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Marine algae are thought to be a source of various metabolites that have a wide range of positive effects on human health. The pharmacological properties of algal metabolites, including their antioxidant, anti-inflammatory, cholesterol homeostasis, protein clearance, and anti-amyloidergic effects, lend credence to their protective efficacy against oxidative stress, neuroinflammation, mitochondrial dysfunction, and impaired proteostasis, all of which are involved in the pathophysiology of neurodegenerative disorders. There are currently no clinical trials on the effects of marine algae on neuroinflammation; however, considering the significant biological activities that have been established by in vitro and animal research, we expect that there will be clinical trials on this topic in the not-too-distant future. The most recent and important findings on the potentially neuroprotective effects of the antiinflammatory properties of marine algae were chosen for this study. Next, we conducted a literature review on the neuroprotective potential of algal compounds, along with the underlying pharmacological mechanism, and finally, we evaluated recent advances in therapeutics. [ABSTRACT FROM AUTHOR]

Euglena sp. is a unicellular, flagellated microalga considered one of the most promising microalgal feedstock species for biofuels. Reducing the level of liquid waste pollutants can be done biologically by using microalgal organisms. Its metabolites, including lipids, proteins, carbohydrates, and pigments, are appropriate for producing biorefinery products such as biodiesel and jet fuels. They can be isolated from extreme environments, such as highly acidic and ammonia-rich environments, that are not conducive to their proliferation. This study sought to determine the effect of the photoperiod or (light: dark) cycle (24 L:0 D, 12 L:12 D, 14 L:10 D, and 16 L:8 D) on the growth, biomass, metabolite content consisting of lipids, carbohydrates, and proteins, and the rate of CO 2 uptake by Euglena sp. As stated previously, the study was conducted by cultivating Euglena sp. on a laboratory scale with four photoperiod regimens. The results indicated that optimal growth, biomass content, and metabolite content were obtained with a 24 D:0 L lighting cycle. The control treatment (24 L: 0 D) had the highest biomass productivity (0.032 g.L-1.day-1 ± 0.004), lipid content (0.387 g.L-1 ± 0.031), protein content (0.542 mg.Ml-1 ± 0.007), carbohydrate content (0.409 x104 g.L-1), chlorophyll a (6.237 g.L-1 ± 0.184), chlorophyll b (2.838 g.L-1 ± 0.253), and total carotenoid (1.566 g.L-1 ± 0.105). Full light illumination (24 L:0 D) was significantly producing carotenoid content, including phaeophytin a, phaeophytin b, violaxanthin, 9'-cis-neoxanthin, dino xanthin, and fucoxanthin. [ABSTRACT FROM AUTHOR]

Marine algae are thought to be a source of various metabolites that have a wide range of positive effects on human health. The pharmacological properties of algal metabolites, including their antioxidant, anti-inflammatory, cholesterol homeostasis, protein clearance, and anti-amyloidergic effects, lend credence to their protective efficacy against oxidative stress, neuroinflammation, mitochondrial dysfunction, and impaired proteostasis, all of which are involved in the pathophysiology of neurodegenerative disorders. There are currently no clinical trials on the effects of marine algae on neuroinflammation; however, considering the significant biological activities that have been established by in vitro and animal research, we expect that there will be clinical trials on this topic in the not-too-distant future. The most recent and important findings on the potentially neuroprotective effects of the anti-inflammatory properties of marine algae were chosen for this study. Next, we conducted a literature review on the neuroprotective potential of algal compounds, along with the underlying pharmacological mechanism, and finally, we evaluated recent advances in therapeutics.

Algal biomass is a promising feedstock for sustainable production of a range of value-added compounds and products including food, feed, fuel. To further augment the commercial value of algal metabolites, efficient valorization methods and biorefining channels are essential. Algal extracts are ideal sources of biotechnologically viable compounds loaded with anti-microbial, anti-oxidative, anti-inflammatory, anti-cancerous and several therapeutic and restorative properties. Emerging technologies in biomass valorisation tend to reduce the significant cost burden in large scale operations precisely associated with the pre-treatment, downstream processing and waste management processes. In order to enhance the economic feasibility of algal products in the global market, comprehensive extraction of multi-algal product biorefinery is envisaged as an assuring strategy. Algal biorefinery has inspired the technologists with novel prospectives especially in waste recovery, carbon concentration/sequestration and complete utilisation of the value-added products in a sustainable closed-loop methodology. This review critically examines the latest trends in the algal biomass valorisation and the expansive feedstock potentials in a biorefinery perspective. The recent scope dynamics of algal biomass utilisation such as bio-surfactants, oleochemicals, bio-stimulants and carbon mitigation have also been discussed. The existing challenges in algal biomass valorisation, current knowledge gaps and bottlenecks towards commercialisation of algal technologies are discussed. This review is a comprehensive presentation of the road map of algal biomass valorisation techniques towards biorefinery technology. The global market view of the algal products, future research directions and emerging opportunities are reviewed. [ABSTRACT FROM AUTHOR]

A novel liquid phase microextraction method based on solvent oil droplets was optimized and validated for sample pretreatment of algal odorous metabolites (i.e., 2-Methylisoborneol, Geosmin, etc.) in drinking water supplies prior to gas chromatography. Segregation and condensation are based on the diffusion of solvent oil micro drops as an extracting solvent in the sample solution (drinking water supplies) and then back extraction of the analytes to another organic solvent, which is a three-phase direct immersion type of LPME. The important variables influencing the microextraction procedure such as type and volume of extracting oil and back extracting solvent, time and temperature of extraction, and ionic strength were optimized separately. Under optimal conditions, the correlation coefficient, limits of detection, linear dynamic ranges, preconcentration factors, and precision of the method were evaluated. The method displayed a high linearity range for the analytes (R2 ≥ 0.9808–0.9959), low limit of detection (0.03–3.01 μg L−1), and a good linear dynamic range (0.08–50 μg L−1). The precision comprised of reproducibility and repeatability were evaluated by computing the relative standard deviation (RSD %), which was ranged as 3.48–3.87%. Consequently, the optimized method along with the GC-FID method was successfully extracted the algal metabolites from water samples, with satisfactory recoveries (94–97%). [ABSTRACT FROM AUTHOR]

In this study an attempt has been made to evaluate the feasibility of utilizing ultrasonication as pretreatment process to treat pulping wastewater. Bio-electrochemical treatment and microalgal treatment have been used as secondary treatment process. Ultrasonication was performed in bath type sonicator at 60 kHz for various time intervals of 15, 30, 45 and 60 min. There were no significant changes in pH, TDS and COD of pulping wastewater after ultrasonication. The bio-electrochemical treatment of pretreated wastewater did not show significant improvement in treatment efficiency and color removal. Rather the MFC operating with pretreated wastewater showed poor electrochemical performance. Microalgae consortia collected from lily pond in the institute could decolorize the ultrasonically pretreated wastewater, but color of raw wastewater could not be decolorized by micro algal consortia. Ultrasonication could have modified the compounds in pulping wastewater, making them more accessible to microalgal metabolism. [ABSTRACT FROM AUTHOR]

Abstract In order to investigate the stimulating effect of TiO2 nanoparticles on the growth rate and the increase of some metabolites in the microalgae Spirulina platensis, the anatase and rutile forms of the TiO2 nanoparticle were compared to the bulk form, in the presence or absence of citrate, on the microalga. The highest chlorophyll, carotenoid, phycocyanin (PC), allophycocyanin (APC), and phycoerythrin (PE) were observed on 3rd day. The highest PC and APC/PE were obtained by rutile and anatase, respectively. Rutile NPs could stimulate the increase of dry biomass and maximum specific growth rate (µm) better than anatase and even the bulk form. Carbohydrate production was stimulated by bulk and rutile. Low concentrations of nanoparticles often had a better effect in increasing PC, APC, and PE pigments. The addition of citrate without TiO2 stimulated the production of astheaxanthin, lipid, protein, and ROS. The simultaneous treatment by citrate-TiO2 was able to reduce the negative effect of nanoparticles on dry weight, but totally, its effect was dependent on the form of TiO2 and stress time. Antioxidant activity was stimulated by the bulk form and caused a decrease in Malondialdehyde (MDA), but an increase in MDA was observed by nanoparticles. The highest ROS was observed in the treatment with rutile (with citrate) on the 3rd day. In general, the stimulating effect of TiO2 on the improvement of indices or its negative effects on S.platensis microalga depended on the form and concentration of TiO2, the presence or absence of citrate, and the duration of treatments. IntroductionThe titanium element, in some cases, improves plant metabolic processes (Gohari et al., 2022; Carvajal and Alcaraz 1998). TiO2 nanoparticles in different forms have many applications in industry, and it is possible to find their way into aquatic ecosystems (Yang et al., 2015). The two forms of anatase and rutile have different surfaces, structural, and toxicity properties (Parrino et al., 2021). Some studies have shown that anatase has more cytotoxicity and photocatalytic activity than the rutile form (Clément et al., 2013). Of course, some sources mention TiO2 with low toxicity (Parrino et al., 2021). However, the effects of TiO2 nanoparticles depend on the type of organism under investigation, nanoparticle concentration, physicochemical and morphological characteristics such as its size and crystal structure. S. platensis, a spiral filamentous blue-green microalgae, has attracted the attention of researchers due to its numerous economic applications, including as a fertilizer and enhancer in agriculture, and has valuable minerals, vitamins, and nutritional compounds (Godlewska et al., 2019; Deng and Chow, 2010). Citric acid is required for various biological processes (Mudunkotuwa and Grassian, 2010). The citrate-nanometal complex can facilitate the entry of NPs along with citrate into the cell (Rupasinghe, 2011); hence the citrate form of nanometals has been recommended for the growth of plants (Chandrika et al., 2021). Some studies on plants have also shown that citrate reduces the adverse effects of nanoparticles (Tirani et al., 2018). Citrate can be adsorbed on the oxides of nanoparticles through Van der Waals bonds and prevent particles from aggregation (Park and Shumaker-Parry 2014; Rupasinghe 2011; Mudunkotuwa and Grassian, 2010).The aim of researchThe goal of this research was a comparative evaluation of the possible stimulating or adverse effects of bulk forms and nanoparticles of TiO2 (anatase and rutile), with or without citrate (in concentrations of 12.5, 25, 50, 100 and 200 mg. L-1) on the growth, biomass and intracellular compounds of microalgae S. platensis in 5 days. Materials and Methods Zarrouk nutrient medium was used for the growth of microalgae. Anatase nanoparticles 10-25 nm (Purity 99.9%, Specific surface area, SSA 200-240 m2 g-1), rutile nanoparticles 30 nm, (Purity 99.9%, SSA 35-60 m2 g-1) and bulk sample (diameter

In order to investigate the stimulating effect of TiO2 nanoparticles on the growth rate and the increase of some metabolites in the microalgae Spirulina platensis, the anatase and rutile forms of the TiO2 nanoparticle were compared to the bulk form, in the presence or absence of citrate, on the microalga. The highest chlorophyll, carotenoid, phycocyanin (PC), allophycocyanin (APC), and phycoerythrin (PE) were observed on 3rd day. The highest PC and APC/PE were obtained by rutile and anatase, respectively. Rutile NPs could stimulate the increase of dry biomass and maximum specific growth rate (μm) better than anatase and even the bulk form. Carbohydrate production was stimulated by bulk and rutile. Low concentrations of nanoparticles often had a better effect in increasing PC, APC, and PE pigments. The addition of citrate without TiO2 stimulated the production of astheaxanthin, lipid, protein, and ROS. The simultaneous treatment by citrate-TiO2 was able to reduce the negative effect of nanoparticles on dry weight, but totally, its effect was dependent on the form of TiO2 and stress time. Antioxidant activity was stimulated by the bulk form and caused a decrease in Malondialdehyde (MDA), but an increase in MDA was observed by nanoparticles. The highest ROS was observed in the treatment with rutile (with citrate) on the 3rd day. In general, the stimulating effect of TiO2 on the improvement of indices or its negative effects on S.platensis microalga depended on the form and concentration of TiO2, the presence or absence of citrate, and the duration of treatments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Algal-derived bioactive compounds (ABC) provide great health and nutritional benefits. • Novel technologies, like precision fermentation, uplift algal nutritional quality and bioactivity. • Encapsulation and cold plasma boost ABC stability and bioavailability. • Minimizing ABC allergenicity is crucial to optimize their digestibility and bioavailability. As a rapidly growing source of human nutrients, algae biosynthesize diverse metabolites which have promising bioactivities. However, the potential allergenicity of algal components hinder their widespread adoption. This review provides a comprehensive review of various macro and micronutrients derived from algal biomass, with particular focus on bioactive compounds, including peptides, polyphenols, carotenoids, omega-3 fatty acids and phycocyanins. The approaches used to produce algal bioactive compounds and their health benefits (antioxidant, antidiabetic, cardioprotective, anti-inflammatory and immunomodulatory) are summarised. This review particularly focuses on the state-of-the-art of precision fermentation, encapsulation, cold plasma, high-pressure processing, pulsed electric field, and subcritical water to reduce the allergenicity of algal compounds while increasing their bioactivity and bioavailability. By providing insights into current challenges of algae-derived compounds and opportunities for advancement, this review contributes to the ongoing discourse on maximizing their application potential in the food nutraceuticals, and pharmaceuticals industries. [ABSTRACT FROM AUTHOR]

Covid-19 pandemic severely affected human health worldwide. Till October 19, 2020, total confirmed patients of COVID-19 are 39,944,882, whereas 1,111,998 people died across the globe. Till to date, we do not have any specific medicine and/or vaccine to treat COVID-19; however, research is still going on at war footing. So far vaccine development is concerned, here it is noteworthy that till now three major variants (named A, B, and C) of severe acute respiratory syndrome-coronavirus2 (SARS-CoV-2) have been recognized. Increased mutational rate and formation of new viral variants may increase the attrition rate of vaccines and/or candidate chemotherapies. Herbal remedies are chemical cocktails, thus open another avenue for effective antiviral therapeutics development. In fact, India is a large country, which is densely populated, but the overall severity of COVID-19 per million populations is lesser than any other country of the world. One of the major reasons for the aforesaid difference is the use of herbal remedies by the Government of India as a preventive measure for COVID-19. Therefore, the present review focuses on the epidemiology and molecular pathogenesis of COVID-19 and explores algal metabolites for their antiviral properties. [ABSTRACT FROM AUTHOR]

The development of biofuels as an alternative to the use of fossil fuels is growing worldwide due to environmental concerns and energy independence; thus, considerable technical progress has been achieved in biofuel production. Microalgae have been widely used for nutrient removal during wastewater treatment and produce compounds that can be used as feedstock for biofuel synthesis. In this work, the green microalga Coelastrum sp. was cultivated using industrial wastes: molasses as the carbon source and synthetic wastewater as the culture medium to determine the potential of its use for biofuel production. The use of synthetic wastewater (SWW) and molasses improved biomass production when compared with cultures carried out in a standard laboratory culture medium, such as tris-acetate-phosphate (TAP). Growth rates of 0.31 and 1.4 day−1 were attained during exponential growth rate with SWW and molasses and TAP media, respectively. The best results in biomass and lipid content, 2.29 ± 0.05 and 0.71 ± 0.03 g L−1, were obtained after 15 days of culture in SWW with molasses. The analysis of the lipid profile, produced by Coelastrum sp. cultured under these conditions, determined that the microalga can be considered as a high-quality feedstock for producing green diesel, bio-jet fuel, or biodiesel. [ABSTRACT FROM AUTHOR]

Covering: 1957 to 2017 Algae constitute a heterogeneous group of eukaryotic photosynthetic organisms, mainly found in the marine environment. Algae produce numerous metabolites that help them cope with the harsh conditions of the marine environment. Because of their structural diversity and uniqueness, these molecules have recently gained a lot of interest for the identification of medicinally useful agents, including those with potential anticancer activities. In the current review, which is not a catalogue-based one, we first highlight the major biological events that lead to various types of cancer, including metastatic ones, to chemoresistance, thus to any types of current anticancer treatment relating to the use of chemotherapeutics. We then review algal metabolites for which scientific literature reports anticancer activity. Lastly, we focus on algal metabolites with promising anticancer activity based on their ability to target biological characteristics of cancer cells responsible for poor treatment outcomes. Thus, we highlight compounds that have, among others, one or more of the following characteristics: selectivity in reducing the proliferation of cancer cells over normal ones, potential for killing cancer cells through non-apoptotic signaling pathways, ability to circumvent MDR-related efflux pumps, and activity in vivo in relevant pre-clinical models. [ABSTRACT FROM AUTHOR]

Abstract It is necessary and important to investigate the formation of disinfection byproducts (DBPs) in water treatment systems for the management of disinfection formation risk. In the present study, the formation potential of trichloromethane (TCM) and haloacetic acids in different algal metabolites were compared, and the formation kinetics of these DBPs were investigated. The results indicated that DBP formation potential, the traditional index widely used to evaluate the disinfection formation risk, can represent neither the total precursors of DBPs nor the possible generated amounts of DBPs in drinking water systems. Kinetic analyses showed that the formation of DBPs could be well described by a classical second-order reaction kinetic model and that the actual concentrations of DBPs during chlorination were predictable with the model. The formation of DBPs in drinking water treatment systems was highly dependent on the total precursors of DBPs in water and the formation rate of DBPs with chlorine; the latter is usually underestimated in previous studies. Because of their high reactivity, TCM in hydrophilic extracellular organic matter and trichloroacetic acid in all algal metabolites should be serious considerations in the management of disinfection formation risk. Graphical abstract Image 1 Highlights • DBPFP could not represent the actually generated DBPs in DWTPs. • DBPs formation can be well described by a second order reaction kinetic model. • Actual formation of DBPs depends on the total precursors and the reactivity of precursors. • High reactive DBPFP, such as TCAAFP and hydrophilic EOM, should be concerned. [ABSTRACT FROM AUTHOR]

Efficient production of beneficial metabolites by microalgae using light-emitting diodes (LED) is attracting more interest. In batch cultures, metabolic changes that occur with nutrient deficiency over time must be monitored to estimate the metabolite content. Our previous study showed that nutrient deficiency in Nannochloropsis oculata can be briefly evaluated by measuring the absorption ratio at 490 and 680 nm (Abs490/Abs680). However, little is known about the relation with this ratio and metabolic change, particularly in LED light-conditioned cultures. In this study, we investigate if Abs490/Abs680 can be an indicator of the biochemical status of N. oculata cultured under various LED color regimes. Three LED treatments were used: Blue (B), Blue + Red (BR), and Red (R). In all LED treatments, the Abs490/Abs680 decreased for several days and then increased when phosphate was limited or non-existent. The trends in the C16:0 and C20:5ɷ3 proportions and chlorophyll a content commonly changed at the turning points of the Abs490/Abs680. Furthermore, significant correlations were found among the metabolic state and absorption ratio, except in treatment R. We suggest that spectrophotometry can be used for monitoring metabolic changes in N. oculata cultures under various LED irradiance, unless there is excessive 630 nm-red light exposure. [ABSTRACT FROM AUTHOR]

Abstract Most of the studies regarding the impact of ocean acidification on macroalgae have been carried out for short-term periods, in controlled laboratory conditions, thus hampering the possibility to scale up the effects on long-term. In the present study, the volcanic CO 2 vents off Ischia Island were used as a natural laboratory to investigate the metabolic response of the brown alga Sargassum vulgare to acidification at different time scales. For long-term effects, algal populations naturally growing at acidified and control sites were compared. For short-term responses, in situ reciprocal transplants from control to acidified site and vice-versa were performed. Changes in the levels of sugars, fatty acids (FAs), amino acids (AAs), antioxidants, and phenolic compounds were examined. Our main finding includes variable metabolic response of this alga at different time scales to natural acidification. The levels of sugars, FAs, and some secondary metabolites were lower in the natural population at the acidified site, whereas the majority of AAs were higher than those detected in thalli growing at control site. Moreover, in algae transplanted from control to acidified site, soluble sugars (glucose and mannose), majority of AAs, and FAs increased in comparison to control plants transplanted within the same site. The differences in the response of the macroalga suggest that the metabolic changes observed in transplants may be due to acclimation that supports algae to cope with acidification, thus leading to adaptation to lowered pH in long time scale. Graphical abstract Unlabelled Image Highlights • Sargassum vulgare growing at CO 2 vents was compared with those growing at control site. • S. vulgare from control site was transplanted to CO 2 vents for 2 weeks. • In short-term responses, S. vulgare showed increased level of sugars, PUFAs, and EAAs. • Natural population at vents showed decreased sugars, PUFAs, phenols, and increased EAAs. • Nutritional values of algae will decrease under acidification in long time scale. [ABSTRACT FROM AUTHOR]

Background and Purpose: Several preclinical studies have demonstrated the unique profiles of levetiracetam (LEV), inhibits spontaneous absence epilepsy models but does not affect traditional convulsion models; however, the detailed pharmacological mechanisms of action of LEV remain to be clarified.Experimental Approach: We determined the interaction between LEV and IFNγ regarding astroglial release of anti-convulsive (kynurenic acid and xanthurenic acid), pro-convulsive (quinolinic acid) and anti-convulsive but pro-absence (cinnabarinic acid) kynurenine-pathway metabolites from rat cortical primary cultured astrocytes using ultra-HPLC equipped with MS.Key Results: IFNγ increased basal astroglial release of cinnabarinic acid and quinolinic acid but decreased that of kynurenic acid and xanthurenic acid. IFNγ enhanced inositol 1,4,5-trisphosphate (IP3 ) receptor agonist (adenophostin A, AdA)-induced astroglial release of kynurenine-pathway metabolites, without affecting AMPA-induced release. LEV increased basal astroglial release of kynurenic acid and xanthurenic acid without affecting cinnabarinic acid or quinolinic acid. Chronic and acute LEV administration inhibited AMPA- and AdA-induced kynurenine-pathway metabolite release. Upon chronic administration, LEV enhanced stimulatory effects of IFNγ on kynurenic acid and xanthurenic acid, and reduced its stimulatory effects on cinnabarinic acid and quinolinic acid. Furthermore, LEV inhibited stimulatory effects of chronic IFNγ on AdA-induced release of kynurenine-pathway metabolites.Conclusions and Implications: This study demonstrated several mechanisms of LEV: (i) inhibition of AMPA- and AdA-induced astroglial release, (ii) inhibition of IFNγ-induced IP3 receptor activation and (iii) inhibition of release of cinnabarinic acid and quinolinic acid with activation of that of kynurenic acid induced by IFNγ. These combined actions of LEV may contribute to its unique profile. [ABSTRACT FROM AUTHOR]

Abstract In a previous study, we synthesized endocyclic enone jasmonate derivatives that function as anti-inflammatory and PPAR-γ-activating entities by using key functional moieties of anti-inflammatory algal metabolites. Herein, we designed additional derivatives containing an exocyclic enone moiety that resembles the key structure of the natural PPAR-γ ligand, 15-deoxy-Δ12, 14-prostaglandin J 2 (15 d-PGJ 2). The exocyclic enone moiety of 15 d-PGJ 2 is essential for covalent bonding with the Cys285 residue in the PPAR-γ ligand-binding domain (LBD). In silico analysis of the designed compounds indicated that they may form hydrogen bonds with key amino acid residues in the PPAR-γ LBD, and thus, secure a position in the bioactive cavity in a similar fashion as does rosiglitazone and 15 d-PGJ 2. By a luciferase reporter assay on rat liver Ac2F cells, the synthesized compounds were evaluated for PPAR-γ transcriptional activity. The differential PPAR-γ transcriptional activities of the geometric and enantiomeric isomers of the selected analog were also evaluated; based on our results, the enantiopure compound (+)-(R,E)- 6a1 was suggested as a potential PPAR-γ ligand. Graphical abstract Image 1 Highlights • New PPAR-γ ligands were designed based on algal metabolites and endogenous ligand. • Synthetic analogs were evaluated for PPAR-γ activation by luciferase reporter assay. • The stereoisomers of the selected analog were compared for PPAR-γ activation. • (+)-(R , E)- 6a1 was proposed as a potential PPAR-γ agonist. [ABSTRACT FROM AUTHOR]

Microalgae cultivation is booming in agriculture, aquaculture, and bioenergy sectors. A wide range of bioactive compounds with attractive properties can be produced with microalgae, including pigments, vitamins, proteins, carbohydrates, and lipids. The biofuel yields from microalgae can exceed the yields obtained with energy crops by 10-100 times. Therefore, such cultivation is promising for the regulation of the biosynthesis of microalagae with phytohormones, which can enhance the production of high-valued bioproducts. This review reports the effect of auxins, abscisic acid, cytokinins, gibberellins, and ethylene on microalgal growth and metabolites, as well as the crosstalk of different phytohormones. The use of phytohormones is also promising because it can also reduce the inputs necessary to grow the selected microalgae and maximize the yields. [ABSTRACT FROM AUTHOR]

In many regions of the world, aeroterrestrial green algae of the Trebouxiophyceae (Chlorophyta) represent very abundant soil microorganisms, and hence their taxonomy is crucial to investigate their physiological performance and ecological importance. Due to a lack in morphological features, taxonomic and phylogenetic studies of Trebouxiophycean algae can be a challenging task. Since chemotaxonomic markers could be a great assistance in this regard, 22 strains of aeroterrestrial Trebouxiophyceae were chemically screened for their polyol‐patterns as well as for mycosporine‐like amino acids (MAAs) in their aqueous extracts using RP‐HPLC and LC‐MS. d‐sorbitol was exclusively detected in members of the Prasiolaceae family. The novel MAA prasiolin and a related compound (“prasiolin‐like”) were present in all investigated members of the Prasiola‐clade, but missing in all other tested Trebouxiophyceae. While prasiolin could only be detected in field material directly after extraction, the “prasiolin‐like” compound present in the other algae was fully converted into prasiolin after 24 h. These findings suggest d‐sorbitol and prasiolin‐like compounds are suitable chemotaxonomic markers for the Prasiolaceae and Prasiola‐clade, respectively. Additional UV‐exposure experiments with selected strains show that MAA formation and accumulation can be induced, supporting their role as UV‐sunscreen. [ABSTRACT FROM AUTHOR]

Management of type-II diabetes through regulating the activity of α-glucosidase is a promising therapeutic approach. Here, bioassay-guided isolation of algal secondary metabolites (ASM) from microalgae (Chlorella minutissima) inhibiting α-glucosidase was explored. In this study, the purified column fractions (SIV-P2) of C. minutissima acetone extract obtained from flash chromatography exhibited α-glucosidase inhibition potential with the IC 50 value of 1.61 mg mL−1, and the active fractions were dominated by terpenoids and alkaloids. Further, molecular dynamics simulations revealed that Lucidine B, an alkaloid compound possesses the least binding energy (BE) of −318 KJ mol−1 when compared to the standard drug acarbose (−216.781 KJ mol−1). Lucidine B formed a hydrogen bond with Glu408 which possibly induced cleft closure and prevented the substrate entry to the active site (non-competitive inhibition). The present study unveils that ASM could be exploited as a potential inhibitor of α-glucosidase and may be used for the alleviation of type-II diabetes. [Display omitted] • C. minutissima purified fractions are potential source of AG inhibitors. • The algal fraction recorded least IC 50 of 1.61 mg mL−1 against AG. • HR LCMS of bioactive fractions were dominated by terpenoids and alkaloids. • Lucidine B found to be potential AG inhibitor with −318 KJ mol−1 binding energy. • Lucidine B inhibits AG activity through non-competitive inhibition. [ABSTRACT FROM AUTHOR]

The study examined the effect of varying concentrations of iron in the form of ethylene diamine tetra-acetic acid ferric sodium salt (Fe-EDTA) for cultivation of Chlorella sp. under mixotrophic condition to evaluate biomass growth and metabolites production. The experimental data depicted enhanced biomass production along with lipids, carbohydrates and proteins at an optimal iron concentration (8 mg/L). Relatively higher biomass production (5.4 g/L; 96 h) with simultaneous total chlorophyll (5 mg/mL ( Chl a/b: 3.7/1.3 mg/mL)), carbohydrates (105 mg/g) and proteins (593 mg/g) was observed with 8 mg/L Fe-EDTA. Total and neutral lipid content of 38% and 15.6% was observed under nutrient deprived conditions. The presence of iron showed distinct influence on the saturated fraction of FAME and increment in oleic acid (omega fatty acids; edible oil). Higher concentrations of Fe-EDTA (10/12 mg/L) depicted incremental fraction of oleic acid. [ABSTRACT FROM AUTHOR]

Microalgae, due to various environmental stresses, constantly tune their cellular mechanisms to cope with them. The accumulation of the stress metabolites is closely related to the changes occurring in their metabolic pathways. The biosynthesis of metabolites can be triggered by a number of abiotic stresses like temperature, salinity, UV- radiation and nutrient deprivation. Although, microalgae have been considered as an alternative sustainable source for nutraceutical products like pigments and omega-3 polyunsaturated fatty acids (PUFAs) to cater the requirement of emerging human population but inadequate biomass generation makes the process economically impractical. The stress metabolism for carotenoid regulation in green algae is a 2-step metabolism. There are a few major stresses which can influence the formation of phycobiliprotein in cyanobacteria. This review would primarily focus on the cellular level changes under stress conditions and their corresponding effects on lipids (including omega-3 PUFAs), pigments and polymers. [ABSTRACT FROM AUTHOR]

This article reviews the role of microbial biofilms in infection, and the antimicrobial chemical diversity of marine macroalgae and their associated microbiomes. Antimicrobial resistance (AMR) represents one of the major health threats faced by humanity over the next few years. To prevent a global epidemic of antimicrobial-resistant infections, the discovery of new antimicrobials and antibiotics, better anti-infection strategies and diagnostics, and changes to our current use of antibiotics have all become of paramount importance. Numerous studies investigating the bioactivities of seaweed extracts as well as their secondary and primary metabolites highlight the vast biochemical diversity of seaweeds, with new modes of action making them ideal sources for the discovery of novel antimicrobial bioactive compounds of pharmaceutical interest. In recent years, researchers have focused on characterizing the endophytic and epiphytic microbiomes of various algal species in an attempt to elucidate host-microbe interactions as well as to understand the function of microbial communities. Although environmental and host-associated factors crucially shape microbial composition, microbial mutualistic and obligate symbionts are often found to play a fundamental role in regulating many aspects of host fitness involving ecophysiology and metabolism. In particular, algal ‘core’ epiphytic bacterial communities play an important role in the protection of surfaces from biofouling, pathogens and grazers through the production of bioactive metabolites. Together, marine macroalgae and their associated microbiomes represent unique biological systems offering great potential for the isolation and identification of novel compounds and strategies to counteract the rise and dissemination of AMR. [ABSTRACT FROM PUBLISHER]

LC with photodiode array and APCI-ion trap mass spectrometry has made it possible to tentatively identify 76 carotenyl fatty acid esters (cFAEs) in solvent extracts from Dreissena bugensis, collected from Lake Erie: 16 mono- and 33 diFAEs of fucoxanthinol (FOH), and 27 diFAEs of mactraxanthin (MX). FOH and MX, previously identified in cFAE hydrolysates, were confirmed as parent carotenoids of the cFAEs, and as primary metabolites of fucoxanthin and violaxanthin, respectively, derived from diatoms and chlorophytes in the dreissenids’ diet. The most abundant fatty acid substituents of cFAEs were 16:0 and 16:1; abundant fatty acid biomarkers were 16:1 and 20:5, from diatoms, and 17:0, from bacteria. Cleanup of solvent extracts by solid phase extraction (Florisil) was necessary to reduce neutral background lipids, which interfered with detection of MX-diFAEs by APCI(+), and detection of FOH-diFAEs by APCI(+/−). The FOH-monoFAEs, MX-diFAEs and FOH-diFAEs were found to elute in a well-defined chromatographic order, by two regression models for retention times increasing as a function of: i) increasing number of carbons but decreasing number of double bonds in the fatty acid and decreasing number of non-esterified OH-groups on the parent carotenoids; ii) increasing dispersive but decreasing polar and hydrogen-bonding interactions, described by solubility parameters calculated for each cFAE. The best separations of the dreissenid cFAEs, with free OH-groups decreasing from four to one, were achieved between 20 and 68 min, using a C18-column and moderately polar mobile phase (acetone, water), to obtain a reverse-phase gradient with a 56% decrease in hydrogen-bonding interactions. [ABSTRACT FROM AUTHOR]

Background: The use of enriched stable isotopes is of outstanding importance in chemical metrology as it allows the application of isotope dilution mass spectrometry (IDMS). Primary methods based on IDMS ensure the quality of the analytical measurements and traceability of the results to the international system of units. However, the synthesis of isotopically labelled molecules from enriched stable isotopes is an expensive and a difficult task. Either chemical and biochemical methods to produce labelled molecules have been proposed, but so far, few cost-effective methods have been described. Results: The aim of this study was to use the microalgae Chlamydomonas reinhardtii to produce, at laboratory scale, N-labelled amino acids with a high isotopic enrichment. To do that, a culture media containing NHCl was used. No kinetic isotope effect (KIE) was observed. The labelled proteins biosynthesized by the microorganism were extracted from the biomass and the N-labelled amino acids were obtained after a protein hydrolysis with HCl. The use of the wall deficient strain CC503 cw92 mt+ is fit for purpose, as it only assimilates ammonia as nitrogen source, avoiding isotope contamination with nitrogen from the atmosphere or the reagents used in the culture medium, and enhancing the protein extraction efficiency compared to cell-walled wild type Chlamydomonas. The isotopic enrichment of the labelled amino acids was calculated from their isotopic composition measured by gas chromatography mass spectrometry (GC-MS). The average isotopic enrichment for the 16 amino acids characterized was 99.56 ± 0.05% and the concentration of the amino acids in the hydrolysate ranged from 18 to 90 µg/mL. Conclusions: Previously reported biochemical methods to produce isotopically labelled proteins have been applied in the fields of proteomics and fluxomics. For these approaches, low amounts of products are required and the isotopic enrichment of the molecules has never been properly determined. So far, only C-labelled fatty acids have been isolated from labelled microalga biomass as valuable industrial products. In this study, we propose Chlamydomonas reinhardtii CC503 as a feasible microorganism and strain to produce labelled biomass from which a standard containing sixteen N-labelled amino acids could be obtained. [ABSTRACT FROM AUTHOR]

Background: An inducible promoter for recombinant protein expression provides substantial benefits because under induction conditions cellular energy and metabolic capability can be directed into protein synthesis. The most widely used inducible promoter for diatoms is for nitrate reductase, however, nitrogen metabolism is tied into diverse aspects of cellular function, and the induction response is not necessarily robust. Silicon limitation offers a means to eliminate energy and metabolic flux into cell division processes, with little other detrimental effect on cellular function, and a protein expression system that works under those conditions could be advantageous. Results: In this study, we evaluate a number of promoters for recombinant protein expression induced by silicon limitation and repressed by the presence of silicon in the diatoms Thalassiosira pseudonana and Cyclotella cryptica. In addition to silicon limitation, we describe additional strategies to elevate recombinant protein expression level, including inclusion of the 5' fragment of the coding region of the native gene and reducing carbon flow into ancillary processes of pigment synthesis and formation of photosynthetic storage products. We achieved yields of eGFP to 1.8% of total soluble protein in C. cryptica, which is about 3.6-fold higher than that obtained with chloroplast expression and ninefold higher than nuclear expression in another well-established algal system. Conclusions: Our studies demonstrate that the combination of inducible promoter and other strategies can result in robust expression of recombinant protein in a nuclear-based expression system in diatoms under silicon limited conditions, separating the protein expression regime from growth processes and improving overall recombinant protein yields. [ABSTRACT FROM AUTHOR]

A comprehensive risk management on human exposure to cyanotoxins, whose production is actually unpredictable, is limited by reliable analytical tools for monitoring as many toxic algal metabolites as possible. Two analytical approaches based on a LC-QTOF system for target analysis and suspect screening of cyanotoxins in freshwater were presented. A database with 369 compounds belonging to cyanobacterial metabolites was developed and used for a retrospective data analysis based on high resolution mass spectrometry (HRMS). HRMS fragmentation of the suspect cyanotoxin precursor ions was subsequently performed for correctly identifying the specific variants. Alternatively, an automatic tandem HRMS analysis tailored for cyanotoxins was performed in a single chromatographic run, using the developed database as a preferred precursor ions list. Twenty-five extracts of surface and drinking waters contaminated by cyanobacteria were processed. The identification of seven uncommon microcystins (M(O)R, MC-FR, MSer 7 -YR, D -Asp 3 MSer 7 -LR, MSer 7 -LR, dmAdda-LR and dmAdda-YR) and 6 anabaenopeptins (A, B, F, MM850, MM864, oscyllamide Y) was reported. Several isobaric variants, fully separated by chromatography, were pointed out. The developed methods are proposed to be used by environmental and health agencies for strengthening the surveillance monitoring of cyanotoxins in water. [ABSTRACT FROM AUTHOR]

Caulerpa taxifolia is a marine alga of tropical and subtropical distribution and a well-known invasive species in several temperate regions. Its invasiveness mainly stems from the production of secondary metabolites, some of which are toxic or repellent substances. In this study we investigated the possible inhibitory effects of C. taxifolia secondary metabolites on the activity of two zebrafish ( Danio rerio ) uptake transporters that transport organic anions (Oatp1d1) and cations (Oct1). Both transporters were transiently transfected and overexpressed in human embryonic kidney HEK293T cells. Transport activity assays using lucifer yellow (LY) and 4-(4-(dimethylamino)styryl)- N -methylpyridinium iodide (ASP+) as model substrates were applied for the determination of Oatp1d1 and Oct1 interactors. A two-step Effect-Directed Analysis (EDA) procedure was applied for the separation and identification of compounds. We identified caulerpenyne (CYN) as the major metabolite in C. taxifolia and reveal its potent inhibitory effect towards zebrafish Oatp1d1 as well as weak effect on zebrafish Oct1 transport. The observed effect was confirmed by testing CYN purified from C. taxifolia , resulting in an IC 50 of 17.97 μM, and a weak CYN interaction was also determined for the zebrafish Oct1 transporter. Finally, using Michaelis-Menten kinetics experiments, we identified CYN as a non-competitive inhibitor of the zebrafish Oatp1d1. In conclusion, this study describes a novel mechanism of biological activity in C. taxifolia , shows that CYN was a potent non-competitive inhibitor of zebrafish Oatp1d1, and demonstrates that EDA can be reliably used for characterization of environmentally relevant complex biological samples. [ABSTRACT FROM AUTHOR]

Secondary metabolites play an important ecological role as a defense mechanism in seaweeds. Chemical defenses are well known to change in response to herbivory, but other driving factors, either biotic or abiotic, are often neglected. Epibiosis may not only reduce seaweed fitness, but also increase attractiveness to consumers, and thus defense production should also be triggered by epibionts. In this study, three Southwestern Atlantic seaweeds, Gracilaria cearensis , Pterocladiella capillacea (Rhodophyceae) and Codium decorticatum (Chlorophyceae) were investigated in laboratory bioassays designed to test whether the action of herbivory or simulated epibiosis influences chemical defenses. Crossed induction experiments were also performed in order to assess whether herbivore induction influences antifouling chemical defense, as well as whether epibiont induction would affect defense against herbivores. The effect of laboratory conditions on seaweeds in the absence of field stimuli was also investigated by comparing consumption of artificial food with extracts from acclimatized and non-acclimatized seaweeds (i.e., natural defense levels). Only the green seaweed C . decorticatum exhibited inducible antifouling defenses triggered by simulated epibiosis, but not by herbivores. In the other seaweeds there was no induction either by herbivory or simulated epibiosis. Acclimatization did not affect C . decorticatum defenses. However, non-acclimatized G . cearensis artificial foods were preferred over acclimatized ones, while extracts from acclimatized P . capillacea increased herbivore consumption, highlighting the need to acclimatize seaweeds before the main induction experiments. This is the first report of inducible defenses due to simulated fouling in seaweeds. [ABSTRACT FROM AUTHOR]

This study attempted to investigate the reuse potential of flocculated wastewater for the growth of microalgae species and to understand the relationship between microalgae growth parameters and metabolites extraction using a fuzzy logic model. For these purposes, batch experiments were conducted using two microalgae species, namely, Chlorella sorokiniana and Scenedesmus obliquus , cultivated in different types of flocculated wastewater, viz., BlueGreen (BG11), polymer (P ww ), chitosan (CH ww ) and alum (A ww ). Results indicated that a logistic model fitted well the biomass profiles with r 2 -values >0.95. The carrying capacities of C. sorokiniana (K: 45.13 mg L −1 ) and S. obliquus (K: 71.59 mg L −1 ) grown in the CH ww medium were significantly ( p < 0.01) higher than other flocculants. Additionally, the two microalgae species cultivated in CH ww showed a good physiological health throughout the growth period. It was found that higher extraction yields of lipids: 16.0–19.8% and carbohydrates: 19.98–20.43% (w/w) of the dry weight were obtained when the microalgae species were grown in the CH ww wastewater. Further, a fuzzy inference system confirmed the experimental data by predicting the yields of lipids, carbohydrates, and proteins at particular inputs of logistic model parameters and physiological health condition ( r 2 -values > 0.98). It was concluded that CH ww could be used as an efficient flocculated wastewater for the growth of microalgae species and that the suggested modeling technique was promising. [ABSTRACT FROM AUTHOR]

Cyanobacterial and algal toxins comprise a large group of harmful metabolites, belonging to different chemical classes, with a variety of chemical structures, physicochemical properties and toxic activities. In this study, a fast, simple and sensitive analytical method was developed for the simultaneous determination of multi-class cyanobacterial and algal toxins in water. The target compounds were: Cylindrospermopsin, Anatoxin-a, Nodularin, 12 Microcystins ([D-Asp3]MC-RR, MC-RR, MC-YR, MC-HtyR, [D-Asp3]MC-LR, MC-LR, MC-HilR, MC-WR, MC-LA, MC-LY, MC-LW and MC-LF), Okadaic acid and Domoic acid. Analytes were determined using liquid chromatography–tandem mass spectrometry (LC–MS/MS). A dual Solid Phase Extraction (SPE) cartridge assembly was applied for the extraction of target compounds from water. Optimized SPE parameters included cartridge material, initial sample pH, sequence of the cartridges in the SPE assembly as well as composition and volume of the elution solvent. The method was validated, providing acceptable mean recoveries and reproducibility for most analytes. Limits of detection were at the ng L −1 level. The method was successfully applied in real lake water samples from Greece, where a wide range of Microcystins were detected for the first time, at concentrations ranging from 0.034 to 63 μg L −1 . [ABSTRACT FROM AUTHOR]

In this study the stereoselective bioaccumulation and transformation of triadimefon and the toxicity of triadimefon and its metabolite triadimenol to the green algae Scenedesmus obliquus were studied. In growth inhibition experiments, triadimenol was more toxic than triadimefon, and (1S,2R)-triadimenol, which has the largest fungicidal activity, presented the highest toxicity to the algae. In bioaccumulation experiments, triadimefon was rapidly taken up by algae cells, and the decrease in the concentration of triadimefon was accompanied by an increase in triadimenol. The transformation of S-(+)- triadimefon was faster than that of the R-(−)-enantiomer, resulting in four triadimenol stereoisomers at different forming rates: B2 (1S, 2S) > B1 (1R, 2R) > A2 (1S, 2R) > A1 (1R, 2S). Thus, it is necessary to explore the enantioselective toxicology and ecological fate of these chiral pesticides in an environmental risk assessment. Also, their metabolites should be paid specific attention to since they may pose higher ecological risks. [ABSTRACT FROM AUTHOR]

Distinct microbial habitats on glacial surfaces are dominated by snow and ice algae, which are the critical players and the dominant primary colonisers and net producers during the melt season. Here for the first time we have evaluated the role of these algae in association with the full microbial community composition (i.e., algae, bacteria, archaea) in distinct surface habitats and on 12 glaciers and permanent snow fields in Svalbard and Arctic Sweden. We cross-correlated these data with the analyses of specific metabolites such as fatty acids and pigments, and a full suite of potential critical physico-chemical parameters including major and minor nutrients, and trace metals. It has been shown that correlations between single algal species, metabolites, and specific geochemical parameters can be used to unravel mixed metabolic signals in complex communities, further assign them to single species and infer their functionality. The data also clearly show that the production of metabolites in snow and ice algae is driven mainly by nitrogen and less so by phosphorus limitation. This is especially important for the synthesis of secondary carotenoids, which cause a darkening of glacial surfaces leading to a decrease in surface albedo and eventually higher melting rates. [ABSTRACT FROM AUTHOR]

Microalgae are diverse microorganisms that are of interest as novel sources of metabolites for various industrial, nutritional, and pharmaceutical applications. Recent studies have demonstrated transcriptional engineering of some metabolic pathways. We propose here that transcriptional engineering could be a viable means to manipulate the biosynthesis of specific high-value metabolic products. [ABSTRACT FROM AUTHOR]

Cultivation of algae (micro and macro) can be used to produce several high- value metabolites to supply industries as cosmetics, additives, and pigments, among others. Those metabolites can have physiological and nutritional benefits for human and animal health. However, the availability of high-value metabolites from algae is still unaffordable due to traditional extraction techniques and their requirements of energy and use of pollutant solvents. Recently, green extraction technologies for the extraction of high-value metabolites have become more desirable due to their sustainability and environmental benefits. However, the information about green extraction metabolites from algae is limited. Therefore, this review highlights the main green extraction technologies - supercritical fluid extraction ( SFE), microwave assisted extraction ( MAE), and pressurized liquid extraction ( PLE) - and their optimal parameters for the extraction of high-value metabolites from algae. First, general information is given regarding high- value metabolites from algae. Then, the review summarizes the principles, processes, advantages, and disadvantages of each technology. Finally, it presents recommendations and concluding remarks to select the best extraction technology. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Botryococcus braunii is a colonial green microalga which can produce extracellular hydrocarbons at a high rate, it is considered as one of the most promising feedstocks for sustainable biofuel production. However, B. braunii is generally recognized difficulties for cultivating and has limited amount of substantive scale-up and productivity assessments with conventional aqua-suspended cultivation systems (open pond and varieties of closed photobioreactors). This paper introduces a novel cultivation system based on biofilm technology, which is called "attached cultivation". To investigate the potential of attached cultivation method, attached cultivation of B. braunii SAG 807-1 was compared with aqueous-suspension cultivation (flat plate reactors). The growth, hydrocarbon accumulation and metabolites were studied under identical conditions (e.g. temperature, light intensity, CO2 concentration). The main research results obtained are as follows: compared with conventional aqueous-suspension cultivation, the biomass productivity of B. braunii under biofilm attached cultivation was 4.78 g/(m²·d), which was higher than of 4.43 g/(m²·d) by aqueous-suspension, and hydrocarbon productivity of the two cultivation methods were 2.52 g/(m²·d) and 2.37 g/(m²·d), respectively. The contents of carbohydrate and protein were also similar. This attached cultivation method showed a new model of commercialization for the microalgae-derived biofuels. [ABSTRACT FROM AUTHOR]

Perennial macroalgae within the genus Fucus are known to exude metabolites through their outer thallus surface. Some of these metabolites have pro- and/or antifouling properties. Seasonal fluctuations of natural fouling pressure and chemical fouling control strength against micro- and macrofoulers have previously been observed in Fucus, suggesting that control strength varies with threat. To date, a study on the seasonal composition of surface associated metabolites, responsible for much of the fouling control, has not been done. We sampled individuals of the two co-occurring species F. vesiculosus and F. serratus at monthly intervals (six per species and month) during a one-year field study. We analysed the chemical composition of surface associated metabolites of both Fucus species by means of gas chromatography-mass spectrometry (GC-MS) to describe temporal patterns in chemical surface composition. Additionally, we correlated abiotic and biotic parameters recorded monthly within the sampled habitat with the variation in the chemical surface landscape of Fucus. Our study revealed that the chemical surface composition of both Fucus species exhibits substantial seasonal differences between spring/summer and autumn/winter months. Light and temperature explained most of the seasonal variability in surface metabolite composition of both Fucus species. A strong summerly up-regulation of eighteen saccharides and two hydroxy acids in F. vesiculosus as well as of four fatty acids and two saccharides in F. serratus was observed. We discuss how these up-regulated molecules may have a complex effect on associated microfoulers, both promoting or decreasing fouling depending on metabolite and bacterial identity. These seasonal shifts in the surface metabolome seem to exert a compound control of density and composition of the Fucus associated biofilm. [ABSTRACT FROM AUTHOR]

The marine microalga Nannochloropsis oculata is a potential source of eicosapentaenoic acid (EPA, C20:5n3) and carotenoids for use in functional foods and nutraceuticals. Mixotrophic culture of N. oculata using glycerol was examined as a possible way of increasing the biomass and metabolite productivity relative to a pure photoautotrophic culture in modified f/2 medium. The effect of CO 2 supply was also tested. EPA production in semi-continuous culture with and without glycerol and CO 2 was evaluated. The effects of glycerol supplementation and light/dark cycling on the production of the biomass and EPA are reported for cultures conducted at a constant pH controlled using CO 2 . Consumption of glycerol was small, but its effects were significant. Glycerol enhanced the lipid content of the biomass but reduced the chlorophyll a content. Mixotrophic cultivation favored the production of lipids with a high percentage of saturated fatty acids that are generally desired in oils for making biodiesel. EPA concentration (5.3 ± 0.6 to 27.5 ± 1.6 mg EPA/L) in N. oculata cultures depended strongly on growth conditions. The highest EPA concentration occurred in non-aerated mixotrophic culture with intermittent CO 2 supply without pH control. This EPA concentration (= 27.5 ± 1.6 mg/L) was comparable to that obtained in semi-continuous culture without glycerol and pH control, and aerated with CO 2 enriched air during the light period (= 23.6 ± 1.1 mg/L). [ABSTRACT FROM AUTHOR]

The red seaweed Laurencia dendroidea belongs to the Rhodophyta, a phylum of eukaryotic algae that is widely distributed across the oceans and that constitute an important source of bioactive specialized metabolites. Laurencia species have been studied since 1950 and were found to contain a plethora of specialized metabolites, mainly halogenated sesquiterpenes, diterpenes and triterpenes that possess a broad spectrum of pharmacological and ecological activities. The first committed step in the biosynthesis of triterpenes is the cyclization of 2,3-oxidosqualene, an enzymatic reaction carried out by oxidosqualene cyclases (OSCs), giving rise to a broad range of different compounds, such as the sterol precursors cycloartenol and lanosterol, or triterpene precursors such as cucurbitadienol and β-amyrin. Here, we cloned and characterized the first OSC from a red seaweed. The OSC gene was identified through mining of a L. dendroidea transcriptome dataset and subsequently cloned and heterologously expressed in yeast for functional characterization, which indicated that the corresponding enzyme cyclizes 2,3-oxidosqualene to the sterol precursor cycloartenol. Accordingly, the gene was named L. dendroidea cycloartenol synthase (LdCAS). A phylogenetic analysis using OSCs genes from plants, fungi and algae revealed that LdCAS grouped together with OSCs from other red algae, suggesting that cycloartenol could be the common product of the OSC in red seaweeds. Furthermore, profiling of L. dendroidea revealed cholesterol as the major sterol accumulating in this species, implicating red seaweeds contain a ‘hybrid’ sterol synthesis pathway in which the phytosterol precursor cycloartenol is converted into the major animal sterol cholesterol. [ABSTRACT FROM AUTHOR]

SUMMARY Dipeptidyl peptidase IV ( DPP-IV) catalyzes conversion of GLP-1 (glucagon like peptide 1) to inert structure, which results in insufficient secretion of insulin and increase in postprandial blood glucose level. The present study attempts to identify novel inhibitors from bioactive metabolites present in microalgae against DPP-IV through virtual screening, molecular docking, and pharmacophore modeling for the active target. Possible binding modes of all 60 ligands against DPP-IV receptor were constructed using MTiOpenScreen virtual screening server. Pharmacophore model was built based on identified 38 DPP-IV test ligands by using the web-based PharmaGist program which encompasses hydrogen-bond acceptors, hydrophobic groups, spatial features, and aromatic rings. The pharmacophore model having highest scores was selected to screen active DPP-IV ligands. Highest scoring model was used as a query in ZincPharmer screening. All identified ligands were filtered, based on the Lipinski's rule-of-five and were subjected to docking studies. In the process of docking analyses, we considered different bonding modes of one ligand with multiple active cavities of DPP-IV with the help of AutoDock 4.0. The docking analyses indicate that the bioactive constituents, namely, β-stigmasterol, barbamide, docosahexaenoic acid, arachidonic acid, and harman showed the best binding energies on DPP-IV receptor and hydrogen bonding with ASP545, GLY741, TYR754, TYR666, ARG125, TYR547, SER630, and LYS554 residues. This study concludes that docosahexaenoic acid, arachidonic acid, β-stigmasterol, barbamide, harman, ZINC58564986, ZINC56907325, ZINC69432950, ZINC69431828, ZINC73533041, ZINC84287073, ZINC69849395, and ZINC10508406 act as possible DPP-IV inhibitors. [ABSTRACT FROM AUTHOR]

We found that microalgae exposed to a mixture of polycyclic aromatic hydrocarbons (PAHs) did not show growth inhibition. Thus, we assumed that they could metabolize these compounds. In this study, the dihydrodiol-type PAH metabolites of benzo( a )pyrene (BaP), benzo( a )anthracene (BaA), benzo( b )fluoranthene (BbF) and benzo( k )fluoranthene (BkF) produced by the freshwater microalgae Selenastrum capricornutum were monitored and quantified using high-performance liquid chromatography with fluorescence detection (HPLC-FD) techniques. Exposure bioassays with S. capricornutum were performed using a 266 ng mL −1 mixture of PAHs at different exposure times (0.75, 1, 3, 8, 16, 24 and 48 h) under controlled temperature (25 °C); the dihydrodiol metabolites formed in the liquid medium and the biomass were quantified. Metabolite identities were confirmed using HPLC-mass spectrometry; most of the metabolites formed were derived from BaA degradation. At 48 h after exposure 5,6-dBaA and 8,9-dBaA/10,11-dBaA were present in the liquid medium at 20% and 67% of the initial mass of BaA, respectively. Three metabolites of BaP were monitored in the liquid medium and biomass and, at 24 h, 4,5-dBaP accounted for 19%; , 7,8-dBaP, 5%; and 9,10-dBaP, 5% relative to the initial BaP mass. Microalgae exposed to BbF showed the presence of 1,2-dBbF and 9,10-dBbF (at 0.3% and 0.1% of the initial BbF mass, respectively) and those exposed to BkF produced 8,9-dBkF (6.5% of the initial BkF mass) in the liquid medium. Seven unknown compounds were formed after exposure; two compounds were identified as the metabolites of BaA and BaP. The results could facilitate the elucidation of the controversial biodegradation mechanism in microalgae. [ABSTRACT FROM AUTHOR]

Several ecological models explain the success of introduced seaweeds by herbivore-prey interactions. The 'enemy release hypothesis' states that invaders benefit from a lack of natural enemies compared to the recipient community. The 'novel weapons hypothesis,' however, highlights the importance of chemical defense compounds of introduced species that are more effective in invaded regions than native counterparts. In order to explain the tremendous invasion success of the brown alga Sargassum muticum, we compared the palatability and nutritional value of S. muticum individuals from their native and invaded habitat (Japan and North Sea, respectively) with noninvasive congeneric species from Japan ( S. fusiforme, S. horneri), and a native competitor from the North Sea ( Fucus vesiculosus). Different feeding assays using artificial food with either freeze-dried algae or algal extracts and three dominant North Sea mesograzers were performed to detect feeding preferences. All herbivores preferred the local brown alga F. vesiculosus, followed by North Sea S. muticum, while Sargassum spp. from Japan were the least preferred. Since nutritional value did not correlate with feeding preference and algal extracts had the same effect as algal powder, we could demonstrate a deterrent activity of algal secondary metabolites. The preference of herbivores for the sympatric S. muticum population compared to the allopatric Japanese population could indicate a resource allocation from chemical defense to reproduction and growth. Due to the low palatability of Sargassum spp. from Japan, it might be reasonable to include additional Sargassum species in North Sea monitoring to prevent their establishment in European waters. [ABSTRACT FROM AUTHOR]

The aim of this research was to screen plant growth biostimulant properties of supercritical CO2 macroalgal extracts. To this end secondary metabolites were isolated from the biomass of marine macroalgae from the Baltic Sea (species of Polysiphonia, Ulva and Cladophora). Chemical characteristics of the algal extracts were determined by inductively coupled plasma atomic emission spectroscopy for inorganic constituents and high-performance liquid chromatography and spectrophotometry for organic constituents. Inorganic (macro- and microelements) and organic (plant hormones: auxins and cytokinins; polyphenols) compounds were detected in the extract. Algal extracts were tested primarily on garden cress (Lepidium sativum L.; Brassicaceae) and wheat (Triticum aestivum L.; Poaceae). The extracts enhanced chlorophyll and carotenoid content in plant shoots, as well as root thickness and above-ground biomass. The most effective method of application of the extract was by foliar feed on cress and seed maceration for wheat. Algal extracts obtained by supercritical fluid extraction (SFE) were found to be a novel natural source of compounds, stimulating growth of cultivated plants. However, field trials will be required to show that the extracts can act as plant biopesticides and growth biostimulants. [ABSTRACT FROM AUTHOR]

This study aimed to improve understanding of the strategies developed by the Mediterranean seaweedTaonia atomariato chemically control bacterial epibiosis. An experimental protocol was optimized to specifically extract algal surface-associated metabolites by a technique involving dipping in organic solvents whilst the integrity of algal cell membranes was assessed by fluorescent microscopy. This methodology was validated using mass spectrometry-based profiles of algal extracts and analysis of their principal components, which led to the selection of methanol as the extraction solvent with a maximum exposure time of 15 s. Six compounds (A–F) were identified in the resulting surface extracts. Two of these surface-associated compounds (BandC) showed selective anti-adhesion properties against reference bacterial strains isolated from artificial surfaces while remaining inactive against epibiotic bacteria ofT. atomaria. Such specificity was not observed for commercial antifouling biocides and other molecules identified in the surface or whole-cell extracts ofT. atomaria. [ABSTRACT FROM AUTHOR]

Caulerpenyne is the main secondary metabolite synthesized by the Caulerpa green marine algae family (Ulvophyceae, Caulerpales). Caulerpenyne is a sesquiterpene containing a bis-enol acetate group, which is proposed to be the responsible of its biological actions. In an ecological context, caulerpenyne inhibits the microorganisms growth, interferes with the development of fertilized sea urchin eggs, and some of its degradation products reduce the palatability of the algae against herbivores, so that reducing grazing pressure by some fishes and invertebrates. Some of these Caulerpa species, such as the tropical alga C. taxifolia, are very invasive and have successfully invaded temperate waters on a global level in recent years. In contrast, C. taxifolia is poorly affected by herbivores of temperate waters, as a consequence of its chemical defence mediated by the major secondary metabolite caulerpenyne. In addition and in a clinical ambit, caulerpenyne has been found to exert some pharmacological actions, such as antidyslipidemic activity and antiproliferative effects via inhibiting the assembly of tubulin. Taking into account all these characteristics, the aim of the current work is reviewing the last knowledge related to caulerpenyne. [ABSTRACT FROM AUTHOR]