Seaweed-derived β-glucan as potential immune modulating agents

A significant portion of seaweed or marine macroalgae consists of polysaccharides, displaying diverse properties and health benefits. Laminarin, also known as β-glucan, is a storage polysaccharide derived from brown algae. It has been recognized for its potential pharmacological effects, encompassing antioxidant, anti- anticancer, immunomodulatory and vaccine adjuvant properties. Laminarin, being biodegradable, biocompatible and minimally toxic, has been extensively explored as a functional material in various biomedical applications. This chapter summarizes laminarin's molecular characteristics andelucidates the mechanisms of action of the reported health benefits. As we decipher its molecular intricacies and immunomodulatory effects, further research promises to reveal new insights, enhancing our understanding of laminarin's potential in diverse fields

Insights from a zebrafish model to combat dyslipidemia using microbe-derived bioactive compounds

Every year approximately 18 million people die from heart diseases, making them the most common non-communicable disease. Long-term consumption of fatty foods can alter the normal blood lipid profile by increasing ‘bad cholesterol’ levels and reducing ‘good cholesterol’ levels in the blood, a condition known as dyslipidemia. Dyslipidemia is a major risk factor for the development of heart diseases. Although several drugs have been developed to prevent dyslipidemia, they are often associated with side effects. The search for diet-based approaches to controlling dyslipidemia has therefore attracted the interest of researchers. The objective of the research presented in this PhD thesis was to determine whether two dietary compounds, microbial β-glucans and microbial oil, are effective in preventing the development of dyslipidemia. To explore this, two microbe-derived bioactive compounds were fed to zebrafish, which, like humans, can develop dyslipidemia and fatty liver through the consumption of a cholesterol-rich diet. The results indicated that both microbial β-glucans and microbial oil can reduce the ‘bad cholesterol’ level and raise the ‘good cholesterol’ level in the blood. Furthermore, microbe-derived β-glucans and oils can reduce the fat droplets in the liver and shape the lipid profile during dyslipidemia. Thus, this PhD project provides interesting information about the suitability of zebrafish as a research model for studying the efficacy of bioactive compounds in preventing non-communicable diseases. The findings presented in this thesis are quite interesting, so it is expected that the generated knowledge will be used to develop new treatments and preventative measures

Seaweed based nutraceutical in aquaculture

Aquaculture has emerged as an essential source of seafood for the ever growing human population, playing a significant role in ensuring global food security. With the increasing demand for nutritious seafood driven by population growth and the depletion of wild fish stocks, aquaculture serves as a vital link between supply and demand (Garlock, et al., 2022). However, continually increasing aquafeed costs and disease outbreaks have become common challenges and questioning the sustainability of aquaculture (Barasa et al., 2022; Afewerki et al., 2023). Addressing these challenges is imperative, necessitating the urgent need to find a cost-effective and health-promoting feed ingredients. The goal is to support fish growth while preventing diseases in aquaculture production. In recent times, there has been a surge in interest regarding the utilization of diverse seaweeds—such as red seaweed (e.g., Gracilaria, Porphyra), brown seaweed (e.g., Laminaria, Ascophyllum), and green seaweed (e.g., Ulva, formerly Enteromorpha)—as potential sources of bioactive compounds and feed ingredients for incorporation into aquafeed given their favorable nutritional composition, environmental sustainability, and potential health-promoting factors for farmed fish (Wan et al., 2019). Numerous studies suggest that seaweed and seaweed-based functional metabolites, when included as supplements in aquafeed, can enhance serum immune and antioxidant status, as well as disease resistance in fish (Akbary et al., 2018; Thepot et al., 2021)

Validity of zebrafish and mice models to study hyperlipidemia and its mitigation by seaweed-derived bioactive compounds

Cardiovascular diseases pose a significant global health challenge, claiming over 20 million lives annually. In India, cardiovascular diseases contribute to two-thirds of all recorded deaths, exhibiting a sharp increase over the years. One major risk factor for cardiovascular diseases is hyperlipidemia, characterized by elevated blood lipid levels. Seaweed-derived compounds, rich in polyphenols, sulfated polysaccharides, and other bioactive molecules, have demonstrated antihyperlipidemic effects through various mechanisms. This chapter explores the potential of seaweed-derived bioactive compounds in combating hyperlipidemia, focusing on their mechanisms of action. The use of animal models, especially mice and zebra fish in studying the bioactivity of seaweed-derived compounds is also discussed in detail. We provide an overview of the strengths and limitations of both models in studying the efficacy of seaweed-derived compounds in combating hyperlipidemia. The combined knowledge gained from studying mice and zebra fish models can help in the use of high-value compounds from seaweeds for the health and well-being of humans in the future

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Not AvailableThe present study aimed to assess growth performance and health status of Lates calcarifer larvae fed with crude microalgal extracts. Larvae weighing 5.96 ± 0.39 mg were randomly divided into four experimental groups in triplicates, with each replicate having 35 larvae. Four diets formulated to contain 55% protein and 12% lipid, were prepared with pigment rich microalgal extracts at 0% (T1) and 1% each of crude phycocyanin (T2), chlorophyll (T3) and astaxanthin (T4) extracts. The experiment was carried out in 30 l plastic tanks by feeding experimental diets to satiation. There was no significant difference (p<0.05) in growth performance in larval groups fed different experimental diets. Percentage survival during the feeding experiment was significantly higher in the astaxanthin fed group (77.14±1.65) and lower in chlorophyll fed group (36.19±0.95) compared to control group. Cannibalism (%) was significantly reduced in the treatments fed astaxanthin (7.61±0.95) and phycocyanin (8.57±0.3) pigmented diets compared to chlorophyll fed group (13.33±0.95) and control group. Bacterial challenge with pathogenic Vibrio alginolyticus revealed highest resistance in astaxanthin and phycocyanin fed larvae. The study confirms that astaxanthin and phycocyanin at 1% dietary levels improve survival and disease resistance in Asian seabass larvae but do not affect growth performance.Not Availabl

Effect of dietary Sargassum wightii and its fucoidan-rich extract on growth, immunity, disease resistance and antimicrobial peptide gene expression in Labeo rohita

Abstract This work aimed to appraise growth performance, immune responsiveness, bacterial disease resistance and mRNA expression of two antimicrobial peptides in Labeo rohita fingerlings fed diets supplemented with seaweed Sargassum wightii and its fucoidan-rich extract. Two hundred and twenty-five fingerlings were divided into five experimental groups in triplicates, each replicate having 15 fish in a 90-L tank. Different groups were fed with isonitrogenous (35% crude protein) and isoenergetic (1408.16 kJ/100 g) diets containing either 0% fucoidan-rich seaweed extract (FRSE), 1% FRSE, 2% FRSE, 3% seaweed powder and 6% seaweed powder for 60 days. Partial nucleotide sequences of the antimicrobial peptides, hepcidin and defensin, were characterized in Labeo rohita fingerlings, and gene expression in the different tissues of experimental fish was studied. The fish-fed FRSE-supplemented diets showed significant increase (P < 0.05) in the mRNA expression of antimicrobial peptides in liver, skin and intestine tissues. Bacterial challenge study using Aeromonas hydrophila showed higher survival in the FRSE-fed groups. Fish-fed FRSE-supplemented diets also showed better non-specific immune response (NBT reduction, serum lysozyme activity, serum albumin: globulin ratio and phagocytic activity) in pre-challenge and post-challenge periods. No significant difference was observed in the growth performance in the different experimental groups. The study indicates that although dietary FRSE is a potential immunostimulant in Labeo rohita fingerlings, it does not improve growth performance

Polystyrene nanoplastics enhance the toxicological effects of DDE in zebrafish (Danio rerio) larvae

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Polystyrene nanoplastics enhance the toxicological effects of DDE in zebrafish (Danio rerio) larvae

Anthropogenic releases of plastics, persistent organic pollutants (POPs), and heavy metals can impact the environment, including aquatic ecosystems. Nanoplastics (NPs) have recently emerged as pervasive environmental pollutants that have the ability to adsorb POPs and can cause stress in organisms. Among POPs, DDT and its metabolites are ubiquitous environmental pollutants due to their long persistence. Despite the discontinued use of DDT in Europe, DDT and its metabolites (primarily p,p′-DDE) are still found at detectable levels in fish feed used in salmon aquaculture. Our study aimed to look at the individual and combined toxicity of NPs (50 mg/L polystyrene) and DDE (100 μg/L) using zebrafish larvae as a model. We found no significant morphological, cardiac, respiratory, or behavioural changes in zebrafish larvae exposed to NPs alone. Conversely, morphological, cardiac and respiratory alterations were observed in zebrafish larvae exposed to DDE and NPs + DDE. Interestingly, behavioural changes were only observed in zebrafish larvae exposed to NPs + DDE. These findings were supported by RNA-seq results, which showed that some cardiac, vascular, and immunogenic pathways were downregulated only in zebrafish larvae exposed to NPs + DDE. In summary, we found an enhanced toxicological impact of DDE when combined with NPs.publishedVersio

Metabolic and haematological responses of Labeo rohita to dietary fucoidan

Immunomodulatory properties of fucoidan have been extensively studied in fish. However the effect of dietary fucoidan on the metabolic enzymes is not studied in detail with respect to aquatic organisms. An investigation of the effect of dietary fucoidan on the metabolic and haematological status of Labeo rohita fingerlings is presented. One hundred and eighty fingerlings were distributed into four experimental groups in triplicates. Each group was fed isonitrogenous and isoenergetic diets containing 0% fucoidan (T1), 1% fucoidan (T2), 2% fucoidan (T3) and 3% (T4) seaweed powder to satiation for a period of sixty days. Dietary fucoidan was found to significantly (P < 0.05) reduce malate dehydrogenase and aspartate aminotransferase activity in the liver tissue. Alanine aminotransferase activity in the muscle tissue of fucoidan fed groups was significantly higher than the control. The liver and gill superoxide dismutase activity was significantly reduced in the fucoidan fed groups compared to the control. The catalase activity in the liver and gill was significantly lowered in the T3 group. The blood profile of the different experimental groups also revealed beneficial effects of dietary fucoidan yielding a superior haematological status in the groups fed with fucoidan

Fish as the lesser-known counterpart to mammalian models to explore the biofunctionality of polyphenols

Dietary polyphenols improve gut health either through their direct effects on the intestinal barrier and antioxidant and immune systems of the host or through the action of metabolites produced by the microbiota. We have focused on phenolic acids like gallic acid and curcumin, stilbenes like resveratrol, and flavonoids such as quercetin, daidzein, and anthocyanins that can chelate metals and scavenge free radicals to prevent or treat intestinal inflammation and brain disorders. Although polyphenols undergo both phase I and II metabolisms, only a tiny fraction of the catabolites is bioavailable. The gut microbiota catabolizes these compounds to produce beneficial metabolites for the host.Fish can be suitable models for obtaining in-depth knowledge about the absorption and metabolism of polyphenols, and their breakdown by the gut microbiota. Gathering such knowledge along with their effects on the immune system could reveal the effectiveness of bioactive compounds like polyphenols in tackling intestine and brain disorders