Antimutagenic properties of lactic acid-cultured milk on chemical and fecal mutagens

Effect of combination treatment with Lactobacillus rhamnosus and corticosteroid in reducing airway inflammation in a mouse asthma model

BACKGROUND

Asthma is a complex multifactorial chronic airway inflammatory disease with diverse phenotypes and levels of severity and is associated with significant health and economic burden. In a certain population of asthma patients, the symptoms cannot be well controlled with steroid. There has been long standing interest in the use of probiotics for treating allergic diseases. The purpose of this study is to investigate whether the combination of Lactobacillus rhamnosus GG (LGG) with prednisolone could reduce the dosage of glucocorticoid in controlling airway inflammation in a murine model for allergic asthma.

MATERIAL AND METHODS

We used Der p 2-sensitized asthma model in female BALB/c mice. The animals were treated with 75 μl or 50 μl oral prednisolone or combination treatment of these two doses of oral prednisolone with LGG. Airway hyperresponsiveness, serum specific IgE/IgG1/IgG2a, infiltrating inflammatory cells in lung and cytokines were assessed.

RESULTS

Compared to 75 μl prednisolone, a lower dose of prednisolone with 50 μl was less satisfactory in suppressing airway hyperresponsives, serum IgE and IgG1, Th2 cytokines and inflammatory cytokines such as IL-6, IL-8 and IL-17 as well as infiltrating inflammatory cells. However, combination of 50 μl prednisolone and LGG decreased airway resistance and serum IgE and IgG1, inhibited the production of IL-4, IL-5, IL-6, IL-8, IL-13 and IL-17, upregulated serum IgG2a and enhanced Th1 immune response.

CONCLUSIONS

LGG may reduce the dosage of prednisolone and thus may be beneficial in the treatment of asthma.

Natural therapeutics and nutraceuticals for lung diseases: Traditional significance, phytochemistry, and pharmacology

BACKGROUND

Lung diseases including chronic obstructive pulmonary disease (COPD), infections like influenza, acute respiratory distress syndrome (ARDS), asthma and pneumonia lung cancer (LC) are common causes of sickness and death worldwide due to their remoteness, cold and harsh climatic conditions, and inaccessible health care facilities.

PURPOSE

Many drugs have already been proposed for the treatment of lung diseases. Few of them are in clinical trials and have the potential to cure infectious diseases. Plant extracts or herbal products have been extensively used as Traditional Chinese Medicine (TCM) and Indian Ayurveda. Moreover, it has been involved in the inhibition of certain genes/protiens effects to promote regulation of signaling pathways. Natural remedies have been scientifically proven with remarkable bioactivities and are considered a cheap and safe source for lung disease.

METHODS

This comprehensive review highlighted the literature about traditional plants and their metabolites with their applications for the treatment of lung diseases through experimental models in humans. Natural drugs information and mode of mechanism have been studied through the literature retrieved by Google Scholar, ScienceDirect, SciFinder, Scopus and Medline PubMed resources against lung diseases.

RESULTS

In vitro, in vivo and computational studies have been explained for natural metabolites derived from plants (like flavonoids, alkaloids, and terpenoids) against different types of lung diseases. Probiotics have also been biologically active therapeutics against cancer, anti-inflammation, antiplatelet, antiviral, and antioxidants associated with lung diseases.

CONCLUSION

The results of the mentioned natural metabolites repurposed for different lung diseases especially for SARS-CoV-2 should be evaluated more by advance computational applications, experimental models in the biological system, also need to be validated by clinical trials so that we may be able to retrieve potential drugs for most challenging lung diseases especially SARS-CoV-2.

Bugs as Drugs: Understanding the Linkage between Gut Microbiota and Cancer Treatment Microbiome in Cancer Therapy

BACKGROUND

The commensal microbiota is known to regulate host physiology. Dysbiosis or compromised Resilience in the microbial ecology is related to the impending risk of cancer. A potential link between cancer and microbiota is indicated by a lot of evidence.

OBJECTIVE

The current review explores in detail the various links leading to and /or facilitating oncogenesis, providing sound reasoning or a basis for its utilization as potential therapeutic targets. The present review emphasizes the existing knowledge of the microbiome in cancer and further elaborates on the factors like genetic modifications, effects of dietary components, and environmental agents that are considered to assess the direct and indirect effect of microbes in the process of oncogenesis and on the host's health. Strategies modulating the microbiome and novel biotherapeutics are also discussed. Pharmacomicrobiomics is one such niche accounting for the interplay between the microbiome, xenobiotic, and host responses is also looked upon.

METHODS

The literature search strategy for this review was conducted by following the methodology of the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). The method includes the collection of data from different search engines like PubMed, ScienceDirect, SciFinder etc. to get coverage of relevant literature for accumulating appropriate information regarding microbiome, cancer, and their linkages.

RESULTS

These considerations are made to expand the existing literature on the role of gut microbiota on the host's health, the interaction between host and microbiota, and the reciprocal relationship between the microbiome and modified neoplastic cells.

CONCLUSION

Potential therapeutic implications of cancer microbiomes that are yet unexplored and have rich therapeutic dividends improving human health are discussed in detail in this review.

An Update on the Effectiveness of Probiotics in the Prevention and Treatment of Cancer

Probiotics are living microbes that play a significant role in protecting the host in various ways. Gut microbiota is one of the key players in maintaining homeostasis. Cancer is considered one of the most significant causes of death worldwide. Although cancer treatment has received much attention in recent years, the number of people suffering from neoplastic syndrome continues to increase. Despite notable improvements in the field of cancer therapy, tackling cancer has been challenging due to the multiple properties of cancer cells and their ability to evade the immune system. Probiotics alter the immunological and cellular responses by enhancing the epithelial barrier and stimulating the production of anti-inflammatory, antioxidant, and anticarcinogenic compounds, thereby reducing cancer burden and growth. The present review focuses on the various mechanisms underlying the role of probiotics in the prevention and treatment of cancer.

The Antimutagenic and Antioxidant Activity of Fermented Milk Supplemented with Cudrania tricuspidata Powder

In this study, Cudrania tricuspidata (CT) containing abundant phytochemicals, such as xanthones and flavonoids, was evaluated as an additive to fortify the functionality and organoleptic quality of fermented milk. The physicochemical, functional, and sensory properties of fermented milk supplemented with different concentrations of CT powder were investigated. Increasing amounts of CT powder elevated the malic acid concentration, increasing the total acidity and decreasing the pH of fermented milk supplemented with CT powder. The viable cell count and free sugar contents of fermented milk indicated that supplementing with CT powder improved lactic acid fermentation slightly. The color of fermented milk supplemented with CT powder was darker, redder, yellower, and more pleasing than the control fermented milk. The total phenolic and flavonoid contents of fermented milk supplemented with CT powder rose as the concentration of supplemented CT powder increased, resulting in enhanced antioxidant and antimutagenic activities. The CT powder improved the functionality of the fermented milk; still, at 2% or more, it had some unfavorable sensory properties, such as sourness, taste, and texture, which reduced the overall consumer preference. Therefore, a CT powder concentration of 0.5% or 1% may be acceptable to consumers.

Purification of a dimeric arginine deiminase from Enterococcus faecium GR7 and study of its anti-cancerous activity

The arginine deiminase (ADI, E.C 3.5.3.6) - a key enzyme of ADI pathway of Enterococcus faecium GR7 was purified to homogeneity. A sequential purification strategy involving ammonium sulfate fractionation, molecular sieve followed by Sephadex G-100 gel filtration was applied to the crude culture filtrate to obtain a pure enzyme preparation. The enzyme was purified with a fold of 16.92 and showed a final specific activity of 76.65IU/mg with a 49.17% yield. The dimeric ADI has a molecular mass of about 94,364.929Da, and comprises of hetrodimers of 49.1kDa and 46.5kDa as determined by MALDI-TOF and PAGE analysis. To assess anti-cancerous activity of ADI by MTT assay was carried out against cancer cell lines (MCF-7, Sp2/0-Ag14 and Hep-G2). Purified ADI exhibited the most profound antiproliferative activity against Hep-G2 cells; with half-maximal inhibitory concentration (IC50) of 1.95μg/ml. Purified ADI from E. faecium GR7 was observed to induce apoptosis in the Hep-G2 cells by DNA fragmentation assay. Our findings suggest the possibility of a future use of ADI from E. faecium GR7 as a potential anticancer drug.

Safety and mutagenicity evaluation of Vigiis 101 powder made from Lactobacillus paracasei subsp. paracasei NTU 101

The aim of the present work was to assess the genotoxic activity and the potential for toxicity upon repeated dosing of "Vigiis 101" powder, a probiotic consisting of dried bacteria Lactobacillus paracasei subsp. paracasei NTU 101. Results of the Ames test in Salmonella typhimurium strains TA1537, TA98, TA100, TA102, and TA1535 showed that Vigiis 101 (⩽5 mg per plate) was not mutagenic. We used experiments on ICR mice to evaluate the genotoxicity of Vigiis 101. Compared to the control, high-dose Vigiis 101 administration (16.72 g per kg of body weight) did not cause significant changes either in the number of reticulocytes or in the percentage (occurrence) of micronucleated reticulocytes. A mammalian chromosomal aberration test showed that the number of Chinese hamster ovary cells with abnormal chromosomes was <4% after Vigiis 101 treatment (maximal concentration was 5 mg/ml). A 28-day oral toxicity assay in Wistar rats was performed to assess the no-observed-adverse-effect level of Vigiis 101. Compared to the control, high-dose Vigiis 101 administration (5000 mg/kg/day) had no effects on mortality and body weight and did not cause toxicopathological lesions. Taken together, these results show that Vigiis 101 has no significant mutagenic or toxic effects.

Probiotics in the management of lung diseases

The physiology and pathology of the respiratory and gastrointestinal tracts are closely related. This similarity between the two organs may underlie why dysfunction in one organ may induce illness in the other. For example, smoking is a major risk factor for COPD and IBD and increases the risk of developing Crohn's disease. Probiotics have been defined as "live microorganisms which, when administered in adequate amounts, confer health benefits on the host." In model systems probiotics regulate innate and inflammatory immune responses. Commonly used probiotics include lactic acid bacteria, particularly Lactobacillus, Bifidobacterium, and Saccharomyces, and these are often used as dietary supplements to provide a health benefit in gastrointestinal diseases including infections, inflammatory bowel disease, and colon cancer. In this respect, probiotics probably act as immunomodulatory agents and activators of host defence pathways which suggest that they could influence disease severity and incidence at sites distal to the gut. There is increasing evidence that orally delivered probiotics are able to regulate immune responses in the respiratory system. This review provides an overview of the possible role of probiotics and their mechanisms of action in the prevention and treatment of respiratory diseases.

Immunomodulatory and antioxidant potential of Lactobacillus exopolysaccharides

BACKGROUND

Immunomodulation by probiotic microorganisms has become a topic of increasing interest in food microbiology. Polysaccharides are broadly used in the food industry as gelling, thickening, stabilizing, or emulsifying agents. Some probiotics such as lactic acid bacteria also produce exopolysaccharides that stimulate macrophage production of cytokines. The aim of this study was to characterize the effects of exopolysaccharides of Lactobacillus paracasei subsp. paracasei NTU 101 (101EP) and Lactobacillus plantarum NTU 102 (102EP) exopolysaccharides on antioxidant activity and immunomodulation in vitro.

RESULTS

The sugar composition (including arabinose, galactose, glucose, fructose, mannose, and maltose) of 101EP and 102EP was quantified by high-performance anion-exchange chromatography. Cytokine production (including IL-6, TNF-α, and IL-1β) was induced by 101EP and 102EP in Raw 264.7 in a dose-dependent manner (5-500 µg mL(-1) ). 101EP and 102EP also demonstrated potential antioxidant properties (1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, chelation of ferrous ions, inhibition of linoleic acid peroxidation, and reducing power) in vitro.

CONCLUSION

101EP and 102EP stimulate cell proliferation and may be useful as a mild immune modulator of macrophages.

Review: functional properties of kefir

Kefir is a unique cultured dairy product due to combined lactic acid and alcoholic fermentation of lactose in milk. Kefir is produced by microbial activity of "kefir grains" which have a relatively stable and specific balance of lactic acid bacteria and yeast. Due to the claimed health benefits of kefir which include reduction of lactose intolerance symptoms, stimulation of the immune system, lowering cholesterol, and antimutagenic and anticarcinogenic properties, kefir has become an important functional dairy food and consequently, research on kefir has increased in the past decade. In the following review, recent studies on the functional properties of kefir are reviewed.

Peptides from Lactobacillus hydrolysates of bovine milk caseins inhibit prolyl-peptidases of human colon cells

Prolyl-rich peptides derived from hydrolysates of bovine caseins have been previously shown to inhibit angiotensin converting enzyme (ACE) activity, suggesting that they may also be able to inhibit the enzymatic activities of prolyl-specific peptidases. This study shows that peptides derived from α(S1)-casein and β-casein inhibited the enzymatic activities of purified recombinant matrix metalloprotease (MMP)-2, MMP-7, and MMP-9. The inhibitory efficacy was sequence-dependent. These peptides also selectively inhibited the enzymatic activities of prolyl-amino-peptidases, prolyl-amino-dipeptidases, and prolyl-endopeptidases in extracts of HT-29 and SW480 human colon carcinoma cells, but not in intact cells. They were not cytotoxic or growth inhibitory for these cells. Thus, the prolyl-rich selected peptides were good and selective inhibitors of MMPs and post-proline-cleaving proteases, demonstrating their potential to control inadequate proteolytic activity in the human digestive tract, without inducing cytotoxic effects.

Antimutagenic activity of whole casein on the pepper-induced mutagenicity to streptomycin-dependent strain SD 510 of Salmonella typhimurium TA 98

When the antimutagenic activity of milk or cultured milk components on the pepper-induced mutagenicity to streptomycin-dependent strain SD 510 of Salmonella typhimurium TA 98 was investigated, whole casein showed a significant antimutagenic activity. Heating at 121 °C for 15 min completely destroyed the antimutagenic activity of casein, which was temperature dependent. While acid or papain digestion resulted in the loss of antimutagenic activity of casein, trypsin digestion had little effect although the digestion of casein by each proteinase was over 75%. β-Casein, egg albumin, and bovine serum albumin also had a similar antimutagenic activity to that of whole casein.

Probiotics and their fermented food products are beneficial for health

Probiotics are usually defined as microbial food supplements with beneficial effects on the consumers. Most probiotics fall into the group of organisms' known as lactic acid-producing bacteria and are normally consumed in the form of yogurt, fermented milks or other fermented foods. Some of the beneficial effect of lactic acid bacteria consumption include: (i) improving intestinal tract health; (ii) enhancing the immune system, synthesizing and enhancing the bioavailability of nutrients; (iii) reducing symptoms of lactose intolerance, decreasing the prevalence of allergy in susceptible individuals; and (iv) reducing risk of certain cancers. The mechanisms by which probiotics exert their effects are largely unknown, but may involve modifying gut pH, antagonizing pathogens through production of antimicrobial compounds, competing for pathogen binding and receptor sites as well as for available nutrients and growth factors, stimulating immunomodulatory cells, and producing lactase. Selection criteria, efficacy, food and supplement sources and safety issues around probiotics are reviewed. Recent scientific investigation has supported the important role of probiotics as a part of a healthy diet for human as well as for animals and may be an avenue to provide a safe, cost effective, and 'natural' approach that adds a barrier against microbial infection. This paper presents a review of probiotics in health maintenance and disease prevention.

Effect of milk fermented with a Lactobacillus helveticus R389(+) proteolytic strain on the immune system and on the growth of 4T1 breast cancer cells in mice

Previous studies on a murine model have demonstrated that the administration of Lactobacillus helveticus and Lactobacillus casei inhibits the development of fibrosarcoma and colon carcinoma, respectively. The aim of this work was to study the beneficial effects of the consumption of milk fermented by L. helveticus on a murine model for mammary carcinoma. Female BALB/c mice were challenged by a single subcutaneous injection of tumoral cells (American Type Culture Collection 4T1) in the left mammary gland. Prior to tumour injection, mice were fed for two, five or seven consecutive days with fermented milk. The following factors were monitored for 2 months: rate of tumour development, histological studies, apoptosis, phagocytic index, peritoneal macrophages, determination of beta-glucuronidase enzyme in peritoneal macrophages, determination of gamma-interferon (INFgamma) and tumour necrosis factor-alpha (TNF-alpha) in blood serum, determination of CD4+, CD8+, interleukin-6 (IL-6), IL-10, TNF-alpha and INFgamma by immunoperoxidase, and measurement of beta-glucuronidase activity in intestinal fluid. The administration of L. helveticus delayed the development of the tumour in all cases, a 2- or 7-day feeding period being most effective. This work demonstrates that milk fermented with L. helveticus decreases the growth rate of mammary tumours. The effect was mediated by increased apoptosis and decreased production of pro-inflammatory cytokines, in particular IL-6, implicated in oestrogen synthesis.

Mutagenicity and antimutagenic effect of soymilk fermented with lactic acid bacteria and bifidobacteria

In this study, soymilk was first fermented with lactic acid bacteria (Streptococcus thermophilus, Lactobacillus acidophilus) and bifidobacteria (Bifidobacterium infantis, Bifidobacterium longum) both individually and simultaneously. Mutagenicity and the suppression of fermented soymilk against the mutagenesis induced by 4-nitroquinoline-N-oxide (4-NQO), a direct-acting mutagen, and 3,2'-dimethyl-4-amino-biphenyl (DMAB), an indirect-acting mutagen, on Salmonella typhimurium TA 100, was then investigated. It was found that the fermented soymilk shows no mutagenic activity on Sal. typhimurium TA 100. Fermentation, in general, significantly (p<0.05) enhanced the antimutagenicity of soymilk. The levels of increased antimutagenicity of fermented soymilk varied with the starter organism and the type of mutagen tested. Although unfermented soymilk exerted lower antimutagenic activity against DMAB than 4-NQO, the fermented soymilk, generally, showed a higher antimutagenic activity against DMAB than 4-NQO. Among the various fermented soymilk tested, soymilk fermented with both Str. themophilus and B. infantis simultaneously exhibited the highest antimutagenicity of 85.07% and 85.78%, respectively, against 4-NQO and DMAB Further investigation on this fermented soymilk revealed that both the antimutagenic factors formed during fermentation and the cells of the starter organisms contributed to the increased antimutagenic activity against DMAB, while the former led to the increased activity against 4-NQO.

Screening of potential lactobacilli antigenotoxicity by microbial and mammalian cell-based tests

Antigenotoxicity is considered an important property for probiotic lactobacilli. The ability of non probiotic lactobacilli from dairy products and starters to inhibit two reference genotoxins: 4-nitroquinoline-1-oxide and N-methyl-N'-nitro-N-nitrosoguanidine was evaluated. The study was carried out using short-term assays with different targets, such as procaryotic cells (SOS-Chromotest for genotoxicity in Escherichia coli and Ames test for mutagenicity in Salmonella typhimurium) and eucaryotic cells (Comet assay for genotoxicity in Caco-2 enterocytes). A high proportion of strains inhibiting 4-nitroquinoline-1-oxide activity was found in Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus plantarum. Inhibition of N-methyl-N'-nitro-N-nitrosoguanidine activity occurred in only one L. acidophilus strain. All the strains with antigenotoxic properties also demonstrated antimutagenic activity and produced modifications in genotoxin spectroscopic profiles. Strain viability during and after genotoxin exposure was confirmed. Concordance of the results obtained with microbial and mammalian cell-based tests is underlined.

Fermented milks, probiotic cultures, and colon cancer

Colorectal cancer (CRC) is a major cause of death from cancer in the Western world. Approximately 70% of CRC is associated with environmental factors, probably mainly the diet. There is interest in the potential protective role of fermented milks containing probiotic cultures against CRC. This article analyzes the existing data from human, animal, and in vitro studies that explore whether consumption of milks fermented with probiotic cultures could play a role in colon cancer risk reduction. Cohort studies have failed to detect significant effects, but most case-control studies favor a protective role of fermented milks against colon cancer. Interventional studies have shown a shift of intermediate markers of CRC risk in human subjects from a high- to low-risk pattern after ingestion of fermented milks or probiotics. Animal studies consistently show a reduction in chemically induced colorectal tumor incidence and aberrant crypt formation accompanying probiotic administration. In vitro studies also provide evidence of protection, and permit a better understanding of active compounds involved, and of the mechanisms underlying their anticarcinogenic effects. Probiotics may beneficially modulate several major intestinal functions: detoxification, colonic fermentation, transit, and immune status, which may accompany the development of colon cancer. Although the evidence is not conclusive and much further research is required, the data reviewed constitute a promising body of evidence supporting the protective role of milks fermented with probiotic cultures in colon cancer risk reduction.

Antimutagenic and antioxidant properties of milk-kefir and soymilk-kefir

This study was aimed at evaluating the antimutagenic and antioxidant properties of milk-kefir and soymilk-kefir. Such antimutagenic activity was determined by means of the Salmonella mutagenicity assay, whereas the antioxidant properties of kefir were evaluated by assessing the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, lipid peroxidation inhibition activity, ferrous ion chelating ability, reducing power, and antioxidative enzyme activity. Both milk-kefir and soymilk-kefir demonstrated significantly greater antimutagenic activity than milk and soymilk. Milk-kefir and soymilk-kefir also displayed significantly greater scavenging activity upon DPPH radicals, an inhibition effect upon linoleic acid peroxidation, and more substantial reducing power but displayed a reduced glutathione peroxidase activity than was the case for milk and soymilk. Milk and soymilk fermented by kefir grains did not alter the ferrous ion chelating ability and superoxide dismutase activity of the original materials. These findings have demonstrated that milk-kefir and soymilk-kefir possess significant antimutagenic and antioxidant activity and suggest that milk-kefir and soymilk-kefir may be considered among the more promising food components in terms of preventing mutagenic and oxidative damage.

Antimutagenic effect of amino acids on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)

The antimutagenic activity of protein-constituting amino acids except histidine on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was investigated in vitro using Salmonella typhinurium TA-100 as an indicator bacterium (Ames test), and concentrations (IC50) of amino acids that inhibit 50% of the mutagenecity were measured. Cysteine was found to be most active and glycine, tryptophan, lysine, and arginine were strong antimutagenic amino acids. Other amino acids showed moderate or weak antimutagenic activities, depending on the amino acids. The results indicate that amino acids play a substantial role in chemoprevention of N-nitroso amine-induced mutagenicity.

Probiotic bacteria: safety, functional and technological properties

During the past two decades probiotic (health promoting) micro-organisms have been increasingly included in various types of food products, especially in fermented milks. Several aspects, including safety, functional and technological characteristics, have to be taken into consideration in the selection process of probiotic micro-organisms. Safety aspects include specifications such as origin (healthy human GI-tract), non-pathogenicity and antibiotic resistance characteristics. Functional aspects include viability and persistence in the GI-tract, immunomodulation, antagonistic and antimutagenic properties. Before probiotic strains, chosen on the basis of their good safety and functional characteristics, can benefit the consumer, they must first be able to be manufactured under industrial conditions. Furthermore, they have to survive and retain their functionality during storage, and also in the foods into which they are incorporated without producing off-flavours. Factors related to the technological and sensory aspects of probiotic food production are of utmost importance since only by satisfying the demands of the consumer can the food industry succeed in promoting the consumption of functional probiotic products in the future.

Viability of Lactobacillus gasseri and its cholesterol-binding and antimutagenic activities during subsequent refrigerated storage in nonfermented milk

The effect storage at 4 degrees C on the viability of Lactobacillus gasseri and its sodium taurocholate-deconjugating and cholesterol-binding abilities as well as desmutagenic activity was investigated. Unfermented milks containing L. gasseri strains SBT0274 and SBT0270 at 10(9) cfu/ml were prepared using 10% skim milk. Total and bile-tolerant lactobacilli for strains SBT0274 and SBT0270 generally decreased after 14 d of storage at 4 degrees C; however, viable cells of these strains were still at 10(8) cfu/ml after 28 d of storage. The amounts of cholic acid released and of cholesterol bound by strains SBT0274 and SBT0270 declined over time, especially at 21 d of storage. Antimutagenic activity of unfermented milk made from both strains was attributed to the bacterial cells, and the activity was stable during storage at 4 degrees C for 28 d.

Desmutagenicity of milk cultured with Lactobacillus acidophilus strains against mutagenic heated tauco

Desmutagenicity of milk cultured with Lactobacillus acidophilus strains on the mutagenicity of heated salty and sweet tauco were examined using streptomycin dependent (SD) 510 strain of Salmonella typhimurium TA98 as tester culture. Cultured milk samples widely exhibited desmutagenic effects against mutagenic heated salty and sweet tauco. Mutagenicity of heated salty tauco was inhibited by acidophilus cultured milks stronger than that of heated sweet tauco. Milk cultured with strains SBT2054, SBT0299, SBT0274, SBT10238. SBT1702, SBT10240, SBT10241 and SBT10239 showed high inhibition against the mutagenicity of both heated salty and sweet taucos. Maximum inhibition was reached after 24 hr of incubation which corresponded to stationary growth phase. Desmutagenic activities of the acidophilus cultured milks against mutagenic heated tauco were mainly attributed to the bacterial cells and also to casein of milk.

Antimutagenicity and the influence of physical factors in binding Lactobacillus gasseri and Bifidobacterium longum cells to amino acid pyrolysates

Antimutagenic and binding properties of 28 strains of Lactobacillus gasseri and 2 strains of Bifidobacterium longum on the mutagenicity of amino acid pyrolysates were investigated in vitro using a streptomycin-dependent (SD510) strain of Salmonella typhimurium TA 98. Four strains of L. acidophilus (SBT0274, SBT1703, SBT10239, and SBT10241) and 1 strain of B. longum (SBT 2928) exhibited the highest percentage of antimutagenicity and binding. These 5 strains were further optimized for other physical factors influencing the mechanism of binding, such as cell and mutagen concentration, pH, and incubation time. In all of the selected strains, 2 mg of cells bound with 88 to 95% of 0.2 mg of 3-amino-1,4 dimethyl-5H-pyrido[4,3-b]indole in 30 min at pH 7.0. Other amino acid pyrolysates, such as 3-amino-1-methyl-5H-pyrido[4,3-b]indole, 2-amino-6-methyldi-pyrido[1,2-a:3',2'-d]imidazole, 2-amino-3-methyl-imidazo[4,5,f]quinoline, and 2-amino-3,4-dimethyl-imidazo[4,5,f]quinoline were also tested for the binding ability of these strains. We observed that the complexity of the mutagens greatly influenced the binding properties. The binding of 3-amino-1,4 dimethyl-5H-pyrido[4,3-b]indole to the purified cell walls was very high compared with that of the crude cell wall, peptidoglycan, or the cell extract. Binding was inhibited when the cell walls were subjected to treatment with metaperiodate or trichloroacetic acid but not when they were subjected to treatment with lysozyme, trypsin, or proteinase K, reflecting the role of the carbohydrate component as a binding site.

Antimutagenic properties of probiotic bacteria and of organic acids

Antimutagenic activities of live and killed cells of 6 strains of Lactobacillus acidophilus and 9 strains of bifidobacteria and of organic acids usually produced by these probiotic bacteria were determined using 8 potent chemical mutagens and promutagens. The mutagens and promutagens used were N-methyl, N'-nitro, N-nitrosoguanidine; 2-nitroflourene; 4-nitro-O-phenylenediamine; 4-nitroquinoline-N-oxide; Aflatoxin-B; 2-amino-3-methyl-3H-imidazoquinoline; 2-amino-1-methyl-6-phenyl-imidazo (4,5-b) pyridine, and 2-amino-3-methyl-9H-pyrido (3,3-6) indole. The mutagenicity of these mutagens and antimutagenic activity of probiotic bacteria against the mutagens were determined according to the Ames TA-100 assay using a mutant of Salmonella typhimurium. Efficiency of bacterial cells in binding or inhibiting these mutagens was also investigated. Live cells of probiotic bacteria showed higher antimutagenic activity and their efficiency in inhibiting the mutagens was better than killed bacterial cells. Live bacterial cells bound or inhibited the mutagens permanently, whereas killed bacteria released mutagens upon extraction with dimethyl sulfoxide. Among the organic acids, butyric acid showed highest inhibition of mutagens followed by acetic acid. Lactic and pyruvic acids did not show appreciable levels of inhibition.

Effect of administration of milk fermented with Lactobacillus acidophilus LA-2 on fecal mutagenicity and microflora in the human intestine

To demonstrate the antimutagenic effect of fermented milk in the human intestine, fecal mutagenicity and bacterial composition of six healthy subjects consuming their regular diet were investigated before and during the administration of milk fermented with Lactobacillus acidophilus LA-2. The administration of the fermented milk caused a remarkable decrease (71.9% on the average; range of 19.4 to 90.6%) in fecal mutagenicity compared with that before the administration; Lactobacillus spp. and Bifidobacterium spp. population increased in the feces of all subjects. The suppression of fecal mutagenicity appeared to be due to the change in fecal microflora caused by the presence of strain LA-2 in the human intestine.

Antimutagenicity of components of dairy products

This paper reports the potential antimutagenicity of some components of dairy products. For both milk and fermented milk, Bifidobacterium sp. Bio (strain Danone 173010), casein and calcium showed a dose-dependent antimutagenic activity against benzo[a]pyrene mutagenicity in the Ames test using Salmonella typhimurium TA98. Fatty compounds present in milk had no antimutagenic effect. At the level occurring in cultured or uninoculated milks, and even more, the bifidobacteria, casein and calcium showed less antimutagenic activity than fermented and uninoculated milks. So, the mix of all these components must contribute to the total protective effect of dairy products against induced mutagenicity, and this does not rule out the possibility of contribution of other unknown substances. The total antimutagenicity of uninoculated skim milk corresponds to the additional activity of casein and calcium. The observed antimutagenic activity of fermented skim milk remains lower than expected.

Antimutagenicity of an acetone extract of yogurt

Reconstituted non-fat dry milk powder, fermented by a mixture of Streptococcus thermophilus CH3 and Lactobacillus bulgaricus 191R to produce yogurt, was freeze-dried and extracted in acetone. After evaporation of the acetone, the extract was dissolved in dimethyl sulfoxide (DMSO) and tested for antimutagenicity. In the Ames test, significant dose-dependent activity was observed against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 4-nitro-quinoline-N-oxide (4NQO), 3,2'-dimethyl-4-aminobiphenyl (DMAB), 9,10-dimethyl-1,2-benz[a]anthracene (DMBA), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole acetate (Trp-P-2). Weak activity was observed against 1,2,7,8-diepoxyoctane (DEO), and no activity was observed against methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), or aflatoxin B1 (AFB1). In a related assay (Saccharomyces cerevisiae D7), significant antimutagenic activity was detected against MNNG and 4NQO. Activity against the experimental colon carcinogens MNNG and DMAB was examined further, as assayed in the Ames test (Salmonella typhimurium TA100). Compounds responsible for both activities were less soluble in aqueous solutions than in DMSO. Adjustment of yogurt pH to 3, 7.6, or 13 prior to freeze-drying and acetone extraction did not significantly alter the amount of anti-MNNG activity recovered. In contrast, extractability of anti-DMAB activity was significantly greater at acidic pH. Conjugated linoleic acid, a known dairy anticarcinogen, failed to inhibit mutagenesis caused by either mutagen, suggesting that other yogurt-derived compound(s) are responsible. Unfermented milk was treated with lactic acid, yogurt bacteria without subsequent growth, or both, to determine if formation of antimutagenic activity required bacterial growth. Extracts of the milk treatments exhibited the same weak antimutagenicity observed in unfermented milk, approximately 2.5-fold less than in the yogurt extracts, suggesting that antimutagenic activity is associated with bacterial growth.

Binding of mutagenic heterocyclic amines by intestinal and lactic acid bacteria

Lactic acid bacteria have been reported to have antimutagenic/anticarcinogenic properties in vitro and in vivo. One possible mechanism for this effect involves a physical binding of the mutagenic compounds to the bacteria. The purpose of the present investigation was to study the binding capacity of eight human intestinal or lactic acid bacterial strains for mutagenic heterocyclic amines formed during cooking of protein-rich food. Binding of the mutagens Trp-P-2, PhIP, IQ and MeIQx by the bacterial strains was analyzed by HPLC. There were only minor differences in the binding capacities of the tested strains but the mutagenic compounds were bound with markedly different efficiencies. Trp-P-2 was almost completely bound and the binding tended not to be of a reversible nature. The binding of PhIP, which reached about 50%, was important as PhIP is a major mutagen in the western diet. IQ and MeIQx were slightly less well bound. pH appeared to be of importance for the binding efficacy. Binding correlated well with the reduction in mutagenicity observed after exposure of the heterocyclic amines to the bacterial strains. The results indicate that cooked food mutagenic compounds, commonly found in the western meat-rich diet, can be bound to bacteria from the normal intestinal microflora in vitro.

Inhibitory effect of dairy products on the mutagenicities of chemicals and dietary mutagens

The antimutagenic effects of uninoculated milk and milks cultured with Bifidobacterium or Lactobacillus strains towards the mutagenicity induced by two direct mutagens, 4-nitroquinoline N-oxide and 2-nitrofluorene, and three dietary indirect mutagens, aflatoxin B1, benzo(a)pyrene and quercetin, were investigated using the in vitro Salmonella typhimurium test. Each cultured milk sample and control milk had a significant antimutagenic effect, to an extent varying with the mutagen used. Uninoculated milk had a greater inhibitory effect than cultured milks towards dietary indirect mutagens.

Antimutagenicity of fermented milk

Reconstituted nonfat dry milk was fermented by Lactobacillus helveticus CH65, Lactobacillus acidophilus BG2FO4, Streptococcus salivarius ssp. thermophilus CH3, Lactobacillus delbrueckii ssp. bulgaricus 191R, and by a mixture of the latter two organisms. The fermented milks were then freeze-dried, extracted in acetone, dissolved in dimethylsulfoxide, and assayed for antimutagenicity in the Ames test (Salmonella typhimurium TA 100) against N-methyl, N'-nitro, N-nitroso-guanidine, and 3,2'-dimethyl-4-amino-biphenyl. Dose-dependent activity was significant against both mutagens in all extracts. Maximal inhibitory activity against 3,2'-dimethyl-4-aminobiphenyl and N-methyl, N'-nitro, N-nitroso-guanidine was 2- and 2.7-fold greater, respectively, than that exhibited by extracts of unfermented milk. Extracts of milk fermented by L. delbrueckii ssp. bulgaricus 191R were examined further. Compounds that were responsible for activity against both mutagens were less soluble in aqueous solutions than in dimethylsulfoxide. Adjustment of milk fermented by L. delbrueckii ssp. bulgaricus 191R to pH 3, 7.6, or 13 prior to freeze-drying and acetone extraction did not significantly alter the activity specific for 3,2'-dimethyl-4-aminobiphenyl. In contrast, compounds with activity specific for N-methyl, N'-nitro, N-nitrosoguanidine were less extractable at pH 7.6. The weak antimutagenicity of unfermented milk was not increased by addition of 2% L-lactic acid.

Effect of yogurt feeding on the small and large intestine associated lymphoid cells in mice

The effect of giving yogurt supplements to BALB/c mice on the various gut-associated lymphoid cells was studied. Animals were fed for 2, 5, 7 and 10 consecutive days. The different lymphoid cell types were identified and counted by haematoxylin-eosin staining of histological slices. The numbers of cells secreting IgA, IgG and IgM and the numbers of T lymphocytes were determined by direct immunofluorescence. The degree of activation of the intestinal macrophages in the small intestine was assessed by measuring the beta-glucuronidase (EC 3.2.1.31) released into the intestinal fluid, and also by a histochemical method. Throughout the feeding period, there were no histological alterations in the gut, but there was marked cell infiltration, mainly of plasma cells and lymphocytes. The number of macrophages on the small intestine increased significantly after feeding for 2 d, while the beta-glucuronidase activity was only slightly higher that of the controls. After a 7 d feeding period, the number of IgA secreting cells increased, while the values for cells secreting IgM and IgG and for T lymphocytes remained similar to those of the controls. The effect of giving yogurt on lymphoid cells associated with the large intestine was mainly on the numbers of IgA secreting B cells and T lymphocytes, with a marked increase during the whole feeding period in the latter type of cell. Since giving yogurt mainly enhanced the IgA secreting B cells in both small and large intestines, this increase would strengthen the host's defence mechanisms in the intestinal mucosa. Although the number of macrophages was increased, there was no enhancement in their activity, which might have harmed the host by producing an inflammatory response.

A cell culture model to identify biologically active peptides generated by bacterial hydrolysis of casein

Consumption of fermented dairy foods has been linked to reduced incidence of colon cancer in population groups. Recently, biologically active compounds have been isolated from these products. Bacterial proteinases, produced by dairy starter cultures, generate a variety of peptides from casein. Some of these casein-derived peptides are likely to alter intestinal cell kinetics. Effects on colon cell kinetics because of the presence of casein-derived peptides may be a mechanism through which fermented dairy foods reduce the risk of colon cancer. We have used two intestinal cell lines (IEC-6 cells, derived from normal rat intestine, and Caco-2 cells, derived from human colon adenocarcinoma) to identify casein peptides that affect intestinal cell kinetics. Cell culture media containing casein were inoculated with three commercial starter cultures and incubated for 4, 8, or 24 h. The bacteria-conditioned media were then filter-sterilized and incubated with the intestinal cells for 6 or 24 h. Rates of [3H]thymidine incorporation and cell cycle kinetics determined by flow cytometry were affected by the culture-modified media in both cell lines. The IEC-6 cells tended to reduce, and Caco-2 cells to increase, rates of cell division after exposure to the media. Intestinal cell response varied among the starter cultures. The results support the use of intestinal cell cultures to identify casein peptides generated by dairy starter cultures, which affect intestinal cell kinetics.

Antimutagenic effects of casein and its digestion products

The antimutagenic potential of casein was investigated using several mutagens, including some food-related mutagens, and the Salmonella/microsome and Escherichia coli DNA-repair tests. The effect depended on the type of mutagen and the incubation time of casein with the mutagens. Casein was very effective against benzo[a]pyrene, N-methylnitrosourea and nitrosated 4-chloroindole, and was less effective towards sodium azide and N-nitroquinoline-1-oxide (NQO). Preincubation increased the antimutagenic potential of casein towards NQO. Heating of casein (up to 20 min at 130 degrees C) did not alter its antimutagenic capacity. The effect of pepsin hydrolysis under simulated gastric conditions on the antimutagenic capacity of casein was tested with sodium azide and NQO in the Salmonella/microsome test. The peptides formed were separated by ultrafiltration or by isoelectric precipitation of casein, and were characterized by HPLC size-exclusion and Kjeldahl analysis. The antimutagenic potential of casein increased with pepsin hydrolysis; this increase was due to the peptides formed and might be explained by a better accessibility of casein peptides for interaction with mutagens. The antimutagenic potential of pepsin-hydrolysed casein towards sodium azide was observed over the whole dose-response curve.

Antimutagenicity of milk cultured with lactic acid bacteria against N-methyl-N'-nitro-N-nitrosoguanidine

The antimutagenic effect of cultured milk using 71 strains of lactic acid bacteria belonging to the genus Lactobacillus, Streptococcus, Lactococcus, and Bifidobacterium on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine was investigated in vitro using Salmonella typhimurium TA 100 as an indicator bacterium. Each cultured milk sample displayed its characteristic antimutagenic effect on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine. The milk cultured with Lactobacillus acidophilus LA 106 (LA2) showed the highest inhibition of 77% against the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine among the strains tested. Changes in the antimutagenic effect of the milk cultured by Lb. acidophilus LA 106 (LA2) during incubation were also examined using N-methyl-N'-nitro-N-nitrosoguanidine as a mutagen.

The possible role of probiotics as dietary antimutagen

Possible antimutagenic actions of probiotics--mainly lactic acid bacteria--were examined using in vitro and in vivo test systems. In the Ames test with Salmonella typhimurium TA1538 beef extract and nitrosated beef extract were used as mutagens. L. casei showed high antimutagenic activity on mutagenicity induced by nitrosated beef extract only without S9 mix, whereas Omniflora (a lyophilized preparation of lactobacilli and E. coli) and its cell-free culture broth exhibited antimutagenic action only on beef extract. The actions of probiotics were more homogeneous when living animals were used in the tests. Using busulfan as a mutagen both the chromosome aberration test (with Chinese hamster bone marrow cells) and the micronucleus test (with bone marrow cells of Chinese hamsters and mice) showed strong anticlastogenic action when L. casei, Omniflora or yoghurt (with living bifiobacteria) were given orally at the same time as the mutagen. Lactobacilli were effective also after i.p. injection. Cell-free culture broths had no or only weak antimutagenic effects. Mutagen-induced chromosome aberrations and micronuclei were reduced by up to 80% by the lactobacilli.

Antimutagenic activity of milk fermented by Streptococcus thermophilus and Lactobacillus bulgaricus

Antimutagenic activity of acetone or ethylacetate extracts of skim milk fermented by Streptococcus thermophilus, Lactobacillus bulgaricus, or a combination of both the organisms was studied using Salmonella typhimurium (TA 98 and TA 100). Mutagens used were 4-nitroquinoline-N-oxide (a direct-acting mutagen) and 2-aminofluorene (a mutagen requiring S9 activation). Extracts from all fermented milks showed significant (P less than .05) dose response in suppressing the number of revertants caused by NQNO and 2-aminofluorene in both tester strains, whereas extracts from unfermented milk had no effect. Extracts prepared from milk fermented by L. bulgaricus plus S. thermophilus showed significantly (P less than .05) more antimutagenic activity than extracts prepared from milk fermented by S. thermophilus alone. Solvent (acetone vs. ethyl acetate) effect was not significant with 4-nitroquinoline-N-oxide as mutagen. However, in the case of 2-aminofluorene, acetone extracts showed significantly (P less than .05) higher antimutagenic activity. The results of this and related studies strongly indicate that antimutagenic compounds are produced in milk during fermentation by S. thermophilus and L. bulgaricus.