Stability and Antioxidant Activity of Food-Grade Phycocyanin Isolated from Spirulina platensis

Unraveling the unique bioactivities of highly purified C-phycocyanin and allophycocyanin

BACKGROUND

The blue-green microalgae Spirulina, used in human nutrition for centuries, includes phycobiliproteins such as C-phycocyanin (CPC) and allophycocyanin (APC). Assessing their unique bioactivities separately is difficult as they have similar properties, such as molecular weight and isoelectric point. In the present study, we aimed to separate CPC and APC and to evaluate their bioactivities. CPC and APC were separated using a hydrophobic membrane and ammonium sulfate, which promotes reversible and specific protein binding to the membrane. Spectroscopic analysis, HPLC, and SDS-PAGE revealed a successful separation of CPC and APC. Their bioactivities were evaluated through CCK- 8 assays for anticancer activity, radical scavenging assays for antioxidant activity, and albumin denaturation assays for anti-inflammatory activity, respectively.

RESULTS

The results revealed that highly purified APC showed 40% higher anticancer activity than the control, whereas CPC increased the viability of cancer cells, resulting in a 30% decrease in anticancer activity compared to the control. In contrast, highly purified CPC showed approximately 25% higher antioxidant activity and twice as much anti-inflammatory activity as APCs; moreover, the presence of both showed higher antioxidant activity.

CONCLUSION

This study provides important insights into the unique bioactivities of CPC and APC for their appropriate application as anticancer, antiphlogistic, and antioxidant agents.

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.

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.

Thermal degradation kinetics and purification of C-phycocyanin from thermophilic and mesophilic cyanobacteria

The natural blue colorant C-phycocyanin (C-PC) has many potential applications but its poor heat stability limits its commercial use. This study compares the production and thermal stability of C-PC from two cyanobacteria: the thermophilic Thermosynechococcus sp. TUBT-T01 and the mesophilic Synechococcus cedrorum TISTR8589. Thermosynechococcus sp. produced nearly 1.9-fold more C-PC than S. cedrorum. Batch adsorption using a chromatographic cationic ion exchange resin (Streamline Direct HST1) was used to effectively purify the C-PC. The equilibrium adsorption capacity (Qeq) of the resin for C-PC was the highest at pH 5. At this pH, the Qeq for the thermophilic C-PC was 5.5 ± 0.1 mg mL⁻¹ , whereas for the mesophilic C-PC it was 1.5 ± 0.2 mg mL⁻¹ . Purification increased the concentration of the thermophilic C-PC by 5.9-fold, and that of mesophilic C-PC by 4.2-fold. The purity ratios of the final products from the two cyanobacteria were similar at ∼2.2. At 60 °C and pH 7, the C-PC of Thermosynechococcus sp. had ∼12-times longer half-life than the mesophilic C-PC; however, the productivity of the thermophilic C-PC was comparatively low because of a low biomass productivity of Thermosynechococcus sp.

Antioxidant activity and mechanism of action of phycocyanin in bulk sunflower oil and respective oil-in-water emulsion

This study compared the inhibitory mechanism of phycocyanin in sunflower oil with its activity in a sunflower oil-in-water emulsion. Additionally, the impact of lecithin on the inhibitory mechanism of phycocyanin in sunflower oil was evaluated. A sigmoidal model effectively described the oxidation kinetics. In both sunflower oil and sunflower oil-in-water emulsion, phycocyanin pro-oxidatively attacked lipid hydroperoxides besides inhibiting lipid hydroperoxides. The antioxidant activity of sunflower oil containing phycocyanin and lecithin was 2.2-fold greater than that of sunflower oil containing lecithin alone. The addition of lecithin enhanced the interfacial activity of phycocyanin and altered its hydrogen donating and electron transfer mechanisms. Also, by comparing the reverse micelles size samples of sunflower oil samples containing lecithin, we discovered that lecithin can enhance the potency of phycocyanin by boosting the ability of reverse micelles to incorporate lipid hydroperoxides within their structure.

Integration of STING activation and COX-2 inhibition via steric-hindrance effect tuned nanoreactors for cancer chemoimmunotherapy

Integrating immunotherapy with nanomaterials-based chemotherapy presents a promising avenue for amplifying antitumor outcomes. Nevertheless, the suppressive tumor immune microenvironment (TIME) and the upregulation of cyclooxygenase-2 (COX-2) induced by chemotherapy can hinder the efficacy of the chemoimmunotherapy. This study presents a TIME-reshaping strategy by developing a steric-hindrance effect tuned zinc-based metal-organic framework (MOF), designated as CZFNPs. This nanoreactor is engineered by in situ loading of the COX-2 inhibitor, C-phycocyanin (CPC), into the framework building blocks, while simultaneously weakening the stability of the MOF. Consequently, CZFNPs achieve rapid pH-responsive release of zinc ions (Zn2+) and CPC upon specific transport to tumor cells overexpressing folate receptors. Accordingly, Zn2+ can induce reactive oxygen species (ROS)-mediated cytotoxicity therapy while synchronize with mitochondrial DNA (mtDNA) release, which stimulates mtDNA/cGAS-STING pathway-mediated innate immunity. The CPC suppresses the chemotherapy-induced overexpression of COX-2, thus cooperatively reprogramming the suppressive TIME and boosting the antitumor immune response. In xenograft tumor models, the CZFNPs system effectively modulates STING and COX-2 expression, converting "cold" tumors into "hot" tumors, thereby resulting in ≈ 4-fold tumor regression relative to ZIF-8 treatment alone. This approach offers a potent strategy for enhancing the efficacy of combined nanomaterial-based chemotherapy and immunotherapy.

Development of a new extraction method and functional analysis of phycocyanobilin from unique filamentous cyanobacteria

As current methods of production of phycocyanobilin, a photosynthetic blue pigment derived from phycocyanin of filamentous cyanobacteria, Pseudanabaena sp. ABRG5-3, Limnothrix sp. SK1-2-1, and Spirulina sp., exhibit a low extraction efficiency, a new extraction method using ethanol extraction as a type of solvolysis with an autoclave (130 ℃, 5.7 bar, 10 min) was developed in this study. This method exhibited high efficiency and enabled easy recovery of the three types of phycocyanobilins. The identity of the three types of phycocyanobilins was confirmed by high-performance liquid chromatography and electrospray ionization-tandem mass spectrometry. Phycocyanobilins were stable at high temperatures (80 ℃) and acidic (pH 3) conditions. Phycocyanobilins also possessed a remarkable antioxidant property. This is the first time that a simple phycocyanobilin extraction method with a recovery rate of more than 60 % and approximately 1 % per dry cell weight of filamentous cyanobacteria has been demonstrated. This novel production method is thus convenient and effective for obtaining high-purity phycocyanobilins.

Bioactive compounds and in vitro biological properties of Arthrospira platensis and Athrospira maxima: a comparative study

Cyanobacteria, especially Arthrospira, are valuable resources of nutrients and natural pigments with many beneficial health-related properties. This study optimized the extraction conditions of Arthrospira to achieve high phenolic contents and antioxidant activities. Under optimized extraction conditions, the bioactive compounds (phenolics and pigment components), antioxidant activities, and inhibitions of the key enzymes relevant to some non-communicable diseases were compared between Arthrospira platensis and Arthrospira maxima. Optimized extraction conditions were determined as 2 h shaking time, 50 °C extraction temperature, and 1% (w/v) solid-to-liquid ratio, giving effective phenolic and phycocyanin contents using aqueous extraction, while 80% (v/v) aqueous ethanolic extraction provided high total chlorophyll content. Most antioxidant activities were higher using 80% (v/v) aqueous ethanolic extracts. Both Arthrospira species inhibited the key enzymes involved in controlling non-communicable diseases including hyperlipidemia (lipase), diabetes (α-amylase, α-glucosidase, and dipeptidyl peptidase-IV), Alzheimer's disease (acetylcholinesterase, butyrylcholinesterase and β-secretase), and hypertension (angiotensin-converting enzyme). High inhibitory activities were detected against β-secretase (BACE-1), the enzyme responsible for β-amyloid plaque formation in the brain that acts as a significant hallmark of Alzheimer's disease. Arthrospira extract and donepezil (Alzheimer's disease drug) synergistically inhibited BACE-1, suggesting the potential of Arthrospira extracts as effective BACE-1 inhibitors. Interestingly, A. maxima exhibited higher bioactive compound contents, antioxidant activities, and key enzyme inhibitions than A. platensis, indicating high potential for future food and medicinal applications.

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.

Development of pH-Sensitive hydrogel for advanced wound Healing: Graft copolymerization of locust bean gum with acrylamide and acrylic acid

Wounds pose a formidable challenge in healthcare, necessitating the exploration of innovative tissue-healing solutions. Traditional wound dressings exhibit drawbacks, causing tissue damage and impeding natural healing. Using a Microwave (MW)-)-assisted technique, we envisaged a novel hydrogel (Hg) scaffold to address these challenges. This hydrogel scaffold was created by synthesizing a pH-responsive crosslinked material, specifically locust bean gum-grafted-poly(acrylamide-co-acrylic acid) [LBG-g-poly(AAm-co-AAc)], to enable sustained release of c-phycocyanin (C-Pc). Synthesized LBG-g-poly(AAm-co-AAc) was fine-tuned by adjusting various synthetic parameters, including the concentration of monomers, duration of reaction, and MW irradiation intensity, to maximize the yield of crosslinked LBG grafted product and enhance encapsulation efficiency of C-Pc. Following its synthesis, LBG-g-poly(AAm-co-AAc) was thoroughly characterized using advanced techniques, like XRD, TGA, FTIR, NMR, and SEM, to analyze its structural and chemical properties. Moreover, the study examined the in-vitro C-Pc release profile from LBG-g-poly(AAm-co-AAc) based hydrogel (HgCPcLBG). Findings revealed that the maximum release of C-Pc (64.12 ± 2.69 %) was achieved at pH 7.4 over 48 h. Additionally, HgCPcLBG exhibited enhanced antioxidant performance and compatibility with blood. In vivo studies confirmed accelerated wound closure, and ELISA findings revealed reduced inflammatory markers (IL-6, IL-1β, TNF-α) within treated skin tissue, suggesting a positive impact on injury repair. A low-cost and eco-friendly approach for creating LBG-g-poly(AAm-co-AAc) and HgCPcLBG has been developed. This method achieved sustained release of C-Pc, which could be a significant step forward in wound care technology.

Effective cultivation conditions and safety evaluation of filamentous cyanobacteria producing phycocyanins with antiglycation activities

We investigated suitable culture conditions for the production of the blue pigment phycocyanin (PC) from the unique filamentous cyanobacteria Pseudanabaena sp. ABRG5-3 and Limnothrix sp. SK1-2-1. White, green, or red LED irradiation at 30 μmol photons/m2/s was effective for phycocyanin production when compared with Arthrospira platensis (Spirulina) sp. NIES-39, which is generally grown under high light irradiation. To investigate the safety of the cyanobacteria, ABRG5-3 cells were subjected to Ames (reverse mutation) tests and single oral-dose rat studies, which revealed non-mutagenic and non-toxic properties. When three purified phycocyanins (abPC, skPC, and spPC) were subjected to agarose gel electrophoresis, they showed different mobility, indicating that each phycocyanin has unique properties. abPC exhibited strong antiglycation activities as novel function.

Unveiling the impact of additives on structural integrity, thermal and color stability of C-phycocyanin - Agar hydrocolloid

C-Phycocyanin and sugar (C-PC/S) blended agar hydrocolloid was prepared and its rheological, thermo-functional and morphological properties were examined based on the fluorescence excitation-emission matrix profile. Sucrose (40%, w/v) determined as a superior preservative, maintaining the native conformation of C-PC effectively. C-PC/S exhibited enhanced structural integrity with high storage modulus (G') and 86.4% swelling index. FT-IR demonstrated strong intramolecular bonding. TGA revealed that the presence of sucrose prolonged the devolatilization peak up to 325 °C, with a degradation rate of -2.273 mg/min, it the thermal stability. C-PC/S fortified hydrocolloid in ice cream (5.0% w/w), reduced melting rate up to five times. In conclusion, sucrose as a promising enhancer of color stability and structural integrity for C-PC, and this combination effectively improves the functional and rheological properties. Further, the findings exposed the agar hydrocolloid as a potential enhancer of color retention and improved performance for various food and cosmetic products.

Natural Pigments Recovery from Food By-Products: Health Benefits towards the Food Industry

Given the health risks associated with synthetic colorants, natural pigments have emerged as a promising alternative. These renewable choices not only provide health benefits but also offer valuable technical and sensory properties to food systems. The effective application of natural colorants, however, requires the optimization of processing conditions, exploration of new sources, and development of novel formulations to ensure stability and maintain their inherent qualities. Several natural pigment sources have been explored to achieve the broad color range desired by consumers. The purpose of this review is to explore the current advances in the obtention and utilization of natural pigments derived from by-products, which possess health-enhancing properties and are extracted through environmentally friendly methods. Moreover, this review provides new insights into the extraction processes, applications, and bioactivities of different types of pigments.

Phycocyanin from microalgae: A comprehensive review covering microalgal culture, phycocyanin sources and stability

As food safety continues to gain prominence, phycocyanin (PC) is increasingly favored by consumers as a natural blue pigment, which is extracted from microalgae and serves the dual function of promoting health and providing coloration. Spirulina-derived PC demonstrates exceptional stability within temperature ranges below 45 °C and under pH conditions between 5.5 and 6.0. However, its application is limited in scenarios involving high-temperature processing due to its sensitivity to heat and light. This comprehensive review provides insights into the efficient production of PC from microalgae, covers the metabolic engineering of microalgae to increase PC yields and discusses various strategies for enhancing its stability in food applications. In addition to the most widely used Spirulina, some red algae and Thermosynechococcus can serve as good source of PC. The genetic and metabolic manipulation of microalgae strains has shown promise in increasing PC yield and improving its quality. Delivery systems including nanoparticles, hydrogels, emulsions, and microcapsules offer a promising solution to protect and extend the shelf life of PC in food products, ensuring its vibrant color and health-promoting properties are preserved. This review highlights the importance of metabolic engineering, multi-omics applications, and innovative delivery systems in unlocking the full potential of this natural blue pigment in the realm of food applications, provides a complete overview of the entire process from production to commercialization of PC, including the extraction and purification.

Effect of dietary Arthrospira platensis phycocyanin on broiler chicken growth performance, physiological status, fatty and amino acid profiles

Background and Aim

Natural antioxidants are crucial for preserving and enhancing the health, survival, reproduction, and reproductive function of poultry. Phycocyanin (PC) is a natural blue food colorant with various health benefits. The aim of this study was to extract Arthrospira platensis phycocyanin (ApPC) from A. platensis using simple and economical methods and investigate the impact of phytocyanin supplementation on the performance and fatty and amino acid profiles of broiler chicks.

Materials and Methods

PC was extracted from A. platensis by freezing and thawing, and optimization conditions such as pH and temperature were applied during storage periods. A total of 270 1-week-old Ross breed broiler chicks were randomly assigned to the following three treatment groups: basal diet supplemented with 0 mg of PC/kg diet (control), basal diet supplemented with 1 g PC/kg diet (T1), and basal diet supplemented with 2 g PC/kg (T2). In a completely randomized design, three cage replicates (30 birds each) were assigned to each of the three groups. The dietary effects of ApPC on growth performance (body weight gain [BWG], body weight [BW], feed intake, feed conversion ratio, serum constituents, and antioxidant indices) in broiler chickens, free amino acids, and fatty acids in muscles were evaluated.

Results

Total BWG and BW increased without a significant effect on the total feed consumption. Serum levels of total proteins and albumin increased with increasing ApPC supplementation. In addition, globulin levels significantly increased. There was a significant decrease in serum total cholesterol levels among the treatments. The activity of antioxidant enzymes (superoxide dismutase, catalase, glutathione, and total antioxidant capacity) is significantly increased. In contrast, an increase in ApPC caused a significant decrease in malondialdehyde. The content and quantity of fatty acids and amino acids in the meat of broiler chicks supplemented with PC varies.

Conclusion

The addition of PC to broiler chicken diets enhances antioxidant activities, BW, BWG, and meets quality requirements.

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.

Phycocyanin/tannic acid complex nanoparticles as Pickering stabilizer with synergistic interfacial antioxidant properties

This study reported a type of phycocyanin (PC)-tannic acid (TA) complex nanoparticles (NPs) fabricated by simply mixing PC with TA at appropriate mass ratios. The assembly of PC-TA NPs was driven by secondary forces involving hydrophobic interactions and hydrogen bonding. PC-TA NPs promoted formations of Pickering emulsions with an oil volume fraction (φ) of 0.1-0.8. The interfacial antioxidant ability of PC-TA NPs was evaluated by comparing the contents of hydroperoxides, malonaldehyde, and hexanal due to lipid oxidation. The results showed that PC-TA NPs retarded lipid oxidation more efficiently than did PC, TA, tween 20, or tween 80, which suggested the synergistic antioxidant action of PC and TA. Besides, the PC-TA NPs stabilized high internal phase emulsion facilitated a higher retention of β-carotene under UV irradiation. Altogether, our findings demonstrate that the modification of PC by TA represents a strategy to fabricate PC-TA NPs with enhanced emulsification and antioxidant efficiency.

Effect of C-phycocyanin purified from Spirulina platensis on cooled ram semen quality and in vivo fertility

This research sought to purify C-phycocyanin (C-PC) from Spirulina platensis and investigate its potential in enhancing the quality parameters and in vivo fertility of ram semen subjected to cooled storage at 5 °C, when using a skim milk (SM) based semen extender. The purification process of C-PC involved cold maceration, pre-purification using chitosan and activated charcoal, followed by purification through aqueous two-phase extraction (ATPE) and ion-exchange chromatography. Afterward, fifty ejaculates were collected from 4 fertile Boujaâd rams and extended using the SM extender at 37 °C, enriched with 0 μg/mL (control), 1.2 μg/mL, 2.4 μg/mL, 3.6 μg/mL, or 4.8 μg/mL of C-PC. The diluted semen was subsequently cooled to 5 °C using a controlled cooling process, with a gradual cooling rate of approximately 0.5 °C per minute, and its quality parameters were evaluated after 0, 4, 8, and 24 h of cooling storage. Then, its fertilization ability after 4 h of cooling storage was evaluated using artificial insemination. The adopted purification process yielded a grade analytical purity of 4.06. Additionally, semen extended in SM with a 2.4 μg/mL C-PC supplement displayed significant (P < 0.0001) enhancement in total motility, progressive motility, curvilinear velocity, straight-line velocity, average path velocity, viability and lipid peroxidation of ram semen at 0, 4, 8, and 24 h of cooling storage. These improvements were observed in direct comparison to both the control group and the other C-PC concentrations. Regarding fertility rates, semen extended in SM with a 2.4 μg/mL C-PC recorded a 76 % rate, a notable increment from the 63 % observed in ewes inseminated by semen extended in SM alone, although the difference was not statistically significant (p > 0.05). These findings underscore the promising potential of C-PC as a natural supplement for enhancing semen quality, warranting further investigations.

Effects of chitosan molecular weight and mass ratio with natural blue phycocyanin on physiochemical and structural stability of protein

Phycocyanin (PC), an algae-extracted colorant, has extensive applications for its water-solubility and fresh blue shade. When PC is added to acidified media, dispersions are prone to aggregate and decolorize into cloudy systems. For palliating this matter, chitosan with high, medium, and low molecular weights (HMC, MMC, and LMC) were adopted in PC dispersions, and their protective effects were compared based on physiochemical stabilities. The optimal mass ratio between chitosan and PC was identified as 1:5 based on preliminary evaluations and was supported by the higher ζ-potential (31.0-32.1 mV), lower turbidity (39.6-43.6 NTU), and polyacrylamide gel electrophoresis results. Through interfacial and antioxidant capacity analyses, LMC was found to display a higher affinity to PC, which was also confirmed by SEM images and the maximum increase in transition temperature of their complex (155.70 °C) in DSC measurements. The mechanism of electrostatic interaction reinforced by hydrophobic effects and hydrogen bonding was elucidated by FT-IR and Raman spectroscopy. Further comprehensive stability evaluations revealed that, without light exposure, LMC kept PC from internal secondary structure to external blueness luster to the maximum extent. While with light exposure, LMC was not so flexible as HMC, to protect chromophores from attack of free radicals.

Enhancement of phycocyanin productivity and thermostability from Arthrospira platensis using organic acids

Intracellular hyperaccumulation of phycocyanin (PC) and its high susceptibility to degradation at higher temperatures are major challenging problems associated with its production from cyanobacteria. The present study evaluated different concentrations of organic acids (1, 2, and 3 mM) (citric acid, acetic acid, succinic acid, fumaric acid, and oxalic acid) under fed-batch mode on the biomass and phycobiliproteins' production from Arthrospira platensis. Besides they were evaluated at 2.5-7.5 mM as preservative to stabilize PC at high temperatures. The incorporation of 3 mM of succinic acid into the cultivation medium enhanced the biomass and PC productivity to 164.05 and 26.70 mg L-1 day-1, which was ~ 2- and threefold higher than control, respectively. The produced PC in this treatment was food-grade with a 2.2 purity ratio. The use of organic acids also enhanced the thermal stability of PC. Citric acid (7.5 mM) markedly promoted the half-life values of PC to 189.44 min compared to 71.84 min in the control. The thermodynamic analysis confirmed higher thermostability of PC in the presence of organic acids and indicated the endothermic and non-spontaneity of the thermal denaturation process. The findings of the present study confirmed that organic acids could be utilized as cost effective and sustainable compounds for promoting not only phycobiliproteins' production but also the thermostability of PC for potential application in food industry.

An interventional clinical trial investigating the effects of Spirulina platensis on dental fluorosis and antioxidant system in lambs reared in endemic areas

This study aimed to evaluate the protective effect of Spirulina platensis primary against dental fluorosis and secondary against oxidative stress in lambs reared in endemic fluorosis areas. Forty-eight lambs aged 5 months were divided into four equal groups (each one including 6 males and 6 females). Groups I and II served as controls belonging respectively to fluorosis-free (Settat) and endemic fluorosis (El Fokra) areas, while the other two Groups III and IV (belonging to El Fokra) received respectively a fixed daily intake of 250 and 500 mg/kg bodyweight (BW) of Spirulina platensis. The experiment was carried out for 13 months until the adult incisors appeared for all animals. According to the Dean's Fluorosis Index (DFI), 500 mg/kg BW/day of Spirulina platensis (Group IV) protected against dental fluorosis. Moreover, in both male and female lambs, this dose significantly (p < 0.0001) reduced the plasmatic levels of fluoride, proteins, GSH, and MDA compared to the Group II. Furthermore, enzymatic activities of catalase and SOD increased significantly (p < 0.0001) in male and female lambs of the Group IV as compared to Group II. In conclusion, our findings support the potential use of Spirulina platensis as a valuable solution for addressing fluorosis in sheep, warranting further clinical trials.

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.

Complexation of phycocyanin with hydroxypropyl-β-cyclodextrin and its application in blue beer containing quinoa saponins as foaming agents

Introduction

With the increasing importance attached to human health, the inclusion complex (IC) of phycocyanin (PC) into hydroxypropyl-β-cyclodextrin (HP-β-CD) have been devoted to developing the use of food preservation in this study.

Methods

In this experiment, the IC of PC into HP-β-CD was prepared by the freeze-drying method and characterized by OM, TEM, UV, FTIR and TG/DSC methods.

Results and discussion

The spectroscopic features were evaluated by Ultraviolet-visible (UV-vis) spectroscopy and Fourier transform infrared spectroscopy (FT-IR) confirming that PC was located in the hydrophobic cavity of HP-β-CD. Consistent with the structural properties, optical microscopy (OM) and Transmission electron microscope (TEM) observed that the addition of PC subjected the IC to an aggregation state with irregular lamellar structures. Stability assessment showed that pH, heat and light tolerance of PC significantly regulated and improved due to the PC/HP-β-CD complexation. The formation of ICs was helpful to enhancing the antioxidant activity of PC. Molecular modeling suggested that the D-pyrrole ring and its associated C=C group of phycocyanin entered the HP-β-CD cavity from the wider edge. On this basis, the development of blue beer with quinoa saponins as foaming agent and ICs as colorant was explored. The addition of quinoa saponins made the foam richer and more delicate without destroying the overall taste coordination of beer. Moreover, the protective effect of HP-β-CD presents a positive impact on the stability of blue beer pigment. Hence, PC encapsulated into HP-β-CD will be an impressive approach in food-related application of PC.

Photochromic biodegradable film based on polyvinyl alcohol modified with silver chloride nanoparticles and spirulina; investigation of physicochemical, antimicrobial and optical properties

In this study, biodegradable film was prepared from polyvinyl alcohol (PVA), Silver chloride (AgCl) and spirulina (Sp). Surface morphology, mechanical properties, antioxidant, antimicrobial, optical properties, etc. were investigated. The FTIR results confirmed the effect of AgCl and Sp on PVA structure. Sp increased the moisture content and solubility in water. The XRD results showed the semi-crystalline structure of PVA. AgCl nanoparticles activated the antibacterial property of the film against Escherichia coli and Staphylococcus aureus bacteria and Sp caused a strong increase in the antioxidant property of the film. Examining the light transmittance of films containing AgCl nanoparticles showed that the transmittance of films containing nanoparticles decreased with exposure to sunlight and ultraviolet light with increasing treatment time, which indicates the activation of the photochromic property of films containing AgCl in the presence of light. The results showed the suitable photochromic property of the PVA/AgCl films.

Phycobiliproteins from algae: Current updates in sustainable production and applications in food and health

Phycobiliproteins are light-harvesting complexes found mainly in cyanobacteria and red algae, playing a key role in photosynthesis. They are extensively applied in food, cosmetics, and biomedical industry due to bright color, unique fluorescence characteristics and diverse physiological activities. They have received much attention in the past few decades because of their green and sustainable production, safe application, and functional diversity. This work aimed to provide a comprehensive summary of parameters affecting the whole bioprocess with a special focus on the extraction and purification, which directly determines the application of phycobiliproteins. Food grade phycobiliproteins are easy to prepare, whereas analytical grade phycobiliproteins are extremely complex and costly to produce. Most phycobiliproteins are denatured and inactivated at high temperatures, severely limiting their application. Inspired by recent advances, future perspectives are put forward, including (1) the mutagenesis and screening of algal strains for higher phycobiliprotein productivity, (2) the application of omics and genetic engineering for stronger phycobiliprotein stability, and (3) the utilization of synthetic biology and heterologous expression systems for easier phycobiliprotein isolation. This review will give a reference for exploring more phycobiliproteins for food and health application development.

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.

Food Antioxidants and Their Interaction with Human Proteins

Common to all biological systems and living organisms are molecular interactions, which may lead to specific physiological events. Most often, a cascade of events occurs, establishing an equilibrium between possibly competing and/or synergistic processes. Biochemical pathways that sustain life depend on multiple intrinsic and extrinsic factors contributing to aging and/or diseases. This article deals with food antioxidants and human proteins from the circulation, their interaction, their effect on the structure, properties, and function of antioxidant-bound proteins, and the possible impact of complex formation on antioxidants. An overview of studies examining interactions between individual antioxidant compounds and major blood proteins is presented with findings. Investigating antioxidant/protein interactions at the level of the human organism and determining antioxidant distribution between proteins and involvement in the particular physiological role is a very complex and challenging task. However, by knowing the role of a particular protein in certain pathology or aging, and the effect exerted by a particular antioxidant bound to it, it is possible to recommend specific food intake or resistance to it to improve the condition or slow down the process.

Schiff base crosslinked gelatin-Spirulina platensis protein concentrate films with enhanced antioxidant activity

The aim of this work is to produce bioactive films suitable for aerobic packaging applications by combining the bioactivity of Spirulina platensis protein concentrate (PC; 1% and 2% w/w), the sustainable nature of bovine gelatin (Ge), and sodium alginate dialdehyde (ADA, 5% w/w) as Schiff base crosslinking agent. PC was obtained by an optimized acid-base extraction process and characterized. PC showed a dose-dependent radical scavenging activity (RSA; IC₅₀  = 24.3 mg/L) related to its high content of C-phycocyanin and total phenolic compounds (32.44 ± 1.37 mg gallic acid equivalents per gram of PC). As a general trend, crosslinking decreased the water solubility, improved mechanical properties, and helped improve RSA of Ge-ADA-PC films. Ge-5ADA-2PC film recorded best compromise between solubility (only 33.6%), high UV barrier (0.134% transmittance at 400 nm), reasonable extensibility (217.00 ± 2.34%), tensile strength (3.50 ± 0.43 MPa), water vapor permeability (2.00 ± 0.17 × 10^-12  kg·m/m² ·Pa·s), and RSA (44.70 ± 2.19%). Wrapping hake fillets in this filmdelayed lipid oxidation during storage under refrigerated conditions for 11 days, maintaining the thiobarbituric acid index below 0.5 mg malonaldehyde/kg muscle. Results suggest that Ge-ADA-PC films have potential as aerobic packaging materials for oxidation-sensitive food. PRACTICAL APPLICATION: The combination of gelatin, alginate dialdehyde and Spirulina platensis protein concentrate gave rise to fully biobased films with reduced water solubility and enhanced antioxidant activity, which were able to delay the secondary lipid oxidation of refrigerated seafood. This study also shows the potential of cyanobacteria as renewable resources of high-value ingredients for the design of active and intelligent aerobic packaging solutions.

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.

C-phycocyanin production with high antioxidant activity of a new thermotolerant freshwater Desertifilum tharense UAM-C/S02 strain

A native cyanobacterial strain, Desertifilum tharense UAM-C/S02, was studied as a possible C-phycocyanin (C-PC) producer. Photosynthetic activity (PA) assays through oxygen production determined the proper temperature and range of irradiances to be tested in a stirred tank photobioreactor. The highest C-PC productivity (97 mg L^-1 d^-1), with a yield of 86.46 mg_C-PC g_B^-1 was obtained at 730 µmol photons m^-2 s^-1 with a biomass productivity of 608 mg L^-1 d^-1 and the CO₂ fixation rate was 1,194  mg L^-1 d^-1. The 1.81 crude extract purity value is the highest reported for this genus, which was improved to biomarker-grade purity after a two-step purification strategy comprising precipitation with ammonium sulfate, followed by dialysis. The purified C-PC was almost entirely radical-free using 1 mg mL^-1, which validates its potential use in therapeutic formulations.

Microalgae-Derived Pigments for the Food Industry

In the food industry, manufacturers and customers have paid more attention to natural pigments instead of the synthetic counterparts for their excellent coloring ability and healthy properties. Microalgae are proven as one of the major photosynthesizers of naturally derived commercial pigments, gaining higher value in the global food pigment market. Microalgae-derived pigments, especially chlorophylls, carotenoids and phycobiliproteins, have unique colors and molecular structures, respectively, and show different physiological activities and health effects in the human body. This review provides recent updates on characteristics, application fields, stability in production and extraction processes of chlorophylls, carotenoids and phycobiliproteins to standardize and analyze their commercial production from microalgae. Potential food commodities for the pigment as eco-friendly colorants, nutraceuticals, and antioxidants are summarized for the target products. Then, recent cultivation strategies, metabolic and genomic designs are presented for high pigment productivity. Technical bottlenecks of downstream processing are discussed for improved stability and bioaccessibility during production. The production strategies of microalgal pigments have been exploited to varying degrees, with some already being applied at scale while others remain at the laboratory level. Finally, some factors affecting their global market value and future prospects are proposed. The microalgae-derived pigments have great potential in the food industry due to their high nutritional value and competitive production cost.

Comparative Study of the Efficiency of Additives in the Extraction of Phycocyanin-C from Arthrospira maxima Using Ultrasonication

Several phycocyanin extraction methods have been proposed, however, most of them present economical or productive barriers. One of the most promising methods that has been suggested is ultrasonication. We have analyzed here the effect of operational conditions and additives on the extraction and purity of phycocyanin from Arthrospira maxima. We followed three experimental designs to determine the best combination of buffered pH solutions, additives, fresh and lyophilized biomass. We have found that additives such as citric acid and/or disaccharides could be beneficial to the extraction process. We concluded that the biomass-solvent ratio is a determining factor to obtain high extraction and purity ratios with short ultrasonication times.

Evaluation of the spectral characteristics, purity and antioxidant activity of C-phycocyanin from the cyanobacteria collected in Kaunas Lagoon (Lithuania)

The physicochemical characteristics of phycocyanin extracted from cyanobacteria collected in Kaunas Lagoon were studied (spectrum characteristics, C-PC content in the dry mass and chemical purity). It was determined that the tested concentrations of C-PC in purified water should be in the range of 0.02–0.16% for measuring C-PC content in the dry mass and its spectrum characteristics. The two clear absorption maxima were detected in the spectrum of C-PC at the wavelengths of 277 and 619 nm. The content of C-PC in the dry powder form was in the range of 7.25% to 9.30% depending on its concentration in the solution and type of spectrophotometer. Furthermore, a purity factor of 1.5 was calculated, which indicated the food qualification of the obtained biomass of C-PC. Finally, the analytical procedure for studying the pro- and anti-oxidant activity of C-PC was developed and the antioxidant activity of C-PC was measured for the available markers. It was revealed that C-PC has dual properties (pro- and anti-oxidant ones) depending on its concentration, more exactly, its content in reaction mixtures with 2,2-diphenyl-1-picrylhydrazyl (DPPH). The following issues were resolved during the research: the concentration of ethanol in the DPPH solution was chosen in order to avoid precipitation of proteins in the reaction mixtures (50%); the ratio of the solution of C-PC to the DPPH solution was selected; the selected concentrations of the markers for the construction of their calibration curves were chosen for quercetin and for rutin. The antioxidant activity of the obtained C-PC sample was determined. Keywords: antioxidant activity, C-phycocyanin, cyanobacteria, DPPH, quercetin, rutin

Improvement in the Sequential Extraction of Phycobiliproteins from Arthrospira platensis Using Green Technologies

Arthrospira platensis (commercially known as Spirulina) is an excellent source of phycobiliproteins, especially C-phycocyanin. Phycobiliproteins are significant bioactive compounds with useful biological applications. The extraction process plays a significant role in downstream microalga production and utilisation. The important pigments found in A. platensis include chlorophyll and carotenoids as nonpolar pigments and phycobiliproteins as polar pigments. Supercritical fluid extraction (SFE) as a green extraction technology for the high-value metabolites of microalgae has potential for trends in food and human health. The nonpolar bioactive compounds, chlorophyll and carotenoids of A. platensis, were primarily separated using supercritical carbon dioxide (SC-CO₂) solvent-free fluid extraction pressure; the temperature and ethanol as cosolvent conditions were compared. The residue from the A. platensis cells was subjected to phycobiliprotein extraction. The phosphate and water extraction of A. platensis SFE residue were compared to evaluate phycobiliprotein extraction. The SFE results exhibited higher pressure (350 bar) and temperature extraction (50 °C) with ethanol-free extraction and increased nonpolar pigment. Phycobiliprotein yield was obtained from A. platensis SFE residue by ethanol-free buffer extraction as a suitable process with antioxidant properties. The C-phycocyanin was isolated and enhanced to 0.7 purity as food grade. This developed method can be used as a guideline and applied as a sustainable process for important pigment extraction from Arthrospira microalgae.

Coproduction of lipids and carotenoids by the novel green alga Coelastrella sp. depending on cultivation conditions

A novel green alga Coelastrella sp. D3-1 was isolated, and its unique and significant lipid and carotenoid coproduction capability was characterised depending on cultivation conditions. The main component of produced lipids was triacylglycerol under nutrient depletion conditions, in which fatty-methyl-esters made up 20-44% of the dry cell weight (DCW) and consisted of abundant C16:0 and C18:1 fatty acids. The red (orange)-stage cells also produced a large portion of carotenoids (38.5% of the DCW) involving echinenone, canthaxanthin, and astaxanthin as major components accumulated over only 5-6 days under optimal conditions. Stress tests revealed resistance of the cells to pH 2-11, high temperatures (40-60 °C), ultraviolet irradiation, drought, and H₂O₂ treatment, thereby showing a robust nature. Both green- and red (orange)-stage cell extracts also showed antioxidant and anti-inflammatory abilities, implying that they have significant functions as useful biorefinery materials.

Phycobiliproteins, the pigment-protein complex form of natural food colorants and bioactive ingredients

Currently, the use of synthetic pigments in foods is restricted since synthetic pigments are proven and suspected to be harmful to human health. Phycobiliproteins (PBPs), existed in phycobilisomes (PBSs) of algae, are a kind of pigment-proteins with intense color. The specific color of PBPs (red and blue) is given by the water-soluble open-chained tetrapyrrole chromophore (phycobilin) that covalently attaches to the apo-protein via thioether linkages to cysteine residues. According to the spectral characteristics of PBPs, they can be categorized as phycoerythrins (PEs), phycocyanins (PCs), allophycocyanins (APCs), and phycoerythrocyanins (PECs). PBPs can be used as natural food colorants, fluorescent substances, and bioactive ingredients in food applications owing to their color characteristics and physiological activities. This paper mainly summarizes the extraction and purification methods of the PBPs and reviews their characteristics and applications. Moreover, the use of several strategies such as additives, microencapsulation, electrospray, and cross-linking to improve the stability and bioavailability of PBPs as well as the future outlooks of PBPs as natural colorants in food commercialization are elucidated.

Integration of Arthrospira platensis (spirulina) into the brewing process to develop new beers with unique sensory properties

Microalgae, and particularly the cyanobacterium Arthrospira platensis (spirulina), have attracted much attention due to their wide range of uses. The potential use of spirulina in food is mainly driven by its high content of macro and micronutrients including proteins, γ-linolenic acid, sulfated polysaccharides, minerals, vitamins, and the natural pigment phycocyanin. Despite these potential benefits, spirulina is still not widely used in the food industry due to numerous technological challenges during manufacturing or specific sensory issues in the final product. This research deals with the feasibility of integrating spirulina into the brewing process to create a tasty beer with high consumer acceptance. In the novel recipes, 5% (w/w) of the malt was replaced by spirulina powder. The first part of the study investigated inclusion at different time points throughout manufacturing of a reference beer style (mild pale ale). Compared to the control, alcoholic fermentation was slightly influenced by cyanobacterial biomass but resulted in a beer with a typical beer-like character. Sensory evaluations including a simple descriptive test, a popularity analysis, and Just-About-Right-Questions, indicated a complex alteration in the sensory properties. This includes a dominant algal taste that disturbs the character of the pale ale beers but also a deep blue color of the beer, if spirulina was included during the wort cooling phase. Based on these results, another set of beers with a higher original extract concentration and increased hop dosages was produced. These beers had a high popularity (6.0 original TESTSCORE; 7.12 and 6.64 optimized TESTSCORE), and also exhibited a deep blue color due to the natural pigment phycocyanin from spirulina. Further, bitterness and algal taste was rated by most of the panelists to be “just right” and the simple descriptive test indicated “sweetness” as important attribute which was not expected for this hoppy beer style.

The Antioxidant Activity of a Commercial and a Fractionated Phycocyanin on Human Skin Cells In Vitro

The protective effects for cells against chemical and UVA stress of a commercial phycocyanin (PC) for food use and a PC extracted from Arthrospira platensis (Spirulina) in phosphate buffer were assessed. The purity of the commercial PC, spectrophotometrically estimated as A620/A280 and confirmed by HPLC, was higher than that of the fractionated PC (2.0 vs. 1.5) but was twofold less concentrated. The oxygen radical antioxidant capacities (ORACs) of the commercial and fractionated PCs were 12,141 ± 1928 and 32,680 ± 3295 TE/100 g, respectively. The degradation of PCs upon exposure to UVA was spectrophotometrically estimated, and cytotoxicity was evaluated with the MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) test on human fibroblasts and keratinocytes. A lower level of reactive oxygen species (ROS) was recorded in the two cell lines incubated with the commercial PC after menadione treatment (p < 0.01) and UVA exposure (p < 0.001) on fibroblasts after 5 min and keratinocytes up to 25 min, compared with controls. Differently, the fractionated PC was not protective and showed significant (p < 0.01) paradoxical prooxidant effects. Overall, the PC for food consumption demonstrated a high safety threshold and antioxidant ability to cells that, along with its coloring power, make it an excellent candidate for cosmetic formulations.

Improving the Thermal and Oxidative Stability of Food-Grade Phycocyanin from Arthrospira platensis by Addition of Saccharides and Sugar Alcohols

The water-soluble pigment protein phycocyanin (C-PC) from cyanobacteria Arthrospira sp. is an excellent natural food colorant and nutritional supplement with a brilliant blue color. However, C-PC is highly unstable, especially at high temperatures and when exposed to oxidative stress. The lack of simple and economical methods for improving the stability of C-PC greatly limits the application of this functional protein in the food industry. This study investigated the effect of adding saccharides (glucose, mannose, galactose, and maltose) and sugar alcohols (mannitol and maltitol) on the stability of food-grade C-PC extracted from Arthrospira platensis; the relevant reaction kinetics were also analyzed. The results revealed that glucose, mannose, mannitol, galactose, and maltose could effectively improve the thermal stability of C-PC. This improvement was positively correlated with the concentration of the additives and decreased sharply when the temperature exceeded 60 °C. Furthermore, the results also revealed the instability of C-PC when subjected to oxidative stress and the effectiveness of glucose, mannose, mannitol, and maltose in preventing the oxidative degradation of C-PC. In general, this study demonstrates that glucose, mannose, mannitol, and maltose are promising compounds for promoting the thermal and oxidative stability of C-PC, providing an economical and effective method for C-PC preservation.

Preparation, Characterization, and Antioxidant Properties of Phycocyanin Complexes Based on Sodium Alginate and Lysozyme

In this study, phycocyanin-sodium alginate/lysozyme complex (PC-SLC) was prepared for the first time and characterized by UV spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and circular dichroism spectroscopy (CD). The stability of PC-SLC under light, temperature, pH and simulated gastrointestinal fluid was investigated. The scavenging ability of the complexes against DPPH and ABTS radicals was determined. The results showed that the complex formed by the mass ratio of SA-LZM of 0.1 showed the highest PC encapsulation rate (89.9 ± 0.374%). The combination of SA and LZM changed the secondary conformation of PC. The PC-SLC complex shows an irregular spherical structure and the spheres are clustered together. Compared with phycocyanin (PC), its thermal stability was obviously improved, but it was still greatly influenced by light. It could exist stably in simulated gastric fluid (SGF) for 2 h and be slowly digested in simulated intestinal fluid (SIF), which helped to promote the absorption of nutrients in the intestinal tract. Meanwhile, the complex PC-SLC showed high scavenging ability for DPPH and ABTS radicals. It can be concluded that the complexes have good antioxidant activity. This study provides an idea for the construction of PC delivery system and makes it more widely used in food industry and other fields.

Exploring cyanobacterial diversity for sustainable biotechnology

Cyanobacteria are an evolutionarily ancient and diverse group of microorganisms. Their genetic diversity has 
allowed them to occupy and play vital roles in a wide range of ecological niches, from desert soil crusts to tropical oceans. Owing to bioprospecting efforts and the development of new platform technologies enabling their study and manipulation, our knowledge of cyanobacterial metabolism is rapidly expanding. This review explores our current understanding of the genetic and metabolic features of cyanobacteria, from the more established cyanobacterial model strains to the newly isolated/described species, particularly the fast-growing, highly productive, and genetically amenable strains, as promising chassis for renewable biotechnology. It also discusses emerging technologies for their study and manipulation, enabling researchers to harness the astounding diversity of the cyanobacterial genomic and metabolic treasure trove towards the establishment of a sustainable bioeconomy.

Microalgal drugs: A promising therapeutic reserve for the future

Over the decades, a variety of chemically synthesized drugs are being used to cure existing diseases but often these drugs could not be effectively employed for the treatment of serious and newly emerging diseases. Fortunately, in nature there occurs immense treasure of plants and microorganisms which are living jewels with respect to their richness of medically important metabolites of high value. Hence, amongst the existing microorganism(s), the marine world offers a plethora of biological entities that can contribute to alleviate numerous human ailments. Algae are one such photosynthetic microorganism found in both marine as well as fresh water which are rich source of metabolites known for their nutrient content and health benefits. Various algal species like Haematococcus, Diatoms, Griffithsia, Chlorella, Spirulina, Ulva, etc. have been identified and isolated to produce biologically active and pharmaceutically important high value compounds like astaxanthin, fucoxanthin, sulphur polysaccharides mainly galactose, rhamnose, xylose, fucose etc., which show antimicrobial, antifungal, anti-cancer, and antiviral activities. However, the production of either of these bio compounds is favored under conditions of stress. This review gives detailed information on various nutraceutical metabolites extracted from algae. Additionally focus has been made on the role of these bio compounds extracted from algae especially sulphur polysaccharides to treat several diseases with prospective treatment for SARS-CoV-2. Lastly it covers the knowledge gaps and future perspectives in this area of research.

Phycobiliproteins extract from Spirulina protects against single-dose cadmium-induced reproductive toxicity in male mice

Cadmium (Cd) is known for its many toxic effects on male population such as hypogonadism and fertility difficulties, which are oftenly associated with oxidative stress. As beneficial food, Spirulina(Sp) has been proved efficient against the heavy metal toxicity. This capacity can be associated with its phycobiliproteins (PBP). In this study, the capability of PBP and Sp to treat Cd-induced oxidative damage on the testes and spermatozoa was considered. CD-1 strain mice were orally treated with either Sp or PBP for 10 days prior to single-dose Cd challenge. Sperm quality determinations and testicle histology analysis were performed. Testosterone on serum was measured using enzyme-linked immunosorbent assay (ELISA). Oxidative damage was determined. Antioxidant enzyme activity was analyzed by measuring the activity of super oxide dismutase (SOD), catalase (Cat), and glutathione peroxidase (GpX). The motility and viability of sperm decrease with Cd and improve with PBP and Sp, as the acrosomal reaction (AR) is diminished by PBPs. Testosterone levels decrease due to Cd, and only Sp maintains elevated levels. Cd increases the production of malondialdehyde in the spermatozoa, but not in testes; this production of malondialdehyde in the spermatozoa decreases in the presence of PBP. ROS only decreases with Cd, FBP, and Sp at high concentrations. Advanced oxidative protein products (AOPP) decrease with Cd and PBPs. Cat and GpX increase their activity with Cd and are altered by FBP. Cd produces vascular alterations testes. Within the seminiferous tubule, it produces areas of necrosis and apoptosis, which improve with PBPs and Sp. PBPs have a strong antioxidant activity as they show protective properties against Cd oxidative-induced toxicity on testes and sperm.