ascorbic-acid and allyl-isothiocyanate

The antimicrobial activity of the essential oils (EOs) from cinnamon bark, oregano, mustard, and of their major components cinnamaldehyde, carvacrol, and allyl isothiocyanate (AIT) was evaluated as a gaseous treatment to reduce Salmonella enterica serovar Typhimurium in vitro and on tomatoes. In vitro tests showed that mustard EO and AIT had the greatest inhibition of Salmonella, followed by cinnamon EO and cinnamaldehyde, while oregano and carvacrol showed the least inhibition. Scanning electron microscopy images of S. Typhimurium on tomatoes suggest that the EOs and their major components damaged the bacteria, and the damage was more obvious after posttreatment storage at 10 °C for 4 and 7 d. Salmonella on inoculated tomatoes was reduced by more than 5 log colony forming units (CFU)/g by mustard EO and AIT, by 4.56 and 3.79 log CFU/g following cinnamon EO and cinnamaldehyde treatments, respectively, and 1.54 and 3.37 log CFU/g after oregano EO and carvacrol treatments, respectively. Mustard EO and AIT induced discoloration, softening, and loss of the vitamin C and lycopene during 21 d of storage at 10 °C, while treatment with cinnamon EO and cinnamaldehyde did not result in significant changes in tomato quality. Tomatoes treated with oregano EO had better quality than nontreated samples after storage. Therefore, treatment with cinnamon and oregano EO and their major components appeared to be feasible for inactivation of Salmonella on tomatoes and maintaining quality.

Topics: Acrolein; Anti-Bacterial Agents; Ascorbic Acid; Cinnamomum zeylanicum; Colony Count, Microbial; Cymenes; Food Contamination; Food Microbiology; Food Preservation; Food Storage; Isothiocyanates; Monoterpenes; Mustard Plant; Oils, Volatile; Origanum; Plant Extracts; Salmonella typhimurium; Solanum lycopersicum

The aim of this study was to investigate the inhibitory effect of natural antimicrobials on the growth of typical spoilage bacteria from marinated pork. Minimum inhibitory concentrations (MIC) of thymol, cinnamaldehyde, allyl isothiocyanate, citric acid, ascorbic acid, a rosemary extract, and a grapefruit seed extract against Lactobacillus algidus, Leuconostoc mesenteroides, Leuconostoc carnosum, Carnobacterium maltaromaticum, Carnobacterium divergens, Brochothrix thermosphacta, and Serratia proteamaculans were determined in a microplate assay. Combinations of antimicrobials were tested and several combinations showed synergistic effects in inhibiting bacterial growth. Single and combined antimicrobials were added to vacuum-packed pork meat to evaluate preserving effects. Antimicrobial concentrations of up to 10 times the MIC values showed no effect on total bacterial growth in vacuum packed pork meaning that although most antimicrobials inhibited the growth of spoilage bacteria in vitro, results from the microplate assay could not be transferred to the meat system. Most natural antimicrobials possess strong odor and flavor that limit their use as a food preservative. In conclusion, this study showed that the use of natural antimicrobials in meat products is limited and that bacterial quality and shelf life was not enhanced under the chosen conditions.

Topics: Acrolein; Animals; Anti-Infective Agents; Ascorbic Acid; Citric Acid; Citrus paradisi; Food Microbiology; Food Packaging; Food Preservation; Gram-Negative Bacteria; Gram-Positive Bacteria; Isothiocyanates; Meat; Microbial Sensitivity Tests; Plant Extracts; Rosmarinus; Swine; Thymol; Vacuum

The aim of this study was to investigate the protective effect of isothiocyanates alone or in combination with vitamin C towards N-nitrosodibutylamine (NDBA) or N-nitrosopiperidine (NPIP)-induced oxidative DNA damage in the single cell gel electrophoresis (SCGE)/HepG2 assay. Phenethyl isothiocyanate (PEITC) and indole-3-carbinol (I3C) alone showed a weak protective effect towards NDBA (0.1 microm, 26-27%, respectively) or NPIP (1 microm, 26-28%, respectively)-induced oxidative DNA damage. Allyl isothiocyanate (AITC) alone did not attenuate the genotoxic effect provoked by NDBA or NPIP. In contrast, HepG2 cells simultaneously treated with PEITC, I3C and AITC in combination with vitamin C showed a stronger inhibition of oxidative DNA-damage induced by NDBA (0.1 microm, 67%, 42%, 32%, respectively) or NPIP (1 microm, 50%, 73%, 63%, respectively) than isothiocyanates (ITCs) alone. One feasible mechanism by which ITCs alone or in combination with vitamin C exert their protective effects towards N-nitrosamine-induced oxidative DNA damage could be by the inhibition of their cytochrome P450 dependent bioactivation. PEITC and I3C strongly inhibited the p-nitrophenol hydroxylation (CYP2E1) activity (0.1 microm, 66-50%, respectively), while the coumarin hydroxylase (CYP2A6) activity was slightly reduced (0.1 microm, 25-37%, respectively). However, the ethoxyresorufin O-deethylation (CYP1A1) activity was only inhibited by PEITC (1 microm, 55%). The results indicate that PEITC and I3C alone or PEITC, I3C and AITC in combination with vitamin C protects human-derived cells against the oxidative DNA damaging effects of NDBA and NPIP, two food carcinogenic compounds.

Topics: Anticarcinogenic Agents; Aryl Hydrocarbon Hydroxylases; Ascorbic Acid; Carcinogens; Carcinoma, Hepatocellular; Cell Line, Tumor; Comet Assay; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP2A6; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP2E1 Inhibitors; DNA Breaks; DNA-Formamidopyrimidine Glycosylase; Dose-Response Relationship, Drug; Enzyme Inhibitors; Humans; Indoles; Isothiocyanates; Liver Neoplasms; Microsomes, Liver; Mixed Function Oxygenases; Nitrosamines; Oxidative Stress

Three strains of Bifidobacterium sp., B. pseudocatenulatum, B. adolescentis, and B. longum were studied for their ability to digest glucosinolates, sinigrin (SNG) and glucotropaeolin (GTL), in vitro. All strains digested both glucosinolates during 24-48 h cultivation, accompanied by a decline in the medium pH from 7.1 to 5.2. The digestion of glucosinolates by a cell-free extract prepared from sonicated cells of B. adolescentis, but not cultivated broth, increased in the presence of 0.5 mM l-ascorbic acid. Also, a time-dependent formation of allyl isothiocyanate (AITC) was observed when the cell-free extract was incubated with 0.25 mM SNG for 120 min at pH 7.0. These reaction features suggest that the digestive activity may have been due to an enzyme similar to myrosinase, an enzyme of plant origin. GC-MS analysis of the Bifidobacterial cultured broth showed that the major products were 3-butenenitrile (BCN) and phenylacetonitrile (PhACN), from SNG and GTL, respectively and nitriles, probably due to a decrease in the pH of the media. AITC and benzyl isothiocyanate (BzITC) were barely detectable in the broth. It was concluded that the three species of Bifidobacteria could be involved in digestive degradation of glucosinolates in the human intestinal tract.

Topics: Acetonitriles; Ascorbic Acid; Bifidobacterium; Biotransformation; Culture Media, Conditioned; Digestive System; Gas Chromatography-Mass Spectrometry; Glucosinolates; Hydroxamic Acids; Isothiocyanates; Nitriles; Thioglucosides