An Electrophilic Natural Product Provides a Safe and Robust Odor Neutralization Approach To Counteract Malodorous Organosulfur Metabolites Encountered in Skunk Spray.

The anal secretions of skunks comprise several types of malodorous organosulfur compounds. The pungent metabolites are used defensively by skunks to repel threats posed by predators, and in many parts of the world, those perceived threats include humans and their pets. The extremely low thresholds for detection of the organosulfur metabolites make efforts to "de-skunk" people, animals, and clothing a process fraught with many challenges. The fungal-derived metabolite pericosine A (4) is a promiscuous yet stabile electrophilic compound that we propose is used by some fungi as a novel form of chemical defense. Our investigations have indicated that pericosine A readily reacts with skunk-spray secretions to transform them into odorless products. Mechanistic and computational studies suggested that pericosine A and its synthetic analogues react via SN2'-type mechanisms with thiols and thioacetates under aqueous conditions to generate stable thioethers. Testing revealed that pericosine A did not cause skin or eye irritation and was highly effective at deodorizing skunk anal gland secretions when formulated to include adjunctive cosmetic ingredients.

Mode of action of sulfoxaflor on α-bungarotoxin-insensitive nAChR1 and nAChR2 subtypes: Inhibitory effect of imidacloprid.

Cockroach neurosecretory cells, dorsal unpaired median (DUM) neurons, express two distinct α-bungarotoxin-insensitive nicotinic acetylcholine receptor subtypes, nAChR1 and nAChR2 which are differently sensitive to the neonicotinoid insecticides and intracellular calcium pathways. The aim of this study is to determine whether sulfoxaflor acts as an agonist of nAChR1 and nAChR2 subtypes. We demonstrated that 1 mM sulfoxaflor induced high current amplitudes, compared to acetylcholine, suggesting that it was a full agonist of DUM neuron nAChR subtypes. Sulfoxaflor evoked currents were not inhibited by the nicotinic acetylcholine receptor antagonist d-tubocurarine (dTC) which reduced nAChR1. But, sulfoxaflor evoked currents were reduced in the presence of 5 µM mecamylamine which is known to reduce nAChR2 subtype. Interestingly, when 1 µM imidacloprid was added in the extracellular solution, sulfoxaflor-induced currents were significantly suppressed. Moreover, when extracellular calcium concentration was increased, bath application of 1 µM imidacloprid partially reduced sulfoxaflor activated currents when nAChR1 was inhibited with 20 µM dTC and completely suppressed sulfoxaflor currents when nAChR2 was inhibited with 5 µM mecamylamine. Our data demonstrated therefore that sulfoxaflor activates both nAChR1 and nAChR2 subtypes.

Inhibition of methionine gamma lyase deaminase and the growth of Porphyromonas gingivalis: A therapeutic target for halitosis/periodontitis.

BACKGROUND AND OBJECTIVES: Pathogenic infections caused by Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia can result in the production of volatile sulfur compounds (VSC's) and other toxic compounds from methionine catabolism that can lead to halitosis and periodontitis. Our aim is to block the activity of methionine gammalyase-deaminase (Mgld) of methionine catabolism to prevent halitosis/periodontitis. DESIGNS: Cloned, expressed, Mgld protein was tested for purity by SDS-PAGE and western blotting. Mgld activity was tested by UV-vis spectroscopy and DTNB assay. Effects of Mgld inhibitor propargylglycine (PGLY) was tested on P. gingivalis growth by turbidity measurements. The effects of PGLY on oral epithelial and periodontal ligament cells in culture at different concentrations and time were tested for cell viability by MTT and Live-Dead assays. Amino acid comparisons of Mgld from different oral pathogens were done using standard bioinformatics program. RESULTS: Propargylglycine (PGLY) inhibited purified Mgld activity completely. In vivo, PGLY is a potent inhibitor on the growth of the P. gingivalis over 24 h, grown at 25 °C and 37 °C. Correspondingly in vivo Mgld activity was also affected by PGLY. Amino acid comparisons of oral pathogens showed 100% identity on the key residues of Mgld catalysis. Mammalian oral cell lines with PGLY, showed no difference in cell death over untreated controls assessed by MTT and Live-Dead assays. CONCLUSIONS: PGLY arrest's VSC's production by P. gingivalis. Since initial Mgld activity is inhibited subsequent enzymatic and nonenzymatic products formed will be prevented. PGLY showed no toxicity towards cultured mammalian oral cells. Thus, PGLY can serve as a mouthwash ingredient to prevent halitosis/periodontitis.

Short-term effect of strontium- and zinc-containing toothpastes and mouthrinses on volatile sulphur compounds in morning breath: a randomized, double-blind, cross-over clinical study.

Zinc (Zn) reduces the formation of volatile sulphur compounds (VSCs) associated with oral malodour. Although strontium (Sr) is included in some products for reducing dental hypersensitivity, it may also have anti-halitosis properties. This randomized, double-blind, cross-over clinical study compared the anti-VSC effect of brushing with commercial toothpastes and rinses containing Zn and Sr. The volunteers (n = 30) either brushed/rinsed with/without tongue brushing using Zn-containing toothpaste/rinse, Sr-containing toothpaste/rinse, or placebo (control). Volatile sulphur compounds [hydrogen sulphide (H2 S) and methyl mercaptan (CH3 SH)] were measured, in morning breath, using gas chromatography. The anti-VSC effects of the test toothpastes and test rinses were significantly better than the anti-VSC effects of the respective controls. Toothbrushing with test toothpastes gave median reductions, compared with the control, of 70% for H2 S and 55-57% for CH3 SH. Rinsing with the Sr- and Zn-containing solutions had the same anti-VSC effect as toothbrushing and tooth- and tongue brushing with the Sr- and Zn-containing toothpastes. Zinc-containing rinse resulted in a significantly higher median salivary level of Zn compared with brushing with Zn-containing toothpaste, although this effect did not correlate with the anti-VSC effect. It can be concluded that the Sr- and Zn-containing toothpastes and the Zn- and Sr-containing rinses, when used in the evening, are equally effective in reducing morning-breath VSCs the following day.

Characterization of phenolic constituents inhibiting the formation of sulfur-containing volatiles produced during garlic processing.

Garlic (Allium sativum L.), which is a widely distributed plant, is globally used as both spice and food. This study identified five novel phenolic compounds, namely, 8-(3-methyl-(E)-1-butenyl)diosmetin, 8-(3-methyl-(E)-1-butenyl)chrysin, 6-(3-methyl-(E)-1-butenyl)chrysin, and Alliumones A and B, along with nine known compounds 6-14 from the ethanol extract of garlic. The structures of these five novel phenolic compounds were established via extensive 1D- and 2D-nuclear magnetic resonance spectroscopy experiments. The effects of the phenolic compounds isolated from garlic on the enzymatical or nonenzymatical formation of sulfur-containing compounds produced during garlic processing were examined. Compound 12 significantly reduced the thermal decomposition of alliin, whereas compound 4 exhibited the highest percentage of alliinase inhibition activity (36.6%).

The effect of zinc acetate and magnolia bark extract added to chewing gum on volatile sulfur-containing compounds in the oral cavity.

OBJECTIVE: A controlled, clinical, double-blind study was conducted to assess the efficacy of a sugar-free chewing gum containing zinc acetate and magnolia bark extract (MBE) on oral volatile sulfur-containing compounds (VSC) versus a placebo sugar-free chewing gum for two hours. METHODS: To participate in the study, subjects had to have at least 24 of their teeth, no report of oral and systemic diseases, and no removable dentures. All 168 eligible participants had to avoid any professional oral hygiene, refrain from taking medicine for two weeks, and not be menstruating. They were also instructed not to brush their teeth and tongue, smoke, drink alcohol, or eat onion, garlic, or licorice for the six-hour period before the visit and during the test. Moreover, to join the protocol, they had to show a VSC score of > or = 75 ppb at the baseline measurement. One-hundred and twenty-three subjects (67 men and 56 women, mean age 37) met the criteria at baseline and were entered into either the test or control group by assignment from a table of randomized numbers. The test chewing gum (2.23 g) contained zinc acetate 0.012% and magnolia bark extract 0.15% in weight; the control gum was equivalent without these active agents. The OralChroma device was utilized to evaluate total oral VSC. Their levels were recorded at baseline, after ten minutes of mastication, after one hour, and after two hours. Data were analyzed with SPSS software and the level of significance was set at alpha = 0.05. RESULTS: One-hundred and twenty-three subjects completed the trial (62 in the control group and 61 in the test group); none reported problems linked to zinc acetate or magnolia bark extract. The mean percentage reductions from baseline at the end of the 10-minute chewing were 31.2% in the control group (p < 0.05) and 50.9% in the test group (p < 0.05). One hour later the reductions were 6.9% in the control group and 27.6% in the test group (p < 0.05); two hours later the reductions were 2.3% in the control group and 13.6% in the test group. The comparison of the two groups after baseline adjustment showed a statistically significant difference (p < 0.05) in VSC reductions between the test and control chewing gums at the end of the mastication period and after one hour. CONCLUSION: Chewing gum containing zinc acetate and magnoliabark extract can significantly reduce the oral VSC levels for more than one hour. Moreover, the test chewing gum reduces oral VSC significantly more than a control chewing gum.

Tea catechin EGCg suppresses the mgl gene associated with halitosis.

Epigallocatechin gallate (EGCg), the main antimicrobial tea catechin, has been reported to inhibit growth and virulence factors of oral pathogens in vitro. Although the mechanism is unclear, the potential of EGCg in reducing halitosis caused by volatile sulfur compounds (VSCs) has been suggested. This study tested the hypothesis that EGCg reduces VSCs by suppressing mgl, the gene encoding L-methionine-α-deamino-γ-mercaptomethane-lyase, responsible for methyl mercaptan (CH3SH) production by oral anaerobes. In this study, the effect of EGCg on in vitro growth, CH3SH production, and mgl gene expression in P. gingivalis W83 was investigated. EGCg inhibited growth of P. gingivalis W83 (MIC = 97.5 µg/mL) and was bactericidal (MBC = 187.5 µg/mL). At sub-MIC levels, EGCg inhibited CH3SH production, and mgl mRNA and protein expression (p < 0.05). We conclude that EGCg may represent a natural and alternative agent to the antimicrobial chemicals currently available for halitosis control.

Use of 0.1% chlorine dioxide to inhibit the formation of morning volatile sulphur compounds (VSC).

The aim of this study was to evaluate the VSC-inhibiting effect of a commercially available mouthrinse (0.1% chlorine dioxide) when compared to its placebo. A 2-step double blind, crossover, randomised study was conducted with 14 dental students with healthy periodontium, who refrained from any mechanical plaque and tongue coating control during two 4-day experimental periods. The subjects were instructed to rinse 3 times daily with the assigned product during each period. A 7-day washout interval was established. VSCs levels were measured by a sulphide monitor at the beginning (baseline) and at the end of each experimental period. Statistical analyses were performed using Wilcoxon's and Mann-Whitney's non-parametric tests. At baseline, intragroup analysis revealed that VSCs levels did not differ between groups (p > 0.05); at day 5, the use of the chlorine dioxide mouthrinse did not change the baseline VSCs scores in the control group (p > 0.05), while a 2-fold increase was observed with the use of the placebo mouthrinse (p < 0.05). Intergroup analysis showed a significant difference between the VSCs levels of the test and control groups (40.2 +/- 30.72 and 82.3 +/- 75.63 ppb, p < 0.001) at day 5. Within the limits of this study, the findings suggest that a mouthrinse containing chlorine dioxide can maintain VSCs at lower levels in the morning breath.

Use of 0.1 percent chlorine dioxide to inhibit the formation of morning volatile sulphur compounds (VSC)

The aim of this study was to evaluate the VSC-inhibiting effect of a commercially available mouthrinse (0.1 percent chlorine dioxide) when compared to its placebo. A 2-step double blind, crossover, randomised study was conducted with 14 dental students with healthy periodontium, who refrained from any mechanical plaque and tongue coating control during two 4-day experimental periods. The subjects were instructed to rinse 3 times daily with the assigned product during each period. A 7-day washout interval was established. VSCs levels were measured by a sulphide monitor at the beginning (baseline) and at the end of each experimental period. Statistical analyses were performed using Wilcoxon's and Mann-Whitney's non-parametric tests. At baseline, intragroup analysis revealed that VSCs levels did not differ between groups (p > 0.05); at day 5, the use of the chlorine dioxide mouthrinse did not change the baseline VSCs scores in the control group (p > 0.05), while a 2-fold increase was observed with the use of the placebo mouthrinse (p < 0.05). Intergroup analysis showed a significant difference between the VSCs levels of the test and control groups (40.2 ± 30.72 and 82.3 ± 75.63 ppb, p < 0.001) at day 5. Within the limits of this study, the findings suggest that a mouthrinse containing chlorine dioxide can maintain VSCs at lower levels in the morning breath.

O objetivo do presente estudo foi avaliar o efeito inibitório do enxaguatório de dióxido de cloro a 0,1 por cento sobre a formação dos CSVs, quando comparados a um placebo. Um estudo randomizado, cruzado, duplo cego foi conduzido com 14 estudantes de odontologia apresentando saúde periodontal, os quais se abstiveram dos hábitos de escovação dentária e limpeza da língua durante dois períodos experimentais de 4 dias. Os voluntários foram orientados a utilizar o enxaguatório designado 3 vezes ao dia conforme indicado no rótulo. Um intervalo de 7 dias foi estabelecido entre os períodos experimentais. No início ("baseline") e no final de cada período experimental, os níveis de CSVs foram medidos com o uso do monitor de sulfetos. Análise estatística foi realizada utilizando-se os testes não-paramétricos de Wilcoxon e Mann-Whitney. No "baseline", uma análise intragrupo revelou que os níveis de CSVs não diferiram entre os grupos (p > 0.05); no dia 5, o uso do dióxido de cloro não promoveu mudanças significativas nos níveis de CSVs em relação ao "baseline" no grupo controle (p > 0,05), entretanto os níveis de CSVs duplicaram com a utilização enxaguatório placebo (p < 0,05). Uma análise entre os grupos teste e controle revelou diferença significante para os níveis de CSVs (40,2 ± 30,72 e 82,3 ± 75,63 ppb, p < 0,001) no dia 5. Dentro dos limites deste estudo, os achados sugerem que o uso de enxaguatórios contendo dióxido de cloro pode promover a manutenção de baixos níveis de CSVs no hálito matinal.

Inhibitory effect of Weissella cibaria isolates on the production of volatile sulphur compounds.

AIMS: The objective of this study was to characterize the inhibitory effects of Weissella cibaria isolates on volatile sulphur compounds (VSC) production both in vitro and in vivo. MATERIAL AND METHODS: We isolated and identified three hydrogen peroxide-generating lactobacilli from children's saliva, and assessed their inhibitory effects on VSC production and Fusobacterium nucleatum proliferation. Clinical studies were conducted with 46 subjects in order to measure the VSC of their mouth air. RESULTS: These lactobacilli were identified as W. cibaria. These isolates inhibited the production of VSC by F. nucleatum (p<0.05). The concentration of F. nucleatum was decreased by 5-log cycles as a result of exposure to the W. cibaria strains (p<0.05), whereas the catalase-treated W. cibaria cultures exerted no evident inhibitory effects on F. nucleatum replication. In the clinical studies, gargling with one isolate resulted in a significant reduction in the levels of H2S and CH3SH by approximately 48.2% (p<0.01) and 59.4% (p<0.05), respectively. CONCLUSIONS: These results indicate that W. cibaria isolates possess the ability to inhibit VSC production under both in vitro and in vivo conditions, demonstrating that they bear the potential for development into novel probiotics for use in the oral cavity.

Effect of a triclosan/PVM/MA copolymer/fluoride dentifrice on volatile sulfur compounds in vitro.

OBJECTIVE: The objective of the investigation was to document the in vitro efficacy of a triclosan/PVM/MA copolymer/fluoride (TCF) dentifrice against the formation of volatile sulfur compounds (VSC) as well as the growth of H2S-producing bacteria. Clinical studies using organoleptic judges, gas chromatography, or a portable sulfide monitor have generally been employed in the assessment of treatments for the control of oral malodor. However, these studies are not appropriate for screening purposes because of the expense and time required. METHODS: An in vitro method was developed for the purpose of screening new compounds, agents or formulations for their ability to control VSC formation and for determining bio-equivalence of efficacy when implementing changes in existing formulations. The method combines basic microbiological methods, dynamic flow cell techniques and head space analysis. The in vitro VSC method was validated by comparing the efficacy of two dentifrices containing TCF with a control fluoride dentifrice as the TCF products have been clinically proven to control oral malodor. RESULTS: In the validation studies, the TCF-containing dentifrices were significantly better (P < 0.05) than the control dentifrice in inhibiting VSC formation and reducing H(2)S-producing bacteria. For example, when compared with baseline, the TCF dentifrices reduced VSC formation between 42 and 49% compared with the control dentifrice which reduced VSC formation 3%. There was no significant difference (P > 0.05) between the two TCF dentifrice formulations. CONCLUSION: Using an in vitro breath VSC model, it has been demonstrated that two variants of a dentifrice containing triclosan, PVM/MA copolymer and fluoride have efficacy that is significantly better than a control fluoridated dentifrice and that there is no significant difference between the triclosan/PVM/MA copolymer/fluoride dentifrice variants.

Inhibition of orally produced volatile sulfur compounds by zinc, chlorhexidine or cetylpyridinium chloride--effect of concentration.

Zinc ions, chlorhexidine (CHX) and cetylpyridinium chloride (CPC) are all known to inhibit production of volatile sulfur compounds (VSCs). The objective was to examine the anti-VSC dose-response effects of each of the above agents. Oral malodor was induced in 13 test subjects using the cysteine challenge method. The oral VSC response to rinses with 6 mm l-cysteine (pH 7.2) before and 1, 2 and 3 h after rinsing with zinc ions (Zn2+: 0.1, 0.3 and 1.0%), CHX and CPC (0.025 and 0.2%) was measured. Mouth air was analysed for VSC by gas chromatography (GC) according to current methodology. Zinc had a marked dose- and time-dependent anti-VSC effect. Zinc at 1% concentration had a somewhat unpleasant taste, whereas the lowest concentration was found acceptable. Chlorhexidine maintained a moderate anti-VSC effect over time. At 3 h, 0.2% CHX was the most effective agent but tasted relatively unpleasant. Cetylpyridinium at a concentration of 0.2% was only marginally more effective than 0.025% CHX over the 3 h, while 0.025% CPC had no better anti-VSC effect than water at both 2 h and 3 h. It was concluded that the three test agents demonstrated different anti-VSC kinetics. Although Zn had the best anti-VSC effect at 1 h, 0.2% CHX was at least as effective as 1% Zn at 3 h, most likely as a result of its unique substantivity.

Combined effect of zinc ions and cationic antibacterial agents on intraoral volatile sulphur compounds (VSC).

OBJECTIVE: Volatile sulphur compounds (VSC) are major components of oral malodour. As both zinc ions and cationic antibacterial agents inhibit the formation of oral VSC, this study aimed to determine whether these agents combined have synergistic anti-VSC actions. METHODS: Baseline oral VSC measurements of mouth air from 10 volunteers following cysteine rinsing (6mM, pH 7.2) were obtained using gas chromatography (GC). Subjects rinsed for 1 min with 10ml of the test solutions, 0.3% zinc acetate (Zn), 0.025% chlorhexidine (CHX), 0.025% cetyl pyridinium (CPC), and the combinations Zn+CHX and Zn+CPC. Cysteine rinses were repeated at 1h, 2h and 3h and VSC measurements recorded. Three subjects rinsed with the Zn+CHX combination and fasted for 9h, undergoing cysteine rinses and VSC measurements at 3h intervals. 10 microl of the test solutions were also added to 1ml aliquots of human whole saliva (n=8). Following incubation at 37 degrees C for 24h VSC levels in the saliva headspace were measured by GC. Inhibition of VSC formation and the fractional inhibitory index indicating synergy were calculated. RESULTS: Zn+CHX mouthrinse had a synergistic anti-VSC effect, and was effective for at least 9h. Zn+CPC mouthrinse was less effective. Both combinations showed a synergistic inhibiting effect in-vitro. CONCLUSIONS: Synergy between Zn and the antibacterial agents confirms different mechanisms of operation.

The significance of the source of zinc and its anti-VSC effect.

UNLABELLED: The anti-VSC (volatile sulphur compounds) effect of zinc is known to be associated with free zinc ions. OBJECTIVE: To examine whether zinc salts with low stability constants were more suitable as sources of zinc in zinc lozenges than zinc salts with high stability constants. The former provide free zinc ions upon dissolution in water, whereas the latter provide few such ions. DESIGN AND PARTICIPANTS: Identical lozenges were produced which contained either zinc acetate, zinc gluconate (low stability constants), zinc citrate or amino-acid chelated zinc (extremely high stability constants). All the lozenges contained 0.1 per cent of zinc. A test panel of 10 volunteers used the different lozenges randomly. VSC were measured by GC. RESULTS AND CONCLUSION: The lozenge with the highest stability constant was as effective as those with very low stability constants. The anti-VSC effect was thus not related to this constant. These findings may be explained by the possibility that alternative ligands with stronger affinity for zinc than the original ligands in the lozenges may be present in the oral cavity. An in vitro experiment indicated that the sulphide ion (S2-) may be such a ligand.

Review of the treatment strategies for oral malodour.

Breath malodour, a significant social and/or psychological handicap, may be caused by several intra- and extraoral factors. Malodour of intraoral origin is the result of microbial putrefaction, during which volatile sulphur compounds (VSC) and other volatile compounds are produced. The treatment of oral malodour can therefore be focused on the reduction of the intraoral bacterial load and/or the conversion of VSC to nonvolatile substrates. This article outlines the efficacy and mechanisms of different antimalodour approaches. Most approaches were found to be inefficient and/or short lasting. The most successful treatment involves mechanical debridement (including toothbrushing, flossing, and tongue cleaning), possibly combined with the use of an antimicrobial mouthrinse.

The oral anti-volatile sulphur compound effects of zinc salts and their stability constants.

Volatile sulphur compounds (VSC) produced in the oral cavity, are a major cause of oral malodour. Zinc (Zn) ions inhibit VSC formation. The objective of this study was to examine whether Zn salts with low stability constants were more suitable as sources of Zn in lozenges than salts with high stability constants. The former provide free Zn ions upon dissolution in water, whereas the latter provide almost no free Zn. Identical lozenges containing Zn-acetate and -gluconate, which have low stability constants, and Zn citrate and amino acid-chelated Zn, which have extremely high stability constants, were tested. All the lozenges contained 0.9% w/w Zn. Ten volunteers sucked the lozenges until dissolved, and oral VSC were measured by gas chromatography. Zn-acetate, -gluconate and -chelate had an impressive anti-VSC effect even 3 h after the lozenges were taken. Zn citrate had significantly less effect than the other lozenges except Zn acetate after 2 and 3 h. It was concluded that the anti-VSC effect was not related to the stability constants of the Zn compounds tested. Alternative ligands. with stronger affinity for Zn than the ligands in the lozenges, must be present in the oral cavity to explain these results. It is suggested that the sulphide ion may serve this function.

A multifactorial investigation of the ability of oral health care products (OHCPs) to alleviate oral malodour.

UNLABELLED: AIM, BACKGROUND: Oral malodour (halitosis) is generally ascribable to oral microbial putrefaction generating malodorous volatile sulphur compounds which predominantly comprise dihydrogen sulphide and methyl mercaptan. This study assesses the relative effectiveness of 6 oral health care products in reducing oral cavity volatile sulphur compound concentrations. METHOD: A mixed model 3-factor factorial experimental design involving 6 volunteers, 7 treatment regimens (products I-VI* and water placebo) and 5 time-points (0.00-5.29 h) was undertaken. Electron-donating volatile sulphur compound levels were determined in triplicate using a sulphide monitor (Interscan model 1170) both prior to (0.00 h) and following oral rinsing (20 ml of 5 of the products) or chewing (2 capsules of the remaining product) episodes with each product examined (0.29, 1.29, 2.29 and 5.29 h post-administration). RESULTS: Results were recorded as peak and steady-state volatile sulphur compound equivalents (ppb). With the exception of one of the products, each oral health care product tested was found to reproducibly reduce volatile sulphur compound concentrations within 20 min of treatment; the mean % decreases in peak (and corresponding steady-state) levels ranging from 3.6 (0.0) to 16.8 (16.4)%. Subsequently, volatile sulphur compound concentrations returned to their zero-control (baseline) values within 5 h, the rate of this regression being in the reverse of the order observed for the magnitude of the primary 20 min reduction for both peak and steady-state measurements. As expected, the water placebo exerted no influence on oral cavity volatile sulphur compound levels. The most effective oral health care products contained admixtures of chlorite anion and chlorine dioxide (both of these agents have the ability to directly oxidise volatile sulphur compounds to non-malodorous products and the latter is also powerfully cidal towards odourigenic micro-organisms). CONCLUSIONS: We therefore conclude that oral health care products containing such oxohalogen oxidants may provide a useful therapeutic strategy for the treatment of oral malodour.

Volatile sulfur production by pig cecal bacteria in batch culture and screening inhibitors of sulfate reducing bacteria.

We studied the effects of specific inhibitors of methanogenesis (2-bromoethane sulfonate, BES) and sulfate reduction (sodium molybdate) on volatile sulfur production in batch cultures of pig cecal bacteria. The volatile sulfur concentration in headspace gas was determined by flame-photometric detector gas chromatography. BES stimulated production of hydrogen sulfide (H2S) and methanethiol, and sodium molybdate completely inhibited the production of these volatile sulfur compounds. The results indicated that dissimilate sulfate reduction is mainly responsible for volatile sulfur production in the hindgut. Therefore the extracts of herbs, food colors, and aroma chemicals were tested for their inhibitory effects on H2S production by a dissimilatory sulfate-reducing bacteria. Desulfovibrio desulfuricans DSM642. H2S was measured by the chromatography of the headspace gas, using a flame photometric detector. Of 306 herbal extracts tested, 69 extracts from 38 herbs inhibited H2S production at 1.0 mg/mL. Sisymbrium officinale (hedge mustard) was the most potent inhibitor. Six pigments inhibited H2S release. Erythrosine and rose bengal showed inhibitory effects at 0.01 mg/mL. Peppermint oil and 96 aroma chemicals were assayed for their effects on H2S release. Thirty-two aroma chemicals suppressed H2S production at 0.1 mg/mL, and camphene, 1-decanol, and 2-nonanone were effective at 0.01 mg/mL.

Efficacy of a chlorine dioxide-containing mouthrinse in oral malodor.

Studies have suggested that when chlorine dioxide is contained in a mouthrinse, it neutralizes volatile sulfur compounds in mouth air. The efficacy of a chlorine dioxide-containing mouthrinse in the reduction of oral malodor was evaluated in a randomized, controlled, double-blind, parallel group study of 31 men and women. Subjects with a maximum odor pleasantness score of < or = -1 (slightly unpleasant/stale) on a 7-point ordinal scale at both screening and baseline were randomized to treatment with the chlorine dioxide-containing rinse (n = 16) or distilled water (negative control) (n = 15). Oral malodor was evaluated at baseline (prerinse) and at 2, 4, 8, 24, 48, 72, and 96 hours postrinse by both a trained, previously calibrated panel of organoleptic judges and a factory-calibrated portable sulfide monitor. The sulfide monitor measured concentrations of volatile sulfur compounds in the subjects' mouth air 3 minutes after completion of the organoleptic assessment at each time point. The correlation between the organoleptic assessments and log-transformed sulfide monitor values was evaluated. With the chlorine dioxide mouthrinse, a statistically significant improvement in odor pleasantness, reduction in odor intensity, and reduction in oral volatile sulfur compound concentrations compared to the water control were evident at 2 hours postrinse and persisted through 8 hours postrinse. The mean (+/- SD) odor pleasantness improved from -1.25 +/- 0.31 at baseline to -0.73 +/- 0.33 at 2 hours postrinse in the chlorine dioxide group compared to -1.40 +/- 0.38 at baseline to -1.31 +/- 0.67 at 2 hours in the control group (P < 0.01). Odor pleasantness reached its maximum change from baseline to 0.63 +/- 0.45 at 8 hours postrinse. The mean (+/- SD) log-transformed sulfide monitor measurement decreased from 5.40 +/- 0.29 at baseline to 5.17 +/- 0.13 at 2 hours postrinse in the chlorine dioxide group, but increased from 5.47 +/- 0.40 at baseline to 5.56 +/- 0.54 at 2 hours in the control group (P < 0.01). As measured by the sulfide monitor, the mean volatile sulfur compound concentration in the chlorine dioxide group reached its minimum level at 8 hours postrinse (change from baseline in the log-transformed Halimeter measurement of -0.35 +/- 0.31). Thus, this study demonstrates that a one-time use of a chlorine dioxide-containing mouthrinse significantly improves mouth odor pleasantness, reduces mouth odor intensity, and reduces volatile sulfur compound concentrations in mouth air for at least 8 hours after use.