Inhibitory effects of spices on growth and toxin production of toxigenic fungi

The inhibitory effects of 29 commercial powdered spices on the growth and toxin production of three species of toxigenic Aspergillus were observed by introducing these materials into culture media for mycotoxin production. Of the 29 samples tested, cloves, star anise seeds, and allspice completely inhibited the fungal growth, whereas most of the others inhibited only the toxin production. Eugenol extracted from cloves and thymol from thyme caused complete inhibition of the growth of both Aspergillus flavus and Aspergillus versicolor at 0.4 mg/ml or less. At a concentration of 2 mg/ml, anethol extracted from star anise seeds inhibited the growth of all the strains.     

Inhibitory effects of condiments and herbal drugs on the growth and toxin production of toxigenic fungi

The effects of thirteen kinds of powdered herbal drugs and seven kinds of commercial dry condiments on the growth and toxin production ofAspergillus parasiticus, A. flavus,A. ochraceus, andA. versicolor were observed by introducing these substances into culture media for mycotoxin production.Of the twenty samples tested, cinnamon bark completely inhibited the fungal growth, while the others only inhibited the toxin production.The inhibitors were easily extracted from the samples with solvents such as hot water, chloroform, or ethanol.The extracts from coptis, philodendron bark, mustard, green tea leaves, and zanthoxylum completely inhibited the aflatoxin production ofA. parasiticus, however, they had little or no inhibitory effect againstA. flavus.     

Inhibitory effects of Bacillus probionts on growth and toxin production of Vibrio harveyi pathogens of shrimp

Aim:  To investigate the effects of Bacillus subtilis , Bacillus licheniformis and Bacillus megaterium in terms of toxin and growth of pathogenic Vibrio harveyi .
Methods and Results:  Three Bacillus probionts were isolated from probiotic BZT aquaculture and identified using a 16S rDNA sequence. Growth inhibition assay showed that supernatants from the 24-h culture of three Bacillus species were able to inhibit the growth of V. harveyi (LMG 4044); B. subtilis was the most effective based on the well diffusion method. Results of a liquid culture model showed that B. subtilis was also widely effective in inhibiting three strains of V. harveyi (isolated from Thailand, the Philippines and LMG 4044), and that both B. licheniformis and B. megaterium inhibit the growth of V. harveyi isolated from the Philippines. Moreover, a haemolytic activity assay demonstrated that V. harveyi (IFO 15634) was significantly decreased by the addition of B. licheniformis or B. megaterium supernatant.
Conclusions:  Bacillus subtilis inhibited Vibrio growth, and both B. licheniformis and B. megaterium suppressed haemolytic activity in Vibrio .
Significance and Impact of the Study:  The cell-free supernatants produced by Bacillus probionts inhibit Vibrio disease, and Bacillus probionts might have an influence on Vibrio cell-to-cell communications.     

Assessment of toxigenic fungi on Argentinean medicinal herbs

This work was performed to determine the incidence of toxigenic fungi and their mycotoxins on 152 dried medicinal and aromatic herbs, belonging to 56 species, which are used as raw material for drugs. International methodologies for fungal enumeration and identification were applied as well as TLC and HPLC techniques for toxins detection. The 52% out of 152 samples were contaminated with species from Aspergillus genus, 27% belonging to the Flavi section and 25% to the Circumdati section. The 16% of the total samples was contaminated with species from Fusarium genus. Aspergillus flavus and A. parasiticus (Flavi section), were the predominant species isolated, 50% out of 40 isolates were toxigenic. Aflatoxin concentrations ranged from 10 to 2000 ng/g. Only 26% of isolates from the Circumdati section (A. alliaceus, A. ochraceus and A. sclerotiorum) produced ochratoxin A in low concentrations between 0.12 and 9 ng/g. From a total of 29 strains of Fusarium spp., 27.5% were Fusarium verticillioides and F. proliferatum, which produced fumonisin Bland fumonisin B2 ranged from 20 to 22000 microg/g and from 5 to 3000 microg/g respectively. The remaining species, F. equiseti, F. oxysporum, F. semitectum, F. compactum, F. sombucinum and F. solani were able to produce neither group A and B trichothecenes nor zearalenone. The incidence of A. ochraceus and Fusarium spp. and their toxigenic capacities on medicinal herbs were studied for the first time in Argentina. It would be important to look for natural contamination to define acceptability Limits which allow the control of sanitary quality of medicinal herbs used as phytotherapic medicines in several countries.     

Inhibitory effects of essential oils of medicinal plants from growth of plant pathogenic fungi

Plant cells produce a vast amount of secondary metabolites. Production of some compounds is restricted to a single species. Some compounds are nearly always found only in certain specific plant organs and during a specific developmental period of the plant. Some secondary metabolites of plants serve as defensive compounds against invading microorganisms. Nowadays, it is attempted to substitute the biological and natural agents with chemically synthesized fungicides. In the present research, the antifungal activities of essential oils of seven medicinal plants on mycelial growth of three soilborne plant pathogenic fungi were investigated. The plants consisted of Zataria multiflora, Thymus carmanicus, Mentha pieperata, Satureja hortensis, Lavandual officinolis, Cuminum cyminum and Azadirachta indica. The first five plants are from the family Labiatae. Examined fungi, Fusarium oxysporum f.sp. lycopersici, Fusarium solani and Rhizoctonia solani are the causal agents of tomato root rot. Essential oils of Z. multiflora, T. carmanicus, M. pieperata, S. hortensis and C. cyminum were extracted by hydro-distillation method. Essential oils of L. officinalis and A. indica were extracted by vapor-distillation method. A completely randomized design with five replicates was used to examine the inhibitory impact of each concentration (300, 600 and 900 ppm) of each essential oil. Poisoned food assay using potato dextrose agar (PDA) medium was employed. Results showed that essential oils of A. indica, Z. multiflora, T. carmanicus and S. hortensis in 900 ppm at 12 days post-inoculation, when the control fungi completely covered the plates, prevented about 90% from mycelial growth of each of the fungi. While, the essential oils of M. pieperata, C. cyminum and L. officinalis in the same concentration and time prevented 54.86, 52.77 and 48.84%, respectively, from F. solani growth. These substances did not prevent from F. oxysporum f.sp. lycopersici and R. solani growth. Minimum inhibitory concentration (MIC) of essential oils of T. carmanicus, Z. multiflora and A. indica from R. solani and F. solani growth was 900 and 600 ppm, respectively. In addition, the MIC of essential oils of these plants and essential oil of S. hortensis from F. oxysporum f.sp. lycopersici growth was 900 ppm. The MIC of essential oils of M. pieperata, C. cyminum and L. officinalis from F. solani growth was 900 ppm.     

Inhibitory effects of botulinum toxin on pyloric and antral smooth muscle

Botulinum toxin injection into the pylorus is reported to improve gastric emptying in gastroparesis. Classically, botulinum toxin inhibits ACh release from cholinergic nerves in skeletal muscle. The aim of this study was to determine the effects of botulinum toxin on pyloric smooth muscle. Guinea pig pyloric muscle strips were studied in vitro. Botulinum toxin type A was added; electric field stimulation (EFS) was performed every 30 min for 6 h. ACh (100 microM)-induced contractile responses were determined before and after 6 h. Botulinum toxin caused a concentration-dependent decrease of pyloric contractions to EFS. At a low concentration (2 U/ml), botulinum toxin decreased pyloric contractions to EFS by 43 +/- 9% without affecting ACh-induced contractions. At higher concentrations (10 U/ml), botulinum toxin decreased pyloric contraction to EFS by 75 +/- 7% and decreased ACh-induced contraction by 79 +/- 9%. In conclusion, botulinum toxin inhibits pyloric smooth muscle contractility. At a low concentration, botulinum toxin decreases EFS-induced contractile responses without affecting ACh-induced contractions suggesting inhibition of ACh release from cholinergic nerves. At higher concentrations, botulinum toxin directly inhibits smooth muscle contractility as evidenced by the decreased contractile response to ACh.     

Inhibitory activity of spices and essential oils on psychrotrophic bacteria

This study was designed to evaluate "in vitro" the inhibitory effects of spices and essential oils on the growth of psycrotrophic food-borne bacteria: Aeromonas hydrophila, Listeria monocytogenes and Yersinia enterocolitica. The sensitivity to nine spices and their oils (chilli, cinnamon, cloves, ginger, nutmeg, oregano, rosemary, sage, thyme) was studied. Antibacterial activity was evaluated on liquid and solid medium. Spices: 1% concentration of each spice was added separately to Triptic Soy Broth and then inoculated to contain 10(8)/ml organism and held to 4 degrees C for 7 days. Populations of test organism were determined on Triptic Soy Agar. Oils: Inhibition of growth was tested by using the paper disc agar diffusion method (at 35, 20 and 4 degrees C) and measuring their inhibition zone. MIC was determined by the broth microdilution method. Some culinary spices produce antibacterial activity: inhibition of growth ranged from complete (cinnamon and cloves against A. hydrophila) to no inhibition. Antibacterial inhibition zone ranged from 8 mm to 45 mm: thyme essential oil showed the greatest inhibition against A. hydrophila.     

Inhibitory effect of garlic on bacterial pathogens from spices

An unconventional technique for primary screening of bacterial susceptibility to garlic (Allium sativum Linn.), using a slice from its clove, was described. Aqueous extracts of garlic were found to possess a potent bacteriostatic principle against Gram-positive as well as Gram-negative foodborne bacterial pathogens. In agar medium, the minimum inhibitory concentrations (MICs) of garlic were 6–10 mg ml^–1 for Bacillus cereus, 30–40 mg ml^–1 for Staphylococcus aureus (excepting the isolate from garlic, where the MIC was 100 mg ml^–1), 20–30 mg ml^–1 for Clostridium perfringens, 10 mg ml^–1 for Escherichia coli (30 mg ml^–1 for the garlic isolate), 40–100 mg ml^–1 for Salmonella, and 10–40 mg ml^–1 for Shigella. It inhibited the growth of all these strains, which were resistant to some commonly used antibiotics. Most of the tested strains were resistant to penicillins, although sensitive to garlic. While the growth of B. cereus and Cl. perfringens was completely inhibited at 10 and 70 mg garlic, respectively, ml^–1 test broth, their respective enterotoxin production ceased at 10 and 50 mg garlic ml^–1.     

Decrease of growth and aflatoxin production in Aspergillus parasiticus caused by spices

Non-commercial spices and herbs Tetrapleura tetrapetra, Triumfetta cordifolia, Garcina kola, Monodora myristica and Xylopia aethiopica at 0.08 to 0.32% (w/v) decreased the mycelial weight of Aspergillus parasiticus NRRL 2999 in yeast extract/sucrose broth by up to 68%. Aflatoxin production, monitored with ELISA, was most effectively decreased, from 97 to 23 g/ml, when the extract of G. kola was added at 0.32% (w/v).     

Inhibitory effects of glutathione on dengue virus production

Reduced glutathione (GSH) is the most powerful intracellular antioxidant and also involved in viral infections. The pathogenesis of dengue virus (DV) infection has not been completely clarified. This study investigated the relationship between DV serotype 2 (DV2) infections and host intracellular GSH content. Results showed infection with DV2 resulted in a decrease in intracellular GSH, which caused NF-κB activation and increased DV2 production. Supplemental GSH significantly inhibited activation of NF-κB, resulting in a decreased production of DV2 in HepG2 cells. Furthermore, high activity of NF-κB and increased production of DV2 was observed in HepG2 cells treated with buthionine sulfoximine (BSO), an inhibitor of GSH synthesis. In conclusion, DV2 infection could reduce host intracellular GSH concentration and benefited from this process. Supplemental GSH could inhibit viral production, indicating GSH might be valuable in the prevention and treatment of DV2 infection.     

Inhibitory effects of H2 on growth of Clostridium cellobioparum.

Hydrogen inhibits the growth of hydrogen-producing Clostridium cellobioparum, but not of Escherichia coli or Bacteroides ruminicola. The inhibition is reversible. When hydrogen was removed either by palladium black or by gassing out the tube, glucose utilization increased as did optical density and hydrogen production of C. cellobioparum. Removal of the H2 by methanogenic bacteria favors the growth of C. cellobioparum. Grown with Methanobacterium ruminantium in various concentrations of glucose, the Clostridium reaches a higher optical density and produces more H2 and a higher viable cell count. The cell yield is also higher than in pure culture. In mixed culture, C. cellobioparum produces more acetic acid and less lactic acid, ethanol, and butyric acid than in pure culture. The significance of this metabolic shift and hydrogen utilization in methanogenesis is discussed.     

石菖蒲(Acorus tatarinowii)克藻效应的研究

石菖蒲（Ａｃｏｒｕｓ ｔａｔａｒｉｎｏｗｉｉ）抑制藻类的机制除了对光和矿质营养的竞争外,主要是由于石菖蒲水系向水体分泌的化学物质,能伤害和清除藻类（化感作用ａｌｌｅｌｏｐａｔｈｉｃ ｅｆｆｅｃｔ）,用培植石菖蒲的水培养藻类,可破坏藻类的叶绿素ａ,使其光合速率,细胞还原ＴＴＣ能力显著下降;在荧光显微镜下可看到藻细胞从鲜红色变为淡蓝色,表明石菖蒲对藻类有显著的克制效果,可用于治理富营养化水体中的藻类繁     

Inhibitory effects of polyphenols on gastric injury by Helicobacter pylori VacA toxin

Background. Helicobacter pylori induces gastric damage and may be involved in the pathogenesis of gastric cancer. H. pylori‐vacuolating cytotoxin, VacA, is one of the important virulence factors, and is responsible for H. pylori‐induced gastritis and ulceration. The aim of this study is to assess whether several naturally occurring polyphenols inhibit VacA activities in vitro and in vivo. Materials and Methods. Effects of polyphenols on VacA were quantified by the inhibition of: 1, vacuolation; 2, VacA binding to AZ‐521 or G401 cells or its receptors; 3, VacA internalization. Effects of hop bract extract (HBT) containing high molecular weight polymerized catechin on VacA in vivo were investigated by quantifying gastric damage after oral administration of toxins to mice. Results. HBT had the strongest inhibitory activity among the polyphenols investigated. HBT inhibited, in a concentration‐dependent manner: 1, VacA binding to its receptors, RPTPα and RPTPβ; 2, VacA uptake; 3, VacA‐induced vacuolation in susceptible cells. In addition, oral administration of HBT with VacA to mice reduced VacA‐induced gastric damage at 48 hours. In vitro, VacA formed a complex with HBT. Conclusions. HBT may suppress the development of inflammation and ulceration caused by H. pylori VacA, suggesting that HBT may be useful as a new type of therapeutic agent for the prevention of gastric ulcer and inflammation caused by VacA.     

Inhibitory effects of some spice essential oils on Aspergillus ochraceus NRRL 3174 growth and ochratoxin A production

Inhibitory effects of essential oils of oregano (Origanum vulgare), mint (Menta arvensis), basil (Ocimum basilicum), sage (Salvia officinalis) and coriander (Coriandrum sativum), on the mycelial growth and ochratoxin A production by Aspergillus ochraceus NRRL 3174 were studied. Cultures were incubated on yeast extract-sucrose (YES) broth, at concentrations of 0, 500, 750 and 1000 p.p.m. of essential oils during 7, 14 and 21 d at 25 degrees C. At 1000 p.p.m., oregano and mint completely inhibited the fungal growth and ochratoxin A production up to 21 d, while basil was only effective up to 7 d. At 750 p.p.m., oregano was completely effective up to 14 d, whereas mint allowed fungal growth but no ocratoxin A production up to 14 d. At 500 p.p.m., no evident inhibition could be in observed with any of the essential oils under analysis. Sage and coriander showed no important effect at any of the concentrations studied. These inhibitory effects are interesting in connection with the prevention of mycotoxin contamination in many foods and they could be used instead of synthetic antifungal products.     

Natural occurrence of toxigenic fungi and mycotoxins in rice bran

Thirty four samples of rice bran, of which 9 were from raw (untreated) rice (RR) and 25 from parboiled rice (PbR) were collected from commercial rice mills in and around Madras and analysed for storage mycoflora and mycotoxins. Fungi of the Aspergillus flavus group were present in 29 of the 34 samples (8 from RR and 21 from PbR) in quantities ranging from <1–432 thousand propagules/g, though not always as the dominant mycoflora. Fungal numbers were usually higher in RR than in PbR samples.Five of the 9 RR samples and 6 of the 25 PbR samples were positive for aflatoxins. Among 29 isolates of A. flavus obtained from the bran samples, 16 isolates –6 from RR bran and 10 from PbR bran — were found to be toxigenic in vitro. Some isolates of A. candidus also seemed to produce aflatoxin and other fluorescent substances.     

Inhibitory effects of monoterpenes on seed germination and seedling growth

Monoterpenes, the chemical constituents of essential oils found in plants, are known biologically active compounds. The present study was conducted to investigate the inhibitory effects of 30 monoterpenes including monoterpene hydrocarbons and oxygenated monoterpenes on seed germination and seedling growth of Amaranthus retroflexus, Chenopodium album and Rumex crispus under laboratory conditions. The monoterpenes were applied at contents of 10 and 20 microl for liquid compounds and 10 and 20 microg for solid compounds. The results show that most of the monoterpenes significantly inhibited seed germination and seedling growth of the tested plants. Oxygenated monoterpenes including beta-citronellol, nerol and terpinen-4-ol completely inhibited seed germination and seedling growth of all tested plants. Their inhibitory effects were also stronger than that of the herbicide 2,4-D. In general, monoterpenes were less effective against seed germination and seedling growth of C. album as compared with R. crispus and A. retroflexus. Phytotoxic effects of monoterpene hydrocarbons were found to be lower than those of oxygenated monoterpenes. The alcohol derivatives of oxygenated monoterpenes were also found to be more phytotoxic as compared with their acetate derivatives. Based on the present results, it can be concluded that the oxygenated monoterpenes can be used as potential bio-herbicides.     

Effect of iron on growth and toxin production byClostridium botulinum type A

The kinetics of growth and toxin production by the Hall strain ofClostridium botulinum type A was examined in the presence of various concentrations of iron (0.1 to 10.1 g/ml, 1.8 to 182 M) in a chemically defined medium. At concentrations below 0.5 g/ml, iron insufficiency limited the growth of the organism. The maximum amount of toxin produced varied by only twofold (6×10⁵ to 1.2×10⁶ mouse median lethal doses/ml per A₅₄₀ unit) over the 100-fold range of iron concentrations used. High concentrations of iron did not reduce the elaboration of botulinum toxin, in contrast with its marked inhibitory effects on the production of many bacterial toxins. Iron is unlikely to be a regulatory effector for the formation of botulinum toxin by the Hall strain of type A.     

Inhibitory effects of transforming growth factor-β on laminin production and growth exhibited by endoderm-like cells derived from embryonal carcinoma cells

Previous studies have shown that two mouse embryonal carcinoma (EC) cell lines do not express cell surface receptors for transforming growth factor type-beta (TGF-beta) until they are induced to differentiate. To understand the effects of TGF-beta in this model system, we have examined the effects of TGF-beta on parietal endoderm-like cells derived from EC cells. We have determined that TGF-beta exerts three effects on these cells. TGF-beta inhibits proliferation of the parietal endoderm-like cells, and this occurs even in the presence of growth factors that stimulate their proliferation. TGF-beta also alters the morphology of the parietal endoderm-like cells by increasing their spreading. Moreover, the morphological effect of TGF-beta is observed in the presence of dibutyryl cyclic AMP (dbcAMP), which reduces the spreading of these cells. Lastly, TGF-beta, but not other growth factors, decreases the production of laminin by the parietal endoderm-like cells. This was unexpected since TGF-beta has been shown to increase the production of extracellular matrices in other systems. Thus, our findings indicate that parietal endoderm-like cells provide a useful system for broadening the study of TGF-beta. Furthermore, our findings provide additional support for the possibility that TGF-beta plays important roles during the early stages of mammalian development.