κ-Carrageenan hexamer have significant anti-inflammatory activity and protect RAW264.7 Macrophages by inhibiting CD14

Macroalgae-derived bioactive compounds for functional food and pharmaceutical applications-a critical review

The rising demand for global food resources, combined with an overreliance on land-based agroecosystems, poses a significant challenge for the sustainable production of food products. Macroalgae cultivation is a promising approach to mitigate impending global food insecurities due to several key factors: independence from terrestrial farming, rapid growth rates, unique biochemical makeup, and carbon capture potential. Furthermore, macroalgae are rich in vitamins, minerals, essential amino acids, polyunsaturated fatty acids and fiber, demonstrating significant potential as sustainable alternatives for enhancing dietary diversity and fulfilling nutritional requirements. This review provides an overview of the nutritional composition and functional properties of commercially cultivated macroalgae species, with emphasis on their viability as value additions to the functional food market. Furthermore, the review discusses the technological aspects of integrating macroalgae into food products, covering both innovative solutions and existing challenges. Macroalgae, beyond being nutritional powerhouses, contain a plethora of bioactive compounds with varied biological activities, including anti-diabetic, anti-cancer, cardioprotective, and neuroprotective properties, making them excellent candidates in developing novel pharmaceuticals. Thus, this review also summarizes the pharmaceutical applications of macroalgae, identifies research gaps and proposes potential strategies for incorporating macroalgae-derived bioactive compounds into therapeutic products.

Carrageenan oligosaccharide alleviates intestinal damage via gut microflora through activating IMD/relish pathway in female Drosophila melanogaster

Recent evidence suggests the anti-inflammatory effect of carrageenan oligosaccharides (COS). The effects of COS on intestinal injury induced by 0.6% sodium dodecyl sulfate (SDS) and the molecular mechanisms involved were investigated in this study. 0.625, 1.25, and 2.5 mg/mL COS in diet had no toxic effect in flies, and they could all prolong SDS-treated female flies' survival rate. 1.25 mg/mL COS prevented the development of inflammation by improving the intestinal barrier integrity and maintaining the intestinal morphology stability, inhibited the proliferation of intestine stem cells (ISCs), and the production of lysosomes induced by SDS, accompanied by a decrease in the expression of autophagy-related genes. Moreover, COS decreased the active oxygen species (ROS) content in gut and increased the antioxidant activity in SDS-induced female flies, while COS still played a role in increasing survival rate and decreasing intestinal leakage in CncC-RNAi flies. The improvement of anti-inflammation capacity may be associated with the regulation of intestinal microflora with COS supplementation for Drosophila melanogaster. COS changed the gut microbiota composition, and COS had no effect on germ-free (GF) flies. It is highlighted that COS could not work in Relish-RNAi flies, indicating relish is required for COS to perform beneficial effects. These results provide insights into the study of gut microbiota interacting with COS to modulate intestinal inflammation in specific hosts.

Biochemical characterization and elucidation of the action mode of a GH16 family κ-carrageenase for efficient preparation of carrageenan oligosaccharides

κ-Carrageenan oligosaccharides have a variety of biological activities. Degradation of κ-carrageenan by κ-carrageenase leads to degradation products with different degrees of polymerization (DPs). A novel gene (CecgkA) encoding a new κ-carrageenase was cloned from Colwellia echini and heterologously expressed in Escherichia coli BL21 (DE3). The enzyme is 1104 bp in length, encodes 367 amino acid residues and has a molecular weight of 41.30 kDa. Multiple alignment analysis showed that CeCgkA belongs to the glycoside hydrolase (GH16) family and has the highest homology with the κ-carrageenase of Rhodopirellula maiorica SM1, with 58% homology. The CeCgkA showed maximum activity (453.15 U/mg) at pH 8.0 and 35 °C. Determination of biochemical properties showed that CeCgkA was a thermal recovery enzyme, and 51.6% of the initial enzyme activity was recovered by immediately placing the sample at 35 °C for 60 min after enzymatic inactivation by boiling for 10 min. K⁺, Na⁺, and EDTA had an activating effect on the enzyme activity, while Ni²⁺, Cu²⁺, and Zn²⁺ inhibited the activity of the enzyme. In addition, TLC and ESI-MS analysis showed that the maximum recognition unit of CecgkA was decasaccharide and that the main degradation products were disaccharides, tetrasaccharides and hexasaccharides, indicating that the enzyme is an endo-type carrageenase.

Algae-derived hydrocolloids in foods: applications and health-related issues

Hydrocolloids are a class of food additives with broad applications in the food industry to develop structure in food ingredients. Hydrocolloids can be synthetic, plant-based, or animal-based. Increasing consumer awareness has led to the use of natural food ingredients derived from natural sources, making algae-derived hydrocolloids more appealing nowadays. Algae-derived hydrocolloids such as carrageenan, agar, and alginate are widely used in the food industry as thickening, gelling, and emulsifying agents. Carrageenans are sulfated polysaccharides with diverse structural specificities. The safety of carrageenan use in the food industry has been widely debated recently due to the reported pro-inflammatory activities of carrageenan and the probable digestion of carrageenan by the gut microbiota to generate pro-inflammatory oligosaccharides. In contrast, both agar and alginate are primarily nontoxic, and generally no dispute regarding the use of the same in food ingredients. This review provides an overview of the algae industry, the food additives, the algae-derived hydrocolloids, the applications of algae-derived hydrocolloids in food industries, health-related studies, and other sectors, along with future perspectives. Even though differences of opinion exist in the use of carrageenan, it is continued to be used by the food industry and will be used until suitable alternatives are available. In summary, algal hydrocolloids are 'label-friendly' and considered a safe option against synthetic additives.

Ovotransferrin exerts bidirectional immunomodulatory activities via TLR4-mediated signal transduction pathways in RAW264.7 cells

The immune regulation function of ovotransferrin (OVT) explored using the RAW264.7 was induced by lipopolysaccharide (LPS) as vitro model in this study. The results showed that RAW264.7 cultured with OVT (200 μg/ml) alone not only enhanced the phagocytic activity and the production and expression of inflammatory factors, but also expression of toll-like receptor 4 (TLR4) gene was significantly promoted by OVT. OVT (50 μg/ml) significantly inhibited the secretion and expression of inflammatory factors in LPS-stimulated RAW264.7, but CD14 and TLR4 genes expressions were no obvious effects. Inflammatory cytokines and NO secreted by OVT-induced macrophages pretreated with inhibitors of TLR4 were down-regulated. We further verified the effects of OVT on inflammatory signaling pathway-related proteins through immunofluorescence and western blotting, MyD88, TLR4 and the phosphorylation of IκBα and p65 were significantly promoted by OVT, but there was no significant effects on the phosphorylation of IRF3. OVT promoted the phosphorylation of ERK and p38 in RAW264.7 and inhibited the phosphorylated expression of MAPK in LPS-mediated inflammation. These results indicated that OVT had the bidirectional immunoregulatory function through TLR4-mediated NF-κB/MAPK signaling pathway, that is, anti-inflammatory effect of low concentration and immune-enhancing activity of high concentration were showed. That provides a theoretical utilization for the development and utilization of OVT.

Optimization of Fermentation Conditions for Carrageenase Production by Cellulophaga Species: A Comparative Study

Simple Summary

Cellulophaga species are rarely studied marine bacteria with the potential for carrageenase production. We examined the carrageenase secretion ability of six bacterial species from the Cellulophaga genus. Among them, C. algicola produced the maximum amount of ι-carrageenase. Most of the bacteria produced their highest quantity of enzymes at 25 °C after 48 h of incubation time. The maximum enzyme production was achieved with the fermentation medium composition of 30 g/L sea salt, 1.4 g/L furcellaran and 3 g/L yeast extract. In addition, the properties of the ultrafiltered ι-carrageenase extracted from C. algicola were studied.

Abstract

Carrageenases appear in various species of marine bacteria and are widely used for the degradation of carrageenans, the commercially significant sulphated polysaccharides. The carrageenase production ability of six different Cellulophaga species was identified, with ι-carrageenase being the most abundant carrageenolytic enzyme. C. algicola was the most potent strain, followed by C. fucicola and C. geojensis, whereas C. pacifica was the least effective carrageenase producer among the studied strains. The enzyme production was maximized using the one-factor-at-a-time optimization method. The optimal incubation temperature was identified as 25 °C and the incubation time was set as 48 h for all tested species. The optimal medium composition for Cellulophaga strains was determined as 30 g/L sea salt, 1.4 g/L furcellaran, and 3 g/L yeast extract. An ultrafiltered enzyme extracted from C. algicola had the highest activity at around 40 °C. The optimal pH for enzymatic degradation was determined as 7.8, and the enzyme was fairly stable at temperatures up to 40 °C.

Module function analysis of a full-length κ-carrageenase from Pseudoalteromonas sp. ZDY3

κ-Carrageenan oligosaccharides with many excellent biological properties could be produced by κ-carrageenases selectively. In this study, based on the encoding gene of full length κ-carrageenase obtained from Pseudoalteromonas sp. ZDY3 and the reported mature secreted κ-carrageenase composed of 275 amino acid residues (N26-T300), CgkPZ_GH16 was expressed in E. coli, but no soluble active protein could be detected. Fortunately, the signal peptide of wild-type κ-carrageenase was recognized, and cleaved in the soluble and folding form in E. coli, the K_m and k_cat values of CgkPZ_SP_GH16 was 1.007 mg/mL and 362.8 s^-1. By molecular dynamics simulations, it was showed that YjdB domain might affect the activity of κ-carrageenase. Due to the absence of mature processing modification system in E. coli, YjdB was remained in recombinant full length κ-carrageenase, and the lost catalytic efficiency of CgkPZ was compensated by expression level and thermal stability. Interestingly, CgkPZ_GH16_YjdB was expressed soluble without the signal peptide, which indicated that YjdB could contribute to the expression and folding of κ-carrageenase. These results provide new insight into the effects of different modules of κ-carrageenase on the expression and properties of enzyme.

Immunomodulatory sulfated polysaccharides from Caulerpa racemosa var. peltata induces metabolic shifts in NF-κB signaling pathway in RAW 264.7 macrophages

Algal polysaccharide activates macrophages to alter physiologic biomarkers to drive the immunomodulatory phenotype, but it lacks specific biomarkers involved in the biochemical underpinning process. Here, we undertook an extensive analysis of the RAW 264.7 macrophages induced by an immunostimulating sulfated polysaccharide from Caulerpa racemosa var. peltata (CRVP-1) employing combined transcriptomic, proteomic, and metabolomic analyses to reveal the molecular details occurring in the CRVP-1-induced immunomodulatory process. The omics profiling of CRVP-1-activated macrophage demonstrated a total of 8844 genes (4354 downregulated and 4490 upregulated), 1243 proteins (620 downregulated and 623 upregulated), and 68 metabolites (52 downregulated and16 upregulated). Further, the co-mapped correlation network of omics combined with Western blot and immunofluorescence staining indicated that the cluster of differentiation 14 (CD14) might assist Toll-like receptor 4 (TLR4) involved in nuclear factor kappa-B (NF-κB) signaling pathway to drive the immunomodulatory phenotype. Together, our results discover novel physiologic biomarkers in the immunomodulatory activities of algal polysaccharides.

Review on marine carbohydrate-based gold nanoparticles represented by alginate and chitosan for biomedical application

Gold nanoparticles (AuNPs) have been attracted considerable attention in cancer therapy, drug delivery and other applications due to their unique physical, chemical, and optical properties. Marine carbohydrates are important biological macromolecules that widely exist in marine algae and animals, such as alginate, carrageenan, porphyran, fucoidan, ulvan, agarose, and chitosan. Their excellent properties, such as biocompatibility, biodegradability and no irritation, make them widely used in biomedicine and nanomaterials fields. More importantly, they can be easily modified by functional groups, such as sulfation, acetylation, and carboxylation, to further extend their applications. The marine carbohydrates functionalized AuNPs can increase their biocompatibility and targeting in a green preparation method. Here, we review recent advances on marine carbohydrate-based AuNPs for cancer therapy, imaging, drug delivery and other biomedical fields. The topics of selective surface modification in different carbohydrates and further biomedical applications of AuNPs are also discussed.

Sotetsuflavone Induces Autophagy in Non-Small Cell Lung Cancer Through Blocking PI3K/Akt/mTOR Signaling Pathway in Vivo and in Vitro

Non-small cell lung cancer (NSCLC) is a globally scaled disease with a high incidence and high associated mortality rate. Autophagy is one of the important physiological activities that helps to control cell survival, influences the dynamics of cell death, and which plays a crucial role in the pathophysiology of NSCLC. Sotetsuflavone is a naturally derived and occurring flavonoid, and previous studies have demonstrated that sotetsuflavone possesses potential anti-cancer activities. However, whether or not sotetsuflavone induces autophagy, as well as has effects and influences cell death in NSCLC cells remains unclear. Thus, in our study, we examined and elucidated the roles and underlying mechanisms of sotetsuflavone upon the dynamics of autophagy in NSCLC in vivo and in vitro. The results indicated that sotetsuflavone was able to inhibit proliferation, migration, and invasion of NSCLC cells. Mechanistically, sotetsuflavone was able to induce apoptosis by increasing the levels of expression of cytochrome C, cleaved-caspase 3, cleaved-caspase 9, and Bax, and contrastingly decreased levels of expression of Bcl-2. In addition, we also found that decreased levels of expression of cyclin D1 and CDK4 caused arrest of the G0/G1 phases of the cell cycle. Furthermore, we also found that sotetsuflavone could induce autophagy which in turn can play a cytoprotective effect on apoptosis in NSCLC. Sotetsuflavone-induced autophagy appeared related to the blocking of the PI3K/Akt/mTOR pathway. Our in vivo study demonstrated that sotetsuflavone significantly inhibited the growth of xenograft model inoculated A549 tumor with high a degree of safety. Taken together, these findings suggest that sotetsuflavone induces autophagy in NSCLC cells through its effects upon blocking of the PI3K/Akt/mTOR signaling pathways. Our study may provide a theoretical basis for future clinical applications of sotetsuflavone and its use as a chemotherapeutic agent for treatment of NSCLC.