Effect of total secondary carotenoids extracts from Chlorococcum sp on Helicobacter pylori-infected BALB/c mice

Plant-derived extracts or compounds for Helicobacter-associated gastritis: a systematic review of their anti-Helicobacter activity and anti-inflammatory effect in animal experiments

BACKGROUND

Helicobacter infection, which is the leading cause of gastritis and stomach cancer, has become common worldwide. Almost all Helicobacter-infected patients have chronic active gastritis, also known as Helicobacter-associated gastritis (HAG). However, the eradication rate of Helicobacter is decreasing due to the poor efficacy of current medications, which causes infection to recur, inflammation to persist, and stomach cancer to develop. Natural components have robust antibacterial activity and anti-inflammatory capacity, as confirmed by many studies of alternative natural medicines.

PURPOSE

This article aimed to conduct a comprehensive search and meta-analysis to evaluate the efficacy of anti-Helicobacter and anti-inflammatory activities of plant-derived extracts or compounds that can treat HAG in animal experiments. We intended to provide detailed preclinical-research foundation including plant and compound information, as well as the mechanisms by which these plant-derived substances inhibit the progression of Helicobacter infection, gastritis and neoplasms for future study.

METHODS

The systematic review is aligned with the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, and the protocol was registered in PROSPERO (CRD42024527889). An extensive search was performed across multiple databases, including PubMed, Scopus, Web of Science, Embase, China National Knowledge Infrastructure (CNKI), the Chinese Scientific Journal database (VIP), the Wanfang database, and the China biomedical literature service system (SinoMed), up until November 2023. Meta-analysis on Review Manager software (RevMan 5.4) estimating anti-Helicobacter and anti-inflammatory activity was performed. We used the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) risk of bias tool to evaluate the risk of bias of each study included.

RESULTS

Our study encompassed 61 researches, comprised 36 extracts and 37 compounds improving HAG by inhibiting Helicobacter infection, the inflammatory response, oxidative stress, and regulating apoptosis and proliferation. Sixteen families especially Asteraceae, Fabaceae and Rosaceae and nine classes including Terpenoids, Alkaloids, Phenols, and Flavonoids may be promising directions for valuable new drugs. The Meta-analyse demonstrated the plant-base substance treatments possess significant anti-Helicobacter and anti-inflammation activity comparing to control groups. The included plants and compounds confirmed that signaling pathways NF-κB, JAK2/STAT3, MAPK, TLR4/MyD88, PI3K/AKT, NLRP3/Caspase-1 and NRF2/HO-1 play a key role in the progression of HAG.

CONCLUSION

Plant-derived extracts or compounds actively improve HAG by modulating relevant mechanisms and signaling pathways, particularly through the anti-Helicobacter and inflammatory regulation ways. Further researches to apply these treatments in humans are needed, which will provide direction for the future development of therapeutic drugs to increase eradication rate and alleviate gastritis.

Astaxanthin: a nature's versatile compound utilized for diverse applications and its therapeutic effects

Astaxanthin (ASTX), red-colored xanthophyll, also known as the "king of carotenoids" exhibits a strong antioxidant property that can be naturally found in green algae Haematococcus pluvialis, red yeast Phaffia rhodozyma, and various aquatic species including salmon, krill, trout, and fish eggs. Due to their strong antioxidant qualities, ASTX nanoparticles may be crucial in fighting against phytotoxicity caused by heavy metal ions. Similarly, it may also reduce the uptake of heavy metal, i.e. cadmium, and translocation by improving the morpho-physiological profiles of plants. Furthermore, it can also have the ability to scavenge free radicals, therefore, it can protect plants from reactive oxygen species (ROS). Implementing ASTX nanoparticles on crops can also help to achieve higher food production while minimizing toxic effects. Additionally, it can also possess several therapeutic activities including anti-cancerous, anti-diabetic, antioxidant, anti-aging, anti-inflammation, hepatoprotective, and cardiovascular, etc. that can be beneficial to treat various types of diseases in humans and animals. Recently, it has gained more interest in food, agriculture, aquaculture, neutraceuticals, and pharmaceutical industries due to its wide range of applications including food-coloring agents, food supplements, and strong antioxidant property that helps in skin protection, and boosts immune function. However, ASTX possesses poor water solubility and chemical stability so the implementation of ASTX on human health is facing various issues. Therefore, nanoencapsulation of ASTX is very crucial to improve its chemical stability and solubility, ultimately leading to its bioavailability and bioaccessibility. Recently, ASTX has been commercially available with specific dosages in the market mainly in the form of tablets, gels, powders, creams, syrups, etc. The current review mainly highlights the present state of ASTX nanoparticle applications in various fields explaining its natural and synthetic sources, extraction methods, chemical structure, stability, nanoformulations, nano encapsulation, and various commercial aspects.

Natural anti-adhesive components against pathogenic bacterial adhesion and infection in gastrointestinal tract: case studies of Helicobacter pylori, Salmonella enterica, Clostridium difficile, and diarrheagenic Escherichia coli

Antimicrobial resistance (AMR) poses a global public health concern. Recognizing the critical role of bacterial adhesion in pathogenesis of infection, anti-adhesive therapy emerges as a promising approach to impede initial bacterial attachment, thus preventing pathogenic colonization and infection. Natural anti-adhesive agents derived from food sources are generally safe and have the potential to inhibit the emergence of resistant bacteria. This comprehensive review explored diverse natural dietary components exhibiting anti-adhesive activities against several model enteric pathogens, including Helicobacter pylori, Salmonella enterica, Clostridium difficile, and three key diarrheagenic Escherichia coli (i.e., enterotoxigenic E. coli, enteropathogenic E. coli, and enterohemorrhagic E. coli). Investigating various anti-adhesive products will advance our understanding of current research of the field and inspire further development of these agents as potential nutraceuticals or adjuvants to improve the efficacy of conventional antibiotics.

A comprehensive evaluation of an animal model for Helicobacter pylori-associated stomach cancer: Fact and controversy

Even though Helicobacter pylori infection was the most causative factor of gastric cancer, numerous in vivo studies failed to induce gastric cancer using H. pylori infection only. The utilization of established animal studies in cancer research is crucial as they aim to investigate the coincidental association between suspected oncogenes and pathogenesis as well as generate models for the development and testing of potential treatments. The methods to establish gastric cancer using infected animal models remain limited, diverse in methods, and showed different results. This study investigates the differences in animal models, which highlight different pathological results in gaster by literature research. Electronic databases searched were performed in PubMed, Science Direct, and Cochrane, without a period filter. A total of 135 articles were used in this study after a full-text assessment was conducted. The most frequent animal models used for gastric cancer were Mice, while Mongolian gerbils and Transgenic mice were the most susceptible model for gastric cancer associated with H. pylori infection. Additionally, transgenic mice showed that the susceptibility to gastric cancer progression was due to genetic and epigenetic factors. These studies showed that in Mongolian gerbil models, H. pylori could function as a single agent to trigger stomach cancer. However, most gastric cancer susceptibilities were not solely relying on H. pylori infection, and numerous factors are involved in cancer progression. Further study using Mongolian gerbils and Transgenic mice is crucial to conduct and establish the best models for gastric cancer associated H. pylori.

Diet and gastric cancer risk: an umbrella review of systematic reviews and meta-analyses of prospective cohort studies

BACKGROUND

Several systematic reviews and meta-analyses evaluated the associations between dietary factors and the incidence of gastric cancer (GC).

OBJECTIVES

To evaluate the strength and validity of existing evidence, we conducted an umbrella review of published systematic reviews and meta-analyses that investigated the association between diets and GC incidence.

METHODS

We searched the PubMed, Embase, and Cochrane databases for systematic reviews and meta-analyses of prospective cohort studies investigating the association between dietary factors and GC risk. For each association, we recalculated the adjusted summary estimates with their 95% confidence interval (CI) and 95% prediction interval (PI) using a random-effects model. We used the I2 statistic and Egger's test to assess heterogeneity and small-study effects, respectively. We also assessed the methodological quality of each study and the quality of evidence.

RESULTS

Finally, we identified 16 meta-analyses that described 57 associations in this umbrella review. Of the 57 associations, eight were statistically significant using random-effects, thirteen demonstrated substantial heterogeneity between studies (I2 > 50%), and three found small-study effects. The methodological quality of meta-analyses was classified as critically low for two (13%), low for thirteen (81%), and only one (6%) was rated as high confidence. Quality of evidence was rated high for a positive association for GC incidence with a higher intake of total alcohol (RR = 1.19, 95% CI 1.06-1.34) and moderate-quality evidence to support that increased processed meat consumption can increase GC incidence. Three associations (total fruit, vitamin E, and carotenoids) were determined to be supported by low-quality evidence, and two (pickled vegetables/foods and citrus fruit) were supported by very low-quality.

CONCLUSIONS

Our findings support the dietary recommendations for preventative GC, emphasizing lower intake of alcohol and foods preserved by salting. New evidence suggests a possible role for total fruit, citrus fruit, carotenoids, and vitamin E. More research is needed on diets with lower quality evidence.

REGISTRATION NUMBER

CRD42021255115.

Unlocking the Health Potential of Microalgae as Sustainable Sources of Bioactive Compounds

Microalgae are known to produce a plethora of compounds derived from the primary and secondary metabolism. Different studies have shown that these compounds may have allelopathic, antimicrobial, and antipredator activities. In addition, in vitro and in vivo screenings have shown that several compounds have interesting bioactivities (such as antioxidant, anti-inflammatory, anticancer, and antimicrobial) for the possible prevention and treatment of human pathologies. Additionally, the enzymatic pathways responsible for the synthesis of these compounds, and the targets and mechanisms of their action have also been investigated for a few species. However, further research is necessary for their full exploitation and possible pharmaceutical and other industrial applications. Here, we review the current knowledge on the chemical characteristics, biological activities, mechanism of action, and the enzymes involved in the synthesis of microalgal metabolites with potential benefits for human health.

Astaxanthin and its Effects in Inflammatory Responses and Inflammation-Associated Diseases: Recent Advances and Future Directions

Astaxanthin is a natural lipid-soluble and red-orange carotenoid. Due to its strong antioxidant property, anti-inflammatory, anti-apoptotic, and immune modulation, astaxanthin has gained growing interest as a multi-target pharmacological agent against various diseases. In the current review, the anti-inflammation mechanisms of astaxanthin involved in targeting for inflammatory biomarkers and multiple signaling pathways, including PI3K/AKT, Nrf2, NF-κB, ERK1/2, JNK, p38 MAPK, and JAK-2/STAT-3, have been described. Furthermore, the applications of anti-inflammatory effects of astaxanthin in neurological diseases, diabetes, gastrointestinal diseases, hepatic and renal diseases, eye and skin disorders, are highlighted. In addition to the protective effects of astaxanthin in various chronic and acute diseases, we also summarize recent advances for the inconsistent roles of astaxanthin in infectious diseases, and give our view that the exact function of astaxanthin in response to different pathogen infection and the potential protective effects of astaxanthin in viral infectious diseases should be important research directions in the future.

Astaxanthin from Shrimp Cephalothorax Stimulates the Immune Response by Enhancing IFN-γ, IL-10, and IL-2 Secretion in Splenocytes of Helicobacter Pylori-Infected Mice

Infection with Helicobacter pylori is a critical cause of gastrointestinal diseases. A crucial host response associated with H. pylori infection includes gastric inflammation, which is characterized by a sustained recruitment of T-helper (Th) cells to the site of infection and distinct patterns of cytokine production. Adequate nutritional status, especially frequent consumption of dietary antioxidants, appears to protect against infection with H. pylori. The aim of the present study was to investigate whether astaxanthin (AXT) from shrimp cephalothorax may modulate cytokine release of splenocytes in H. pylori-infected mice (n = 60). Six- to eight-week-old female mice were divided into three groups (n = 20 per group) to receive a daily oral dose of 10 or 40 mg of AXT for six weeks. After six weeks, a trend toward interferon gamma (IFN-γ) upregulation was found (40 mg; p < 0.05) and a significant dose-dependent increase of interleukin 2 (IL-2) and IL-10 (both p < 0.05) was observed. These results suggest that AXT induces higher levels of IL-2 and a shift to a balanced Th1/Th2 response by increasing IFN-γ and augmenting IL-10. We concluded that AXT may influence the pattern of cytokines during H. pylori infection.

Bioaccessibility of Marine Carotenoids

The benefit of carotenoids to human health is undeniable and consequently, their use for this purpose is growing rapidly. Additionally, the nutraceutical properties of carotenoids have attracted attention of the food industry, especially in a new market area, the 'cosmeceuticals.' Marine organisms (microalgae, seaweeds, animals, etc.) are a rich source of carotenoids, with optimal properties for industrial production and biotechnological manipulation. Consequently, several papers have reviewed the analysis, characterization, extraction and determination methods, biological functions and industrial applications. But, now, the bioaccessibility and bioactivity of marine carotenoids has not been focused of any review, although important achievements have been published. The specific and diverse characteristic of the marine matrix determines the bioavailability of carotenoids, some of them unique in the nature. Considering the importance of the bioavailability not just from the health and nutritional point of view but also to the food and pharmaceutical industry, we consider that the present review responds to an actual demand.

Astaxanthin ameliorates cerulein-induced acute pancreatitis in mice

BACKGROUND

A various of pharmacological effects of astaxanthin has been confirmed. However, the mechanism underlying protective effect of astaxanthin on acute pancreatitis (AP) induced by cerulein still unclear. The present study is to investigate the mechanism underlying the effect of astaxanthin on autophagy and apoptosis via the JAK/STAT3 pathway.

METHODS

Intraperitoneal injection of cerulein at hourly intervals followed by lipopolysaccharide injection were used in Balb/C mice. Vehicle or astaxanthin, which intraperitoneal injected in two doses (20 mg/kg and 40 mg/kg), were injected in mice 1 h before the first cerulein injection. At 3 h after the last injection, when the pathological changes were most severe, pancreatic tissue was analyzed by pathologically scored and hematoxylin and eosin (H&E) staining. The severity of AP was assessed by histological grading, proinflammatory cytokine levels, biochemistry, myeloperoxidase (MPO) activity, and analysis of JAK/STAT3 activity.

RESULTS

Astaxanthin administration markedly reduced serum digestive enzyme activities, pancreatic histological scores, proinflammatory cytokine levels (tumor necrosis factor-α (TNF-α), Interleukin-1β (IL-1β), and Interleukin-6 (IL-6)), MPO and JAK/STAT3 activity.

CONCLUSION

Collectively, these results indicate that astaxanthin inhibits pancreatic injury in AP by targeting JAK/STAT3-mediated apoptosis and autophagy.

Astaxanthin and β-carotene in Helicobacter pylori-induced Gastric Inflammation: A Mini-review on Action Mechanisms

Helicobacter pylori is a dominant bacterium living in the human gastric tissues. In H. pylori-infected tissues, the infiltrated inflammatory cells produce reactive oxygen species (ROS), leading to gastric inflammation with production of various mediators. According to numerous epidemiological studies, dietary carotenoids may prevent gastric inflammation due to their antioxidant properties. Recent studies showed that antioxidant and anti-inflammatory effects of astaxanthin and β-carotene may contribute to inhibition of H. pylori-induced gastric inflammation. Astaxanthin changes H. pylori-induced activation of T helper cell type 1 response towards T helper cell type 2 response in the infected tissues. Astaxanthin inhibits the growth of H. pylori. Even though astaxanthin reduces H. pylori-induced gastric inflammation, it does not reduce cytokine levels in the infected tissues. β-Carotene suppresses ROS-mediated inflammatory signaling, including mitogen-activated protein kinases and redox-sensitive transcription factors, and reduces expression of inflammatory mediators, including interleukin-8, inducible nitric oxide synthase, and cyclooxygenase-2 in the infected tissues. Therefore, consumption of astaxanthin- and β-carotene-rich foods may be beneficial to prevent H. pylori-induced gastric inflammation. This review will summarize anti-inflammatory mechanisms of astaxanthin and β-carotene in H. pylori-mediated gastric inflammation.

Astaxanthin-Producing Green Microalga Haematococcus pluvialis: From Single Cell to High Value Commercial Products

Many species of microalgae have been used as source of nutrient rich food, feed, and health promoting compounds. Among the commercially important microalgae, Haematococcus pluvialis is the richest source of natural astaxanthin which is considered as "super anti-oxidant." Natural astaxanthin produced by H. pluvialis has significantly greater antioxidant capacity than the synthetic one. Astaxanthin has important applications in the nutraceuticals, cosmetics, food, and aquaculture industries. It is now evident that, astaxanthin can significantly reduce free radicals and oxidative stress and help human body maintain a healthy state. With extraordinary potency and increase in demand, astaxanthin is one of the high-value microalgal products of the future.This comprehensive review summarizes the most important aspects of the biology, biochemical composition, biosynthesis, and astaxanthin accumulation in the cells of H. pluvialis and its wide range of applications for humans and animals. In this paper, important and recent developments ranging from cultivation, harvest and postharvest bio-processing technologies to metabolic control and genetic engineering are reviewed in detail, focusing on biomass and astaxanthin production from this biotechnologically important microalga. Simultaneously, critical bottlenecks and major challenges in commercial scale production; current and prospective global market of H. pluvialis derived astaxanthin are also presented in a critical manner. A new biorefinery concept for H. pluvialis has been also suggested to guide toward economically sustainable approach for microalgae cultivation and processing. This report could serve as a useful guide to present current status of knowledge in the field and highlight key areas for future development of H. pluvialis astaxanthin technology and its large scale commercial implementation.

Functional ingredients from microalgae

A wide variety of natural sources are under investigation to evaluate their possible use for new functional ingredient formulation. Some records attested the traditional and ancient use of wild harvested microalgae as human food but their cultivation for different purposes started about 40 years ago. The most popular species are Arthrospira (traditional name, Spirulina), Chlorella spp., Dunaliella spp. and Haematococcus spp. Microalgae provide a bewildering array of opportunities to develop healthier food products using innovative approaches and a number of different strategies. Compared to other natural sources of bioactive ingredients, microalgae have many advantages such as their huge biodiversity, the possibility to grow in arid land and with limited fresh water consumption and the flexibility of their metabolism, which could be adapted to produce specific molecules. All these factors led to very sustainable production making microalgae eligible as one of the most promising foods for the future, particularly as source of proteins, lipids and phytochemicals. In this work, a revision of the knowledge about the use of microalgae as food and as a source of functional ingredients has been performed. The most interesting results in the field are presented and commented upon, focusing on the different species of microalgae and the activity of the nutritionally relevant compounds. A summary of the health effects obtained together with pros and cons in the adoption of this natural source as functional food ingredients is also proposed.

Association of carotenoids with risk of gastric cancer: A meta-analysis

BACKGROUND & AIMS

Prior studies on carotenoids and gastric cancer risk have generated inconsistent results. We performed a meta-analysis of observational studies to summarize the evidence regarding the relation of carotenoids and gastric cancer risk.

METHODS

A comprehensive search was performed to identify all observational studies providing quantitative estimates between gastric cancer risk and carotenoids. The fixed or random effect model was selected based on the homogeneity test among studies in the highest vs. lowest categorical analyses.

RESULTS

13 published case-control studies with 14 results including 3919 cases and 7400 controls, and 8 cohort studies involving 1972 cases of gastric cancer and 96,691 participants, met the inclusion criteria. For case-control studies, only intake of β-carotene and α-carotene were significantly associated with a reduced gastric cancer risk. The summary OR(95%CI) for β-carotene, α-carotene, lycopene and lutein were 0.52(0.46-0.59), 0.59(0.37-0.92), 0.88(0.55-1.41) and 0.85(0.56-1.30) respectively. In contrast, the summary RR(95%CI) for β-carotene, α-carotene, lycopene and lutein were 0.72(0.50-1.03), 0.79(0.58-1.07), 0.80(0.60-1.07) and 0.95(0.77-1.18), respectively.

CONCLUSION

Although data from case-control studies suggested that β-carotene, α-carotene were inversely associated with risk of gastric cancer, there was no conclusive evidence on this association because of inconsistencies between case-control and cohort studies.

Medicinal plant activity on Helicobacter pylori related diseases

More than 50% of the world population is infected with Helicobacter pylori (H. pylori). The bacterium highly links to peptic ulcer diseases and duodenal ulcer, which was classified as a group I carcinogen in 1994 by the WHO. The pathogenesis of H. pylori is contributed by its virulence factors including urease, flagella, vacuolating cytotoxin A (VacA), cytotoxin-associated gene antigen (Cag A), and others. Of those virulence factors, VacA and CagA play the key roles. Infection with H. pylori vacA-positive strains can lead to vacuolation and apoptosis, whereas infection with cagA-positive strains might result in severe gastric inflammation and gastric cancer. Numerous medicinal plants have been reported for their anti-H. pylori activity, and the relevant active compounds including polyphenols, flavonoids, quinones, coumarins, terpenoids, and alkaloids have been studied. The anti-H. pylori action mechanisms, including inhibition of enzymatic (urease, DNA gyrase, dihydrofolate reductase, N-acetyltransferase, and myeloperoxidase) and adhesive activities, high redox potential, and hydrophilic/hydrophobic natures of compounds, have also been discussed in detail. H. pylori-induced gastric inflammation may progress to superficial gastritis, atrophic gastritis, and finally gastric cancer. Many natural products have anti-H. pylori-induced inflammation activity and the relevant mechanisms include suppression of nuclear factor-κB and mitogen-activated protein kinase pathway activation and inhibition of oxidative stress. Anti-H. pylori induced gastric inflammatory effects of plant products, including quercetin, apigenin, carotenoids-rich algae, tea product, garlic extract, apple peel polyphenol, and finger-root extract, have been documented. In conclusion, many medicinal plant products possess anti-H. pylori activity as well as an anti-H. pylori-induced gastric inflammatory effect. Those plant products have showed great potential as pharmaceutical candidates for H. pylori eradication and H. pylori induced related gastric disease prevention.

Future directions for the development of Chlamydomonas-based vaccines

Besides serving as a valuable model in biological sciences, Chamydomonas reinhardtii has been used during the last decade in the biotechnology arena to establish models for the low cost production of vaccines. Antigens from various pathogens including Plasmodium falciparum, foot and mouth disease virus, Staphylococcus aureus, classical swine fever virus (CSFV) as well as some auto-antigens, have been produced in C. reinhardtii. Although some of them have been functionally characterized with promising results, this review identifies future directions for the advancement in the exploitation of this robust and safe vaccine production platform. The present analysis reflects that important immunological implications exist for this system and remain unexplored, including the possible adjuvant effects of algae biomolecules, the effect of bioencapsulation on immunogenicity and the possible development of whole-cell vaccines as an approach to trigger cytotoxic immune responses. Recently described molecular strategies that aim to optimize the expression of nuclear-encoded target antigens are also discussed.

Astaxanthin: sources, extraction, stability, biological activities and its commercial applications--a review

There is currently much interest in biological active compounds derived from natural resources, especially compounds that can efficiently act on molecular targets, which are involved in various diseases. Astaxanthin (3,3'-dihydroxy-β, β'-carotene-4,4'-dione) is a xanthophyll carotenoid, contained in Haematococcus pluvialis, Chlorella zofingiensis, Chlorococcum, and Phaffia rhodozyma. It accumulates up to 3.8% on the dry weight basis in H. pluvialis. Our recent published data on astaxanthin extraction, analysis, stability studies, and its biological activities results were added to this review paper. Based on our results and current literature, astaxanthin showed potential biological activity in in vitro and in vivo models. These studies emphasize the influence of astaxanthin and its beneficial effects on the metabolism in animals and humans. Bioavailability of astaxanthin in animals was enhanced after feeding Haematococcus biomass as a source of astaxanthin. Astaxanthin, used as a nutritional supplement, antioxidant and anticancer agent, prevents diabetes, cardiovascular diseases, and neurodegenerative disorders, and also stimulates immunization. Astaxanthin products are used for commercial applications in the dosage forms as tablets, capsules, syrups, oils, soft gels, creams, biomass and granulated powders. Astaxanthin patent applications are available in food, feed and nutraceutical applications. The current review provides up-to-date information on astaxanthin sources, extraction, analysis, stability, biological activities, health benefits and special attention paid to its commercial applications.

The role of tomato products and lycopene in the prevention of gastric cancer: a meta-analysis of epidemiologic studies

BACKGROUND

Gastric cancer is the second most common cause of death from cancer worldwide. Epidemiologic studies have examined the possible association between tomato products consumption and gastric cancer, but the relationship between tomato products and the risk of gastric cancer is controversial. We performed a meta-analysis of cohort and case-control studies to analyze this association.

METHODS

We systematically searched MEDLINE and EMBASE and contacted authors to identify potential studies published from January 1966 to June 2012. We pooled the relative risks from individual studies using a random-effects model and performed heterogeneity and publication bias analyses.

RESULTS

Twenty-one studies were eligible for our inclusion criteria, in a pooled analysis of all studies, consumption of large amounts of tomato products (in a comparison of the highest and lowest consumption groups) reduced the risk for gastric cancer (odds ratio, 0.73; 95% confidence interval, 0.60-0.90). The pooled OR of lycopene consumption and serum lycopene was 0.88 (95% CI=0.67-1.16) and 0.79 (95% CI=0.59-1.07), respectively.

CONCLUSIONS

Consumption of large amounts of tomato products is associated with a reduced risk of gastric cancer. However, because of potential confounding factors and exposure misclassification, further studies are required to establish these findings.

Microalgal compounds modulate carcinogenesis in the gastrointestinal tract

Gastrointestinal cancers rank second in overall cancer-related deaths. Carotenoids, sulfated polysaccharides, and polyunsaturated fatty acids (PUFAs) from microalgae exhibit cancer chemopreventive features at different stages of carcinogenesis. For instance, sulfated polysaccharides bear a prophylactic potential via blocking adhesion of pathogens to the gastric surface, whereas carotenoids are effective against Helicobacter pylori infection. This effect is notable because H. pylori has been targeted as the primary cause of gastric cancer. Recent results on antitumor and antibacterial compounds synthesized by microalgae are reviewed here, with an emphasis on their impact upon H. pylori infection and derived pathologies accompanying the progression of gastric carcinogenesis.

The inhibition of TNF-alpha-induced NF-kappaB activation by marine natural products

The deregulated activation of NF-kappaB is associated with cancer development and inflammatory diseases. With an aim to find new NF-kappaB inhibitors, we purified and characterized compounds from extracts of the Fijian sponge Rhabdastrella globostellata, the crinoid Comanthus parvicirrus, the soft corals Sarcophyton sp. nov. and Sinularia sp., and the gorgonian Subergorgia sp. after an initial screening of 266 extracts from different marine origins. Results obtained show that selected purified compounds had a cytotoxic effect on the human leukaemia cell line K562, inhibited both TNF-alpha-induced NF-kappaB-DNA binding as well as TNF-alpha-induced IkappaBalpha degradation and nuclear translocation of p50/p65. Furthermore, we observed the inhibition of NF-kappaB activation induced by an overexpression of IKKbeta. Interestingly, natural products inhibited IKKbeta kinase as well as the 26S proteasome proteolytic activity.

Nutrition and gastric cancer risk: an update

Data from epidemiologic, experimental, and animal studies indicate that diet plays an important role in the etiology of gastric cancer. High intake of fresh fruits and vegetables, lycopene and lycopene-containing food products, and potentially vitamin C and selenium may reduce the risk for gastric cancer. Data also suggest that high intake of nitrosamines, processed meat products, salt and salted foods, and overweight and obesity are associated with increased risk for gastric cancer. However, current data provide little support for an association of beta-carotene, vitamin E, and alcohol consumption with risk for gastric cancer.

Antiadhesive property of microalgal polysaccharide extract on the binding of Helicobacter pylori to gastric mucin

The emergence of antibiotic-resistant Helicobacter pylori is of concern in the treatment of H. pylori-associated gastroduodenal diseases. As the organism was reported to bind gastric mucin, we used porcine gastric mucin as substrate to assess the antiadhesive property of polysaccharides derived from Spirulina (PS), a commercially available microalga, against the binding of H. pylori to gastric mucin. Results show that polysaccharides prevented H. pylori from binding to gastric mucin optimally at pH 2.0, without affecting the viability of either bacteria or gastric epithelial cells, thus favouring its antiadhesive action in a gastric environment. Using ligand overlay analysis, polysaccharide was demonstrated to bind H. pylori alkyl hydroperoxide reductase (AhpC) and urease, which have shown here to possess mucin-binding activity. An in vivo study demonstrated that bacteria load was reduced by >90% in BALB/c mice treated with either Spirulina or polysaccharides. It is thus suggested that polysaccharides may function as a potential antiadhesive agent against H. pylori colonization of gastric mucin.