Phycocyanin from Spirulina: A review of extraction methods and stability

Algal protein: Structural functionality, advanced extraction technologies, and challenges for applications in food nutrition security

Algal protein emerges as a promising alternative to traditional crop and animal proteins due to its environmental sustainability, nutritional profile, and versatility in food applications. Additionally, its bioactivity and nutritional value make it a novel ingredient across industries such as medicine, agriculture, and animal feed. This review comprehensively examines the structural-functional properties of algal amino acids, peptides, and proteins, emphasizing their roles in enhancing nutritional and technological characteristics in food systems. Advanced protein pre-treatment, extraction, and enrichment methods are analyzed to improve efficiency and scalability. The potential of algal proteins in food additives, medicinal uses, and meat protein alternatives is highlighted, in addition to the challenges they face in food applications. With continuous improvements in extraction technology, species selection, and production scalability, algal protein is poised to integrate into mainstream food systems, offering innovative solutions for food nutrition security and environmental sustainability.

Phycochemistry and pharmacological significance of filamentous cyanobacterium Spirulina sp

The cyanobacterium, Spirulina sp. is a photosynthetic blue-green alga with essential nutrients, vitamins nucleic acids, proteins, carbohydrates, fatty acids and pigments carotenes; and phycocyanins are the significant components having immunomodulatory, anti-inflammatory properties, which are used in food and cosmetics industries. Spirulina sp. can play an important role in human and animal nutrition for potential health benefits due to their phycochemical and pharmaceutical significance. This study highlights antibacterial, antifungal, antiviral, antioxidant, nephroprotective, cardioprotective, anticancer, neuroprotective, anti-aging, anti-inflammatory, and immunomodulatory properties. It highlights anti-anemic, antidiabetic, probiotic, anti-malarial, anti-obesity and weight loss, anti-genotoxicity, anti-thrombic, radioprotective, and detoxifying effects of Spirulina sp. Pharmaceutical studies indicate it may improve heart health and add to the treatment of diabetes, obesity and weight loss. It can play a major role in protecting the environment by recycling wastewater and providing food for humans and animals. Spirulina sp. can supply ingredients for aquaculture and agricultural feeds, pigments, antioxidants, and essential omega-3 oils, among other human health and wellness products. The amino acid of Spirulina is among the greatest qualititavely of any plant, even higher than that of soybean. Furthermore, cyanobacterium Spirulina sp. could be a future antimicrobial drug agent.

Bioinspired synthesis of copper oxide nanoparticles using aqueous extracts of Cladophora glomerata (L.) Kuetz and their potential biomedical applications

Present study deals with the green fabrication of copper oxide nanoparticles (CuO NPs) employing cell-free aqueous extract of Cladophora glomerata (L.) Kuetz, freshwater algal species. The UV-visible, FTIR, XRD, FESEM, HRTEM, EDX, BET, XPS and Raman spectroscopic techniques were used to confirm and characterize the biosynthesized CuO NPs. The UV-Vis analysis revealed a sharp peak at 264 nm with a band gap of 3.7 eV, which was attributable to the fabrication of CuO NPs. FESEM and HRTEM detect the spherical-shaped morphology with size between 40 and 50 nm. The biochemical profiling of cell free extract of the C. glomerata by Gas chromatography-mass spectrometry (GC-MS) revealed the presence of various bioactive biomolecules that may acts as a precursor for the fabrication of CuO NPs. The antibacterial study of fabricated CuO NPs revealed significant growth inhibitory potential against selected bacterial strains Klebsiella pneumoniae and Bacillus cereus with an IC50 value of 10 μg/ml. The synthesized CuO NPs also displayed strong DPPH radical scavenging (IC50 value 11.25 mg/L) and total antioxidant (IC50 value 11 mg/L) properties. Further, the anticancer activity of fabricated CuO NPs was studied employing a human hepatocellular carcinoma (HepG2) cell line by MTT assay, which marks their ability to diminish the 50% cell with IC50 value of 168.6 µg/ml. Overall, the findings confirmed that CuO NPs fabricated employing cell-free extract of C. glomerata have the potential to be used as active agent in various biomedical applications after further detailed clinical investigations.

A novel two-step purification process for highly stable C-phycocyanin of analytical grade purity and its properties

Efficient and economic purification of phycobiliproteins can be achieved by a novel relatively simple two-step process involving foam fractionation and ion exchange chromatography. Foam fractionation, which has not previously been used to concentrate phycobiliproteins, is a low-cost and environmentally friendly method that provides a significant volume reduction prior to the chromatography step. Two C-phycocyanin fractions with purities of 4.66 and 4.25 with slightly different characteristics and an allophycocyanin fraction with a purity of 3.23 were obtained. Both C-phycocyanins contain α-subunits of 15.0 kDa and β-subunits of 16.4 kDa, whereas the molecular weight of allophycocyanin is 15.5 kDa. The resulting C-phycocyanin retains its properties at pH in the range of 3-10, whereas strong alkaline pH leads to its rapid degradation. The purified protein is completely resistant to temperature changes in the range of 4 to 50 °C and loses only about 13% of its initial concentration during a 5 h incubation at 60 °C. Interestingly, purified C-phycocyanin is relatively resistant to photochemical degradation, as the loss in concentration after 10 h exposure to light is only about 14%. The most suitable storage conditions are temperature of 4 °C and pH in the range 4-5. The final product with an analytical purity greater than 4 is suitable for use in food, biomedicine and as a therapeutic agent. KEY POINTS: • Foam fractionation and ion chromatography for the purification of phycobiliproteins. • C-phycocyanin stable over a wide temperature and pH range without a stabilizing agent. • C-phycocyanin of analytical purity for food, medical and pharmaceutical applications.

Comparison of Pressurized Water Extraction With Ultrasound Assisted Extraction for Isolation of Phycobiliproteins From Arthrospira platensis (Spirulina)

INTRODUCTION

Cyanobacterium Arthrospira platensis (AP) (Nordstedt) Gomont contains high content of phycobiliproteins (PBP), which are an important source for food industry. Methods effectively extracting proteins contained in AP cells are demanded to provide a supply of the material. Water-based extraction methods are advisable due to the high solubility of the PBP.

OBJECTIVES

Extraction techniques such as ultrasound assisted extraction (UAE) and pressurized water extraction (PWE) are popular due to their environmental friendliness, better extraction efficiency, and faster extraction process. In this paper, efficiency of the two methods is compared.

MATERIALS AND METHODS

PWE along with UAE is utilized for release of PBP from the AP cells. The extraction parameters including time, temperature, pressure, and ultrasound intensity are tested to obtain the most efficient setup. The methods were evaluated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and the replicates of PWE extracts were further analyzed by capillary isoelectric focusing with laser-induced fluorescence (cIEF-LIF).

RESULTS

The developed PWE method using higher pressure treatment at lower temperature was significantly faster than UAE methods, and the SDS-PAGE results showed a high content of phycobiliproteins in the extracts. cIEF-LIF analysis showed that the sequential PWE of individual samples was repeatable, and the mild extraction provided a fluorescent profile similar to the commercially available C-phycocyanin standard.

CONCLUSION

Pressurized water extraction was shown to be an efficient, rapid, and well-automated extraction method for AP proteins in general, including bioactive phycobiliproteins. Obtained results encourage the use of PWE in small-scale analytical applications for primary extraction of proteins.

Recent progress in the cyanobacterial products and applications of phycocyanins

Recent developments in the research on cyanobacterial products have drawn increasing attention, especially in the production and application of phycocyanin, which has shown great potential in various fields. Cyanobacteria are photosynthetic prokaryotes that live on Earth and are the ancestors of plant chloroplasts. They have a compact genome size compared to other eukaryotic photosynthesizing microorganisms; some species are genetically engineered and have high growth potential in indoor culture, and some strainscan maintain high growth potential even in outdoor culture. Cyanobacteria are valuable because they can selectively and effectively produce and recover useful substances that are poorly produced by other microalgae, although this depends on the algal species. However, the social implementation of biorefineries using cyanobacteria involves issues such as setting up useful products in addition to the culture methods and strains to be used. This review aims to present research trends over the last 20 years on the production of useful substances such as biodegradable plastics, lipids, polysaccharides, and pigment proteins (phycocyanins) from cyanobacteria. Phycocyanin is mainly recovered and purified by filamentous cyanobacteria and has contributed to the research field, especially in the food and beverage industry. Additionally, the production and functions of phycocyanin are summarized to provide a better understanding of these possibilities. Their potential applications as environmentally friendly materials are also described to further contribute to the research field and social implementation.

Hydrodynamic cavitation mediated Spirulina valorisation with insights into phycocyanin extraction and biogas production

Commercial phycocyanin extraction is energy-intensive and lacks scalability. Alternatively, this study reports the systematic investigation of hydrodynamic cavitation for intensified phycocyanin extraction from Spirulina. Additionally, biomethane potential of the residual biomass, obtained after phycocyanin extraction was also investigated. The biomethane generation rate decreased with an increasing number of passes while the biomethane potential remained unaffected. To reliably compare phycocyanin extraction across systems, dimensionless normalised yields were defined. A normalised phycocyanin yield of 4.3 (52 mg phycocyanin g-1) at an inlet pressure of 150 kPa and 90 passes was identified (optimum cavitation). Lowest specific energy input (0.06kWh kg-1) was calculated for processing 100 g L-1 Spirulina, which is one to two orders of magnitude lower than current state-of-the-art. Furthermore, a net energy gain of 600-2497kWh kg-1 obtained from biomethane generation showcased a viable Spirulina biorefinery, intensified via hydrodynamic cavitation. This work provides a route for phycocyanin extraction with significantly reduced energy input and potential for wider bioproduct extraction and biorefining from a range of biomasses via hydrodynamic cavitation.

Deep Eutectic Solvents based green approach for bioactive molecules recovery from Spirulina

Spirulina is a unicellular microalga, characterized by blue/green color, that has received significant attention for its interesting nutritional composition. Phenolic compounds and phycocyanin (PC) are responsible for the many biological activities of Spirulina. Spirulina phenolic compounds are usually extracted using organic solvents, while PC is extracted with water or phosphate buffer solution, obtaining an extract characterized by low stability and low purity. Deep Eutectic Solvents (DESs) are green solvents, widely applied for bioactive molecules extraction, composed by two or more molecules which act as hydrogen bond acceptor or hydrogen bond donor to create an eutectic mixture. A Natural Deep Eutectic Solvent (NADES), is a DES composed only by natural compounds. This work aimed to optimize a green extraction procedure based on NADES to obtain an extract rich in phenolic compounds and PC from Spirulina. The application of NADESs as extraction solvents is an important strategy for recovering phenolic compounds and to increase and stabilize the protein PC. The optimized extraction procedure involved to use a betaine-glucose NADES under the following conditions: matrix-to-solvent ratio of 1:20 (w/w), temperature of 50 °C and one hour as extraction time. The developed extraction procedure guaranteed to recover a phenolic compounds and PC quantity of 11.77 ± 1.23 mg GAE (gallic acid equivalents) and 27.56 ± 2.46 g per g of Spirulina powder respectively. PC in the NADES extract degraded more slowly than in an aqueous extract. The extract phenolic compounds profile was determined through high performance liquid chromatography coupled with mass spectrometry analysis.

Exploring the biotechnological applications of Spirulina maxima: a comprehensive review

The Spirulina maxima algae is a phototrophic, multicellular, filamentous cyanobacteria of greenish blue tones, without ramifications and is characterized mainly by its helical form, thickness of approximately 3 to 12 µm and length of 500 µm; its development depends on factors such as temperature, light intensity, pH, aeration speed, carbon dioxide concentration, carbon source, nitrogen source which determine its chemical composition, which is composed of proteins, carbohydrates, lipids, minerals, and vitamins; due to this, it is widely used in industries such as food, pharmaceutical, cosmetics, and energy to obtain different products of great value. This S. maxima review addresses morphological characteristics, growth factors, growth methods, and metabolites of biotechnological interest and biotechnological applications for the S. maxima microalgae. A brief review of the enzyme production capacity of S. maxima and other microalgae is also presented, in addition to mentioning some areas of opportunity to study these and the economic viability of implementing a biorefinery with an integrated approach for the production of biomass and metabolites of biotechnological relevance based on the control of growth variables and the productive and economic efficiency of the process is discussed.

Impact of pH and protein/polysaccharide ratio on phycocyanin-okra polysaccharides complex

Phycocyanin is a natural blue pigment that tends to denature and lose its color in acidic solutions. In response to this problem, the complexes of phycocyanin (PC) with okra polysaccharides (OP) were prepared by ultrasonic processing at different pH conditions, and the molecular interactions of the complexes were characterized. The results showed that there were significant differences in the color, functional groups, and surface morphology of the complexes formed at different pH conditions. By colorimetry and particle size tester, it was demonstrated that the complex solution showed a steady blue color at pH 3.4. The highest fluorescence intensity (1.55 × 107 a.u.) and the significant red-shift of the complexes were observed at 0.4 % m/v polysaccharides addition. Infrared spectroscopy test further demonstrated that OP induced the formation of higher-order trimers of PC, which kept the color stable. Molecular dynamics simulations showed that the binding energy of PC/OP complex was -42.21 ± 2.61 kcal/mol, indicating that the binding affinity was very strong. Overall, this study suggests that this complex stabilizes the structure of PC, which in turn exerts a biological effect and will facilitate the use of PC as an artificial color substitute in food or beverage applications.

Direct detection of phycocyanin in sediments by hyperspectral imaging

Cyanobacteria are ubiquitous aquatic organisms with a remarkable evolutionary history reaching as far as 1.9 Ga. They play a vital role in ecosystems yet also raise concerns due to their association with harmful algal blooms. Understanding the historical patterns and drivers behind these blooms is crucial for effective ecosystem management. Lake-sediment cores are valuable natural environmental archives, recording the histories of such blooms. Among others, phycocyanin, a pigment specific to cyanobacteria, emerges as a promising biomarker for reconstructing past cyanobacterial bloom events. However, due to the physicochemical properties of phycocyanin, there is no validated method available to extract and measure this pigment from complex sediment matrix. This study explores the applicability of hyperspectral imaging (HSI), a non-destructive technique, as a novel approach for high resolution in-situ detection and quantification of phycocyanin in lake sediments. Our experiments show that phycocyanin can be detected by HSI with an absorption trough at 620 nm (relative absorption band depth, RABD620). We established a semi-quantitative calibration of the spectral index RABD620 by conducting spiking experiments with phycocyanin standard (known phycocyanin mass) on organic-rich and mineral-rich sediments of varying water contents. We also assessed potential interference from chlorophyll a, another photosynthetic pigment, ensuring the reliability of hyperspectral phycocyanin measurements. Our findings demonstrate a significant correlation (R2 ranging from 0.37 to 0.997) between the RABD620 index and associated phycocyanin amounts in organic-rich and minerogenic sediments. This indicates the potential of the spectral index to directly measure in-situ biomarker concentrations on split sediment cores. Although confounding factors such as water and chlorophyll a content can influence the spectral signal, this method offers a rapid and non-destructive approach for studying historical cyanobacterial blooms in sedimentary records. This opens promising grounds for various applications, including ecosystem-health assessment and environmental change monitoring.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10933-024-00350-y.

Effect of light conditions on phycoerythrin accumulation by thermophilic cyanobacterium Leptothermofonsia sichuanensis and characterization of pigment stability

Phycoerythrin (C-PE) is a cyanobacterial phycobiliprotein with extensive applications. This work sought to investigate the effects of various light conditions on C-PE accumulation by thermophilic Leptothermofonsia sichuanensis and characterize its C-PE stability and purity. Accumulation of C-PE as the predominant phycobiliprotein was significantly affected by light regime and light colours, reaching the highest C-PE accumulation (21.92 mg/gDCW) under blue light. Importantly, the results suggested the superior C-PE thermostability of Leptothermofonsia than the mesophilic counterparts and good pH stability at a range of 4 to 7. Additionally, C-PE indicated advantageous potential for preservation as revealed by photostability experiments. Moreover, sorbitol, sucrose, and NaCl can further stabilise C-PE at 60 °C, of which 10 % sorbitol is the most effective. The extraction process herein resulted in a C-PE purity of 2.68, much higher than the food grade. Collectively, this work demonstrates the Leptothermofonsia strain as a promising bioresource for thermostable C-PE production.

Coloration enhancement in Procambarus clarkii crayfish through dietary supplementation of phycocyanin extracted from Arthrospira platensis BUUC1503

Background and Aim

The effects of phycocyanin (PC) on pigmentation have been extensively studied in fish; however, its specific impact on crustaceans, particularly Procambarus clarkii, remains underexplored. This study aimed to evaluate the impact of PCs extracted from Arthrospira platensis BUUC1503 on the color enhancement of P. clarkii crayfish when added to food pellets.

Materials and Methods

The following five dietary treatments were prepared: a control (without PC) and four experimental diets with PC supplementation at concentrations of 10, 50, 100, and 500 mg/kg. The stability of the pellets in water was ensured for 180 min. P. clarkii crayfish were fed these diets at 5% of their body weight daily for 10 weeks. Body weight and total length were measured. Color changes in P. clarkii were also assessed. After the experiments, we treated the samples according to Animal Welfare Technical Information No.16.8 Correct euthanasia of decapods.

Results

Although PC supplementation did not significantly affect the yellowness (b* value) of P. clarkii, it significantly enhanced the redness (a* value) and lightness (L* value) pigmentation compared with the control. At week 10, crayfish fed a diet containing 100 mg/kg PC exhibited the highest L* value (36.51 ± 1.59) (p < 0.001). Diet with 500 mg/kg PCs had the highest a* value (26.96 ± 0.64) (p < 0.001). Crayfish fed 50, 100, or 500 mg/kg PC had the highest survival rate (100%). PCs appear to positively affect weight gain in P. clarkii crayfish during weeks 8, 9, and 10 (p = 0.013, 0.003, and 0.034, respectively). However, statistical analysis revealed no significant differences in length among the dietary treatments.

Conclusion

PCs effectively weight-gain and enhance red pigment deposition in the epidermal layer of P. clarkii. Further investigation is warranted to elucidate the underlying mechanisms.

Coupling ultrasound and membrane filtration for the fractionation of Spirulina platensis sp. and the recovery of phycocyanin and pigment-free proteins

The cyanobacterium Spirulina platensis was subjected to a fractionation process involving ultrasound-assisted extraction and membrane filtration to obtain a pure phycocyanin fraction and a clarified colorless protein fraction free of chlorophyll and carotenoids. The effects of pressure and power on total protein release were assessed. The retention of the extracted proteins was then assessed by ultrafiltration, with and without ammonium sulfate precipitation. Total protein recovery yields reached 97% in aqueous solution, at a low frequency (12 kHz), atmospheric pressure, and with an ultrasonic power of 200 Watts (W). Ammonium sulfate (25% w/v) precipitation was used to remove pigments and impurities from the crude protein extract. Finally, semi-frontal ultrafiltration resulted in high levels of C-phycocyanin recovery in the retentate: 95% and 91% with 10 and 100 kDa-cutoff membranes, respectively. However, the levels of total non-pigmented proteins in the permeate compartment did not exceed 67% with a 100 kDa-cutoff membrane. A fractionation process is proposed here for the valorization of two different protein fractions from Spirulina platensis.

Recent Advancements in Production and Extraction Methods of Phycobiliprotein C-phycocyanin by Arthrospira (Spirulina) platensis: A Mini Review

Arthrospira platensis has been utilized as a food source since ancient times due to its rich nutrient profile. In recent years, its popularity as a dietary supplement has soared, especially due to the presence of a water-soluble phycobiliprotein, C-phycocyanin C (C-PC), which is abundant and notable for its fluorescent properties. C-PC contains the chromophore phycocyanobilin B (PCB-B), a tetrapyrrole molecule, that is why it plays a dual role as a food colorant and as nutraceutical. However, comprehensive studies have mostly evaluated C-PC's broader health-promoting properties, particularly its antioxidative and anti-inflammatory effects, which are linked to its ability to contrast oxidative stress and related pathological conditions. That is why this review explores recent advancements in optimizing culture conditions to enhance C-PC and PCB-B production, with a particular emphasis on novel extraction and purification techniques that increase yield and bioactivity. This focus on efficient production methods is crucial for expanding the commercial and therapeutic applications of C-PC, contributing to its growing relevance in the food and pharmaceutical industries.

Fabrication of nanocomposite membranes containing Ag/GO nanohybrid for phycocyanin concentration

In this research, silver/graphene oxide (Ag/GO) nanohybrid was first synthesized and used in production of polysulfone (PSF) ultrafiltration (UF) membranes via phase inversion method for concentrating phycocyanin (PC) and treating methylene blue (MB) dye effluent. Designing the experiment (DOE) using Box-Behnken method by Design Expert software helped to calculate the optimal values of the variables under study. The studied variables included PSF polymer concentration, polyvinyl pyrrolidone (PVP) pore-former concentration and Ag/GO nanohybrid content, which were investigated for their effects on pure water flux (PWF) and MB pigment rejection. According to the results of the DOE, the membrane containing 19.485 wt% PSF, 0.043 wt% PVP and 0.987 wt% Ag/GO was selected as the optimal membrane. Due to the high price of PC as drug, and the importance of removing MB pigment from the effluent of dyeing and textile industries, the membranes were first optimized with MB pigment and then the optimal membrane was used for concentrating PC. The results showed that PWF reaches from 40.05 L.m- 2.h- 1 (LMH) for the neat membrane to 156.73 LMH for the optimized membrane, which shows about 4 times improvement. Compared to the neat membrane, flux recovery ratio (FRR) of the optimized membrane increased by about 20% and its total fouling (Rt) decreased by about 10%. Also, the results showed that the optimized membrane can remove 81.6% of MB, as well as to reject 93.8% of PC.

Phycocyanin-Loaded Alginate-Based Hydrogel Synthesis and Characterization

Phycocyanin was extracted from Spirulina platensis using conventional extraction (CE), direct ultrasonic-assisted extraction (direct UAE), indirect ultrasonic-assisted extraction (indirect UAE), and microwave-assisted extraction (MAE) methods at different temperatures, extraction intervals, stirring rate, and power intensities while maintaining the same algae to solvent ratio (1:15 w/v). The optimization of the extraction parameters indicated that the direct UAE yielded the highest phycocyanin concentration (29.31 ± 0.33 mg/mL) and antioxidant activity (23.6 ± 0.56 mg TE/g algae), while MAE achieved the highest purity (Rp = 0.5 ± 0.002). Based on the RP value, phycocyanin extract obtained by MAE (1:15 w/v algae to solvent ratio, 40 min, 40 °C, and 900 rpm) was selected as active compound in an alginate-based hydrogel formulation designed as potential wound dressings. Phycocyanin extracts and loaded hydrogels were characterized by FT-IR analysis. SEM analysis confirmed a porous structure for both blank and phycocyanin loaded hydrogels, while the mechanical properties remained approximately unchanged in the presence of phycocyanin. Phycocyanin release kinetics was investigated at two pH values using Zero-order, First-order, Higuchi, and Korsmeyer-Peppas kinetics models. The Higuchi model best fitted the experimental results. The R2 value at higher pH was nearly 1, indicating a superior fit compared with lower pH values.

In Vitro Study of Cyano-Phycocyanin Release from Hydrogels and Ex Vivo Study of Skin Penetration

BACKGROUND

This study explored the most suitable materials for incorporating cyano-phycocyanin (C-PC) into hydrogels, focusing on maintaining the C-PC's long-term structural integrity and stabilityNext, the release of C-PC from the hydrogels and its skin penetration were investigated.

METHODS

A series of 1% (w/w) C-PC hydrogels was prepared using various gelling agents and preservatives. Spectrophotometric measurements compared the amount of C-PC in the hydrogels to the initially added amount. After selecting the most suitable gelling agent and preservative, two C-PC hydrogels, with and without propylene glycol (PG) (Sigma-Aldrich, St. Louis, MO, USA), were produced for further testing. In vitro release studies utilized modified Franz-type diffusion cells, while ex vivo skin-permeation studies employed Bronaugh-type cells and human skin. Confocal laser scanning microscopy analyzed C-PC accumulation in the skin.

RESULTS

The findings demonstrated that sodium alginate (Sigma-Aldrich, St. Louis, MO, USA), hydroxyethyl cellulose (HEC) (Sigma-Aldrich, St. Louis, MO, USA), and SoligelTM (Givaudan, Vernier, Switzerland) are effective biopolymers for formulating hydrogels while maintaining C-PC stability. After 6 h, C-PC release from the hydrogel containing PG was approximately 10% or 728.07 (±19.35) μg/cm2, significantly higher than the nearly 7% or 531.44 (±26.81) μg/cm2 release from the hydrogel without PG (p < 0.05). The ex vivo qualitative skin-permeation study indicated that PG enhances C-PC penetration into the outermost skin layer.

CONCLUSION

PG's ability to enhance the release of C-PC from the hydrogel, coupled with its capacity to modify the skin barrier ex vivo, facilitates the penetration of C-PC into the stratum corneum.

Chromatographic purification of C-phycocyanin from Spirulina platensis: assessing antioxidant activity and stability

BACKGROUND

The efficient separation and purification of proteins like C-phycocyanin (C-PC) from Spirulina platensis are essential for their commercialization, yet they remain challenging. This study investigated three chromatographic methods for C-PC purification: weak anion exchange chromatography (DEAE), strong anion exchange chromatography (Q Sepharose), and hydrophobic interaction chromatography (HIC).

RESULTS

Weak anion exchange chromatography achieved a recovery of 36.80 mg unit (57.08%) with a purity of 3.23, outperforming Q Sepharose (yield: 23.21 mg unit means that 46.33%, purity: 2.76) and HIC (yield: 22.95 mg unit means that 17.57%, purity: 3.02). The purified C-PC consisted of α and β subunits with molecular masses of 16 kDa and 17 kDa, respectively. Further assessment revealed its antioxidant capacity through a 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. The stability of C-phycocyanin was tested at different pH levels and temperatures. Maximum stability was observed at pH 7, and pH 4 showed the lowest stability. Glutaraldehyde-treated C-PC (GC-PC) demonstrated gradual degradation up to 50 °C, retaining 73.25% after 30 min. Notably, GC-PC exhibited stability even at higher temperatures, with degradation rates of 57.32% at 70 °C and 50.96% at 80 °C.

CONCLUSION

Weak anion exchange chromatography proved superior for C-PC purification, offering higher yields and purity than Q Sepharose and HIC. The purified C-PC showed promising antioxidant capacity and stability, particularly GC-PC, which exhibited resistance to degradation, even at elevated temperatures. These findings underscore the potential of C-PC as a valuable compound for various applications, with DEAE chromatography being an efficient method for its production and commercialization. © 2024 Society of Chemical Industry.

Trends in extracting protein from microalgae Spirulina platensis, using innovative extraction techniques: mechanisms, potentials, and limitations

Microalgal, species are recognized for their high protein content, positioning them as a promising source of this macronutrient. Spirulina platensis, in particular, is noteworthy for its rich protein levels (70 g/100 g dw), which are higher than those of meat and legumes. Incorporating this microalgae into food can provide various benefits to human health due to its diverse chemical composition, encompassing high amount of protein and elevated levels of minerals, phenolics, essential fatty acids, and pigments. Conventional techniques employed for protein extraction from S. platensis have several drawbacks, prompting the exploration of innovative extraction techniques (IETs) to overcome these limitations. Recent advancements in extraction methods include ultrasound-assisted extraction, microwave-assisted extraction, high-pressure-assisted extraction, supercritical fluid extraction, pulse-electric field assisted extraction, ionic liquids assisted extraction, and pressurized liquid extraction. These IETs have demonstrated efficiency in enhancing protein yield of high quality while maximizing biomass utilization. This comprehensive review delves into the mechanisms, applications, and drawbacks associated with implementing IETs in protein extraction from S. platensis. Notably, these innovative methods offer advantages such as increased extractability, minimized protein denaturation, reduced solvent consumption, and lower energy consumption. However, safety considerations and the synergistic effects of combined extraction methods warrant further exploration and investigation of their underlying mechanisms.

Influence of Critical Parameters on the Extraction of Concentrated C-PE from Thermotolerant Cyanobacteria

This work aimed to identify the influence of pH, molarity, w/v fraction, extraction time, agitation, and either a sodium (Na2HPO4·7H2O-NaH2PO4·H2O) or potassium buffer (K2HPO4-KH2PO4) used in the extraction of C-phycoerythrin (C-PE) from a thermotolerant strain of Potamosiphon sp. An experimental design (Minimum Run Resolution V Factorial Design) and a Central Composite Design (CCD) were used. According to the statistical results of the first design, the K-PO4 buffer, pH, molarity, and w/v fraction are vital factors that enhance the extractability of C-PE. The construction of a CCD design of the experiments suggests that the potassium phosphate buffer at pH 5.8, longer extraction times (50 min), and minimal extraction speed (1000 rpm) are ideal for maximizing C-PE concentration, while purity is unaffected by the design conditions. This optimization improves extraction yields and maintains the desired bright purple color of the phycobiliprotein.

Phycocyanin alleviates alcohol-induced testicular injury in male Wistar rats

OBJECTIVE

Given the noteworthy implications of alcohol consumption and its association with male infertility, there has been a notable focus on investigating natural alternatives to mitigate its adverse effects. Thus, this study was conducted to assess the potential protective effect of phycocyanin extract derived from the blue algae Arthrospira (Spirulina) platensis against ethanol-induced oxidative stress, disturbances in testicular morphology, and alterations in sperm production.

METHODS

Male rats were divided into four groups (five rats each): the control group received a saline solution, the ethanol exposed group (EtOH) was subjected to intraperitoneal injections of 10 mL/kg of ethanol solution at a concentration of 38% (v/v), the phycocyanin alone treated group (P) received oral administration of phycocyanin at a dosage of 50 mg/kg, and the phycocyanin-cotreated group (PE) was given oral phycocyanin followed by ethanol injections. All treatments were administered over a period of 14 days.

RESULTS

Our findings demonstrated that ethanol exposure induced reproductive toxicity, characterized by reduced sperm production and viability, alterations in testicular weight and morphology, increased lipid peroxidation levels, and elevated oxidative enzyme activity. In addition, the ethanol-intoxicated group showed perturbations in serum biochemical parameters. However, the simultaneous exposure to ethanol and phycocyanin exhibited a counteractive effect against ethanol toxicity.

CONCLUSION

The results showed that supplementation of phycocyanin prevented oxidative and testicular morphological damage-induced by ethanol and maintained normal sperm production, and viability.

Optimizing Phycocyanin Extraction from Cyanobacterial Biomass: A Comparative Study of Freeze-Thaw Cycling with Various Solvents

Cyanobacterial phycocyanin pigment is widely utilized for its properties in various industries, including food, cosmetics, and pharmaceuticals. Despite its potential, challenges exist, such as extraction methods impacting yield, stability, and purity. This study investigates the impact of the number of freeze-thaw (FT) cycles on the extraction of phycocyanin from the wet biomass of four cyanobacteria species (Arthrospira platensis, Chlorogloeopsis fritschii, Phormidium sp., and Synechocystis sp.), along with the impact of five extraction solutions (Tris-HCl buffer, phosphate buffer, CaCl2, deionized water, and tap water) at various pH values. Synechocystis sp. exhibited the highest phycocyanin content among the studied species. For A. platensis, Tris-HCl buffer yielded maximum phycocyanin concentration from the first FT cycle, while phosphate buffer provided satisfactory results from the second cycle. Similarly, Tris-HCl buffer showed promising results for C. fritschii (68.5% of the maximum from the first cycle), with the highest concentration (~12% w/w) achieved during the seventh cycle, using phosphate buffer. Phormidium sp. yielded the maximum pigment concentration from the first cycle using tap water. Among species-specific optimal extraction solutions, Tris-HCl buffer demonstrated sufficient extraction efficacy for all species, from the first cycle. This study represents an initial step toward establishing a universal extraction method for phycocyanin from diverse cyanobacteria species.

Enhancing phycocyanin yield from Spirulina sp. under salt stress using various extraction methods

Phycocyanin, a blue-coloured pigment, predominantly found and derived from Spirulina sp., has gained researchers' interest due to its vibrant hues and other attractive properties like antioxidant and anti-microbial. However, the lack of reliable and sustainable phycocyanin extraction strategies without compromising the quality has hindered the scaling up of its production processes for commercial purposes. Here in this study, phycocyanin was extracted from wet and dry biomass Spirulina sp., using three different physical cell disruption methods (ultrasonication, homogenization, and freeze-thaw cycles) combined with two different buffers (phosphate buffer and acetate buffer) and water (as control). The result showed that the freeze-thaw method combined with acetate buffer produced the highest yield (25.013 ± 2.572 mg/100 mg) with a purity ratio of 0.806 ± 0.079. Furthermore, when subjected to 30% w/v salt stress, 1.9 times higher phycocyanin yield with a purity ratio of 1.402 ± 0.609 was achieved using the previously optimized extraction method.

Microalgae Biomass Production from Rice Husk as Alternative Media Cultivation and Extraction of Phycocyanin Using 3D-Printed Ohmic Heating Reactor

Phycocyanin is a highly valued pigment present in Spirulina platensis biomass with applications in the food industry in terms of biorefinery concepts; specifically, its antioxidant and antimicrobial capacity are an advantage that could be incorporated into a food matrix. This study aims to use rice husk as an alternative culture medium for S. platensis biomass growth and phycocyanin extraction by ohmic heating processing using a 3D-printed reactor. S. platensis was cultivated in rice husk extract (RHE) from 0-100% (v/v). The highest content of microalgal biomass was 1.75 ± 0.01 g/L, with a specific growth rate of 0.125 ± 0.01 h-1. For the phycocyanin extraction under an ohmic heating process, a 3D-printed reactor was designed and built. To optimize phycocyanin extraction, a central composite rotatable design (CCDR) was evaluated, with three factors: time (min), temperature (°C), and pH. The highest phycocyanin content was 75.80 ± 0.98 mg/g in S. platensis biomass grown with rice husk extract. Ohmic heating is a promising method for rapid phycocyanin extraction, and rice husk as a culture medium is an alternative for the growth of S. platensis biomass in the integration of second- and third-generation biorefineries.

Exploiting Natural Niches with Neuroprotective Properties: A Comprehensive Review

Natural products from mushrooms, plants, microalgae, and cyanobacteria have been intensively explored and studied for their preventive or therapeutic potential. Among age-related pathologies, neurodegenerative diseases (such as Alzheimer's and Parkinson's diseases) represent a worldwide health and social problem. Since several pathological mechanisms are associated with neurodegeneration, promising strategies against neurodegenerative diseases are aimed to target multiple processes. These approaches usually avoid premature cell death and the loss of function of damaged neurons. This review focuses attention on the preventive and therapeutic potential of several compounds derived from natural sources, which could be exploited for their neuroprotective effect. Curcumin, resveratrol, ergothioneine, and phycocyanin are presented as examples of successful approaches, with a special focus on possible strategies to improve their delivery to the brain.

Comparative Analysis of Effect of Culture Conditions on Growth and C-Phycocyanin Production in Helical and Linear Spirulina

Spirulina (Arthrospira and Spirulina spp.) has always been characterized by the helical trichomes, despite the existence of linear forms. A great debate is now open on the morphological flexibility of Spirulina, but it seems that both trichome morphology and C-phycocyanin (C-PC) concentrations are influenced by the culture conditions.This work compared the effect of some key growth factors (medium pH as well as its carbon, potassium, and salt contents) on the growth and C-PC concentration of helical and linear Spirulina strains. Further, two-phase strategies, including light and nitrogen variation, were applied to increase the in vivo C-PC accumulation into the trichomes. Results showed that high pH induced trichomes elongation and improved growth but decreased C-PC content (+ 65 and + 43% vs. -83 and -49%, for helical and linear strains, respectively). Variations in carbon and salt concentrations negatively impacted growth and C-PC content, even if the linear strain was more robust against these fluctuations. It was also interesting to see that potassium increasing improved growth and C-PC content for both strains.The variation of light wavelength during the enrichment phase (in the two-phase strategy) improved by 50% C-PC accumulation in trichomes, especially after blue lighting for 96 h. Similar result was obtained after 48 h of nitrogen reduction, while its removal from the medium caused trichomes disintegration. The current work highlights the robustness of linear Spirulina strain and presents an efficient and scalable way to increase C-PC in vivo without affecting growth.

Stability and bioactivities evaluation of analytical grade C-phycocyanin during the storage of Spirulina platensis powder

C-phycocyanin (C-PC) is a natural high-value blue phycobiliprotein from Spirulina platensis, which has wide biological applications in food, pharmaceutical, and cosmetics. However, the freshness of S. platensis powder (SPP) materials and C-PC purification play critical roles in evaluating the stability and bioactivities of C-PC, which severely affect its commercial application. This study investigated the effect of spray-dried SPP freshness on the biofunctional activities of analytical grade C-PC (AGC-PC). The yield of AGC-PC extracted from spray-dried SPP could reach 101.88 mg/g (75% recovery ratio) after purification by reversed phase high-performance liquid chromatography (RP-HPLC) system. The half-life period (t1/2 ) of AGC-PC stability at 60°C and 8000 lux light could remain 171.70 min and 176.11 h within 6 months storage of spray-dried SPP. The emulsifying activity index (EAI) and foaming capacity (FC) of AGC-PC from fresh-dried SPP showed maximum values of 68.64 m2 /g and 252.9%, respectively. The EC50 of AGC-PC from fresh spray-dried SPP on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline -6-sulfonic acid (ABTS+·) scavenging activity could reach 63.76 and 92.93 mg/L, respectively. The EC50 of AGC-PC from fresh spray-dried SPP on proteinase inhibition and anti-lipoxygenase activity were 302.96 and 178.8 mg/L, respectively. The stability and biofunctional activities of AGC-PC remained stable within 6 months storage of SPP, and then rapidly decreased after 9 months storage due to the disintegration of the trimeric (αβ)3 and hexameric (αβ)6 forms of C-PC. It is concluded that the optimal storage period of SPP for preparation of AGC-PC in commercial use should be less than 6 months. PRACTICAL APPLICATION: The C-phycocyanin (C-PC) from dried Spirulina platensis powder (SPP) has been widely applied in food nutritional, florescent markers, pharmaceuticals, cosmetics, etc, due to its blue color, fluorescence, and antioxidant properties. However, the effect of dried SPP freshness on the stability and functional activity of C-PC has been rarely reported. This study found that the thermostability, photostability, emulsifying, antioxidant, and anti-inflammatory activities of analytical grade C-PC (AGC-PC) significantly decreased after 6 months storage of SPP. Based on investigations, we have proposed that the suitable storage time of dried SPP for preparation of AGC-PC in commercial application should be within 6 months.

Challenges in Functional Food Products with the Incorporation of Some Microalgae

Much attention has been given to the use of microalgae to produce functional foods that have valuable bioactive chemicals, including essential amino acids, polyunsaturated fatty acids, vitamins, carotenoids, fiber, and minerals. Microalgal biomasses are increasingly being used to improve the nutritional values of foods because of their unique nutrient compositions that are beneficial to human health. Their protein content and amino acid composition are the most important components. The microalgal biomass used in the therapeutic supplement industry is dominated by bio-compounds like astaxanthin, β-carotene, polyunsaturated fatty acids like eicosapentaenoic acid and docosahexaenoic acid, and polysaccharides such as β-glucan. The popularity of microalgal supplements is growing because of the health benefits of their bioactive substances. Moreover, some microalgae, such as Dunaliella, Arthrospira (Spirulina), Chlorella, and Haematococcus, are commonly used microalgal species in functional food production. The incorporation of microalgal biomass leads not only to enhanced nutritional value but also to improved sensory quality of food products without altering their cooking or textural characteristics. Microalgae, because of their eco-friendly potential, have emerged as one of the most promising and novel sources of new functional foods. This study reviews some recent and relevant works, as well as the current challenges for future research, using different methods of chemical modification in foods with the addition of a few commercial algae to allow their use in nutritional and sensory areas. It can be concluded that the production of functional foods through the use of microalgae in foods has become an important issue.

Studying the impact of phycoerythrin on antioxidant and antimicrobial activity of the fresh rainbow trout fillets

Marine cyanobacteria present a significant potential source of new bioactive compounds with vast structural diversity and relevant antimicrobial and antioxidant activities. Phycobiliproteins (PBPs) like phycocyanin (PC), phycoerythrin (PE), and water-soluble cyanobacterial photosynthetic pigments, have exhibited strong pharmacological activities and been used as natural food additives. In this study, phycoerythrin (PE) isolated from a marine strain of cyanobacterium Nostoc sp. Ft salt, was applied for the first time as a natural antimicrobial as well as an antioxidant to increase the shelf life of fresh rainbow trout i.e., (Oncorhynchus mykiss) fillets. Fresh trout fillets were marinated in analytical grade PE (3.9 μg/mL) prepared in citric acid (4 mg/mL), and stored at 4 °C and 8 °C for 21 days. Microbiological analysis, antioxidant activity and organoleptic evaluation of both control and treated fish fillets were then statistically compared. The results demonstrated noticeable (P < 0.05) differences in the microbial counts, antioxidant activity, and organoleptic characteristic values between PE-treated and non-treated groups. In addition, we observed that treating fresh fish fillets with a PE solution leads to a significant increase in shelf life by at least 14 days. Consequently, PE could be an alternative to synthetic chemical additives since it does not contain the potentially dangerous residues of the synthetic chemical additives and is thus healthier to the consumers.

Cross-Linked Hyaluronan Derivatives in the Delivery of Phycocyanin

An easy and viable crosslinking technology, based on the "click-chemistry" reaction copper(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (click-crosslinking), was applied to graft copolymers of medium molecular weight (i.e., 270 kDa) hyaluronic acid (HA) grafted with ferulic acid (FA) residues bearing clickable propargyl groups, as well as caffeic acid derivatives bearing azido-terminated oligo(ethylene glycol) side chains. The obtained crosslinked materials were characterized from the point of view of their structure and aggregation liability to form hydrogels in a water environment. The most promising materials showed interesting loading capability regarding the antioxidant agent phycocyanin (PC). Two novel materials complexes (namely HA(270)-FA-TEGEC-CL-20/PC and HA(270)-FA-HEGEC-CL-20/PC) were obtained with a drug-to-material ratio of 1:2 (w/w). Zeta potential measurements of the new complexes (-1.23 mV for HA(270)-FA-TEGEC-CL-20/PC and -1.73 mV for HA(270)-FA-HEGEC-CL-20/PC) showed alterations compared to the zeta potential values of the materials on their own, suggesting the achievement of drug-material interactions. According to the in vitro dissolution studies carried out in different conditions, novel drug delivery systems (DDSs) were obtained with a variety of characteristics depending on the desired route of administration and, consequently, on the pH of the surrounding environment, thanks to the complexation of phycocyanin with these two new crosslinked materials. Both complexes showed excellent potential for providing a controlled/prolonged release of the active pharmaceutical ingredient (API). They also increased the amount of drug that reach the target location, enabling pH-dependent release. Importantly, as demonstrated by the DPPH free radical scavenging assay, the complexation process, involving freezing and freeze-drying, showed no adverse effects on the antioxidant activity of phycocyanin. This activity was preserved in the two novel materials and followed a concentration-dependent pattern similar to pure PC.

Investigation of the Potential of Selected Food-Derived Antioxidants to Bind and Stabilise the Bioactive Blue Protein C-Phycocyanin from Cyanobacteria Spirulina

Blue C-phycocyanin (C-PC), the major Spirulina protein with innumerable health-promoting benefits, is an attractive colourant and food supplement. A crucial obstacle to its more extensive use is its relatively low stability. This study aimed to screen various food-derived ligands for their ability to bind and stabilise C-PC, utilising spectroscopic techniques and molecular docking. Among twelve examined ligands, the protein fluorescence quenching revealed that only quercetin, coenzyme Q10 and resveratrol had a moderate affinity to C-PC (Ka of 2.2 to 3.7 × 105 M-1). Docking revealed these three ligands bind more strongly to the C-PC hexamer than the trimer, with the binding sites located at the interface of two (αβ)3 trimers. UV/VIS absorption spectroscopy demonstrated the changes in the C-PC absorption spectra in a complex with quercetin and resveratrol compared to the spectra of free protein and ligands. Selected ligands did not affect the secondary structure content, but they induced changes in the tertiary protein structure in the CD study. A fluorescence-based thermal stability assay demonstrated quercetin and coenzyme Q10 increased the C-PC melting point by nearly 5 °C. Our study identified food-derived ligands that interact with C-PC and improve its thermal stability, indicating their potential as stabilising agents for C-PC in the food industry.

Influence of cold atmospheric pressure plasma treatment of Spirulina platensis slurry over biomass characteristics

Cold atmospheric pressure plasma (CAPP) technique is an innovative non-thermal approach for food preservation and decontamination. This study aimed to evaluate the effect of CAPP power density on microorganism inactivation and quality of Spirulina platensis (S. platensis) slurry. 91.31 ± 1.61% of microorganism were inactivated within 2.02 ± 0.11 min by 26.67 W/g CAPP treatment under 50 ℃. Total phenolic, Chlorophyll-a (Chl-a), and carotenoids contents were increased by 20.51%, 63.55%, and 70.04% after 20.00 W/g CAPP treatment. Phycobiliproteins (PBPs), protein, intracellular polysaccharide, and moisture content of S. platensis was decreased, while vividness, lightness, color of yellow and green, antioxidant activity, Essential Amino Acid Index were enhanced after CAPP treatment. The nutrient release and filaments breakage of CAPP-treated S. platensis improved its bio-accessibility. The findings provided a deep understanding and insight into the influence of CAPP treatment on S. platensis, which were meaningful for optimizing its sterilization and drying processing condition.

Partitioning Recovery of Natural Pigments from Spirulina platensis

In the last few decades, the recovery of high-added value compounds with high food potential using microalgae as feedstock has been one of the main challenges for both research and industry. This study provides a simple, affordable, and cost-saving approach for the selective recovery of C-phycocyanin (C-PC), chlorophyll a and carotenoids from Spirulina platensis biomass by using biocompatible and industrially approved solvents (such as CaCl2 and ethanol). The concentration and yield of each pigment in the liquid extract have been spectrophotometrically detected, whereas the decolorized protein-rich biomass has been analyzed by CIELab parameters. The most concentrated (566.4 μg/mL) and food-grade C-PC extract (purity index 0.7) was obtained by applying a biomass/solvent ratio (1:10) for the first round of extraction (20 min), followed by a second round at 1:5 using CaCl2 1.5% (w/v) aqueous solution. Additionally, the same trial enabled the production of the brightest decolorized protein-rich biomass (L* = 46.2), characterized by a yellow-orange tonality (h° values = 81.3°).

The Experimental Development of Emulsions Enriched and Stabilized by Recovering Matter from Spirulina Biomass: Valorization of Residue into a Sustainable Protein Source

Spirulina consists of a cluster of green-colored cyanobacteria; it is commonly consumed as a food or food supplement rich in bioactive compounds with antioxidant activity, predominantly C-phycocyanin (C-PC), which is related to anti-inflammatory action and anticancer potential when consumed frequently. After C-PC extraction, the Spirulina residual biomass (RB) is rich in proteins and fatty acids with the potential for developing food products, which is interesting from the circular economy perspective. The present work aimed to develop a vegan oil-in-water emulsion containing different contents of Spirulina RB, obtaining a product aligned with current food trends. Emulsions with 3.0% (w/w) of proteins were prepared with different chickpea and Spirulina RB ratios. Emulsifying properties were evaluated regarding texture and rheological properties, color, antioxidant activity, and droplet size distribution. The results showed that it was possible to formulate stable protein-rich emulsions using recovering matter rich in protein from Spirulina as an innovative food ingredient. All the concentrations used of the RB promoted the formulation of emulsions presenting interesting rheological parameters compared with a more traditional protein source such as chickpea. The emulsions were also a source of antioxidant compounds and maintained the color for at least 30 days after production.

Valuable pigments from microalgae: phycobiliproteins, primary carotenoids, and fucoxanthin

Phycobiliproteins, carotenoids and fucoxanthin are photosynthetic pigments extracted from microalgae and cyanobacteria with great potential biotechnological applications, as healthy food colorants and cosmetics. Phycocyanin possesses a brilliant blue color, with fluorescent properties making it useful as a reagent for immunological essays. The most important source of phycocyanin is the cyanobacterium Arthrospira platensis, however, recently, the Rhodophyta Galdieria sulphuraria has also been identified as such. The main obstacle to the commercialization of phycocyanin is represented by its chemical instability, strongly reducing its shelf-life. Moreover, the high level of purity needed for pharmaceutical applications requires several steps which increase both the production time and cost. Microalgae (Chlorella, Dunaliella, Nannochloropsis, Scenedesmus) produce several light harvesting carotenoids, and are able to manage with oxidative stress, due to their free radical scavenging properties, which makes them suitable for use as source of natural antioxidants. Many studies focused on the selection of the most promising strains producing valuable carotenoids and on their extraction and purification. Among carotenoids produced by marine microalgae, fucoxanthin is the most abundant, representing more than 10% of total carotenoids. Despite the abundance and diversity of fucoxanthin producing microalgae only a few species have been studied for commercial production, the most relevant being Phaeodactylum tricornutum. Due to its antioxidant activity, fucoxanthin can bring various potential benefits to the prevention and treatment of lifestyle-related diseases. In this review, we update the main results achieved in the production, extraction, purification, and commercialization of these important pigments, motivating the cultivation of microalgae as a source of natural pigments.

Enhanced phycocyanin production from Spirulina subsalsa via freshwater and marine cultivation with optimized light source and temperature

To find out optimum and cost-efficient strategy for phycocyanin production, the effect of light source and temperature on Spirulina subsalsa growth were studied in chemically defined freshwater medium and seawater supplied with wastewater from glutamic acid fermentation tank. Maximum growth rate and the highest phycocyanin content were obtained by 35 °C and green light, respectively. A two-stage cultivation strategy was proposed and applied, which combines biomass accumulation at 35 °C and phycocyanin synthesis simulated under green light. As a result, phycocyanin production reached 70 mg/L/d and 11 mg/L/d from freshwater and seawater medium, respectively. With all tested conditions, a strong correlation between biomass and phycocyanin/chlorophyll ratio, rather than phycocyanin, revealed the dependence of Spirulina subsalsa growth on coordinating regulation of photosynthetic pigments. The relationship between growth and phycocyanin production under various light and temperature can be a good basis for improving phycocyanin production from Spirulina subsalsa with or without freshwater consumption.

Efficient extraction of phycobiliproteins from dry biomass of Spirulina platensis using sodium chloride as extraction enhancer

An efficient strategy for phycobiliprotein extraction from Spirulina platensis dry biomass has been developed by using NaCl as an enhancer. Different sodium ion and chloride ion salts were screened, and NaCl was selected as the most appropriate solvent for phycobiliprotein extraction. The extraction parameters with NaCl were optimized using response surface methodology. Under optimal operating conditions, a phycobiliprotein extraction rate of 74.8 % and a phycocyanin extraction yield of 102.4 mg/g with a purity of 74.0 % were achieved. Adding NaCl resulted in smaller fragments and destroyed the cell integrity of S. platensis, facilitating phycobiliprotein exudation. The secondary structure and antioxidant activity of phycobiliproteins were not affected by NaCl extraction. The stability of the phycobiliproteins was improved by adding NaCl. This study provides a potential method for phycobiliprotein extraction with high efficiency and good quality using an inexpensive extraction enhancer.

Exploring the Benefits of Phycocyanin: From Spirulina Cultivation to Its Widespread Applications

Large-scale production of microalgae and their bioactive compounds has steadily increased in response to global demand for natural compounds. Spirulina, in particular, has been used due to its high nutritional value, especially its high protein content. Promising biological functions have been associated with Spirulina extracts, mainly related to its high value added blue pigment, phycocyanin. Phycocyanin is used in several industries such as food, cosmetics, and pharmaceuticals, which increases its market value. Due to the worldwide interest and the need to replace synthetic compounds with natural ones, efforts have been made to optimize large-scale production processes and maintain phycocyanin stability, which is a highly unstable protein. The aim of this review is to update the scientific knowledge on phycocyanin applications and to describe the reported production, extraction, and purification methods, including the main physical and chemical parameters that may affect the purity, recovery, and stability of phycocyanin. By implementing different techniques such as complete cell disruption, extraction at temperatures below 45 °C and a pH of 5.5-6.0, purification through ammonium sulfate, and filtration and chromatography, both the purity and stability of phycocyanin have been significantly improved. Moreover, the use of saccharides, crosslinkers, or natural polymers as preservatives has contributed to the increased market value of phycocyanin.

Arthrospira platensis Variants: A Comparative Study Based on C-phycocyanin Gene and Protein, Habitat, and Growth Conditions

This study aimed to map the differences between Arthrospira sp. and Arthrospira platensis strains and variants from the order Oscillatoriales at the gene and protein levels of C-phycocyanin alpha chain via multiple alignment, phylogenetic trees of species, and analysis of the nucleotide and amino acid composition of the studied sequences. The links between gene/protein and environmental features of the habitat or source of isolation were also investigated. Phycocyanin was extracted from three A. platensis strains: an Egyptian isolate cultivated in the laboratory under static conditions in a highly saline medium and two commercial products. The French commercial strain showed the highest extraction yield but the lowest C-phycocyanin purity, and the color intensity of the extracted pigment from the Egyptian isolate was significantly weaker than those of the two commercial strains. All the analyzed species and strains had GC content of more than 54.5% in C-phycocyanin alpha chain gene and showed high abundance of alanine, an amino acid encoded exclusively by GC-biased codons, in their protein. The frequencies of the acidic amino acids aspartic acid and glutamic acid were 5.2% and 5.0% on average, respectively, which were slightly higher than those of the basic residues (4.3% arginine, 0.6% histidine, and 5.0% lysine). Data relating to the isolation source of most of the analyzed species revealed harsh conditions, such as high alkalinity, salinity, CO2 saturation, and/or temperature. These findings may link the gene/protein of C-phycocyanin, which is one of the most important bioactive proteins of A. platensis, to the adaptation of this organism to harsh environmental conditions and associate the color of the pigment to cultivation conditions and/or isolation source.

The Effect of Storage and Pasteurization (Thermal and High-Pressure) Conditions on the Stability of Phycocyanobilin and Phycobiliproteins

The utilization of natural blue pigments in foods is difficult as they are usually unstable during processing and the commonly applied pH. The current study focuses on natural blue pigment, possessing antioxidant properties, found in Arthrospira platensis (spirulina), and phycobiliproteins (PBP). These pigments are a complex of conjugated protein and non-protein components, known as phycocyanobilin. PBP has low stability during pasteurization (high-pressure or heat treatments), resulting in protein denaturation and color deterioration that limits the application. The phycocyanobilin pigment might also be liable to oxidation during pasteurization and storage, resulting in color deterioration. Yet, the instability of the pigment phycocyanobilin during the pasteurization process and storage conditions was never studied before, limiting the comprehensive understanding of the reasons for PBP instability. In this study, the stability of phycocyanobilin under high-pressure and high-temperature conditions was compared to the stability of phycobiliproteins. We revealed that phycobiliproteins have a higher color deterioration rate at 70–80 °C than at high-pressure (300–600 MPa) whereas phycocyanobilin remained stable during high-pressure and heat processing. During storage at pH 7, phycocyanobilin was oxidized, and the oxidation rate increased with increasing pH, while at lower pH phycocyanobilin had low solubility and resulted in aggregation.

Arthrospira (Spirulina) platensis feeding reduces the early stage of chemically induced rat colon carcinogenesis

Colorectal cancer is the third most diagnosed cancer worldwide and linked to dietary/lifestyle factors. Arthrospira (Spirulina) platensis (AP) contains bioactive compounds with beneficial effects in vivo/in vitro. We evaluated the effects of AP feeding against 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis. Male Sprague Dawley rats were given subcutaneous injections of DMH (4 × 40 mg/kg body weight) (G1-G3) or vehicle (G4-G5) twice a week (weeks 3-4). During weeks 1-4, animals were fed a diet containing 1 % (G2) or 2 % (G3-G4) AP powder (w/w). After this period, all groups received a balanced diet until week 12. Some animals were euthanised after the last DMH injection (week 4) for histological, immunohistochemical (Ki-67, γ-H2AX and caspase-3) and molecular analyses (real time-PCR for 91 genes), while other animals were euthanised at week 12 for preneoplastic aberrant crypt foci (ACF) analysis. Both AP treatments (G2-G3) significantly decreased the DMH-induced increase in γ-H2AX (DNA damage) and caspase 3 (DNA damage-induced cell death) in colonic crypts at week 4. In addition, Cyp2e1 (Drug metabolism), Notch1, Notch2 and Jag1 genes (Notch pathway) and Atm, Wee1, Chek2, Mgmt, Ogg1 and Xrcc6 genes (DNA repair) were also down-regulated by 2 % AP feeding (G3) at week 4. A significant reduction in ACF development was observed in both AP-treated groups (G2-G3) at week 12. In conclusion, findings indicate that AP feeding reduced acute colonic damage after DMH, resulting in fewer preneoplastic lesions. Our study provided mechanistic insights on dietary AP-preventive effects against early colon carcinogenesis.

Spirulina platensis Immobilized Alginate Beads for Removal of Pb(II) from Aqueous Solutions

Microalgae contain a diversity of functional groups that can be used as environmental adsorbents. Spirulina platensis is a blue-green microalga that comprises protein-N, which is advantageous for use in nitrogen-containing biomass as adsorbents. This study aimed to enhance the adsorption properties of alginate hydrogels by employing Spirulina platensis. Spirulina platensis was immobilized on sodium alginate (S.P@Ca-SA) via crosslinking. The results of field-emission scanning electron microscopy, Fourier-transform infrared, and X-ray photoelectron spectroscopy analyses of the N-containing functional groups indicated that Spirulina platensis was successfully immobilized on the alginate matrix. We evaluated the effects of pH, concentration, and contact time on Pb(II) adsorption by S.P@Ca-SA. The results demonstrated that S.P@Ca-SA could effectively eliminate Pb(II) at pH 5, reaching equilibrium within 6 h, and the maximum Pb(II) sorption capacity of S.P@Ca-SA was 87.9 mg/g. Our results indicated that S.P@Ca-SA fits well with the pseudo-second-order and Freundlich models. Compared with Spirulina platensis and blank alginate beads, S.P@Ca-SA exhibited an enhanced Pb(II) adsorption efficiency. The correlation implies that the amino groups act as adsorption sites facilitating the elimination of Pb(II).

Volatile Compounds, Fatty Acids Constituents, and Antimicrobial Activity of Cultured Spirulina (Arthrospira fusiformis) Isolated from Lake Mariout in Egypt

In this study, Arthrospira fusiformis previously isolated from Lake Mariout (Alexandria, Egypt) was cultivated in the laboratory using a medium for pharmaceutical grade Arthrospira, named as Amara and Steinbüchel medium. Hot water extract of the Egyptian Spirulina was prepared by autoclaving dried biomass in distilled water at 121°C for 15 min. This algal water extract was analyzed by GC-MS to evaluate its volatile compounds and fatty acids composition. The antimicrobial activity of phycobiliprotein extract from Arthrospira fusiformis using phosphate buffer was evaluated against thirteen microbial strains (two Gram-positive bacteria, eight Gram-negative bacteria, one yeast, and two filamentous fungi). The major components of fatty acids in the hot extract of Egyptian A. fusiformis were hexadecanoic acid (palmitic acid, 55.19%) and octadecanoic acid (stearic acid, 27.14%). The main constituents of its volatile compounds were acetic acid (43.33%) and oxalic acid (47.98%). The most potent antimicrobial effect of phycobiliprotein extract was obtained against two Gram-negative bacteria Salmonella typhi and Proteus vulgaris, filamentous fungus Aspergillus niger, and the pathogenic yeast Candida albicans (all of which showed MIC values of 58.1 μg/ml). Escherichia coli and Salmonella typhimurium come second in their susceptibility to the phycobiliprotein extract from Arthrospira fusiformis and Serratia marcescens and Aspergillus flavus are the least in susceptibility, with MIC values of 116.2 and 232.5 μg/ml, respectively, while phycobiliprotein extract has no antibacterial effect on methicillin-resistant as well as susceptible Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Shigella sonnei. These findings confirmed the nutritional value of Egyptian A. fusiformis isolated from Lake Mariout and suggest the potential use of this strain as an ingredient in the cooking of some foods to increase the level of stearic acid and palmitic acid. Moreover, its effective antibacterial activities against some important and highly resistant to antibiotics bacterial pathogens in addition to its antifungal effects recommend the therapeutic use of its biomass.

A Review on a Hidden Gem: Phycoerythrin from Blue-Green Algae

Phycoerythrin (PE) is a pink/red-colored pigment found in rhodophytes, cryptophytes, and blue-green algae (cyanobacteria). The interest in PE is emerging from its role in delivering health benefits. Unfortunately, the current cyanobacterial-PE (C-PE) knowledge is still in the infant stage. It is essential to acquire a more comprehensive understanding of C-PE. This study aimed to review the C-PE structure, up and downstream processes of C-PE, application of C-PE, and strategies to enhance its stability and market value. In addition, this study also presented a strengths, weaknesses, opportunities, and threats (SWOT) analysis on C-PE. Cyanobacteria appeared to be the more promising PE producers compared to rhodophytes, cryptophytes, and macroalgae. Green/blue light is preferred to accumulate higher PE content in cyanobacteria. Currently, the prominent C-PE extraction method is repeated freezing-thawing. A combination of precipitation and chromatography approaches is proposed to obtain greater purity of C-PE. C-PE has been widely exploited in various fields, such as nutraceuticals, pharmaceuticals, therapeutics, cosmetics, biotechnology, food, and feed, owing to its bioactivities and fluorescent properties. This review provides insight into the state-of-art nature of C-PE and advances a step further in commercializing this prospective pigment.

Cosmetic Application of Cyanobacteria Extracts with a Sustainable Vision to Skincare: Role in the Antioxidant and Antiaging Process

Nature-based and sustainably sourced cosmetics have been dominating the area of skincare products worldwide. Due to their antioxidant and antiaging properties, compounds from cyanobacteria, such as carotenoids and phycobiliproteins, may replace synthetic ingredients in cosmetic formulations and may be used in products such as sunscreens, skincare creams, and makeup. In this study, we evaluated the potential of acetonic and aqueous extracts from cyanobacteria strains of the genera Cyanobium and Leptothoe and from strains within Synechococcales and Oscillatoriales orders, for use in cosmetics. Extractions were sequentially performed with acetone and water. Extracts were firstly analyzed for their toxicity to keratinocytes, fibroblasts, and endothelial cells (HaCAT, 3T3L1 and hCMEC/D3, respectively). The non-cytotoxic extracts were characterized in terms of total proteins, carotenoids, chlorophyll, phenols, phycobiliproteins, and analyzed for their antioxidant potential against the superoxide anion radical (O2•−), and for their ability to inhibit key enzymes associated with the skin aging process. Aqueous extracts were richer in total proteins and phycobiliproteins. The aqueous extracts of Synechococcales cyanobacterium LEGE 181157 and Synechococcales cyanobacterium LEGE 181150 showed the highest value for total proteins (760.81 and 695.25 μg BSA mL−1dry extract, respectively) and the best values regarding O2•− scavenging (IC50 = 63.24 and 112.18 μg mL−1dry extract, respectively) with a significant negative correlation observed (p < 0.01). Moreover, aqueous extracts of Synechococcales cyanobacterium LEGE 181150 and Synechococcales cyanobacterium LEGE 181157 inhibited hyaluronidase, (IC50 of 483.86 and 645.06 μg mL−1dry extract, respectively), with a significant negative correlation with total proteins (p < 0.05), pointing out the contribution of these compounds to the biological activities observed. Acetonic extracts were richer in carotenoids and phenols. Zeaxanthin and β-carotene were predominant among all strains, being present in higher amount in Cyanobium sp. LEGE 07175 (53.08 μg mg−1) and Leptothoe sp. LEGE 181156 (47.89 μg mg−1), respectively. The same strains also showed the highest values for collagenase inhibition at 750 μg mL−1dry extract (32.88 and 36.61%, respectively). Furthermore, Leptothoe sp. LEGE 181156 exhibited the lowest IC50 value for tyrosinase inhibition (465.92 μg mL−1dry extract) and Synechococcales cyanobacterium LEGE 181157 presented the best values for elastase inhibition (IC50 of 380.50 and IC25 of 51.43 μg mL−1dry extract). In general, cyanobacteria extracts demonstrated potential for being used for antiaging purposes, with aqueous extracts being more efficient at free radicals scavenging and acetonic ones at avoiding degradation of dermal matrix components.

CO2 fixation and cultivation of Thermosynechococcus sp. CL-1 for the production of phycocyanin

Cultivation of Cyanobacteria is preferable for CO2 fixation process due to its efficiency and production of beneficial byproducts like phycocyanin. In this study, Thermosynechococcus sp. CL-1 (TCL-1) was cultivated in a 30 L flat panel photobioreactor using a 3-fold-modified Fitzgerald medium with 113.2 mM dissolved inorganic carbon. The highest CO2 fixation rate of 21.98 ± 1.52 mg/L/h was followed by higher lipid content (49.91 % dry weight content or %dwc) than the generated carbohydrate (24.22 %dwc). TCL-1 also potentially produced phycocyanin that was dominated by C-phycocyanin (98.10 ± 6.67 mg/g) along with a lower amount of allophycocyanin and phycoerythrin under extraction using various types of solvent. Stability of phycocyanin extract was further examined during storage under various temperatures and light illuminations. Extraction with 36 % glucose solvent presented a protective effect to phycocyanin from heat and photo-damage which was proven by the kinetics study of phycocyanin degradation in this study.

High Purity Grade Phycocyanin Recovery by Decupling Cell Lysis from the Pigment Extraction: an Innovative Approach

Phycocyanin, a phycobiliprotein, is one of the few natural blue pigments available as food colourant, and it is largely used in food industry. We have devised an innovative two-step extraction process which allowed to obtain bright blue phycocyanin crude extracts with high purity grade P (within 2.5 and 3.5) directly from fresh biomass of Arthrospira platensis Gomont 1892 (commonly named Spirulina). We found out and for the first time exploited ammonium sulphate capability to minimize the release of water soluble phycobiliproteins in aqueous medium during ultrasound-assisted cell lysis/purification phase. The conventional sequence which is, extraction followed by purification, was reversed. The extraction phase was decoupled from biomass cell lysis. Cell lysis, accomplished by ultrasonication in ammonium sulphate solution, was merged with purification in a single step, before the pigment extraction/recovering phase. The process was entirely carried out in aqueous solutions. No downstream purification was required to obtain products suitable for the most common phycocyanin applications (i.e. foods, nutraceuticals). Production time, hours instead of days, was reduced to the advantage of the product quality. The process has the great advantages of (1) direct use of extracting solutions that cannot be used in the ordinary ultrasound-assisted extraction of phycocyanin (because of the extensive simultaneous extraction of contaminant molecules), (2) gain of high commercial value phycocyanin due to the elevated purity grade and (3) direct production of highly concentrated bright blue pigment crude extracts (up to about 5 mg mL−1) immediately in hand to the market.

Graphical Abstract