Effect of Arthrospira maxima Phycobiliproteins, Rosiglitazone, and 17ß-Estradiol on Lipogenic and Inflammatory Gene Expression during 3T3-L1 Preadipocyte Cell Differentiation.

The study evaluated the effects of Arthrospira maxima phycobiliproteins (PBPs), rosiglitazone (RSG), and 17ß-estradiol (E) on the differentiation process of 3T3-L1 cells and on their regulation of lipogenic and inflammatory gene expression at different stages of the process. The results showed that phycobiliproteins promoted cell proliferation after 24 h of treatment. Furthermore, for all three treatments, the regulation of the highest number of markers occurred on days 6 and 12 of differentiation, regardless of when the treatment was applied. Phycobiliproteins reduced lipid droplet accumulation on days 3, 6, 10, and 13 of the adipogenic process, while rosiglitazone showed no differences compared to the control. On day 6, both phycobiliproteins and rosiglitazone positively regulated Acc1 mRNA. Meanwhile, all three treatments negatively regulated Pparγ and C/ebpα. Phycobiliproteins and estradiol also negatively regulated Ucp1 and Glut4 mRNAs. Rosiglitazone and estradiol, on the other hand, negatively regulated Ppara and Il-6 mRNAs. By day 12, phycobiliproteins and rosiglitazone upregulated Pparγ mRNA and negatively regulated Tnfα and Il-1ß. Additionally, phycobiliproteins and estradiol positively regulated Il-6 and negatively regulated Ppara, Ucp2, Acc1, and Glut4. Rosiglitazone and estradiol upregulate C/ebpα and Ucp1 mRNAs. The regulation exerted by phycobiliproteins on the mRNA expression of the studied markers was dependent on the phase of cell differentiation. The results of this study highlight that phycobiliproteins have an anti-adipogenic and anti-inflammatory effect by reducing the expression of adipogenic, lipogenic, and inflammatory genes in 3T3-L1 cells at different stages of the differentiation process.

Phycobiliprotein from Arthrospira maxima: Conversion to nanoparticles by high-energy ball milling, structural characterization, and evaluation of their anti-inflammatory effect.

Arthrospira maxima is a source of phycobiliproteins with different nutraceutical properties, e.g. antioxidant and anti-inflammatory activities. The current study was aimed at the elaboration, characterization, and evaluation of the anti-inflammatory effect of the phycobiliprotein nanoparticles extracted from Arthrospira maxima. Previously freeze-dried phycobiliproteins were milled by high-energy ball milling until reaching a nanometric size (optimal time: 4 h). Microscopy techniques were used for the characterization of the size and morphology of phycobiliproteins nanoparticles. Additionally, a spectroscopic study evidenced that nanosized reduction induced an increase in the chemical functional groups associated with its anti-inflammatory activity that was tested in a murine model, showing an immediate inflammatory effect. The novelty and importance of this contribution was to demonstrate that high energy ball milling is an emerging and green technology that can produce phycobiliprotein nanoparticles on a large-scale, without the use of organic solvents, to test their nutraceutical properties in a biological model by intragastric administration.

Functional Modification of Cyanobacterial Phycobiliprotein and Phycobilisomes through Bilin Metabolism Control.

Phycobilisomes (PBSs) are light-harvesting antenna complexes in cyanobacteria that adapt to diverse light environments through the use of phycobiliproteins within the PBS structures. Freshwater cyanobacteria, such as Synechococcus elongatus PCC 7942, thrive under red light because of the presence of phycocyanin (PC) and its chromophore, phycocyanobilin (PCB), in the PBS. Cyanobacteria in shorter-wavelength light environments such as green light, employ phycoerythrin paired with phycoerythrobilin (PEB) along with PC in the PBS. Synthetic biology studies have shown that PEB production can be achieved by expression of the heterologous PEB synthases 15,16-dihydrobiliverdin:ferredoxin oxidoreductase (PebA) and PEB:ferredoxin oxidoreductase (PebB), leading to PEB accumulation and cellular browning. This approach is genetically unstable, and the properties of the resulting PEB-bound PBS complexes remain uncharacterized. In this study, we engineered a novel strain of Synechococcus 7942 PEB1 with finely tuned control of PEB biosynthesis. PEB1 exhibited a reversible change in the color of the culture from green to brown and pink based on PebA and PebB induction levels. High induction led to complete PCB-to-PEB substitution, causing the disassembly of the PBS rod complex. In contrast, low induction levels of PebA and PebB resulted in the formation of a stable chimeric PBS complex with partial PCB-to-PEB substitution. This acclimation enabled efficient light harvesting in the green spectrum and energy transfer to the photosynthetic reaction center. These findings, which improve our understanding of PBS and highlight the structural importance of the bilin composition, provide a foundation for future studies on PBS adaptation in bioengineering, synthetic biology, and renewable energy.

Narrative Review of the Current and Future Perspectives of Phycobiliproteins' Applications in the Food Industry: From Natural Colors to Alternative Proteins.

Vivid-colored phycobiliproteins (PBPs) have emerging potential as food colors and alternative proteins in the food industry. However, enhancing their application potential requires increasing stability, cost-effective purification processes, and consumer acceptance. This narrative review aimed to highlight information regarding the critical aspects of PBP research that is needed to improve their food industry potential, such as stability, food fortification, development of new PBP-based food products, and cost-effective production. The main results of the literature review show that polysaccharide and protein-based encapsulations significantly improve PBPs' stability. Additionally, while many studies have investigated the ability of PBPs to enhance the techno-functional properties, like viscosity, emulsifying and stabilizing activity, texture, rheology, etc., of widely used food products, highly concentrated PBP food products are still rare. Therefore, much effort should be invested in improving the stability, yield, and sensory characteristics of the PBP-fortified food due to the resulting unpleasant sensory characteristics. Considering that most studies focus on the C-phycocyanin from Spirulina, future studies should concentrate on less explored PBPs from red macroalgae due to their much higher production potential, a critical factor for positioning PBPs as alternative proteins.

Traditional and new trend strategies to enhance pigment contents in microalgae.

Microalgae are a source of a wide variety of commodities, including particularly valuable pigments. The typical pigments present in microalgae are the chlorophylls, carotenoids, and phycobiliproteins. However, other types of pigments, of the family of water-soluble polyphenols, usually encountered in terrestrial plants, have been recently reported in microalgae. Among such microalgal polyphenols, many flavonoids have a yellowish hue, and are used as natural textile dyes. Besides being used as natural colorants, for example in the food or cosmetic industry, microalgal pigments also possess many bioactive properties, making them functional as nutraceutical or pharmaceutical agents. Each type of pigment, with its own chemical structure, fulfills particular biological functions. Considering both eukaryotes and prokaryotes, some species within the four most promising microalgae groups (Cyanobacteria, Rhodophyta, Chlorophyta and Heterokontophyta) are distinguished by their high contents of specific added-value pigments. To further enhance microalgae pigment contents during autotrophic cultivation, a review is made of the main related strategies adopted during the last decade, including light adjustments (quantity and quality, and the duration of the photoperiod cycle), and regard to mineral medium characteristics (salinity, nutrients concentrations, presence of inductive chemicals). In contrast to what is usually observed for growth-related pigments, accumulation of non-photosynthetic pigments (polyphenols and secondary carotenoids) requires particularly stressful conditions. Finally, pigment enrichment is also made possible with two new cutting-edge technologies, via the application of metallic nanoparticles or magnetic fields.

Nutraceutical Features of the Phycobiliprotein C-Phycocyanin: Evidence from Arthrospira platensis (Spirulina).

Arthrospira platensis, commonly known as Spirulina, is a photosynthetic filamentous cyanobacterium (blue-green microalga) that has been utilized as a food source since ancient times. More recently, it has gained significant popularity as a dietary supplement due to its rich content of micro- and macro-nutrients. Of particular interest is a water soluble phycobiliprotein derived from Spirulina known as phycocyanin C (C-PC), which stands out as the most abundant protein in this cyanobacterium. C-PC is a fluorescent protein, with its chromophore represented by the tetrapyrrole molecule phycocyanobilin B (PCB-B). While C-PC is commonly employed in food for its coloring properties, it also serves as the molecular basis for numerous nutraceutical features associated with Spirulina. Indeed, the comprehensive C-PC, and to some extent, the isolated PCB-B, has been linked to various health-promoting effects. These benefits encompass conditions triggered by oxidative stress, inflammation, and other pathological conditions. The present review focuses on the bio-pharmacological properties of these molecules, positioning them as promising agents for potential new applications in the expanding nutraceutical market.

Growth phase-dependent reorganization of cryptophyte photosystem I antennae.

Photosynthetic cryptophytes are eukaryotic algae that utilize membrane-embedded chlorophyll a/c binding proteins (CACs) and lumen-localized phycobiliproteins (PBPs) as their light-harvesting antennae. Cryptophytes go through logarithmic and stationary growth phases, and may adjust their light-harvesting capability according to their particular growth state. How cryptophytes change the type/arrangement of the photosynthetic antenna proteins to regulate their light-harvesting remains unknown. Here we solve four structures of cryptophyte photosystem I (PSI) bound with CACs that show the rearrangement of CACs at different growth phases. We identify a cryptophyte-unique protein, PsaQ, which harbors two chlorophyll molecules. PsaQ specifically binds to the lumenal region of PSI during logarithmic growth phase and may assist the association of PBPs with photosystems and energy transfer from PBPs to photosystems.

Dehydration, Rehydration and Thermal Treatment: Effect on Bioactive Compounds of Red Seaweeds Porphyra umbilicalis and Porphyra linearis.

The nutritional and bioactive value of seaweeds is widely recognized, making them a valuable food source. To use seaweeds as food, drying and thermal treatments are required, but these treatments may have a negative impact on valuable bioactive compounds. In this study, the effects of dehydration, rehydration, and thermal treatment on the bioactive compounds (carotenoids, phycobiliproteins, total phenolic content (TPC), total flavonoids content (TFC)), antioxidant (ABTS and DPPH radical scavenging activities) and anti-Alzheimer's (Acetylcholinesterase (AchE) inhibitory activities, and color properties of Porphyra umbilicalis and Porphyra linearis seaweeds were evaluated. The results revealed significant reductions in carotenoids, TPC, TFC, and antioxidant activities after the seaweeds' processing, with differences observed between species. Thermal treatment led to the most pronounced reductions in bioactive compound contents and antioxidant activity. AchE inhibitory activity remained relatively high in all samples, with P. umbilicalis showing higher activity than P. linearis. Changes in color (ΔE) were significant after seaweeds' dehydration, rehydration and thermal treatment, especially in P. umbilicalis. Overall, optimizing processing methods is crucial for preserving the bioactive compounds and biological activities of seaweeds, thus maximizing their potential as sustainable and nutritious food sources or as nutraceutical ingredients.

Green and efficient method to acquire high-value phycobiliprotein from microalgal biomass involving deep eutectic solvent-based ultrasound-assisted extraction.

Phycoerythrin (PE) is a phycobiliprotein holding great potential as a high-value food colorant and medicine. Deep eutectic solvent (DES)-based ultrasound-assisted extraction (UAE) was applied to extract B-PE by disrupting the resistant polysaccharide cell wall of Porphyridium purpureum. The solubility of cell wall monomers in 31 DESs was predicted using COSMO-RS. Five glycerol-based DESs were tested for extraction, all of which showed significantly higher B-PE yields by up to 13.5 folds than water. The DES-dependent B-PE extraction efficiencies were proposedly associated with different cell disrupting capabilities and protein stabilizing effects of DESs. The DES-based UAE method could be considered green according to a metric assessment tool, AGREEprep. The crude extract containing DES was further subjected to aqueous two-phase system, two-step ammonium sulfate precipitation, and ultrafiltration processes. The final purified B-PE had a PE purity ratio of 3.60 and a PC purity ratio of 0.08, comparable to the purity of commercial products.

Monomeric Far-red and Near-infrared Fluorescent Biliproteins of Ultrahigh Brightness.

Far-red and near-infrared fluorescent proteins have regions of maximum transmission in most tissues and can be widely used as fluorescent biomarkers. We report that fluorescent phycobiliproteins originating from the phycobilisome core subunit ApcF2 can covalently bind biliverdin, named BDFPs. To further improve BDFPs, we conducted a series of studies. Firstly, we mutated K53Q and T144A of BDFPs to increase their effective brightness up to 190 % in vivo. Secondly, by homochromatic tandem fusion of high-brightness BDFPs to achieve monomerization, which increases the effective brightness by up to 180 % in vivo, and can effectively improve the labeling effect. By combining the above two approaches, the brightness of the tandem BDFPs was much improved compared with that of the previously reported fluorescent proteins in a similar spectral range. The tandem BDFPs were expressed stably while maintaining fluorescence in mammalian cells and Caenorhabditis elegans. They were also photostable and resistant to high temperature, low pH, and chemical denaturation. The tandem BDFPs advantages were proved in applications as biomarkers for imaging in super-resolution microscopy.

Variability in spectral absorption within cryptophyte phycobiliprotein types.

Cryptophytes are known to vary widely in coloration among species. These differences in color arise primarily from the presence of phycobiliprotein accessory pigments. There are nine defined cryptophyte phycobiliprotein (Cr-PBP) types, named for their wavelength of maximal absorbance. Because Cr-PBP type has traditionally been regarded as a categorical trait, there is a paucity of information about how spectral absorption characteristics of Cr-PBPs vary among species. We investigated variability in primary and secondary peak absorbance wavelengths and full width at half max (FWHM) values of spectra of Cr-PBPs extracted from 75 cryptophyte strains (55 species) grown under full spectrum irradiance. We show that there may be substantial differences in spectral shapes within Cr-PBP types, with Cr-Phycoerythrin (Cr-PE) 545 showing the greatest variability with two, possibly three, subtypes, while Cr-PE 566 spectra were the least variable, with only ±1 nm of variance around the mean absorbance maximum of 565 nm. We provide additional criteria for classification in cases where the wavelength of maximum absorbance alone is not definitive. Variations in spectral characteristics among strains containing the same presumed Cr-PBP type may indicate differing chromophore composition and/or the presence of more than one Cr-PBP in a single cryptophyte species.

Structure of the antenna complex expressed during far-red light photoacclimation in Synechococcus sp. PCC 7335.

Far-red light photoacclimation, or FaRLiP, is a facultative response exhibited by some cyanobacteria that allows them to absorb and utilize lower energy light (700-800 nm) than the wavelengths typically used for oxygenic photosynthesis (400-700 nm). During this process, three essential components of the photosynthetic apparatus are altered: photosystem I, photosystem II, and the phycobilisome. In all three cases, at least some of the chromophores found in these pigment-protein complexes are replaced by chromophores that have red-shifted absorbance relative to the analogous complexes produced in visible light. Recent structural and spectroscopic studies have elucidated important features of the two photosystems when altered to absorb and utilize far-red light, but much less is understood about the modified phycobiliproteins made during FaRLiP. We used single-particle, cryo-EM to determine the molecular structure of a phycobiliprotein core complex comprising allophycocyanin variants that absorb far-red light during FaRLiP in the marine cyanobacterium Synechococcus sp. PCC 7335. The structure reveals the arrangement of the numerous red-shifted allophycocyanin variants and the probable locations of the chromophores that serve as the terminal emitters in this complex. It also suggests how energy is transferred to the photosystem II complexes produced during FaRLiP. The structure additionally allows comparisons with other previously studied allophycocyanins to gain insights into how phycocyanobilin chromophores can be tuned to absorb far-red light. These studies provide new insights into how far-red light is harvested and utilized during FaRLiP, a widespread cyanobacterial photoacclimation mechanism.

Protección de la Spirulina maxima sobre la citotoxicidad de la hidroxiurea en células embrionarias de ratón / Protection of Spirulina maxima on cytotoxicity of hydroxyurea in mouse embryonic cells / Proteção de Spirulina maxima em citotoxicidade de hidroxiureia em células embrionárias de camundongo

La Spirulina maxima (SP) tiene efectos farmacológicos protectores por su contenido de ficobiliproteínas que están relacionados con su actividad antioxidante. La hidroxiurea (HU) es un fármaco antineoplásico, citotóxico y teratógeno que implica la inducción del estrés oxidativo. El objetivo de este trabajo fue determinar si la SP y su extracto acuoso de proteína (SPE) protegen contra el efecto citotóxico de HU en cultivos celulares primarios a partir de embriones de ratón de once días. Los efectos de SP, SPE e HU sobre la viabilidad celular se determinaron por el ensayo de fluorescencia de resazurina en cultivos celulares de embriones completos de ratones de once días, de encéfalo y de brotes de extremidades anteriores. Se demostró que ni SP ni su extracto provocaron efectos citotóxicos en ninguna concentración ensayada, por lo que se aumentaba la viabilidad celular. Se encontró que las células expuestas a HU de embriones completos y encéfalo mostraron mayor toxicidad que las células de los miembros anteriores. La SP y el SPE protegieron contra la citotoxicidad de HU de una manera dependiente de la concentración hasta 48 h después de la exposición al fármaco. Este efecto podría ser adecuado para prevenir la muerte celular que deriva en un proceso teratogénico, atribuido a sus propiedades antioxidantes.

Spirulina maxima (SP) has protective pharmacological effects that are related to the antioxidant activity due to its phycobiliprotein content. Hydroxyurea (HU) is an antineoplastic, cytotoxic and teratogenic drug, which involves the induction of oxidative stress. The aim of this study was to determine whether SP and its aqueous protein extract (SPE) protect against the cytotoxic effect of HU in primary cell cultures from mouse embryos. The effects of SP, SPE, and HU on cell viability were determined by resazurin fluorescence assay in whole embryo cell cultures, encephalon, and eleven-day-old forehead bud outbreaks. It was shown that neither SP nor its extract caused cytotoxic effects at any concentration tested, increasing cell viability. It was found that cells exposed to HU of whole embryos and encephalon showed higher toxicity than cells of the previous limbs. SP and SPE protected HU cytotoxicity in a concentration-dependent manner up to 48 hours after exposure to the drug. This effect could be adequate to prevent cell death resulting in a teratogenic process attributed to its antioxidant properties.

Spirulina maxima (SP) tem efeitos farmacológicos protetores devido a seu conteúdo de ficobiliproteínas, que estão relacionadas com sua atividade antioxidante. A hidroxiureia (HU) é uma droga antineoplásica, citotóxica e teratogênica, que envolve a indução do estresse oxidativo. O objetivo deste estudo foi determinar se a SP e seu extrato aquoso de proteína (SPE) protegem contra o efeito citotóxico da HU em culturas celulares primárias a partir de embriões de camundongo de onze dias. Os efeitos de SP, SPE e HU na viabilidade celular foram determinados pelo ensaio de fluorescência de resazurina em culturas celulares de embriões inteiros de camundongos de onze dias, de encéfalo e de surtos de extremidades anteriores. Demonstrou-se que nem a SP nem seu extrato causaram efeitos citotóxicos em qualquer concentração testada, aumentando a viabilidade celular. Verificou-se que as células expostas à HU de embriões completos e encéfalo mostraram maior toxicidade do que as células dos membros anteriores. SP e SPE protegem contra a citotoxicidade de HU de forma dependente da concentração até 48 h após a exposição ao medicamento. Esse efeito poderia ser adequado para prevenir a morte celular, que resulta em um processo teratogênico atribuído a suas propriedades antioxidantes.

Principales propiedades inmunomoduladoras y antinflamatorias de la ficobiliproteína C-ficocianina / Main immunomodulatory and anti-inflamatory properties of phycobiliproteins C-phycocyanin

Las ficobiliproteínas son proteínas solubles en agua, que funcionan como pigmentos fotosintéticos accesorios en diferentes organismos tales como las cianobacterias, las algas rojas y las criptomonadas. En el alga verdeazul Spirulina platensis, una de las ficobiliproteínas más abundantes es la C-ficocianina, la cual tiene unido tres cromóforos ficocianobilina mediante un enlace tioéter a cisteínas específicas. La ficocianobilina es un tetrapirrol lineal asociado a la captación de energía solar en estos organismos. La C-ficocianina ha sido empleada en diferentes investigaciones biomédicas como biomarcador, por sus propiedades fluorescentes, y como posible agente terapéutico para el tratamiento de enfermedades asociadas al estrés oxidativo, por sus propiedades antioxidantes, inmunomoduladoras y antinflamatorias. Se ha demostrado que esta proteína aumenta la liberación de interferón gamma en células mononucleares de sangre periférica y modula la producción de citocinas inflamatorias como el factor de necrosis tumoral alfa, entre otras. Además, se ha encontrado que la C-ficocianina tiene efecto inmunomodulador de citocinas que potencian la activación de las células del sistema inmune, como la IL-6 y la IL-1β, así como la regulación de aproximadamente 190 genes implicados en la inmunidad(AU)

Principales propiedades inmunomoduladoras y antinflamatorias de la ficobiliproteína C-ficocianina / Main immunomodulatory and anti-inflamatory properties of phycobiliproteins C-phycocyanin

Las ficobiliproteínas son proteínas solubles en agua, que funcionan como pigmentos fotosintéticos accesorios en diferentes organismos tales como las cianobacterias, las algas rojas y las criptomonadas. En el alga verdeazul Spirulina platensis, una de las ficobiliproteínas más abundantes es la C-ficocianina, la cual tiene unido tres cromóforos ficocianobilina mediante un enlace tioéter a cisteínas específicas. La ficocianobilina es un tetrapirrol lineal asociado a la captación de energía solar en estos organismos. La C-ficocianina ha sido empleada en diferentes investigaciones biomédicas como biomarcador, por sus propiedades fluorescentes, y como posible agente terapéutico para el tratamiento de enfermedades asociadas al estrés oxidativo, por sus propiedades antioxidantes, inmunomoduladoras y antinflamatorias. Se ha demostrado que esta proteína aumenta la liberación de interferón gamma en células mononucleares de sangre periférica y modula la producción de citocinas inflamatorias como el factor de necrosis tumoral alfa, entre otras. Además, se ha encontrado que la C-ficocianina tiene efecto inmunomodulador de citocinas que potencian la activación de las células del sistema inmune, como la IL-6 y la IL-1ß, así como la regulación de aproximadamente 190 genes implicados en la inmunidad(AU)

Phycobiliproteins are water-soluble proteins that function as accessory photosynthetic pigments in different organisms such as cyanobacteria, red algae and cryptomonads. In the blue-green algae Spirulina platensis one of the most abundant phycobiliproteins is the C-phycocyanin, which has three phycocyanobilin chromophores linked through a thioether bond to specific cysteine. The phycocyanobilin is a linear tetrapyrrole associated with solar energy absorption in these organisms. The C-phycocyanin has been used in several biomedical researches as a biomarker, for their fluorescence properties, and as a possible therapeutic agent for the treatment of diseases associated with oxidative stress for its antioxidant, anti-inflammatory and immunomodulatory properties. It has been shown that this protein increases the release of interferon gamma in peripheral blood mononuclear cells, and modulates the production of inflammatory cytokines such as tumor necrosis factor among others. Furthermore it has been found that the C-phycocyanin has immunomodulatory effect on cytokines that enhance the activation of immune cells, such as IL-6 and IL-1ß, and the regulation of about 190 genes involved in immunity(AU)

Role of pH on antioxidants production by Spirulina (Arthrospira) platensis

Abstract Algae can tolerate a broad range of growing conditions but extreme conditions may lead to the generation of highly dangerous reactive oxygen species (ROS), which may cause the deterioration of cell metabolism and damage cellular components. The antioxidants produced by algae alleviate the harmful effects of ROS. While the enhancement of antioxidant production in blue green algae under stress has been reported, the antioxidant response to changes in pH levels requires further investigation. This study presents the effect of pH changes on the antioxidant activity and productivity of the blue green alga Spirulina (Arthrospira) platensis. The algal dry weight (DW) was greatly enhanced at pH 9.0. The highest content of chlorophyll a and carotenoids (10.6 and 2.4 mg/g DW, respectively) was recorded at pH 8.5. The highest phenolic content (12.1 mg gallic acid equivalent (GAE)/g DW) was recorded at pH 9.5. The maximum production of total phycobiliprotein (159 mg/g DW) was obtained at pH 9.0. The antioxidant activities of radical scavenging activity, reducing power and chelating activity were highest at pH 9.0 with an increase of 567, 250 and 206% compared to the positive control, respectively. Variation in the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) was also reported. While the high alkaline pH may favor the overproduction of antioxidants, normal cell metabolism and membrane function is unaffected, as shown by growth and chlorophyll content, which suggests that these conditions are suitable for further studies on the harvest of antioxidants from S. platensis.

Growth and biopigment accumulation of cyanobacterium Spirulina platensis at different light intensities and temperature

In order to find out optimum culture condition for algal growth, the effect of light irradiance and temperature on growth rate, biomass composition and pigment production of Spirulina platensis were studied in axenic batch cultures. Growth kinetics of cultures showed a wide range of temperature tolerance from 20 ºC to 40 ºC. Maximum growth rate, cell production with maximum accumulation of chlorophyll and phycobilliproteins were found at temperature 35 ºC and 2,000 lux light intensity. But with further increase in temperature and light intensity, reduction in growth rate was observed. Carotenoid content was found maximum at 3,500 lux. Improvement in the carotenoid content with increase in light intensity is an adaptive mechanism of cyanobacterium S.platensis for photoprotection, could be a good basis for the exploitation of microalgae as a source of biopigments.

Photodynamic effect of two kinds of phycobiliproteins on human liver cancer cell line SMMC-7721 in vitro / 生物工程学报

We studied the effect of photodynamic therapy with phycobiliproteins on human liver cancer cells in vitro. With 3-(4, 5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT assay), we used two phycobiliproteins, R-phycoerythrin (R-PE) and C-phycocyanin (C-PC) prepared from Porphyra yezoensis, to determine the killing rates and apoptosis rates of human liver cancer cells (SMMC-7721) mediated by laser. When the concentration of R-PE was 120 mg/L, the survival rate of human liver cancer cells was 27% after treated by Argon laser with 100 J/cm2 doses, while the survival rate in the control group (without adding R-PE) was 65%. When the C-PC concentration was 120 mg/L, the survival cell rate was 47% after treated by He-Ne laser with 35 J/cm2 dose, while the survival rate in the control group (without adding C-PC) was 70%. After handled only with these two kinds of phycobiliproteins for 72 h, the growth of cancer cells presented significant inhibition. The maximal inhibition rates reached up to 31% with R-PE (120 mg/L concentration) and 27% with C-PC (250 mg/L concentration) respectively. After irradiated by laser for 8 h, the maximal cell apoptosis rates were 31.54% with R-PE and 32.54% with C-PC, respectively. It indicated that R-PE and C-PC extracted from Porphyra yezoensis could develop to new photosensitizers for cancer photodynamic therapy.