Bactericidal activity of wasabi (Wasabia japonica) against Helicobacter pylori

Allyl isothiocyanate regulates oxidative stress, inflammation, cell proliferation, cell cycle arrest, apoptosis, angiogenesis, invasion and metastasis via interaction with multiple cell signaling pathways

Cancer growth is a molecular mechanism initiated by genetic and epigenetic modifications that are involved in cell proliferation, differentiation, apoptosis, and senescence pathways. Chemoprevention is an important strategy for cancer treatment that leads to blocking, reversing, or impeding the multistep process of tumorigenesis, including the blockage of its vital morphogenetic milestones viz. normal, preneoplasia, neoplasia, and metastasis. Naturally occurring phytochemicals are becoming ever more popular compared to synthetic drugs for many reasons, including safety, bioavailability, efficacy, and easy availability. Allyl isothiocyanate (AITC) is a natural compound present in all plants of the Cruciferae family, such as Brussels sprouts, cauliflower, mustard, cabbage, kale, horseradish, and wasabi. In vitro and in vivo studies carried out over the decades have revealed that AITC inhibits tumorigenesis without any toxicity and undesirable side effects. The bioavailability of AITC is exceedingly high, as it was reported that nearly 90% of orally administered AITC is absorbed. AITC exhibits multiple pharmacological properties among which its anticancer activity is the most significant for cancer treatment. Its anticancer activity is exerted via selective modulation of multiple cell signaling pathways related to oxidative stress, inflammation, cell proliferation, cell cycle arrest, apoptosis, angiogenesis, invasion, and metastasis. This review highlights the current knowledge on molecular targets that are involved in the anticancer effect of AITC associated with (i) inhibition of carcinogenic activation and induction of antioxidants, (ii) suppression of pro-inflammatory and cell proliferative signals, (iii) induction of cell cycle arrest and apoptosis, and (iv) inhibition of angiogenic and invasive signals related to metastasis.

Glucosinolates, a natural chemical arsenal: More to tell than the myrosinase story

Glucosinolates are a group of thioglucosides that belong to the class of plant nitrogen-containing natural products. So far, very little biological activity has been associated with intact glucosinolates. The hydrolysis of glucosinolates has, for long, attracted attention because of the potent biological activity of the hydrolysis products. From allelopathic to antiparasitic, antimicrobial and antineoplastic effects, the activity spectrum of the degradation products of typical glucosinolates has been the subject of much research. The present review seeks to address the various means of glucosinolate degradation (thermal, enzymatic, or chemical degradation) and the ensuing products. It also aims to draw a comparative profile of the various antimicrobial effects of these degradation products to provide a further understanding of the biological function of these important compounds.

Developing multifunctional crops by engineering Brassicaceae glucosinolate pathways

Glucosinolates (GSLs), found mainly in species of the Brassicaceae family, are one of the most well-studied classes of secondary metabolites. Produced by the action of myrosinase on GSLs, GSL-derived hydrolysis products (GHPs) primarily defend against biotic stress in planta. They also significantly affect the quality of crop products, with a subset of GHPs contributing unique food flavors and multiple therapeutic benefits or causing disagreeable food odors and health risks. Here, we explore the potential of these bioactive functions, which could be exploited for future sustainable agriculture. We first summarize our accumulated understanding of GSL diversity and distribution across representative Brassicaceae species. We then systematically discuss and evaluate the potential of exploited and unutilized genes involved in GSL biosynthesis, transport, and hydrolysis as candidate GSL engineering targets. Benefiting from available information on GSL and GHP functions, we explore options for multifunctional Brassicaceae crop ideotypes to meet future demand for food diversification and sustainable crop production. An integrated roadmap is subsequently proposed to guide ideotype development, in which maximization of beneficial effects and minimization of detrimental effects of GHPs could be combined and associated with various end uses. Based on several use-case examples, we discuss advantages and limitations of available biotechnological approaches that may contribute to effective deployment and could provide novel insights for optimization of future GSL engineering.

Variation in the main health-promoting compounds and antioxidant activity of different organs of Wasabi (Eutrema japonicum) from two producing areas

Wasabi (Eutrema japonicum), also known as Japanese horseradish, is a perennial herb widely used in Japanese cuisine for its special flavour. The health-promoting phytochemicals and antioxidant capacity of four organs (leaf, petiole, rhizome, and root) of two cultivars (Chuankui-1 and Chuankui-2) of wasabi from two producing areas, Leibo and Guangyuan in Sichuan Province, China, were investigated in this study. The results showed that leaves were rich in pigments, soluble protein, ascorbic acid, and total phenolics and had the highest antioxidant capacity. Soluble sugars were highest in the petioles and were 1.1- to 5-fold higher than those in the other three organs. Glucosinolates and glucosinolate breakdown products (GBPs) were the most abundant in rhizomes, and their maximum values were 271.61 mmol kg^-1 DW and 249.78 mmol kg^-1 DW, respectively. The rhizomes of Chuankui-1 in Leibo and the leaves of Chuankui-1 in Guangyuan were superior in terms of glucosinolates and GBPs. These findings provide new insights that will aid the use of wasabi cultivars; they also have implications for the environmental characteristics needed to obtain better quality wasabi products. In the future, metabolome and transcriptome can be used to analyze the potential mechanism of differences among typical varieties, origins and parts.

Effect of CaS Nanostructures in the Proliferation of Human Breast Cancer and Benign Cells In Vitro

We report on the effect of naked CaS nanostructures on the proliferation of carcinoma cancer cells and normal fibroblasts in vitro. The CaS nanostructures were prepared via the microwave-mediated decomposition of dimethyl sulfoxide (DMSO) in the presence of calcium acetate Ca ( CH 3 CO 2 ) 2 . Light scattering measurements revealed that dispersions contain CaS nanostructures in the size range of a few Å to about 1 nanometer, and are formed when DMSO is decomposed in the presence of Ca ( CH 3 CO 2 ) 2 . Theoretical calculations at the DFT/B3LYP/DGDZVP level of theory on ( C a S ) n clusters ( n = 1 , 2 , 3 , and 4) are consistent with clusters in this size range. The absorption spectra of the CaS nanostructures are dominated by strong bands in the UV, as well as weaker absorption bands in the visible. We found that a single dose of CaS nanoclusters smaller than 0.8 nm in diameter does not affect the survival and growth rate of normal fibroblasts and inhibits the proliferation rate of carcinoma cells in vitro. Larger CaS nanostructures, approximately (1.1 ± 0.2) nm in diameter, have a similar effect on carcinoma cell proliferation and survival rate. The CaS nanoclusters have little effect on the normal fibroblast cell cycle. Human carcinoma cells treated with CaS nanocluster dispersion exhibited a decreased ability to properly enter the cell cycle, marked by a decrease in cell concentration in the G0/G1 phase in the first 24 h and an increase in cells held in the SubG1 and G0/G1 phases up to 72 h post-treatment. Apoptosis and necrotic channels were found to play significant roles in the death of human carcinoma exposed to the CaS nanoclusters. In contrast, any effect on normal fibroblasts appeared to be short-lived and non-detrimental. The interaction of CaS with several functional groups was further investigated using theoretical calculations. CaS is predicted to interact with thiol ( R-SH ), hydroxide ( R - OH ), amino ( R - NH 2 ), carboxylic acid ( R - COOH ), ammonium ( R-NH 3 + ), and carboxylate ( R-COO - ) functional groups. None of these interactions are predicted to result in the dissociation of CaS. Thermodynamic considerations, on the other hand, are consistent with the dissociation of CaS into Ca 2 + ions and H 2 S in acidic media, both of which are known to cause apoptosis or cell death. Passive uptake and extracellular pH values of carcinoma cells are proposed to result in the observed selectivity of CaS to inhibit cancer cell proliferation with no significant effect on normal fibroblast cells. The results encourage further research with other cell lines in vitro as well as in vivo to translate this nanotechnology into clinical use.

Horseradish Essential Oil as a Promising Anti-Algal Product for Prevention of Phytoplankton Proliferation and Biofouling

Increased proliferation of algae is a current problem in natural and artificial water bodies. Controlling nutrients is the most sustainable treatment of increased algal proliferation, however in certain cases, it is not sufficiently available, or it does not provide results fast enough. Chemicals derived from natural sources, which could be effective in low concentrations and are biodegradable, may have an advantage over conventional chemical treatments. The main aim of the present study was to investigate the anti-cyanobacterial and anti-algal properties of allyl-isothiocyanate-containing essential oil produced from horseradish roots with a complex approach of the topic: on laboratory strains of cyanobacteria and eukaryotic algae, on microcosms containing natural phytoplankton assemblages, and on semi-natural biofilms. The results show that acute treatment can significantly reduce the viability of all the tested cyanobacteria and eukaryotic algae. Results of microcosm experiments with natural phytoplankton assemblages show that horseradish essential oil from 7.1 × 10⁻⁶% (v/v) is applicable to push back phytoplankton proliferation even in natural assemblages. The individual number in the biofilm was dropped down to one-fifth of the original individual number, so 7.1 × 10⁻⁶% (v/v) and higher concentration of the essential oil can be considered as a successful treatment against biofouling.

Flavonoid and Phenolic Acids Content and In Vitro Study of the Potential Anti-Aging Properties of Eutrema japonicum (Miq.) Koidz Cultivated in Wasabi Farm Poland

Skin aging is a natural, unavoidable, and complex process caused by oxidative stress. As a consequence, it leads to an increase in the activation of extracellular matrix disruption enzymes and DNA damage. The search for natural sources that inhibit these mechanisms can be a good approach to prevent skin aging. The purpose of our study was to evaluate the composition of flavonoids and phenolic acids in the extracts obtained from the flowers, roots, and leaves of Eutrema japonicum cultivated in Poland. Then, the resultant extracts were subjected to an assessment of antioxidant, anti-collagenase, anti-elastase, anti-hyaluronidase, antibacterial, and cytotoxic properties. It was demonstrated that the extract from the flowers had the highest content of flavonoid glycosides (17.15 mg/g DE). This extract showed the greatest antioxidant, anti-collagenase, anti-elastase, and anti-hyaluronidase activities compared to the other samples. Importantly, the collagenase inhibitory activity of this extract (93.34% ± 0.77%) was better than that of positive control epigallocatechin gallate (88.49% ± 0.45%). An undeniable advantage of this extract was also to possess moderate antibacterial properties and no cytotoxicity towards normal human skin fibroblasts. Our results suggest that extracts from E. japonicum flowers may be considered as a promising antiaging compound for applications in cosmetic formulations.

Involvement of ERK1/2-mediated ELK1/CHOP/DR5 pathway in 6-(methylsulfinyl)hexyl isothiocyanate-induced apoptosis of colorectal cancer cells

6-(Methylsulfinyl)hexyl isothiocyanate (6-MSITC) is a major bioactive compound in Wasabi. Although 6-MSITC is reported to have cancer chemopreventive activities in rat model, the molecular mechanism is unclear. In this study, we investigated the anticancer mechanisms using two types of human colorectal cancer cells (HCT116 p53^+/+ and p53^-/-). 6-MSITC caused cell cycle arrest in G₂/M phase and induced apoptosis in both types of cells in the same fashion. Signaling data revealed that the activation of ERK1/2, rather than p53, is recruited for 6-MSITC-induced apoptosis. 6-MSITC stimulated ERK1/2 phosphorylation, and then activated ERK1/2 signaling including ELK1 phosphorylation, and upregulation of C/EBP homologous protein (CHOP) and death receptor 5 (DR5). The MEK1/2 inhibitor U0126 blocked all of these molecular events induced by 6-MSITC, and enhanced the cell viability in both types of cells in the same manner. These results indicated that ERK1/2-mediated ELK1/CHOP/DR5 pathway is involved in 6-MSITC-induced apoptosis in colorectal cancer cells. Abbreviations: CHOP: C/EBP homologous protein; DR5: death receptor 5; ELK1: ETS transcription factor; ERK1/2: extracellular signal-regulated kinase 1/2; JNK: Jun-N-terminal kinase; MAPK: mitogen-activated protein kinase; MEK1/2: MAP/ERK kinase 1/2; 6-MSITC: 6-(methylsulfinyl)hexyl isothiocyanate; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; PARP: poly(ADP-ribose) polymerase.

Wasabi 6-(methylsulfinyl)hexyl isothiocyanate induces apoptosis in human colorectal cancer cells through p53-independent mitochondrial dysfunction pathway

6-(Methylsulfinyl)hexyl isothiocyanate (6-MSITC), a major bioactive compound in Wasabi [Wasabia japonica (Miq.) Matsum.], has revealed the inhibitory effect on colon carcinogenesis in rat cancer model although the underlying mechanism is unclear. In this study, we used two types of human colorectal cancer cells (HCT116 p53+/+ and HCT116 p53-/- ) to investigate the anticancer activity and molecular mechanisms of 6-MSITC. Interestingly, 6-MSITC inhibited the cell proliferation in both types of cells with similar IC50 value although a light increase in the phosphorylation and accumulation of P53 protein was observed in HCT116 p53+/+ cells at 24 h after treatment. In addition, 6-MSITC increased the ratio of proapoptotic cells in both types of cells with the same fashion in a p53-independent manner. The data from mitochondrial analysis revealed that 6-MSITC enhanced the ratio of proapoptotic B-cell lymphoma-2-associated X protein/antiapoptotic myeloid cell leukemia 1, and sequentially caused mitochondrial membrane potential (ΔΨm ) loss, cytochrome c release, and caspase-3 activation in both types of cells. Taken together, Wasabi 6-MSITC induced apoptosis of human colorectal cancer cells in p53-independent mitochondrial dysfunction pathway. These findings suggest that 6-MSITC might be a potential agent for colon cancer chemoprevention although with p53 mutation. © 2018 BioFactors, 2018.

Inhibitory effects of Japanese horseradish (Wasabia japonica) on the formation and genotoxicity of a potent carcinogen, acrylamide

BACKGROUND

The formation of acrylamide (AA) in cooked foods has raised human health concerns. AA is metabolized by cytochrome P450 2E1 (CYP2E1) to glycidamide (GA), which forms DNA adducts. This study examined the inhibitory effects of wasabi (Japanese horseradish, Wasabia japonica) roots and leaves as well as their active component, allyl isothiocyanate (AIT), on the formation and genotoxicity of AA.

RESULTS

AA formation (51.8 ± 4.2 µg kg^-1 ) was inhibited with ≥2 mg mL^-1 of AIT. Wasabi roots also inhibited AA formation (∼90% reduction), but wasabi leaves were not effective at 2 mg mL^-1 . Wasabi roots and leaves decreased the number of cells with micronuclei by approximately 33 and 24% respectively compared with the AA treatment group. Moreover, wasabi roots and leaves (100 mg kg^-1 body weight (BW) day^-1 for each) decreased AA (100 mg kg^-1 BW day^-1 )-induced DNA damage. The AA-induced CYP2E1 activity was decreased by 39 and 26% with wasabi roots and leaves respectively. Further, the activity of glutathione S-transferase, which catalyzes the detoxification of AA via glutathione conjugation, increased by 54 and 33% with wasabi roots and leaves respectively.

CONCLUSION

These results indicate that wasabi roots and leaves are effective ingredients for inhibiting the formation and genotoxicity of AA. © 2016 Society of Chemical Industry.

The therapeutic efficacy of allyl isothiocyanate in cows with bovine digital dermatitis

Bovine digital dermatitis (BDD) is the most prevalent infectious cause of lameness in cattle. Because Treponema infection is a major etiology of BDD, the most common treatment of BDD is an antibiotic. Nonetheless, dairy cows require a withdrawal period after antibiotic treatment before their milk can be marketed. To address the problem, in this study, we tested whether 3 nonantibiotic agents (used separately)—allyl isothiocyanate (AITC), sodium alginate, and calcium hydroxide—alleviate BDD lesions in dairy cows. The AITC treatment improved the BDD lesions, whereas the sodium alginate and calcium hydroxide treatments did not. Therapeutic efficacy of AITC was similar to that of lincomycin, a topical antibiotic prescribed for BDD. These results suggest that AITC is a promising nonantibiotic agent for BDD treatment in dairy cows.

Improvement Effects of Wasabi (Wasabia japonica) Leaves and Allyl Isothiocyanate on Stomach Lesions of Mongolian Gerbils Infected with Helicobacter pylori

The relationship between Helicobacter pylori infection and gastric cancer associated with stomach lesions has been reported. Improvement of the adverse effects induced by H. pylori is required for human health. It has been reported that wasabi ( Wasabia japonica Matsum) leaves have various effects on bacteria and mammals. In this study, the effect was examined of wasabi leaf extract and allyl isothiocyanate (AIT), which is a main functional component of wasabi, on stomach lesions in Mongolian gerbils infected with H. pylori. After the gerbils infected with H. pylori were orally administrated with wasabi leaf extract and AIT for two weeks, colony forming units (CFU) of H. pylori, the degree of gastric mucosal erosion, and petechial hemorrhage in the stomachs of the gerbils were evaluated. Wasabi leaf extract and AIT exhibited a decreasing tendency of CFU in the stomachs. The degree of gastric mucosal erosion and petechial hemorrhage were significantly decreased by the intake of wasabi leaf extract and AIT. Wasabi leaf extract and AIT did not affect body weight, dietary intake, water intake, and the pH of the stomach. From these results, wasabi leaves and AIT may provide a natural remedy for stomach lesions induced by H. pylori.

Antibacterial Activities of Wasabi against Escherichia coli O157:H7 and Staphylococcus aureus

Escherichia coli O157:H7 and Staphylococcus aureus are two of the major pathogens frequently involved in foodborne outbreaks. Control of these pathogens in foods is essential to food safety. It is of great interest in the use of natural antimicrobial compounds present in edible plants to control foodborne pathogens as consumers prefer more natural “green” foods. Allyl isothiocyanate (AITC) is an antimicrobial compound naturally present in wasabi (Japanese horseradish) and several other edible plants. Although the antibacterial effects of pure AITC and wasabi extract (essential oil) against several bacteria have been reported, the antibacterial property of natural wasabi has not been well studied. This study investigated the antibacterial activities of wasabi as well as AITC against E. coli O157:H7 and S. aureus. Chemical analysis showed that AITC is the major isothiocyanate in wasabi. The AITC concentration in the wasabi powder used in this study was 5.91 ± 0.59 mg/g. The minimum inhibitory concentration (MIC) of wasabi against E. coli O157:H7 or S. aureus was 1% (or 10 mg/ml). Wasabi at 4% displayed higher bactericidal activity against S. aureus than against E. coli O157:H7. The MIC of AITC against either pathogen was between 10 and 100 μg/ml. AITC at 500 μg/ml was bactericidal against both pathogens while AITC at 1000 μg/ml eliminated E. coli O157:H7 much faster than S. aureus. The results from this study showed that wasabi has strong antibacterial property and has high potential to effectively control E. coli O157:H7 and S. aureus in foods. The antibacterial property along with its natural green color, unique flavor, and advantage to safeguard foods at the point of ingestion makes wasabi a promising natural edible antibacterial plant. The results from this study may be of significant interest to the food industry as they develop new and safe foods. These results may also stimulate more research to evaluate the antibacterial effect of wasabi against other foodborne pathogens and to explore other edible plants for their antimicrobial properties. To our knowledge, this is the first report on the antibacterial activity of wasabi in its natural form of consumption against E. coli O157:H7 and S. aureus.

Glutathione protects Candida albicans against horseradish volatile oil

Horseradish essential oil (HREO; a natural mixture of different isothiocyanates) had strong fungicide effect against Candida albicans both in volatile and liquid phase. In liquid phase this antifungal effect was more significant than those of its main components allyl, and 2-phenylethyl isothiocyanate. HREO, at sublethal concentration, induced oxidative stress which was characterized with elevated superoxide content and up-regulated specific glutathione reductase, glutathione peroxidase, catalase and superoxide dismutase activities. Induction of specific glutathione S-transferase activities as marker of glutathione (GSH) dependent detoxification was also observed. At higher concentration, HREO depleted the GSH pool, increased heavily the superoxide production and killed the cells rapidly. HREO and the GSH pool depleting agent, 1-chlore-2,4-dinitrobenzene showed strong synergism when they were applied together to kill C. albicans cells. Based on all these, we assume that GSH metabolism protects fungi against isothiocyanates.

Allyl isothiocyanate suppresses the proteolytic activation of sterol regulatory element-binding proteins and de novo fatty acid and cholesterol synthesis

Sterol regulatory element-binding proteins (SREBPs) are a family of transcription factors that regulate lipid homeostasis by controlling the expression of genes involved in fatty acid and cholesterol synthesis. In this study, we used a stable cell line that expresses a luciferase reporter gene driven by an SRE-containing fatty acid synthase promoter to identify allyl isothiocyanate (AITC), one of the major isothiocyanates in cruciferous vegetables, as a novel SREBP inactivator. We found that AITC downregulated the proteolytic processing of SREBPs and the expression of their target genes in human hepatoma Huh-7 cells. Furthermore, AITC reduced the de novo synthesis of both fatty acids and cholesterol. Our results indicate a novel physiological function of AITC in lipid metabolism regulation.

Antibacterial activity and mode of action of selected glucosinolate hydrolysis products against bacterial pathogens

Plants contain numerous components that are important sources of new bioactive molecules with antimicrobial properties. Isothiocyanates (ITCs) are plant secondary metabolites found in cruciferous vegetables that are arising as promising antimicrobial agents in food industry. The aim of this study was to assess the antibacterial activity of two isothiocyanates (ITCs), allylisothiocyanate (AITC) and 2-phenylethylisothiocyanate (PEITC) against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes. The antibacterial mode of action was also characterized by the assessment of different physiological indices: membrane integrity, intracellular potassium release, physicochemical surface properties and surface charge. The minimum inhibitory concentration (MIC) of AITC and PEITC was 100 μg/mL for all bacteria. The minimum bactericidal concentration (MBC) of the ITCs was at least 10 times higher than the MIC. Both AITC and PEITC changed the membrane properties of the bacteria decreasing their surface charge and compromising the integrity of the cytoplasmatic membrane with consequent potassium leakage and propidium iodide uptake. The surface hydrophobicity was also non-specifically altered (E. coli and L. monocytogenes become less hydrophilic; P. aeruginosa and S. aureus become more hydrophilic). This study shows that AITC and PEITC have strong antimicrobial potential against the bacteria tested, through the disruption of the bacterial cell membranes. Moreover, phytochemicals are highlighted as a valuable sustainable source of new bioactive products.

Dose response chemopreventive potential of allyl isothiocyanate against 7,12-dimethylbenz(a)anthracene induced mammary carcinogenesis in female Sprague-Dawley rats

The present study aimed to investigate the dose response chemopreventive potential of allyl isothiocyanate (AITC) against 7,12-dimethylbenz(a)anthracene (DMBA) induced mammary carcinogenesis in female Sprague-Dawley rats. Mammary tumor was induced by a single dose of DMBA (25 mg/rat) injected subcutaneously near mammary gland. We observed reduced body weight and increased in total number of tumors, tumor incidence and tumor volume in DMBA-induced rats. We also observed decreased antioxidant status (SOD, CAT, GPX and GSH) and increased lipid peroxidation (TBARS and LOOH) in plasma and mammary tissues. Increased levels of CYP450, Cyt-b5 and decreased levels of phase II (GST and GR) biotransformation enzymes noticed in liver and mammary tissues of DMBA-induced rats. Further, increased levels of lipid profile (TC, TG, PL and FFA) and lipoprotein (LDL and VLDL) were noticed. Whereas, decreased level of HDL in plasma and decreased levels of PL and FFA in mammary tissue. Oral administration of AITC different doses (10, 20 and 40 mg/kg bw) inhibited the tumor incidence and restored levels of biochemical markers. Biochemical findings are supported by histopathological studies. These results suggested that AITC at a dose of 20 mg/kg bw significantly exert chemopreventive potential against DMBA-induced mammary carcinogenesis.

The role of SBA-15 in drug delivery

In this review, preparation, characterization and application of various types of SBA-15 as drug delivery agents is investigated.

Antimicrobial activity of isothiocyanates (ITCs) extracted from horseradish (Armoracia rusticana) root against oral microorganisms

The antimicrobial activity of isothiocyanates (ITCs) extracted from horseradish root was investigated against oral microorganisms: 6 strains of facultative anaerobic bacteria, Streptococcus mutans, Streptococcus sobrinus, Lactobacillus casei, Staphylococcus aureus, Enterococcus faecalis and Aggregatibacter actinomycetemcomitans; one strain of yeast, Candida albicans, and 3 strains of anaerobic bacteria, Fusobacterium nucleatum, Prevotella nigrescens, and Clostridium perfringens. The ITCs extracted from horseradish root showed antimicrobial activity against all oral microorganisms by the paper disk method. The minimum bactericidal concentration (MBC) of the ITCs extracted from horseradish root ranged from 1.25 to 5.00 mg/ml against 6 strains of facultative anaerobic bacteria and one strain of yeast, and 4.17 to 16.67 mg/ml against 3 strains of anaerobic bacteria. The ITCs extracted from horseradish root showed the strongest antimicrobial activity, with a MBC of 1.25 mg/ml, against C. albicans among facultative microorganisms, and 4.17 mg/ml against F. nucleatum among anaerobic bacteria. These results suggest that the ITCs extracted from horseradish root may be a candidate for use as an antimicrobial agent against oral microorganisms.

Evaluation of the effects of selected phytochemicals on quorum sensing inhibition and in vitro cytotoxicity

Quorum sensing (QS) is an important regulatory mechanism in biofilm formation and differentiation. Interference with QS can affect biofilm development and antimicrobial susceptibility. This study evaluates the potential of selected phytochemical products to inhibit QS. Three isothiocyanates (allylisothiocyanate - AITC, benzylisothiocyanate - BITC and 2-phenylethylisothiocyanate - PEITC) and six phenolic products (gallic acid - GA, ferulic acid - FA, caffeic acid - CA, phloridzin - PHL, (-) epicatechin - EPI and oleuropein glucoside - OG) were tested. A disc diffusion assay based on pigment inhibition in Chromobacterium violaceum CV12472 was performed. In addition, the mechanisms of QS inhibition (QSI) based on the modulation of N-acyl homoserine lactone (AHLs) activity and synthesis by the phytochemicals were investigated. The cytotoxicity of each product was tested on a cell line of mouse lung fibroblasts. AITC, BITC and PEITC demonstrated a capacity for QSI by modulation of AHL activity and synthesis, interfering the with QS systems of C. violaceum CviI/CviR homologs of LuxI/LuxR systems. The cytotoxic assays demonstrated low effects on the metabolic viability of the fibroblast cell line only for FA, PHL and EPI.

Urease from Helicobacter pylori is inactivated by sulforaphane and other isothiocyanates

Infections by Helicobacter pylori are very common, causing gastroduodenal inflammation including peptic ulcers, and increasing the risk of gastric neoplasia. The isothiocyanate (ITC) sulforaphane [SF; 1-isothiocyanato-4-(methylsulfinyl)butane] derived from edible crucifers such as broccoli is potently bactericidal against Helicobacter, including antibiotic-resistant strains, suggesting a possible dietary therapy. Gastric H. pylori infections express high urease activity which generates ammonia, neutralizes gastric acidity, and promotes inflammation. The finding that SF inhibits (inactivates) urease (jack bean and Helicobacter) raised the issue of whether these properties might be functionally related. The rates of inactivation of urease activity depend on enzyme and SF concentrations and show first order kinetics. Treatment with SF results in time-dependent increases in the ultraviolet absorption of partially purified Helicobacter urease in the 260-320 nm region. This provides direct spectroscopic evidence for the formation of dithiocarbamates between the ITC group of SF and cysteine thiols of urease. The potencies of inactivation of Helicobacter urease by isothiocyanates structurally related to SF were surprisingly variable. Natural isothiocyanates closely related to SF, previously shown to be bactericidal (berteroin, hirsutin, phenethyl isothiocyanate, alyssin, and erucin), did not inactivate urease activity. Furthermore, SF is bactericidal against both urease positive and negative H. pylori strains. In contrast, some isothiocyanates such as benzoyl-ITC, are very potent urease inactivators, but are not bactericidal. The bactericidal effects of SF and other ITC against Helicobacter are therefore not obligatorily linked to urease inactivation, but may reduce the inflammatory component of Helicobacter infections.

Effects of Mesua ferrea leaf and fruit extracts on growth and morphology of Staphylococcus aureus

Mesua ferrea is traditionally used for treating bleeding piles, fever, and renal diseases. It has been reported to have antimircobial activity. In the present study, antibacterial efficacy of leaf and fruit extracts on the growth and morphology of Staphylococcus aureus is evaluated. Both extracts display good antibacterial activity against S. aureus with a minimum inhibition concentration of 0.048 mg/mL. Both extracts are bacteriostatic at a minimum bacteriostatic concentration of 0.39 mg/mL. The bacteriostatic activity lasts for 24 h, and then cells start to grow as normal as shown in time-kill analysis. Scanning electron microscopy study indicated potential detrimental effect of the extracts of leaf and fruits of M. ferrea on the morphology of S. aureus. The treatment with the extracts caused extensive lysis of the cells, leakage of intracellular constituents, and aggregation of cytoplasmic contents forming an open meshwork of the matrix.

Suppression of TRIF-dependent signaling pathway of toll-like receptors by allyl isothiocyanate in RAW 264.7 macrophages

Toll-like receptors (TLR) play a significant role in the induction of innate immune responses that are essential for host defense against invading microbial pathogens. In general, TLRs have two major downstream signaling pathways: myeloid differential factor 88 (MyD88)-dependent and toll-interleukin-1 receptor domain-containing adapter inducing interferon-β (TRIF)-dependent pathways. Allyl isothiocyanate (AITC) found in cruciferous vegetables has an effect on treatment of many chronic diseases. However, the exact molecular targets of AITC are still unidentified. Here, it was investigated whether AITC can modulate TLR signaling pathways and what is the molecular target of AITC in TLRs signaling pathways. AITC suppressed the activation of nuclear factor-κB by lipopolysaccharide (LPS) or polyinosinic-polycytidylic acid (poly[I:C]), but not by macrophage-activating lipopeptide of 2kDa (MALP-2) or cytosine-phosphate-guanine dinucleotide (CpG DNA). AITC also suppressed the activation of interferon regulatory factor 3 (IRF3) and the expression of interferon inducible protein-10 (IP-10) induced by LPS or poly[I:C]. These results suggest that AITC can modulate TRIF-dependent signaling pathways of TLRs leading to decreased inflammatory gene expression.

Phytochemical analysis and antimicrobial activity of Cardaria draba (L.) Desv. volatiles

Two different volatile isolates from the aerial parts of Cardaria draba (L.) Desv., obtained either by hydrodistillation (Extract I) or by CH(2) Cl(2) extraction subsequent to hydrolysis by exogenous myrosinase (Extract II), were characterized by GC-FID and GC/MS analyses. The main volatiles obtained by hydrodistillation, i.e., 4-(methylsulfanyl)butyl isothiocyanate (1; 28.0%) and 5-(methylsulfanyl)pentanenitrile (2; 13.8%), originated from the degradation of glucoerucin. In Extract I, also volatiles without sulfur and/or nitrogen were identified. These were mostly hexadecanoic acid (10.8%), phytol (10.2%), dibutyl phthalate (4.5%), and some other compounds in smaller percentages. Extract II contained mostly glucosinolate degradation products. They originated from glucoraphanin, viz., 4-(methylsulfinyl)butyl isothiocyanate (3; 69.2%) and 5-(methylsulfinyl)pentanenitrile (4; 4.5%), glucosinalbin, viz., 2-(4-hydroxyphenyl)acetonitrile (5; 7.2%), and glucoerysolin, viz., 4-(methylsulfonyl)butyl isothiocyanate (6; 5.0%). Moreover, the volatile samples were evaluated for their antimicrobial activity using the disc-diffusion method and determining minimum inhibitory concentrations (MIC). All volatile isolates expressed a wide range of growth inhibition activity against both Gram-positive and Gram-negative bacteria and fungi. The MIC values varied between 4 and 128 μg/ml.

Allyl isothiocyanate as a cancer chemopreventive phytochemical

Allyl isothiocyanate (AITC), which occurs in many common cruciferous vegetables, is widely and often frequently consumed by humans. Besides antimicrobial activity against a wide spectrum of pathogens, it showed anticancer activity in both cultured cancer cells and animal models, although the underlining mechanisms remain largely undefined. Bioavailability of AITC is extremely high, as nearly 90% of orally administered AITC is absorbed. AITC absorbed in vivo is metabolized mainly through the mercapturic acid pathway and excreted in urine. Available data suggest that urinary concentrations of AITC equivalent are at least ten times higher than in the plasma, and tissue levels of AITC equivalent in the urinary bladder were 14-79 times higher than in other organs after oral AITC administration to rats. These findings suggest that AITC may be most effective in the bladder as a cancer chemopreventive compound. AITC at high-dose levels also exhibit a low degree of cytotoxicity and genotoxicity in animal studies, but such adverse effects are unlikely in humans exposed to dietary levels of AITC. Overall, AITC exhibits many desirable attributes of a cancer chemopreventive agent, and further studies are warranted in order to elucidate its mechanism of action and to assess its protective activity in humans.