Components of the cultivated red seaweed Chondrus crispus enhance the immune response of Caenorhabditis elegans to Pseudomonas aeruginosa through the pmk-1, daf-2/daf-16, and skn-1 pathways

An Update on the Chemical Constituents and Biological Properties of Selected Species of an Underpinned Genus of Red Algae: Chondrus

Macroalgae, particularly red seaweeds, have attracted significant attention due to their economic and health benefits. Chondrus, a red algae genus, despite its economic importance, seems to be undervalued. Among all its species, Chondrus crispus has been meticulously documented for its biological properties, and little is known about other species. No comprehensive review of the biological properties of this genus has been acknowledged. Thus, this review aimed to summarize the available information on the chemical constituents and biological properties of a few selected species, including Chondrus crispus, Chondrus ocellatus, Mazzaella canaliculata, and Chondrus armatus. We compiled and discovered that the genus is offering most of the important health-promoting benefits evidenced from in vitro and in vivo studies focused on antimicrobial, immunomodulation, neuroprotection, anti-atopic, anti-inflammatory, anti-viral, anti-diabetic, cytoprotective, antioxidant, anti-coagulation, nephroprotective, anti-tumor, and anti-venom activity, which speaks about the potential of this genus. Data on clinical studies are limited. Further, around 105 chemical constituents have been reported from Chondrus spp. Given its significance, further investigation is warranted, in the form of meticulously planned cell, animal, and clinical studies that concentrate on novel health-enhancing endeavors, in order to unveil the full potential of this genus. The review also outlines challenges and future directions.

Anti-inflammatory Activities of Sulfated Polysaccharides From Ethanol Crude Extract of Spyrida Species Red Seaweed

INTRODUCTION

The extracts derived from red seaweed have shown characteristics that may reduce inflammation. The abovementioned effects can potentially provide positive outcomes in managing inflammatory illnesses, including arthritis, inflammatory bowel disease, and other skin problems.

AIM

The polysaccharides were isolated from the Spyrida species. The water-soluble polysaccharides were extracted and fractionated from several Indian seaweeds (Red) using a simple, cost-effective approach. Anti-inflammatory effects were further evaluated and validated by FTIR and FESEM analyses.

MATERIALS AND METHODS

FT-IR and FESEM were used to assess the structural features of polysaccharides and the surface morphology. In addition, the red seaweed species of the genus Spyrida, which includes polysaccharides, was shown to significantly inhibit the denaturation of bovine serum albumin (BSA), further proving that the substance has anti-inflammatory qualities.

RESULTS

In this work, an assay to suppress protein activity was utilized to investigate the potential anti-inflammatory effects of polysaccharides derived from Spyrida. As predicted, increasing concentrations of the extract, ranging from 25 to 100 µg/ml, led to a rise in the percentage of inhibited protein denaturation.

CONCLUSION

A statistically significant difference was found between these findings and those obtained with aspirin, a commonly used non-steroidal anti-inflammatory medicine (NSAID). The red algae that grow in the shallow waters of the southern Indian Ocean may be used in medicine.

Caenorhabditis elegans as an In Vivo Model for the Discovery and Development of Natural Plant-Based Antimicrobial Compounds

Antimicrobial resistance (AMR) due to the prevalence of multidrug-resistant (MDR) pathogens is rapidly increasing worldwide, and the identification of new antimicrobial agents with innovative mechanisms of action is urgently required. Medicinal plants that have been utilised for centuries with minor side effects may hold great promise as sources of effective antimicrobial products. The free-living nematode Caenorhabditis elegans (C. elegans) is an excellent live infection model for the discovery and development of new antimicrobial compounds. However, while C. elegans has widely been utilised to explore the effectiveness and toxicity of synthetic antibiotics, it has not been used to a comparable extent for the analysis of natural products. By screening the PubMed database, we identified articles reporting the use of the C. elegans model for the identification of natural products endowed with antibacterial and antifungal potential, and we critically analysed their results. The studies discussed here provide important information regarding "in vivo" antimicrobial effectiveness and toxicity of natural products, as evaluated prior to testing in conventional vertebrate models, thereby supporting the relevance of C. elegans as a highly proficient model for their identification and functional assessment. However, their critical evaluation also underlines that the characterisation of active phytochemicals and of their chemical structure, and the unravelling of their mechanisms of action represent decisive challenges for future research in this area.

Recent advances in cellulose, pectin, carrageenan and alginate-based oral drug delivery systems

Polymers-based drug delivery systems constitute one of the highly explored thrust areas in the field of the medicinal and pharmaceutical industries. In the past years, the properties of polymers have been modified in context to their solubility, release kinetics, targeted action site, absorption, and therapeutic efficacy. Despite the availability of diverse synthetic polymers for the bioavailability enhancement of drugs, the use of natural polymers is still highly recommended due to their easy availability, accessibility, and non-toxicity. The aim of the review is to provide the available literature of the last five years on oral drug delivery systems based on four natural polymers i.e., cellulose, pectin, carrageenan, and alginate in a concise and tabulated manner. In this review, most of the information is in tabulated form to provide easy accessibility to the reader. The data related to active pharmaceutical ingredients and supported components in different formulations of the mentioned polymers have been made available.

Sarcodia suae modulates the immunity and disease resistance of white shrimp Litopenaeus vannamei against Vibrio alginolyticus via the purine metabolism and phenylalanine metabolism

Red seaweeds have several biofunctional properties, including immunomodulatory, antitumor, antioxidant, and antibacterial activities. In this study, we examined the effects of diets containing Sarcodia suae on the immune response, immune-related gene expressions, and disease resistance against Vibrio alginolyticus in white shrimp Litopenaeus vannamei. In addition, ¹H NMR metabolomics was applied to analyze the metabolites extracted from shrimp fed with S. suae and their functions in regulating immunity. A diet containing only fish meal was used as the control diet (S₀), and three diets containing different concentrations of S. suae powder, 2.5% (S2.5), 5% (S5), and 7.5% (S7.5) were used as experimental diets. Shrimp were fed diets for 20 days. Compared to the control group (S0), results showed that (1) shrimp fed diets supplemented with 5-7.5% of S. suae powder significantly increased anti-V. alginolyticus activity; (2) phagocytic activity (PA) increased in all shrimp fed with S. suae, but total haemocyte count (THC) only increased in S7.5 group; and (3) the expression of glutathione peroxidase (GPx) in haemocyte were significantly higher in S7.5 groups. Results from the ¹H NMR analysis revealed that 19 heapatopancreatic metabolites were matched and identified among groups. Based on the KEGG enrichment analysis, the up-regulated metabolites in the shrimp fed S5 and S7.5 diets were primarily due to the metabolism of purine and phenylalanine and their respective pathways. Results from these trials reveal that diets containing S. suae can increase immune response, thereby increasing shrimp resistance to V. alginolyticus. The purine and phenylalanine metabolic pathways may be considered as the relevant pathways for optimizing immunomodulatory responses.

C. elegans monitor energy status via the AMPK pathway to trigger innate immune responses against bacterial pathogens

Pathogen recognition and the triggering of host innate immune system are critical to understanding pathogen-host interaction. Cellular surveillance systems have been identified as an important strategy for the identification of microbial infection. In the present study, using Bacillus thuringiensis-Caenorhabditis elegans as a model, we found an approach for surveillance systems to sense pathogens. We report that Bacillus thuringiensis Cry5Ba, a typical pore-forming toxin, caused mitochondrial damage and energy imbalance by triggering potassium ion leakage, instead of directly targeting mitochondria. Interestingly, we find C. elegans can monitor intracellular energy status to trigger innate immune responses via AMP-activated protein kinase (AMPK), secreting multiple effectors to defend against pathogenic attacks. Our study indicates that the imbalance of energy status is a prevalent side effect of pathogen infection. Furthermore, the AMPK-dependent surveillance system may serve as a practicable strategy for the host to recognize and defense against pathogens.

Bacillus thuringiensis toxin Cry5Ba triggers potassium ion leakage, causing mitochondrial damage and energy imbalance. C. elegans can monitor this intracellular energy imbalance via AMP-activated protein kinase to trigger innate immune responses.

Pharmaceutical and nutraceutical activation of FOXO3 for healthy longevity

Life expectancy has increased substantially over the last 150 years. Yet this means that now most people also spend a greater length of time suffering from various age-associated diseases. As such, delaying age-related functional decline and extending healthspan, the period of active older years free from disease and disability, is an overarching objective of current aging research. Geroprotectors, compounds that target pathways that causally influence aging, are increasingly recognized as a means to extend healthspan in the aging population. Meanwhile, FOXO3 has emerged as a geroprotective gene intricately involved in aging and healthspan. FOXO3 genetic variants are linked to human longevity, reduced disease risks, and even self-reported health. Therefore, identification of FOXO3-activating compounds represents one of the most direct candidate approaches to extending healthspan in aging humans. In this work, we review compounds that activate FOXO3, or influence healthspan or lifespan in a FOXO3-dependent manner. These compounds can be classified as pharmaceuticals, including PI3K/AKT inhibitors and AMPK activators, antidepressants and antipsychotics, muscle relaxants, and HDAC inhibitors, or as nutraceuticals, including primary metabolites involved in cell growth and sustenance, and secondary metabolites including extracts, polyphenols, terpenoids, and other purified natural compounds. The compounds documented here provide a basis and resource for further research and development, with the ultimate goal of promoting healthy longevity in humans.

Dihydro-β-agarofuran-type sesquiterpenoids from the seeds of Celastrus virens with lifespan-extending effect on the nematode Caenorhabditis elegans

Twelve dihydro-β-agarofuran-type sesquiterpenoids, including five new ones (1-5), were purified from the seeds of Celastrus virens (Wang et Tang) C. Y. Chent et T. C. Kao. Their chemical structures were characterized via comprehensive spectroscopic analysis, single-crystal X-ray diffraction analysis, and computational prediction of ECD, as well as comparison of observed and reported NMR spectral data. Among the isolates, nine abundant dihydro-β-agarofuran-type sesquiterpenoids were evaluated for their lifespan-extending activity using the nematode Caenorhabditis elegans model. As a result, compounds 1, 2, 5, 6, 8, and 9 (50 μM) significantly extended the mean survival time of C. elegans, respectively, compared with the blank control group (p < 0.05). Further Quantitative RT-PCR showed that the prolonging of lifespan mediated by compounds 1, 6, 8, and 9 were dependent on the transcription factors skn-1 and hsf-1.

Biosafety assessment of Acinetobacter strains isolated from the Three Gorges Reservoir region in nematode Caenorhabditis elegans

Acinetobacter has been frequently detected in backwater areas of the Three Gorges Reservoir (TGR) region. We here employed Caenorhabditis elegans to perform biosafety assessment of Acinetobacter strains isolated from backwater area in the TGR region. Among 21 isolates and 5 reference strains of Acinetobacter, exposure to Acinetobacter strains of AC1, AC15, AC18, AC21, A. baumannii ATCC 19606T, A. junii NH88-14, and A. lwoffii DSM 2403T resulted in significant decrease in locomotion behavior and reduction in lifespan of Caenorhabditis elegans. In nematodes, exposure to Acinetobacter strains of AC1, AC15, AC18, AC21, A. baumannii, A. junii and A. lwoffii also resulted in significant reactive oxygen species (ROS) production. Moreover, exposure to Acinetobacter isolates of AC1, AC15, AC18, and AC21 led to significant increase in expressions of both SOD-3::GFP and some antimicrobial genes (lys-1, spp-12, lys-7, dod-6, spp-1, dod-22, lys-8, and/or F55G11.4) in nematodes. The Acinetobacter isolates of AC1, AC15, AC18, and AC21 had different morphological, biochemical, phylogenetical, and virulence gene properties. Our results suggested that exposure risk of some Acinetobacter strains isolated from the TGR region exists for environmental organisms and human health. In addition, C. elegans is useful to assess biosafety of Acinetobacter isolates from the environment.

Deficiency of innate immunity against P. aeruginosa enhances behavioral avoidance via the HECW-1/NPR-1 module in C. elegans

To antagonize infection of pathogenic bacteria in soil and confer increased survival, Caenorhabditis elegans employs innate immunity and behavioral avoidance synchronously as the two main defensive strategies. Although both biological processes and their individual signaling pathways have been partially elucidated, knowledge of their interrelationship remains limited. The current study reveals that deficiency of innate immunity triggered by mutation of the classic immune gene pmk-1 promotes avoidance behavior in C. elegans; and vice versa. Restoration of pmk-1 expression using the tissue-specific promoters suggested that the functional loss of both intestinal and neuronal pmk-1 is necessary for the enhanced avoidance. Additionally, PMK-1 co-localized with the E3 ubiquitin ligase HECW-1 in OLL neurons and regulated the expressional level of the latter, which consequently affected the production of NPR-1, a G-protein-coupled receptor homologous to the mammalian neuropeptide Y receptor, in RMG neurons in a non-cell-autonomous manner. Collectively, our study illustrates, once the innate immunity is impaired when C. elegans antagonizes bacterial infection, the other defensive strategy of behavioral avoidance can be enhanced accordingly via the HECW-1/NPR-1 module, suggesting that GPCRs in neural circuits may receive the inputs from immune system and integrate those two systems for better adapting to the real-time status.

SKN-1 is involved in combination of apple peels and blueberry extracts synergistically protecting against oxidative stress in Caenorhabditis elegans

Increased consumption of fruits and vegetables is associated with reduced risk of age-related functional declines and chronic diseases, primarily attributed to their bioactive phytochemicals. Apples and blueberries are rich in phytochemicals with a wide range of biological activities and health benefits. Our previous research has shown the combination of apple peel extracts (APE) and blueberry extracts (BE) can synergistically promote the lifespan of Caenorhabditis elegans (C. elegans). The objectives of this study were to determine whether the extension of lifespan was involved in regulation of oxidative stress, and to explore the underlying mechanisms of action. The results showed that the combination of APE and BE could synergistically ameliorate oxidative stress by improving antioxidant enzyme activities and enhancing resistance to paraquat. Meanwhile, treatment with APE plus BE could down-regulate the overexpression of reactive oxygen species (ROS) and affect the expression of antioxidant related genes, including sod-3, cat-1, ctl-1, skn-1, mev-1 and isp-1. However, administration with APE plus BE abolished the extension of the lifespan of skn-1(zu135) mutants, and inhibited the expression of skn-1 downstream genes, including gcs-1, gst-4 and gst-7. In addition, supplementation with APE plus BE could promote the migration of SKN-1 into the nucleus, which eliminated improvement to ROS and paraquat. In conclusion, the combination of APE and BE could synergistically protect against oxidative stress in C. elegans via the SKN-1/Nrf2 pathway. This study provided the theoretical basis to explore the combination of phytochemicals in the prevention of aging regulated by oxidative stress.

The effect of Red Seaweed (Chondrus crispus) on the fertility of male albino rats

At different parts of the world, Red Seaweeds are one component of human diets especially at Southeast Asia. Red Seaweeds structurally contain bioactive molecules so; we studied the effect of Chondrus crispus on increasing the male albino rat fertility. Twelve male albino rats are used in this study as two group pre-treated group and post- treated one each with 6 animals. The pretreated group was dissected before the post-treated group injection. Each post treated rat injected intramuscular with 1 mg of Chondrus crispus with dose 0.1 ml/ twice per week for 48 day (Mukhtar et al., 2013). The results showed that increasing on the total testosterone levels insignificantly, sperm motility significantly, and decreasing in both FSH and DPPH levels insignificantly and significantly for the MDA levels in the post-treated group. The morphological appearance and histological examination for the sperm, testis and liver were normal as the pretreated group. The molecular studies showed absence of any DNA fragmentation for the testis of both group. The Red Seaweed has an enhanced effect in the testicular function of the animal which might increase their fertility and sexual activities.

Ecological and Industrial Implications of Dynamic Seaweed-Associated Microbiota Interactions

Seaweeds are broadly distributed and represent an important source of secondary metabolites (e.g., halogenated compounds, polyphenols) eliciting various pharmacological activities and playing a relevant ecological role in the anti-epibiosis. Importantly, host (as known as basibiont such as algae)–microbe (as known as epibiont such as bacteria) interaction (as known as halobiont) is a driving force for coevolution in the marine environment. Nevertheless, halobionts may be fundamental (harmless) or detrimental (harmful) to the functioning of the host. In addition to biotic factors, abiotic factors (e.g., pH, salinity, temperature, nutrients) regulate halobionts. Spatiotemporal and functional exploration of such dynamic interactions appear crucial. Indeed, environmental stress in a constantly changing ocean may disturb complex mutualistic relations, through mechanisms involving host chemical defense strategies (e.g., secretion of secondary metabolites and antifouling chemicals by quorum sensing). It is worth mentioning that many of bioactive compounds, such as terpenoids, previously attributed to macroalgae are in fact produced or metabolized by their associated microorganisms (e.g., bacteria, fungi, viruses, parasites). Eventually, recent metagenomics analyses suggest that microbes may have acquired seaweed associated genes because of increased seaweed in diets. This article retrospectively reviews pertinent studies on the spatiotemporal and functional seaweed-associated microbiota interactions which can lead to the production of bioactive compounds with high antifouling, theranostic, and biotechnological potential.

Carrageenan: Drug Delivery Systems and Other Biomedical Applications

Marine resources are today a renewable source of various compounds, such as polysaccharides, that are used in the pharmaceutical, medical, cosmetic, and food fields. In recent years, considerable attention has been focused on carrageenan-based biomaterials due to their multifunctional qualities, including biodegradability, biocompatibility, and non-toxicity, in addition to bioactive attributes, such as their antiviral, antibacterial, antihyperlipidemic, anticoagulant, antioxidant, antitumor, and immunomodulating properties. They have been applied in pharmaceutical formulations as both their bioactive and physicochemical properties make them suitable biomaterials for drug delivery, and recently for the development of tissue engineering. This article provides a review of recent research on the various types of carrageenan-based biomedical and pharmaceutical applications.

Potential Anti-Aging Substances Derived from Seaweeds

Aging is a major risk factor for many chronic diseases, such as cancer, cardiovascular disease, and diabetes. The exact mechanisms underlying the aging process are not fully elucidated. However, a growing body of evidence suggests that several pathways, such as sirtuin, AMP-activated protein kinase, insulin-like growth factor, autophagy, and nuclear factor erythroid 2-related factor 2 play critical roles in regulating aging. Furthermore, genetic or dietary interventions of these pathways can extend lifespan by delaying the aging process. Seaweeds are a food source rich in many nutrients, including fibers, polyunsaturated fatty acids, vitamins, minerals, and other bioactive compounds. The health benefits of seaweeds include, but are not limited to, antioxidant, anti-inflammatory, and anti-obese activities. Interestingly, a body of studies shows that some seaweed-derived extracts or isolated compounds, can modulate these aging-regulating pathways or even extend lifespans of various animal models. However, few such studies have been conducted on higher animals or even humans. In this review, we focused on potential anti-aging bioactive substances in seaweeds that have been studied in cells and animals mainly based on their anti-aging cellular and molecular mechanisms.

Structural characterization of ginseng oligopeptides and anti-aging potency evaluation in Caenorhabditis elegans

The functions of ginseng polysaccharide have been widely explored, yet, the antiaging activity of ginseng oligopeptides (GOPs) has not been well explored. In the current study, seven novel GOPs were isolated, and their antiaging activity was explored in a Caenorhabditis elegans (C. elegans) model. Of interest, all the GOPs showed lifespan extending effects in C. elegans models. Out of the GOPs treatments, 0.75 mM GOP-1 (EHGEYE) prolonged the N2 nematodes lifespan by 42.5%. Additionally, GOP-1 had a strong free radical-scavenging activity, and up-regulated the survival of the N2 C. elegans under oxidative and thermal stresses. Further study revealed that GOP-1 up-regulated the transcription factor daf-16 and jnk-1 expressions, thus we inferred that GOP-1 promotes the lifespan and stress resistances through a JNK-1-DAF-16 pathway. The current study revealed that the ginseng oligopeptides are potential antiaging agents.

The Evolution Road of Seaweed Aquaculture: Cultivation Technologies and the Industry 4.0

Seaweeds (marine macroalgae) are autotrophic organisms capable of producing many compounds of interest. For a long time, seaweeds have been seen as a great nutritional resource, primarily in Asian countries to later gain importance in Europe and South America, as well as in North America and Australia. It has been reported that edible seaweeds are rich in proteins, lipids and dietary fibers. Moreover, they have plenty of bioactive molecules that can be applied in nutraceutical, pharmaceutical and cosmetic areas. There are historical registers of harvest and cultivation of seaweeds but with the increment of the studies of seaweeds and their valuable compounds, their aquaculture has increased. The methodology of cultivation varies from onshore to offshore. Seaweeds can also be part of integrated multi-trophic aquaculture (IMTA), which has great opportunities but is also very challenging to the farmers. This multidisciplinary field applied to the seaweed aquaculture is very promising to improve the methods and techniques; this area is developed under the denominated industry 4.0.

The NLRP3-Mediated Neuroinflammatory Responses to CdTe Quantum Dots and the Protection of ZnS Shell

Introduction

Since CdTe quantum dots (QDs) are still widely considered as advanced fluorescent probes because of their far superior optical performance and fluorescence efficiency over non-cadmium QDs, it is important to find ways to control their toxicity.

Methods

In this study, the adverse effects of two cadmium-containing QDs, ie, CdTe QDs and CdTe@ZnS QDs, on the nervous system of nematode C. elegans, the hippocampus of mice, and cultured microglia were measured in order to evaluate the neuroinflammation caused by cadmium-containing QDs and the potential mechanisms.

Results

Firstly, we observed that cadmium-containing QD exposure-induced immune responses and neurobehavioral deficit in nematode C. elegans. In the mice treated with QDs, neuroinflammatory responses to QDs in the hippocampus, including microglial activation and IL-1ß release, occurred as well. When investigating the mechanisms of cadmium-containing QDs causing IL-1ß-mediated inflammation, the findings suggested that cadmium-containing QDs activated the NLRP3 inflammasome by causing excessive ROS generation, and resulted in IL-1ß release.

Discussion

Even though the milder immune responses and neurotoxicity of CdTe@ZnS QDs compared with CdTe QDs indicated the protective role of ZnS coating, the inhibitions of NLRP3 expression and ROS production completely reduced the IL-1ß-mediated inflammation. This provided valuable information that inhibiting target molecules is an effective and efficient way to alleviate  the toxicity of cadmium-containing QDs, so it is important to evaluate QDs through a mechanism-based risk assessment.

Raspberry extract promoted longevity and stress toleranceviathe insulin/IGF signaling pathway and DAF-16 inCaenorhabditis elegans

Increased consumption of fruits and vegetables is associated with a reduced risk of age-related functional decline and chronic diseases, which is primarily attributed to phytochemicals.

Combination of apple peel and blueberry extracts synergistically induced lifespan extension via DAF-16 in Caenorhabditis elegans

Apples and blueberries are rich in phytochemicals with a wide range of biological activities and health benefits. Our research found that the combination of apple peel extracts and blueberry extracts could synergistically promote the lifespan via DAF-16 in C. elegans.

Lipase-like 5 enzyme controls mitochondrial activity in response to starvation in Caenorhabditis elegans

The C. elegans lipase-like 5 (lipl-5) gene is predicted to code for a lipase homologous to the human gastric acid lipase. Its expression was previously shown to be modulated by nutritional or immune cues, but nothing is known about its impact on the lipid landscape and ensuing functional consequences. In the present work, we used mutants lacking LIPL-5 protein and found that lipl-5 is important for normal lipidome composition as well as its remodeling in response to food deprivation. Particularly, lipids with signaling functions such as ceramides and mitochondrial lipids were affected by lipl-5 silencing. In comparison with wild type worms, animals lacking LIPL-5 were enriched in cardiolipins linked to polyunsaturated C20 fatty acids and coenzyme Q-9. Differences in mitochondrial lipid composition were accompanied by differences in mitochondrial activity as mitochondria from well-fed lipl-5 mutants were significantly more able to oxidize respiratory substrates when compared with mitochondria from well-fed wild type worms. Strikingly, starvation elicited important changes in mitochondrial activity in wild type worms, but not in lipl-5 worms. This indicates that this lipase is a determinant of mitochondrial functional remodeling in response to food withdrawal.

Black sea cucumber (Holothuria atra Jaeger, 1833) rescues Pseudomonas aeruginosa-infected Caenorhabditis elegans via reduction of pathogen virulence factors and enhancement of host immunity

A strategy to circumvent the problem of multidrug resistant pathogens is the discovery of anti-infectives targeting bacterial virulence or host immunity. Black sea cucumber (Holothuria atra) is a tropical sea cucumber species traditionally consumed as a remedy for many ailments. There is a paucity of knowledge on the anti-infective capacity of H. atra and the underlying mechanisms involved. The objective of this study is to utilize the Caenorhabditis elegans-P. aeruginosa infection model to elucidate the anti-infective properties of H. atra. A bioactive H. atra extract and subsequently its fraction were shown to have the capability of promoting the survival of C. elegans during a customarily lethal P. aeruginosa infection. The same entities also attenuate the production of elastase, protease, pyocyanin and biofilm in P. aeruginosa. The treatment of infected transgenic lys-7::GFP worms with this H. atra fraction restores the repressed expression of the defense enzyme lys-7, indicating an improved host immunity. QTOF-LCMS analysis revealed the presence of aspidospermatidine, an indole alkaloid, and inosine in this fraction. Collectively, our findings show that H. atra possesses anti-infective properties against P. aeruginosa infection, by inhibiting pathogen virulence and, eventually, reinstating host lys-7 expression.

Integral Utilization of Red Seaweed for Bioactive Production

The hydrocolloids carrageenan and agar are the major fraction industrially extracted and commercialized from red seaweeds. However, this type of macroalgae also contains a variety of components with nutritional, functional and biological properties. In the context of sustainability and bioeconomy, where the integral utilization of the natural resources is incentivized, the sequential separation and valorization of seaweed components with biological properties of interest for food, nutraceuticals, cosmeceuticals and pharmaceuticals is proposed. In this work, a review of the available conventional and alternative greener and efficient extraction for obtaining red seaweed bioactives is presented. The potential of emerging technologies for the production of valuable oligomers from carrageenan and agar is also commented, and finally, the sequential extraction of the constituent fractions is discussed.

Constituent and effects of polysaccharides isolated from Sophora moorcroftiana seeds on lifespan, reproduction, stress resistance, and antimicrobial capacity in Caenorhabditis elegans

Sophora moorcroftiana (S. moorcroftiana) is an endemic leguminous dwarf shrub in Tibet, China. Decoctions of the seeds have been used in Chinese folk medicine for dephlogistication, detoxication, and infectious diseases. The present study aimed to investigate the constituent and biological effects of polysaccharides from S. moorcroftiana seeds in Caenorhabditis elegans (C. elegans). Polysaccharides from S. moorcroftiana seeds (SMpol) were extracted with 60% ethanol and constituent was analyzed by GC-MS. SMpol was composed of glucose, galactose and inositol in the molar ratio of 35.7 : 1.3 : 17.0. Synchronized worms were treated with SMpol and then lifespan, motility, reproduction, stress resistance and antimicrobial activity were examined. Compared with the control group, the lifespan was increased to the average of 27.3 days and the number of laying eggs showed a 1.3-fold increase in nematodes treated with SMpol (4 mg·mL^-1). In SMpol (4 mg·mL^-1) treated worms, there was a 1.1-fold increase in 24-h survival of acute heat stress and a 1.6-fold increase in 2-h survival of oxidative stress The colonization of the bacteria in the SMpol treated nematode was significantly lower than that of the untreated group by 68.3%. In vivo studies showed SMpol significantly extended the life span, improved reproduction, increased stress resistance and antimicrobial capacity of C. elegans. In conclusion, those results indicated that the polysaccharides from S. moorcroftiana seeds were involved in a variety of biological activities leading to its modulatory effects on C. elegans which may be developed as a natural supplement agent.

Seaweed Extract (Stella Maris®) Activates Innate Immune Responses in Arabidopsis thaliana and Protects Host against Bacterial Pathogens

Insects and pathogenic infections (bacteria, viruses and fungi) cause huge losses in agriculturally important crops yearly. Due to the rise in pesticide and antibiotic resistance, our crops and livestock are increasingly at risk. There is a rising demand for environmentally friendly solutions to prevent crop decreases. Components of Ascophyllum nodosum seaweed extracts were recently found to boost plant immunity. The stimulatory activities of the A.nodosum marine alga-derived extract (Stella Maris®) were investigated in a broad range of immune assays. Elevated hydrogen peroxide production measured in a chemiluminescence assay suggested that the extract elicited a strong burst of reactive oxygen species. Arabidopsis seedlings treated with Stella Maris® activated the expression of WRKY30, CYP71A12 and PR-1 genes, the induction of which represent early, mid and late plant immune response, respectively. Finally, this study found that Stella Maris® inhibited the growth of multiple bacterial pathogens, including an opportunistic human pathogen that has demonstrated pathogenicity in plants. In summary, the pre-treatment with the seaweed extract protected Arabidopsis against subsequent infection by these pathogens.

Assessment of the effects of sulfated polysaccharides extracted from the red seaweed Irish moss Chondrus crispus on the immune-stimulant activity in mussels Mytilus spp

Seaweeds contain a number of health enhancing and antimicrobial bioactive compounds including sulfated polysaccharides (SP). In the present study, SP extracted from a European red seaweed Irish moss Chondrus crispus was chemically analyzed, SP content extracted and the immune-response effect on wild Irish mussels Mytilus spp. investigated for the first time. A high percent yield of SP was extracted from C. crispus and the immune-stimulant activity of SP was assessed in a laboratory trial with mussels exposed to three different treatments of low (10 μg mL^-1), medium (20 μg mL^-1) and high (50 μg mL^-1) SP dose concentrations and a control mussel group with no exposure to SP. An initial mussel sample was processed prior to the trial commencing and mussels were subsequently sampled on Days 1, 2, 3, 4, 7, and 10 post SP exposure. Both cell, humoral and immune related gene responses including haemocyte cell viability, haemocyte counts, lysozyme activity and expression of immune related genes (defensin, mytimycin and lysozyme mRNA) were assessed. No mussel mortalities were observed in either the treated or non-treated groups. Mussels exposed with SP showed an increase in haemocyte cell viability and the total number of haemocytes compared to control mussels. Lysozyme activity was also higher in treated mussels. Additionally, up-regulated expression of defensin, mytimycin and lysozyme mRNA was observed in SP treated mussels shortly after exposure (on Days 1, 2, and 3) to SP. These results indicate that a high quality yield of SP can be readily extracted from C. crispus and more importantly based on the animal model used in this study, SP extracted from C. crispus can rapidly induce health enhancing activities in Mytilus spp. at a cellular, humoral and molecular level and with a prolonged effect up to ten days post treatment.

A Marine Actinomycete Rescues Caenorhabditis elegans from Pseudomonas aeruginosa Infection through Restitution of Lysozyme 7

The resistance of Pseudomonas aeruginosa to conventional antimicrobial treatment is a major scourge in healthcare. Therefore, it is crucial that novel potent anti-infectives are discovered. The aim of the present study is to screen marine actinomycetes for chemical entities capable of overcoming P. aeruginosa infection through mechanisms involving anti-virulence or host immunity activities. A total of 18 actinomycetes isolates were sampled from marine sediment of Songsong Island, Kedah, Malaysia. Upon confirming that the methanolic crude extract of these isolates do not display direct bactericidal activities, they were tested for capacity to rescue Caenorhabditis elegans infected with P. aeruginosa strain PA14. A hexane partition of the extract from one isolate, designated as Streptomyces sp. CCB-PSK207, could promote the survival of PA14 infected worms by more than 60%. Partial 16S sequence analysis on this isolate showed identity of 99.79% with Streptomyces sundarbansensis. This partition did not impair feeding behavior of C. elegans worms. Tested on PA14, the partition also did not affect bacterial growth or its ability to colonize host gut. The production of biofilm, protease, and pyocyanin in PA14 were uninterrupted, although there was an increase in elastase production. In lys-7::GFP worms, this partition was shown to induce the expression of lysozyme 7, an important innate immunity defense molecule that was repressed during PA14 infection. GC-MS analysis of the bioactive fraction of Streptomyces sp. CCB-PSK207 revealed the presence of methyl esters of branched saturated fatty acids. In conclusion, this is the first report of a marine actinomycete producing metabolites capable of rescuing C. elegans from PA14 through a lys-7 mediated activity.

Pseudomonas aeruginosa quorum sensing modulates immune responses: An updated review article

Pseudomonas aeruginosa is an opportunistic bacterium which induces some complications in immunocompromised patients. Pseudomonas aeruginosa is a quorum-sensing using bacterium which regulates its genes expression. The bacterium uses two famous pathways for quorum sensing entitled LasI/LasR and RhlI/RhlR systems. It has been documented that the bacteria which use quorum sensing are able to overcome immune responses. This review article aims to present recent information regarding the effects of Pseudomonas aeruginosa quorum sensing systems on the host immune responses.

Cell and small animal models for phenotypic drug discovery

The phenotype-based drug discovery (PDD) approach is re-emerging as an alternative platform for drug discovery. This review provides an overview of the various model systems and technical advances in imaging and image analyses that strengthen the PDD platform. In PDD screens, compounds of therapeutic value are identified based on the phenotypic perturbations produced irrespective of target(s) or mechanism of action. In this article, examples of phenotypic changes that can be detected and quantified with relative ease in a cell-based setup are discussed. In addition, a higher order of PDD screening setup using small animal models is also explored. As PDD screens integrate physiology and multiple signaling mechanisms during the screening process, the identified hits have higher biomedical applicability. Taken together, this review highlights the advantages gained by adopting a PDD approach in drug discovery. Such a PDD platform can complement target-based systems that are currently in practice to accelerate drug discovery.

Beyond Traditional Antimicrobials: A Caenorhabditis elegans Model for Discovery of Novel Anti-infectives

The spread of antibiotic resistance amongst bacterial pathogens has led to an urgent need for new antimicrobial compounds with novel modes of action that minimize the potential for drug resistance. To date, the development of new antimicrobial drugs is still lagging far behind the rising demand, partly owing to the absence of an effective screening platform. Over the last decade, the nematode Caenorhabditis elegans has been incorporated as a whole animal screening platform for antimicrobials. This development is taking advantage of the vast knowledge on worm physiology and how it interacts with bacterial and fungal pathogens. In addition to allowing for in vivo selection of compounds with promising anti-microbial properties, the whole animal C. elegans screening system has also permitted the discovery of novel compounds targeting infection processes that only manifest during the course of pathogen infection of the host. Another advantage of using C. elegans in the search for new antimicrobials is that the worm itself is a source of potential antimicrobial effectors which constitute part of its immune defense response to thwart infections. This has led to the evaluation of effector molecules, particularly antimicrobial proteins and peptides (APPs), as candidates for further development as therapeutic agents. In this review, we provide an overview on use of the C. elegans model for identification of novel anti-infectives. We highlight some highly potential lead compounds obtained from C. elegans-based screens, particularly those that target bacterial virulence or host defense to eradicate infections, a mechanism distinct from the action of conventional antibiotics. We also review the prospect of using C. elegans APPs as an antimicrobial strategy to treat infections.

Red Seaweeds Sarcodiotheca gaudichaudii and Chondrus crispus down Regulate Virulence Factors of Salmonella Enteritidis and Induce Immune Responses in Caenorhabditis elegans

Red seaweeds are a rich source of unique bioactive compounds and secondary metabolites that are known to improve human and animal health. S. Enteritidis is a broad range host pathogen, which contaminates chicken and poultry products that end into the human food chain. Worldwide, Salmonella outbreaks have become an important economic and public health concern. Moreover, the development of resistance in Salmonella serovars toward multiple drugs highlights the need for alternative control strategies. This study evaluated the antimicrobial property of red seaweeds extracts against Salmonella Enteritidis using the Caenorhabditis elegans infection model. Six red seaweed species were tested for their antimicrobial activity against S. Enteritidis and two, Sarcodiotheca gaudichaudii (SG) and Chondrus crispus (CC), were found to exhibit such properties. Spread plate assay revealed that SG and CC (1%, w/v) significantly reduced the growth of S. Enteritidis. Seaweed water extracts (SWE) of SG and CC, at concentrations from 0.4 to 2 mg/ml, significantly reduced the growth of S. Enteritidis (log CFU 4.5–5.3 and log 5.7–6.0, respectively). However, methanolic extracts of CC and SG did not affect the growth of S. Enteritidis. Addition of SWE (0.2 mg/ml, CC and SG) significantly decreased biofilm formation and reduced the motility of S. Enteritidis. Quantitative real-time PCR analyses showed that SWE (CC and SG) suppressed the expression of quorum sensing gene sdiA and of Salmonella Pathogenesis Island-1 (SPI-1) associated genes sipA and invF, indicating that SWE might reduce the invasion of S. Enteritidis in the host by attenuating virulence factors. Furthermore, CC and SG water extracts significantly improved the survival of infected C. elegans by impairing the ability of S. Enteritidis to colonize the digestive tract of the nematode and by enhancing the expression of C. elegans immune responsive genes. As the innate immune response pathways of C. elegans and mammals show a high degree of conservation, these results suggest that these SWE may also impart beneficial effects on animal and human health.

Proteins and Carbohydrates from Red Seaweeds: Evidence for Beneficial Effects on Gut Function and Microbiota

Based on their composition, marine algae, and namely red seaweeds, are good potential functional foods. Intestinal mucosal barrier function refers to the capacity of the intestine to provide adequate containment of luminal microorganisms and molecules. Here, we will first outline the component of seaweeds and will summarize the effects of these on the regulation of mucosal barrier function. Special attention will be paid to unique components of red seaweeds: proteins and derived peptides (e.g., phycobiliproteins, glycoproteins that contain “cellulose binding domains”, phycolectins and the related mycosporine-like amino acids) together with polysaccharides (e.g., floridean starch and sulfated galactans, such as carrageenans, agarans and “dl-hybrid”) and minerals. These compounds have been shown to exert prebiotic effects, to regulate intestinal epithelial cell, macrophage and lymphocyte proliferation and differentiation and to modulate the immune response. Molecular mechanisms of action of peptides and polysaccharides are starting to be elucidated, and evidence indicating the involvement of epidermal growth factor receptor (EGFR), insulin-like growth factor receptor (IGFR), Toll-like receptors (TLR) and signal transduction pathways mediated by protein kinase B (PKB or AKT), nuclear factor-κB (NF-κB) and mitogen activated protein kinases (MAPK) will also be summarized. The need for further research is clear, but in vivo experiments point to an overall antiinflammatory effect of these algae, indicating that they can reinforce membrane barrier function.

Prebiotic effects of diet supplemented with the cultivated red seaweed Chondrus crispus or with fructo-oligo-saccharide on host immunity, colonic microbiota and gut microbial metabolites

Background

Gastrointestinal microbial communities are diverse and are composed of both beneficial and pathogenic groups. Prebiotics, such as digestion-resistant fibers, influence the composition of gut microbiota, and can contribute to the improvement of host health. The red seaweed Chondrus crispus is rich in dietary fiber and oligosaccharides, however its prebiotic potential has not been studied to date.

Methods

Prebiotic effects were investigated with weaning rats fed a cultivated C. crispus-supplemented diet. Comparison standards included a fructo-oligo-saccharide (FOS) diet and a basal diet. The colonic microbiome was profiled with a 16S rRNA sequencing-based Phylochip array. Concentrations of short chain fatty acids (SCFAs) in the feacal samples were determined by gas chromatography with a flame ionization detector (GC-FID) analysis. Immunoglobulin levels in the blood plasma were analyzed with an enzyme-linked immunosorbent assay (ELISA). Histo-morphological parameters of the proximal colon tissue were characterized by hematoxylin and eosin (H&E) staining.

Results

Phylochip array analysis indicated differing microbiome composition among the diet-supplemented and the control groups, with the C. crispus group (2.5 % supplementation) showing larger separation from the control than other treatment groups. In the 2.5 % C. crispus group, the population of beneficial bacteria such as Bifidobacterium breve increased (4.9-fold, p = 0.001), and the abundance of pathogenic species such as Clostridium septicum and Streptococcus pneumonia decreased. Higher concentrations of short chain fatty acids (i.e., gut microbial metabolites), including acetic, propionic and butyric acids, were found in faecal samples of the C. crispus-fed rats. Furthermore, both C. crispus and FOS supplemented rats showed significant improvements in proximal colon histo-morphology . Higher faecal moisture was noted in the 2.5 % C. crispus group, and elevated plasma immunoglobulin (IgA and IgG) levels were observed in the 0.5 % C. crispus group, as compared to the basal feed group.

Conclusions

The results suggest multiple prebiotic effects, such as influencing the composition of gut microbial communities, improvement of gut health and immune modulation in rats supplemented with cultivated C. crispus.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-015-0802-5) contains supplementary material, which is available to authorized users.

Neuroprotective effects of the cultivated Chondrus crispus in a C. elegans model of Parkinson's disease

Parkinson’s disease (PD) is the second most common neurodegenerative disorder in the elderly people, currently with no cure. Its mechanisms are not well understood, thus studies targeting cause-directed therapy or prevention are needed. This study uses the transgenic Caenorhabditis elegans PD model. We demonstrated that dietary supplementation of the worms with an extract from the cultivated red seaweed Chondrus crispus decreased the accumulation of α-synulein and protected the worms from the neuronal toxin-, 6-OHDA, induced dopaminergic neurodegeneration. These effects were associated with a corrected slowness of movement. We also showed that the enhancement of oxidative stress tolerance and an up-regulation of the stress response genes, sod-3 and skn-1, may have served as the molecular mechanism for the C. crispus-extract-mediated protection against PD pathology. Altogether, apart from its potential as a functional food, the tested red seaweed, C. crispus, might find promising pharmaceutical applications for the development of potential novel anti-neurodegenerative drugs for humans.

Selenite enhances immune response against Pseudomonas aeruginosa PA14 via SKN-1 in Caenorhabditis elegans

Background

Selenium (Se) is an important nutrient that carries out many biological processes including maintaining optimal immune function. Here, inorganic selenite (Se(IV)) was evaluated for its pathogen resistance and potential-associated factors in Caenorhabditis elegans. The immune effects of Se(IV) were investigated by examining the responses of C. elegans to Pseudomonas aerugonisa PA14 strain.

Principal Findings

Se(IV)-treated C. elegans showed increased survival under PA14 infection compared with untreated controls. The significant pathogen resistance of Se(IV) on C. elegans might not be attributed to the effects of Se(IV) on PA14 as Se(IV) showed no effect on bacterial quorum-sensing and virulence factors of PA14. This study showed that Se(IV) enhanced the expression of a gene pivotal for the innate immunity in C. elegans. The study found that the pathogen-resistant phenotypes contributed by Se(IV) was absent from the skn-1 mutant worms. Moreover, Se(IV) influenced the subcellular distribution of SKN-1/Nrf in C. elegans upon PA14 infection. Furthermore, Se(IV) increased mRNA levels of SKN-1 target genes (gst-4 and gcs-1).

Conclusions

This study found evidence of Se(IV) protecting C. elegans against P. aeruginosa PA14 infection by exerting effects on the innate immunity of C. elegans that is likely mediated via regulation of a SKN-1-dependent signaling pathway.

Orthosiphon stamineus protects Caenorhabditis elegans against Staphylococcus aureus infection through immunomodulation

Amidst growing concerns over the spread of antibiotic-resistant Staphylococcus aureus strains, the identification of alternative therapeutic molecules has become paramount. Previously, we utilized a Caenorhabditis elegans–S. aureus screening platform to identify potential anti-infective agents from a collection of natural extracts and synthetic compounds. One of the hits obtained from the screen was the aqueous extract of Orthosiphon stamineus leaves (UE-12) that enhanced the survival of infected nematodes without interfering with bacterial growth. In this study, we used a fluorescent transgenic reporter strain and observed that the repressed expression of the lys-7 defense gene in infected nematodes was restored in the presence of UE-12. Analysis of a selected panel of PMK-1 and DAF-16-regulated transcripts and loss-of-function mutants in these pathways indicates that the protective role of UE-12 is mediated via the p38 MAP kinase and insulin-like signaling pathways. Further analysis of a panel of known bioactive compounds of UE-12 proposed eupatorin (C₁₈H₁₆O₇) as the possible candidate active molecule contributing to the anti-infective property of UE-12. Taken together, these findings strongly suggest that the O. stamineus leaf extract is a promising anti-infective agent that confers an advantage in survival against S. aureus infection by modulating the immune response of the infected host.