and cytotoxicity. Fucoxanthin and derivatives accounted for 0.06% of dry weight, and up to 60% (w/w) of all quantified metabolites were lipids. Said extracts displayed high antioxidant capacity, as towards assessed via the NO•- and ABTS•+ assays (IC50  = 109.09 ± 6.73 and 266.46 ± 2.25 µgE  ml-1 , respectively), unlike observed via the O2 •- assay (IC25 reaching 56.06 ± 5.56 µgE  ml-1 ). No signs of cytotoxicity were observed. CONCLUSIONS: Karlodinium veneficum biomass production was consistently optimized in terms of temperature, L1 nutrient concentrations and NaCl concentration. In addition, this strain appears promising for eventual biotechnological exploitation. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides fundamental insights about the growth and potential of value-added compounds of dinoflagellate K. veneficum. Dinoflagellates, as K. veneficum are poorly studied regarding its biomass production and added-value compounds for potential biotechnological exploitation. These organisms are difficult to maintain and grow in the laboratory. Thus, any fundamental contribution is relevant to share with the scientific community.

Diel biochemical and photosynthetic monitorization of Skeletonema costatum and Phaeodactylum tricornutum grown in outdoor pilot-scale flat panel photobioreactors.

Diatoms are currently considered valuable feedstocks for different biotechnological applications. To deepen the knowledge on the production of these microalgae, the diel pattern of batch growth, photosystem II performance, and accumulation of target metabolites of two commercially relevant diatoms, Phaeodactylum tricornutum and Skeletonema costatum, were followed outdoors in 100-L flat panel photobioreactors. S. costatum presented a higher light-to-biomass conversion resulting in higher growth than P. tricornutum. Both fluorescence data and principal component analysis pointed to temperature as a limiting factor for the growth of P. tricornutum. Higher protein and carbohydrate contents were found in P. tricornutum, whereas S. costatum fatty acids were characterized by a higher unsaturation degree. Higher productivities were found at 1 p.m. for protein, lipid, and ash in the case of S. costatum. Overall, S. costatum showed great potential for outdoor cultivation, revealing a broader temperature tolerance and increased biomass productivity than P. tricornutum.

Anti-Hepatocellular Carcinoma (HepG2) Activities of Monoterpene Hydroxy Lactones Isolated from the Marine Microalga Tisochrysis Lutea.

Tisochrysis lutea is a marine haptophyte rich in omega-3 polyunsaturated fatty acids (e.g., docosahexaenoic acid (DHA)) and carotenoids (e.g., fucoxanthin). Because of the nutraceutical applications of these compounds, this microalga is being used in aquaculture to feed oyster and shrimp larvae. In our earlier report, T. lutea organic crude extracts exhibited in vitro cytotoxic activity against human hepatocarcinoma (HepG2) cells. However, so far, the compound(s) accountable for the observed bioactivity have not been identified. Therefore, the aim of this study was to isolate and identify the chemical component(s) responsible for the bioactivity observed. Bioassay-guided fractionation through a combination of silica-gel column chromatography, followed by preparative thin layer chromatography (PTLC), led to the isolation of two diastereomers of a monoterpenoid lactone, namely, loliolide (1) and epi-loliolide (2), isolated for the first time in this species. The structural elucidation of both compounds was carried out by GC-MS and 1D (1H and 13C APT) and 2D (COSY, HMBC, HSQC-ed, and NOESY) NMR analysis. Both compounds significantly reduced the viability of HepG2 cells and were considerably less toxic towards a non-tumoral murine stromal (S17) cell line, although epi-loliolide was found to be more active than loliolide.

A Review on Adventitious Lactic Acid Bacteria from Table Olives.

Spontaneous fermentation constitutes the basis of the chief natural method of processing of table olives, where autochthonous strains of lactic acid bacteria (LAB) play a dominant role. A thorough literature search has unfolded 197 reports worldwide, published in the last two decades, that indicate an increasing interest in table olive-borne LAB, especially in Mediterranean countries. This review attempted to extract extra information from such a large body of work, namely, in terms of correlations between LAB strains isolated, manufacture processes, olive types, and geographical regions. Spain produces mostly green olives by Spanish-style treatment, whereas Italy and Greece produce mainly green and black olives, respectively, by both natural and Spanish-style. More than 40 species belonging to nine genera of LAB have been described; the genus most often cited is Lactobacillus, with L. plantarum and L. pentosus as most frequent species-irrespective of country, processing method, or olive type. Certain LAB species are typically associated with cultivar, e.g., Lactobacillus parafarraginis with Spanish Manzanilla, or L. paraplantarum with Greek Kalamata and Conservolea, Portuguese Galega, and Italian Tonda di Cagliari. Despite the potential of native LAB to serve as starter cultures, extensive research and development efforts are still needed before this becomes a commercial reality in table olive fermentation.

Efficiency of purification methods on the recovery of exopolysaccharides from fermentation media.

De-Man Rogosa and Sharpe (MRS) is a complex medium commonly used to obtain exopolysaccharides (EPS) from lactic acid bacteria. However, the various nutrients (carbon and nitrogen sources) of media and supplements added to enhance the bacterial growth and EPS production, may interfere with the purification of the extracts resulting in an over-estimation of the EPS and erroneous structural assignments. The efficiency of trichloroacetic acid (TCA)/pronase and 5-sulfosalicylic acid - SSA methods was evaluated. In addition, the interference of the major MRS broth components as well as lactose was evaluated using xanthan gum as model control EPS. It was concluded that MRS medium is a major source of interfering compounds in the quantification of EPS, mainly glucose-rich material and to a lesser extent mannoproteins from yeast extract. This effect was found to be potentiated by the presence of lactose. TCA/pronase method was shown to be more efficient in eliminating interferents.

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.

Biotechnological and Pharmacological Applications of Biotoxins and Other Bioactive Molecules from Dinoflagellates.

The long-lasting interest in bioactive molecules (namely toxins) produced by (microalga) dinoflagellates has risen in recent years. Exhibiting wide diversity and complexity, said compounds are well-recognized for their biological features, with great potential for use as pharmaceutical therapies and biological research probes. Unfortunately, provision of those compounds is still far from sufficient, especially in view of an increasing demand for preclinical testing. Despite the difficulties to establish dinoflagellate cultures and obtain reasonable productivities of such compounds, intensive research has permitted a number of advances in the field. This paper accordingly reviews the characteristics of some of the most important biotoxins (and other bioactive substances) produced by dinoflagellates. It also presents and discusses (to some length) the main advances pertaining to dinoflagellate production, from bench to large scale-with an emphasis on material published since the latest review available on the subject. Such advances encompass improvements in nutrient formulation and light supply as major operational conditions; they have permitted adaptation of classical designs, and aided the development of novel configurations for dinoflagellate growth-even though shearing-related issues remain a major challenge.

ß-Lactoglobulin microparticles obtained by high intensity ultrasound as a potential delivery system for bioactive peptide concentrate.

This work attempted to assess the effect of high intensity ultrasound (HIUS) upon development of bio-based delivery systems, from ß-lactoglobulin (ß-Lg) gelled microparticles, for encapsulation of a bioactive peptide concentrate (PepC). Solutions of 150 g L-1 of commercial ß-Lg and 30 g L-1 PepC, at various pH values (3.0, 4.0 and 5.5), were accordingly subjected to gelation for 30 min using a dry bath kept at 80 °C. The gelled systems were then exposed to HIUS at 0-4 °C, and the effect of processing time (2.5-20.0 min) was ascertained. Laser light scattering and confocal microscopy were used to characterize the particle size distribution, prior to and immediately after HIUS treatment. Gels obtained at pH 5.5 and 4.0 were harder than those obtained at pH 3.0. Ultrasound treatment of gels produced an important reduction in particle mean diameter as sonication time elapsed. Confocal microscopy indicated that application of HIUS led to almost round and monodispersed particles, at both pH 5.5 and 4.0. The peptide encapsulation efficiency was assessed by chromatography and accompanied by assay for bioactivity, after precipitation of the encapsulated material and analysis of the soluble peptides therein.

Design of whey protein nanostructures for incorporation and release of nutraceutical compounds in food.

Whey proteins are widely used as nutritional and functional ingredients in formulated foods because they are relatively inexpensive, generally recognized as safe (GRAS) ingredient, and possess important biological, physical, and chemical functionalities. Denaturation and aggregation behavior of these proteins is of particular relevance toward manufacture of novel nanostructures with a number of potential uses. When these processes are properly engineered and controlled, whey proteins may be formed into nanohydrogels, nanofibrils, or nanotubes and be used as carrier of bioactive compounds. This review intends to discuss the latest understandings of nanoscale phenomena of whey protein denaturation and aggregation that may contribute for the design of protein nanostructures. Whey protein aggregation and gelation pathways under different processing and environmental conditions such as microwave heating, high voltage, and moderate electrical fields, high pressure, temperature, pH, and ionic strength were critically assessed. Moreover, several potential applications of nanohydrogels, nanofibrils, and nanotubes for controlled release of nutraceutical compounds (e.g. probiotics, vitamins, antioxidants, and peptides) were also included. Controlling the size of protein networks at nanoscale through application of different processing and environmental conditions can open perspectives for development of nanostructures with new or improved functionalities for incorporation and release of nutraceuticals in food matrices.

Isolation of a euryhaline microalgal strain, Tetraselmis sp. CTP4, as a robust feedstock for biodiesel production.

Bioprospecting for novel microalgal strains is key to improving the feasibility of microalgae-derived biodiesel production. Tetraselmis sp. CTP4 (Chlorophyta, Chlorodendrophyceae) was isolated using fluorescence activated cell sorting (FACS) in order to screen novel lipid-rich microalgae. CTP4 is a robust, euryhaline strain able to grow in seawater growth medium as well as in non-sterile urban wastewater. Because of its large cell size (9-22 µm), CTP4 settles down after a six-hour sedimentation step. This leads to a medium removal efficiency of 80%, allowing a significant decrease of biomass dewatering costs. Using a two-stage system, a 3-fold increase in lipid content (up to 33% of DW) and a 2-fold enhancement in lipid productivity (up to 52.1 mg L-1 d-1) were observed upon exposure to nutrient depletion for 7 days. The biodiesel synthesized from the lipids of CTP4 contained high levels of oleic acid (25.67% of total fatty acids content) and minor amounts of polyunsaturated fatty acids with ≥4 double bonds (<1%). As a result, this biofuel complies with most of the European (EN14214) and American (ASTM D6751) specifications, which commonly used microalgal feedstocks are usually unable to meet. In conclusion, Tetraselmis sp. CTP4 displays promising features as feedstock with lower downstream processing costs for biomass dewatering and biodiesel refining.

Effect of Solvent System on Extractability of Lipidic Components of Scenedesmus obliquus (M2-1) and Gloeothece sp. on Antioxidant Scavenging Capacity Thereof.

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.

Antioxidant properties of sterilized yacon (Smallanthus sonchifolius) tuber flour.

The objective of this research work was to investigate the antioxidant properties of sterilized yacon tuber flour. The results revealed for the first time the high antioxidant activity of sterilized yacon flour. The best extract obtained by boiling 8.9% (w/v) of yacon flour in deionised water for 10 min exhibited a total antioxidant capacity of 222±2 mg (ascorbic acid equivalent)/100 g DW and a total polyphenol content of 275±3 mg (gallic acid equivalent)/100 g DW associated to the presence of four main phenolic compounds: chlorogenic acid, caffeic acid, coumaric acid and protocatechuic acid, as well as the amino acid tryptophan. The most abundant was chlorogenic acid, followed by caffeic acid. Biological assays revealed that the extract had indeed antioxidant protection, and no pro-oxidant activity. In conclusion, sterilized yacon tuber flour has the potential to be used in the food industry as a food ingredient to produce functional food products.

Olive paste as vehicle for delivery of potential probiotic Lactobacillus plantarum 33.

Use of probiotic bacteria and consumes in large - in novel foods to provide beneficial health effects has attracted an increasing interest by the food industry and fermented olives are an excellent example of a new generation of those foods from plant origin so as to assure maximum viability by the time of ingestion during processing and storage of food products, as well as during transit through the gastrointestinal tract. Our study focused on production, characterization and assessment of efficacy of microencapsulation upon survival of probiotic strains and sensory properties of the final olive paste throughout refrigerated storage. Microencapsulation appears to be an effective technique for strain survival, depending on the operating temperature and experimental results on tolerance to gastrointestinal-like conditions, and ability to adhere to intestinal epithelium is thereby presented and discussed. The sensory panel rated all experienced matrices as good, including overall acceptance without significant preference between them. However, the success of microencapsulation was more limited when incorporated into olive paste. Free cells of Lactobacillus plantarum 33 proved able to survive in olive paste during storage at refrigerated temperatures.

Characterization of the bacterial biodiversity in Pico cheese (an artisanal Azorean food).

This work presents the first study on the bacterial communities in Pico cheese, a traditional cheese of the Azores (Portugal), made from raw cow's milk. Pyrosequencing of tagged amplicons of the V3-V4 regions of the 16S rDNA and Operational Taxonomic Unit-based (OTU-based) analysis were applied to obtain an overall idea of the microbiota in Pico cheese and to elucidate possible differences between cheese-makers (A, B and C) and maturation times. Pyrosequencing revealed a high bacterial diversity in Pico cheese. Four phyla (Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes) and 54 genera were identified. The predominant genus was Lactococcus (77% of the sequences). Sequences belonging to major cheese-borne pathogens were not found. Staphylococcus accounted for 0.5% of the sequences. Significant differences in bacterial community composition were observed between cheese-maker B and the other two units that participated in the study. However, OTU analysis identified a set of taxa (Lactococcus, Streptococcus, Acinetobacter, Enterococcus, Lactobacillus, Staphylococcus, Rothia, Pantoea and unclassified genera belonging to the Enterobacteriaceae family) that would represent the core components of artisanal Pico cheese microbiota. A diverse bacterial community was present at early maturation, with an increase in the number of phylotypes up to 2 weeks, followed by a decrease at the end of ripening. The most remarkable trend in abundance patterns throughout ripening was an increase in the number of sequences belonging to the Lactobacillus genus, with a concomitant decrease in Acinetobacter, and Stenotrophomonas. Microbial rank abundance curves showed that Pico cheese's bacterial communities are characterized by a few dominant taxa and many low-abundance, highly diverse taxa that integrate the so-called "rare biosphere".

Evolution of amino acids and biogenic amines throughout storage in sausages made of horse, beef and turkey meats.

The changes in concentration of free amino acids and biogenic amines, along 28 d of storage at 4°C, were monitored in a wide range of European ripened sausages manufactured from horse, beef and turkey meats. Generally speaking, both chemical families became more concentrated with elapsing time--but rather distinct patterns were followed in each meat type: total free amino acids increased by 13-fold in the case of horse sausages, and 5-fold in the case of beef sausages, but decreased to one third in the case of turkey sausages; and total biogenic amines attained 730 mg/kg in turkey sausages, 500 mg/kg in beef sausages and 130 mg/kg in horse sausages by 28 d of refrigerated storage. For putrescine, maximum levels of 285 mg/kg were attained in turkey and 278 mg/kg in beef sausages; for cadaverine, maximum levels of 6 mg/kg in turkey and 9 mg/kg in beef; and for histamine, maximum levels of 263 mg/kg in turkey and 26 mg/kg in beef. Hence, public safety concerns may be raised in the case of turkey sausages.

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.

Microalgal compounds modulate carcinogenesis in the gastrointestinal tract.

Gastrointestinal cancers rank second in overall cancer-related deaths. Carotenoids, sulfated polysaccharides, and polyunsaturated fatty acids (PUFAs) from microalgae exhibit cancer chemopreventive features at different stages of carcinogenesis. For instance, sulfated polysaccharides bear a prophylactic potential via blocking adhesion of pathogens to the gastric surface, whereas carotenoids are effective against Helicobacter pylori infection. This effect is notable because H. pylori has been targeted as the primary cause of gastric cancer. Recent results on antitumor and antibacterial compounds synthesized by microalgae are reviewed here, with an emphasis on their impact upon H. pylori infection and derived pathologies accompanying the progression of gastric carcinogenesis.