The monomeric photosystem I-light-harvesting antenna complex I (PSI-LHCI) supercomplex from the extremophilic red alga Cyanidioschyzon merolae represents an intermediate evolutionary link between the cyanobacterial PSI reaction center and its green algal/higher plant counterpart. We show that the C. merolae PSI-LHCI supercomplex is characterized by robustness in various extreme conditions. By a combination of biochemical, spectroscopic, mass spectrometry, and electron microscopy/single particle analyses, we dissected three molecular mechanisms underlying the inherent robustness of the C. merolae PSI-LHCI supercomplex: (1) the accumulation of photoprotective zeaxanthin in the LHCI antenna and the PSI reaction center; (2) structural remodeling of the LHCI antenna and adjustment of the effective absorption cross section; and (3) dynamic readjustment of the stoichiometry of the two PSI-LHCI isomers and changes in the oligomeric state of the PSI-LHCI supercomplex, accompanied by dissociation of the PsaK core subunit. We show that the largest low light-treated C. merolae PSI-LHCI supercomplex can bind up to eight Lhcr antenna subunits, which are organized as two rows on the PsaF/PsaJ side of the core complex. Under our experimental conditions, we found no evidence of functional coupling of the phycobilisomes with the PSI-LHCI supercomplex purified from various light conditions, suggesting that the putative association of this antenna with the PSI supercomplex is absent or may be lost during the purification procedure.
- MeSH
- biologická adaptace MeSH
- chlorofyl metabolismus MeSH
- cirkulární dichroismus MeSH
- fluorescenční spektrometrie MeSH
- fotosystém I - proteinový komplex chemie metabolismus MeSH
- koncentrace vodíkových iontů MeSH
- molekulární evoluce MeSH
- Rhodophyta chemie fyziologie MeSH
- sinice chemie fyziologie MeSH
- světlo MeSH
- světlosběrné proteinové komplexy chemie metabolismus MeSH
- teplota MeSH
- zeaxanthiny metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The extraction of phenolic compounds from 4 different sea algae samples, three brown algae (Cystoseira abies-marina, C. abies-marina grinded under cryogenic conditions with liquid nitrogen, Undaria pinnatifida and Sargassum muticum) and one red algae (Chondrus crispus) via solid phase extraction using micro-elution solid-phase extraction (μ-SPE) plate method was studied. Prior to μ-SPE, 50mg of algae with 80% methanol mixture was extracted in hyphenated series by various extraction techniques, such as pressurized liquid extraction and Ika Ultra-Turrax(®) Tube Drive, in combination with ultrasound assisted extraction. The μ-SPE plate technique reduced the time of sample pre-treatment thanks to higher sensitivity and pre-concentration effect. Selected groups of benzoic acid derivatives (p-hydroxybenzoic, protocatechuic, gallic, vanillic, and syringic acids), hydroxybenzaldehydes (4-hydroxybenzaldehyde, and 3,4-dihydroxybenzaldehyde), and cinnamic acid derivatives (p-coumaric, caffeic, ferulic, sinapic, and chlorogenic acids) were determined using rapid resolution liquid chromatography coupled to mass spectrometry detection with negative ion electrospray ionization (RRLC-ESI-MS) using multiple reactions monitoring. LOQs of measured samples varied in the range 0.23-1.68ng/mL and LODs in the range 0.07-0.52ng/mL. The applied method allowed a simultaneous determination of phenolics (i.e. free, esters soluble in methanol, glycosides, and esters insoluble in methanol) in less than 5min (including alkaline or acidic hydrolysis of raw extracts) from sea algae extracts.
Structured triacylglycerols (TAGs) were isolated from nine cultivated strains of microalgae belonging to different taxonomic groups, i.e. Audouinella eugena, Balbiania investiens, Myrmecia bisecta, Nannochloropsis limnetica, Palmodictyon varium, Phaeodactylum tricornutum, Pseudochantransia sp., Thorea ramosissima, and Trachydiscus minutus. They were separated and isolated by means of NARP-LC/MS-APCI and chiral LC and the positional isomers and enantiomers of TAGs with two polyunsaturated, i.e. arachidonic (A) and eicosapentaenoic (E) acids and one saturated, i.e. palmitic acid (P) were identified. Algae that produce eicosapentaenoic acid were found to biosynthesize more asymmetrical TAGs, i.e. PPE or PEE, whereas algae which produced arachidonic acid give rise to symmetrical TAGs, i.e. PAP or APA, irrespective of their taxonomical classification. Nitrogen and phosphorus starvation consistently reversed the ratio of asymmetrical and symmetrical TAGs.
- MeSH
- Chlorophyta chemie MeSH
- dusík metabolismus MeSH
- fosfor metabolismus MeSH
- Heterokontophyta chemie MeSH
- kyselina arachidonová metabolismus MeSH
- kyselina eikosapentaenová metabolismus MeSH
- mastné kyseliny analýza izolace a purifikace metabolismus MeSH
- mikrořasy chemie MeSH
- Rhodophyta chemie MeSH
- triglyceridy analýza izolace a purifikace metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The acidophilic red alga Cyanidium sp. is one of the dominant mat-forming species in the highly acidic waters of Río Tinto, Spain. The culture of Cyanidium sp., isolated from a microbial mat sample collected at Río Tinto, was exposed to 9 different pH conditions in a gradient from 0.5 to 5 for 24 h and its physiological status evaluated by variable chlorophyll a fluorescence kinetics measurements. Maximum quantum yield was determined after 30 min, 1 h, 2 h, 4 h, 6 h and 24 h of exposure after 15 min dark adaptation. The effect of pH on photochemical activity of Cyanidium sp. was observable as early as 30 min after exposure and the pattern remained stable or with only minor modifications for 24 h. The optimum pH ranged from 1.5 to 2.5. A steep decrease of the photochemical activity was observed at pH below 1 even after 30 min of exposure. Although the alga had tolerated the exposure to pH = 1 for at least 6 h, longer (24 h) exposure resulted in reduction of the photochemical activity. At pH above 2.5, the decline was more moderate and its negative effect on photochemistry was less severe. According to the fluorescence measurements, the red alga Cyanidium sp. is well-adapted to prevailing pH at its original locality at Río Tinto, i.e. pH of 1 to 3. The short-term survival in pH < 1.5 may be adaptation to rare exposures to such low pH in the field. The tolerance of pH above 3 could be caused by adaptation to the microenvironment of the inner parts of microbial mats in which Cyanidium sp. usually dominates and where higher pH could occur due to photosynthetic oxygen production.
The interest in functional food, both freshwater and marine algal products with their possible promotional health effects, increases also in regions where algae are considered as rather exotic food. Increased attention about algae as an abundant source of many nutrients and dietary fiber from the nutrition point of view, as well as from the scientific approaches to explore new nutraceuticals and pharmaceuticals, is based on the presence of many bioactive compounds including polysaccharides extracted from algal matter. Diverse chemical composition of dietary fiber polysaccharides is responsible for their different physicochemical properties, such as their ability to be fermented by the human colonic microbiota resulted in health benefit effects. Fundamental seaweed polysaccharides are presented by alginates, agars, carrageenans, ulvanes, and fucoidans, which are widely used in the food and pharmaceutical industry and also in other branches of industry. Moreover, freshwater algae and seaweed polysaccharides have emerged as an important source of bioactive natural compounds which are responsible for their possible physiological effects. Especially, sulfate polysaccharides exhibit immunomodulatory, antitumor, antithrombotic, anticoagulant, anti-mutagenic, anti-inflammatory, antimicrobial, and antiviral activities including anti-HIV infection, herpes, and hepatitis viruses. Generally, biological activity of sulfate polysaccharides is related to their different composition and mainly to the extent of the sulfation of their molecules. Significant attention has been recently focused on the use of both freshwater algae and seaweed for developing functional food by reason of a great variety of nutrients that are essential for human health.
- MeSH
- celosvětové zdraví MeSH
- Chlorophyta chemie růst a vývoj MeSH
- dieta škodlivé účinky etnologie MeSH
- funkční potraviny škodlivé účinky analýza MeSH
- lidé MeSH
- mořské řasy chemie MeSH
- Phaeophyceae chemie růst a vývoj MeSH
- polysacharidy škodlivé účinky analýza chemie metabolismus MeSH
- potravní vláknina škodlivé účinky analýza metabolismus MeSH
- Rhodophyta chemie růst a vývoj MeSH
- sinice chemie růst a vývoj MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
New hyphenated technique for the extraction and determination of isoflavones in sea and freshwater algae and cyanobacteria was developed. The method consists of sonication sample pretreatment, extraction by supercritical CO(2) modified by 3% (v/v) of MeOH/H(2)O mixture (9:1, v/v) at 35 MPa and 40°C for 60 min, fast chromatography analysis by the means of Agilent 1200 Series Rapid Resolution and MS/MS determination. Agilent 1200 Series RRLC was used with Zorbax SB-CN chromatographic column (100 mm × 2.1mm, particle size 3.5 μm), 3μl injection volume, mobile phase consisting of 0.2% (v/v) acetic acid in water (solvent A) and acetonitrile (solvent B) and used with linear gradient (30% B at 0 min, from 0 min to 3 min up to 50% B, from 3 to 6 min up to 80% B and from 6 to 10 min down to 30% B). The flow-rate was 0.4 mL/min, column oven temperature 35°C. MS detector Agilent Technologies 6460 Triple quadrupole LC/MS with Agilent Jet Stream was used in a negative ESI mode under following conditions: gas temperature 350°C, gas flow 13 L/min, nebulizer gas pressure 50 psi, sheath gas temperature 400°C, sheath gas flow 12L/min, capillary voltage was 4 kV. Samples were analysed in the multiple reaction monitoring (MRM) mode. Eight isoflavone compounds were found for the first time in seven real samples of sea algae and in three control samples of freshwater algae and cyanobacteria. Usual optimisation study of extraction parameters was performed. Pressure and temperature optima for algae matrix are different from those obtained sooner for other matrices for most of the analytes, but the results of modifier optimisation study are in good accordance with those obtained sooner for spiked samples and red clover matrix. It seems that matrix has very small or no effect on the modifier selection. Two different approaches of sonication pretreatment were tested: sonication bath and the thorn instrument. In longer extraction time experiments, thorn sonication was more efficient and recovery of following supercritical fluid extraction was higher.
- MeSH
- chromatografie kapalinová metody MeSH
- isoflavony analýza izolace a purifikace MeSH
- Phaeophyceae chemie MeSH
- Rhodophyta chemie MeSH
- superkritická fluidní chromatografie přístrojové vybavení metody MeSH
- tandemová hmotnostní spektrometrie metody MeSH
- ultrazvuk MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
In recently, there has been a great interest in natural antioxidants as bioactive components of food, nutraceuticals or potential drugs against several diseases. In our study, 88 extracts from various parts of plants from European Asteraceae and Cichoriaceae were assayed for radical scavenging activity by means of DPPH (1,1-diphenyl-2-picryl hydrazyl radical) test using the SIA (Sequential injection analysis) method developed for this purpose in our laboratory. DPPH radical scavenging activity of all tested plant extracts was evaluated according to the IC(50) parameter. 29 extracts exhibited IC(50) value lower than 0.1 mg/mL. The leaves of Leuzea carthamoides (IC(50) = 0.046 mg/mL) were chosen as the most promising sample for a subsequent phytochemical study, which resulted in isolation of seven natural compounds, namely, 4',5,7-trihydroxy-6-methoxyflavone (hispidulin) (1), 5, 7, 3', 4'- tetrahydroxyflavanone (eriodictyol) (2), 3',4',5,7-pentahydroxy-6-methoxyflavonol (patuletin) (3), eriodictyol-7-beta-glucopyranoside (4), 6-hydroxykaempferol-7-O-(6''-O-acetyl-beta-D-glucopyranoside) (5), 4-hydroxybenzoic acid (6) and 3,4-dihydroxybenzoic acid (protocatechuic acid) (7). Antioxidant activity of the isolated compounds was evaluated by DPPH test and ferric reducing antioxidant power (FRAP) test and compared with trolox and quercetin. Both tests evaluated the flavonoid (5) as the most active antioxidant. This result was confirmed by comparison with known data concerning the structure/activity relationships of flavonoids.
- MeSH
- antioxidancia farmakologie chemie MeSH
- Asteraceae chemie MeSH
- bifenylové sloučeniny MeSH
- biologické přípravky farmakologie chemie MeSH
- chromany (dihydrobenzopyrany) chemie izolace a purifikace MeSH
- financování organizované MeSH
- hydraziny MeSH
- Leuzea chemie MeSH
- molekulární struktura MeSH
- pikráty MeSH
- preklinické hodnocení léčiv MeSH
- quercetin chemie izolace a purifikace MeSH
- Rhodophyta chemie MeSH
- rostlinné extrakty farmakologie chemie izolace a purifikace MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Geografické názvy
- Evropa MeSH
