Allyl-thiosulfinates, the bacteriostatic compounds of garlic against Helicobacter pylori

Allicin and allyl-methyl plus methyl-allyl thiosulfinate from acetonic garlic extracts (AGE) have been isolated by high-performance liquid chromatography. These compounds have shown inhibition of the in vitro growth of Helicobacter pylori (Hp), the bacterium responsible for serious gastric diseases such as ulcers and even gastric cancer. A chromatographic method was optimized and used to isolate these thiosulfinates. The method developed has allowed the isolation of natural thiosulfinates extracted from garlic by organic solvents and is an easy and cheap methodology that avoids complex synthesis and purification procedures. The capacity and effectiveness of isolated natural thiosulfinates have been tested, and this has enabled the identification of the main compounds responsible for the bacteriostatic activity shown by AGE origin of these kinds of organosulfur compounds along with ethanolic garlic extracts (EGE). Additionally, microbiological analyses have suggested that these compounds show a synergic effect on the inhibition of the in vitro growth of Hp. The results described here facilitate the process of obtaining garlic extracts with optimal bacteriostatic properties. The product is obtained in a way that avoids expensive purification methods and will allow the design of live tests with the aim of investigating the potential for the use of these garlic derivatives in the treatment of patients with Hp infections.     

Antimicrobial properties of garlic oil against human enteric bacteria: evaluation of methodologies and comparisons with garlic oil sulfides and garlic powder

The antimicrobial effects of aqueous garlic extracts are well established but those of garlic oil (GO) are little known. Methodologies for estimating the antimicrobial activity of GO were assessed and GO, GO sulfide constituents, and garlic powder (GP) were compared in tests against human enteric bacteria. Test methodologies were identified as capable of producing underestimates of GO activity. Antimicrobial activity was greater in media lacking tryptone or cysteine, suggesting that, as for allicin, GO effects may involve sulfhydryl reactivity. All bacteria tested, which included both gram-negative and -positive bacteria and pathogenic forms, were susceptible to garlic materials. On a weight-of-product basis, 24 h MICs for GO (0.02 to 5.5 mg/ml, 62 enteric isolates) and dimethyl trisulfide (0.02 to 0.31 mg/ml, 6 enteric isolates) were lower than those for a mixture of diallyl sulfides (0.63 to 25 mg/ml, 6 enteric isolates) and for GP, which also exhibited a smaller MIC range (6.25 to 12.5 mg/ml, 29 enteric isolates). Viability time studies of GO and GP against Enterobacter aerogenes showed time- and dose-dependent effects. Based upon its thiosulfinate content, GP was more active than GO against most bacteria, although some properties of GO are identified as offering greater therapeutic potential. Further exploration of the potential of GP and GO in enteric disease control appears warranted.     

Activities of muscadine grape skin and quercetin against Helicobacter pylori infection in mice

Aims: To explore the preventative potential of muscadine grape skin (MGS) and the single flavonoid, quercetin, as an alternative means for ameliorating Helicobacter pylori infection and/or the H. pylori‐induced inflammatory response in mice. Methods and Results: The antimicrobial and anti‐inflammatory properties of MGS and quercetin, a major phenolic constituent, were evaluated against H. pylori in vitro and in vivo. The antimicrobial activity of quercetin was evaluated against 11 H. pylori strains in vitro with inhibition of all strains at 128–64 μg ml^?1. In vivo studies showed a moderate reduction in H. pylori counts following treatment with 5 and 10% MGS or quercetin (25 mg kg^?1 body weight) in addition to significantly reduced inflammatory cytokines (TNF‐α, IL‐1β and IFN‐γ) when compared with untreated mice. Conclusions: MGS and quercetin did not significantly reduce H. pylori growth in a mouse model. However, these products were effective in regulating the inflammatory response to H. pylori infection. Significance and Impact of the Study: Our results suggest that H. pylori infection may be reduced or prevented via the consumption of fruits rich in certain phenolic compounds (e.g. quercetin) such as muscadine grapes.     

Obviation of dyslipidemia by garlic oil and its organosulfur compound,diallyl disulphide,in experimental animals

Background and objectivesGarlic and its number of preparations are known to be effective for treatment of dyslipidemia, but the data about the specific active constituents of the garlic on the possible therapeutic value is scarce. Therefore, the aim of this research was to evaluate the role of garlic oil (GO) and its active element, diallyl disulphide (DADS) for obviating dyslipidemia in animal model.MethodsHigh fat diet (HFD) was given to animals to induce dyslipidemia. Animals of HFD groups were fed with atherogenic diet for 15 days prior to treatment. Animals in their respective groups received vehicle, GO (50 and 100 mg/kg), and DADS (4.47 and 8.94 mg/kg) for five consecutive days. Lipid profiles were estimated in serum, oxidant/antioxidant and liver profile were measured in liver tissue homogenate (LTH).ResultsAnimals fed on HFD developed significant increase in the serum levels of triglycerides (TG), total cholesterol (TC), lactate dehydrogenase (LDL), malondialdehyde (MDA), glutathione peroxidase (GSHPx), glutathione (GSH), and glutathione disulfide (GSSG) that reduced significantly in groups that received GO and DADS treatments. Additionally, significant elevation in serum high density lipoprotein (HDL) level was observed in animals that received GO and DADS. Moreover, hepatic markers such as alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine transferase (ALT), that were abnormally altered by high fat diet, were significantly restored to almost normal values with GO and DADS treatments. Also, antioxidants such as superoxide dismutase (SOD), catalase (CAT), ferric reducing antioxidant power (FRAP), and total thiol (SH) levels in LTH were increased significantly in GO and DADS treated groups. When compared to DADS, GO showed better therapeutic effectiveness in terms of antihyperlipidemic and antioxidant properties.ConclusionIn hyperlipidemic rats, garlic and its principal active component, diallyl disulphide, were effective in avoiding dyslipidemia and neutralizing reactive free radicals induced by a high fat diet. It's an intriguing observation that GO has a larger therapeutic influence than its active constituent, DADS. These findings suggest that other constituents, in addition to GO's DADS, are involved in the compound's synergistic antihyperlipidemic and antioxidant activities.     

Synthesis of plaunotol derivatives and their antibacterial activities against Helicobacter pylori.

Plaunotol, a known antiulcer drug, has antibacterial activities against Helicobacter pylori. Plaunotol thiourea derivatives 2--4 and diol derivatives 6--10 were designed in search for a compound with high antibacterial activities. Thiourea derivatives 2--4 were synthesized regioselectively using our effective synthetic route for plaunotol (1), and diol derivatives 6--10 were also synthesized. Their antibacterial activities against H. pylori are described and we found that the most potent antibacterial agent was C1-thiourea derivative 2c.     

幽门螺杆菌的治疗性疫苗

幽门螺杆菌感染的传统治疗方案面临着耐药性和依从性差的问题,而其治疗性疫苗有着广阔的应用前景.该文综述近年来幽门螺杆菌治疗性疫苗的研究进展,分别阐述幽门螺杆菌的感染免疫机制、主要抗原、佐剂、已有的治疗性疫苗等方面.     

Inhibition of Helicobacter pylori by garlic extract (Allium sativum)

Abstract The antibacterial effect of aqueous garlic extract (AGE) was investigated against Helicobacter pylori . Sixteen clinical isolates and three reference strains of H. pylori were studied. Two different varieties of garlic were used. The concentration of AGE required to inhibit the bacterial growth was between 2–5 mg ml⁻¹. The concentration, for both AGE types, to inhibit 90% (MIC₉₀) of isolates was 5 mg ml⁻¹. The minimum bactericidal concentration (MBC) was usually equal to, or two-fold higher than, minimum inhibitory concentration (MIC). Heat treatment of extracts reduced the inhibitory or bactericidal activity against H. pylori ; the boiled garlic extract showed a loss of efficacy from two-to four-fold the values of MIC and the MBC obtained with fresh AGR. The antibacterial activity of garlic was also studied after combination with a proton pump-inhibitor (omeprazole) in a ratio of 250:1. A synergistic effect was found in 47% of strains studied; an antagonistic effect was not observed.     

Helicobacter pylori defense against oxidative attack

Helicobacter pylori is a microaerophilic, gram-negative pathogen of the human stomach. Despite the chronic active gastritis that develops following colonization, H. pylori is able to persist unharmed in the stomach for decades. Much of the damage caused by gastric inflammation results from the accumulation of reactive oxygen/nitrogen species within the stomach environment, which can induce oxidative damage in a wide range of biological molecules. Without appropriate defenses, this oxidative damage would be able to rapidly kill nearby H. pylori, but the organism employs a range of measures, including antioxidant enzymes, biological repair systems, and inhibitors of oxidant generation, to counter the attack. Despite the variety of measures employed to defend against oxidative injury, these processes are intimately interdependent, and any deficiency within the antioxidant system is generally sufficient to cause substantial impairment of H. pylori viability and persistence. This review provides an overview of the development of oxidative stress during H. pylori gastritis and examines the methods the organism uses to survive the resultant damage.     

Allylsulfide constituents of garlic volatile oil as antimicrobial agents.

Six different mixtures of garlic distilled oils containing diallyl disulfide (DDS) and diallyl trisulfide (DTS), ranging from 1 to 51% and 88 to 38% respectively, have been assayed against a number of yeasts (C. albicans, C. tropicalis and B. capitatus), gram-positive bacteria (S. aureus and B. subtilis) and gram-negative bacteria (P. aeruginosa and E. coli). Results obtained support a specific antifungal more than an antibacterial activity and implicate DDS as the active constituent. Incubation of garlic extracts made up of 1% DDS and 88% DTS resulted, in fact, in the absence of growth inhibition against all the tested microorganisms, whereas garlic oils with higher quantities of DDS showed significant inhibitory activity, increasing with the increase of DDS amount.     

Influence of oral Helicobacter pylori on the success of eradication therapy against gastric Helicobacter pylori

Background. The goal of this study was to see whether Helicobacter pylori ( H. pylori ) in the oral cavity might adversely affect the outcome of eradication therapy for gastric H. pylori.
Materials and Methods. Forty-seven patients (36 males, 11 females) with gastric H. pylori infection were enrolled in this study. Gastric H. pylori infection was confirmed by both immunohistological staining with anti- H. pylori antibody and bacterial culture of biopsy specimens. The therapeutic regimen consisted of 30 mg/day lansoprazole, 750 mg/day metronidazole, and 400 mg/day clarithromycin administered for 2 weeks. A fragment of the H. pylori urease gene was amplified by nested PCR for DNA extracted from saliva and dental plaque from the same patients. We examined the correlation between the gastric eradication success rate and the prevalence of H. pylori in the oral cavity as determined by PCR before and after the eradication therapy.
Results. The eradication success rate was significantly lower in the oral H. pylori -positive cases (12/23, 52.1%) than in the negative cases (22/24, 91.6%) at 4 weeks after the therapy (p = .0028). Two years later, only 16 of the 23 (69.5%) oral H. pylori -positive cases were disease-free, as compared to 23 of the 24 (95.8%) oral H. pylori -negative cases (p = .018).
Conclusions. H. pylori in the oral cavity affected the outcome of eradication therapy and was associated with a recurrence of gastric infection. We recommend that oral H. pylori should be examined by nested PCR and, if positive, should be considered a causal factor in refractory or recurrent cases.     

Identification of a pro-elongation effect of diallyl disulfide,a major organosulfur compound in garlic oil,on microglial process

Microglia are the innate immune cells in the nervous system. In the resting state, they display a ramified morphology, while upon disease stimulation their processes would be retracted, along with pro-inflammatory cytokine overproduction. Reversing microglial process retraction may help reduce pro-inflammatory cytokine production and restore microglia's ability to scan surrounding environments, rendering brain function regulation to be more effective. We found that diallyl disulfide (DADS), a major organosulfur compound in garlic oil, administered at different doses and time points, promoted microglial process elongation in both cultured systems and prefrontal cortexes in mice in a reversible manner. Lipopolysaccharide (LPS), a classical activator of microglia, did not affect this pro-elongation effect of DADS at conditions in vitro and in vivo. Functional studies revealed that DADS pre-treatment attenuated LPS-induced decreases in levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) mRNA as well as LPS-induced increases in levels of IL-10 and CD206 mRNA in both cultured microglia and prefrontal cortexes in mice. Protein kinase B (Akt) inhibition attenuated the pro-elongation effect of DADS on microglial process and blocked the regulatory effects of DADS on LPS-induced inflammatory responses in both cultured microglia and prefrontal cortexes in mice. In an in vivo model of neuroinflammation, DADS pre-treatment prevented LPS-induced retraction of microglial process in the prefrontal cortex in mice and attenuated LPS-induced increase in immobility time in the tail suspension test and forced swim test. These results indicate that DADS induces an Akt-dependent elongation of microglia process, along with the induction of an anti-inflammatory phenotype.     

Progress in vaccine development against Helicobacter pylori

Based on the very high prevalence of diseases caused by Helicobacter pylori, particularly in the developing world, and the rapid emergence of antibiotic resistance among clinical isolates, there is a strong rationale for an effective vaccine against H. pylori. In this review we describe recent promising candidate vaccines and prophylactic or therapeutic immunization strategies for use against H. pylori, as well as studies to identify immune responses that are related to protection in experimental animals. We also describe identification of different types of immune responses that may be related to protection against symptoms based on comparisons of H. pylori-infected patients with duodenal ulcers or gastric cancer and asymptomatic carriers. We conclude that there is still a strong need to clarify the main protective immune mechanisms against H. pylori as well as to identify a cocktail of strong protective antigens, or recombinant bacterial strains that express such antigens, that could be administered by a regimen that gives rise to effective immune responses in humans.     

Chemoprotective effect of diallyl trisulfide from garlic against carbon tetrachloride-induced acute liver injury of rats

Diallyl sulfide (DAS), diallyl disulfide (DADS) and diallyl trisulfide (DATS) are principal constituents of garlic oil. We studied the effect of these sulfides on the phase II drug-metabolizing enzymes, and on the rat model of acute liver injury induced by carbon tetrachloride (CCl4). A highly purified form of each sulfide (more than 99% purity) was administered i.p. to rats at a concentration of 10 or 100 micromol/kg body weight for 14 consecutive days. DATS (10 micromol/kg) and DADS at a 10-fold higher dose (100 micromol/kg) significantly increased the activities of glutathione S-transferase (GST) and quinone reductase (QR); whereas DAS did not. In the CCl4-induced acute liver injury model of rats, DATS (10 micromol/kg) significantly suppressed the increase in plasma lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) activities. In conclusion, hepatic phase II enzymes were induced strongly by the trisulfide and weakly by the disulfide, but not by DAS. DATS significantly reduced the liver injury caused by CCl4. DATS may be one of the important factors in garlic oil that protects our body against the injury caused by radical molecules.     

Antimicrobial activity of essential oils against Helicobacter pylori

Background. Helicobacter pylori is an important pathogen responsible for gastroduodenal diseases in humans. Although the eradication of H. pylori using antibiotics often improves gastroduodenal diseases, resistance to the antibiotics is emerging. Materials and Methods. The antimicrobial effect of essential oils and the development of resistance to the essential oils were evaluated in vitro and in vivo. Results. Thirteen essential oils used in this study completely inhibited the growth of H. pylori in vitro at a concentration of 0.1% (v/v). Cymbopogon citratus (lemongrass) and Lippia citriodora (lemon verbena) were bactericidal against H. pylori at 0.01% at pH 4.0 and 5.0. Resistance to lemongrass did not develop even after 10 sequential passages, whereas resistance to clarithromycin developed under the same conditions. In in vivo studies, the density of H. pylori in the stomach of mice treated with lemongrass was significantly reduced compared with untreated mice. Conclusions. These results demonstrate that the essential oils are bactericidal against H. pylori without the development of acquired resistance, suggesting that essential oils may have potential as new and safe agents for inclusion in anti‐H. pylori regimens.     

The bactericidal activity of tea against Helicobacter pylori

Extracts of black and green tea inhibited in-vitro growth of six clinical isolates of Helicobacter pylori in an agar diffusion assay. Tea extracts killed H. pylori (10⁶ cfu ml^-1) within 5 h. Heat treatment of extracts did not affect the inhibitory or bactericidal activity.     

Assessment of Helicobacter pylori eradication by virgin olive oil

Background: A recent study conducted by Medina et al. disclosed that virgin olive oil has a bactericidal effect in vitro against Helicobacter pylori because of its contents of certain phenolic compounds with dialdehydic structures. We carried out two clinical trials to evaluate the effect of virgin olive oil on H. pylori‐infected individuals. Materials and Methods: Two different pilot studies were performed with 60 H. pylori‐infected adults. In the first study, thirty subjects who tested positive for H. pylori received 30 g of washed virgin olive oil for 14 days, and after 1 month, the patients took 30 g of unwashed virgin olive oil for another 14 days. In a second study, a group of 30 subjects received 30 g of a different virgin olive oil for 14 days. Helicobacter pylori‐infection status was checked by the urea breath test. Results: Helicobacter pylori was eradicated in 8 of 30 individuals when microorganism status was checked after 4–6 weeks from the first clinical intervention although 12 of 30 individuals did not show H. pylori infection at 24–72 hour of the last oil dose. Eradication rates were 27 and 40% by intention to treat and per protocol, respectively. Moreover, only 3 of 30 individuals were H. pylori negative after 4–6 weeks from the second clinical intervention but 5 of 30 were negative at 24–72 hour of the last oil dose. Eradication rates were 10 and 11% by intention to treat and per protocol, respectively. It must also be noted that 13 subjects withdrew from the studies because of taste and nausea drawbacks. Conclusions: The administration of virgin olive oil showed moderate effectiveness in eradicating H. pylori. Further studies are needed to confirm these findings, especially with longer periods, different administration conditions, and several types of olive oils.     

Antibacterial actions of fatty acids and monoglycerides against Helicobacter pylori

The bactericidal potencies of saturated and unsaturated fatty acids (FAs) and monoglycerides (MGs) against Helicobacter pylori were determined following short incubations with freshly harvested cells over a range of pHs. FAs and their derivatives with an equivalent-carbon number of 12 were the most potent: lauric acid had a minimum bactericidal concentration (MBC) at pH 7.4 of 1 mM, myristoleic and linolenic acid were the most potent unsaturated FAs (MBCs of 0.5 mM, pH 7.4), and monolaurin was the most potent MG (MBC 0.5 mM). Potencies of saturated FAs were increased sharply by lowering pH, and a decrease of only 0.5 pH units can cause a change from non-lethal to lethal conditions. Conversely, the bactericidal action of monolaurin was not pH-dependent. The bactericidal potencies of unsaturated FAs increased with degree of unsaturation. When more than one FA or FA plus MGs were present, their combined action was additive. Urea and endogenous urease did not protect H. pylori from the bactericidal action of FAs. These results suggest that H. pylori present in the stomach contents (but not necessarily within the mucus barrier) should be rapidly killed by the millimolar concentrations of FAs and MGs that are produced by pre-intestinal lipase(s) acting on suitable triglycerides such as milk fat.     

Clinical Significance of IgG Antibody Titer against Helicobacter pylori

Background: We clarified the clinical significance of measurement of IgG antibody titers against Helicobacter pylori using data from a nested case–control study from a large-scale cohort study in Japan.
Method: Participants included 36,745 subjects from the Japan Health Center-based Prospective Study who responded to the baseline questionnaire and provided a blood sample. Subjects were aged 40–69 years and were followed over 15 years after initial sampling. Controls were matched to 511 gastric cancer patients. Plasma surface antigen (Hp)-IgG titer was measured using ELISA, and mucosal atrophy was determined by measuring pepsinogen I and II levels.
Results: Seropositive subjects with low Hp-IgG titer and mucosal atrophy showed a higher risk for gastric cancer than high-titer subjects. Odds ratio (OR) referred to cases with true negative IgG titers and no mucosal atrophy. In moderately atrophic subjects, the low titer OR was 19.0, with a 95% confidence interval (CI) of 7.7–46.9, and 12.5 for high titer, with a 95% CI of 5.2–30.0. In severely atrophic subjects, the low titer OR was almost double that of high-titer subjects (OR = 30.2, 95% CI = 12.4–73.7 and OR = 15.9, 95% CI = 6.3–40.3, respectively). These associations were observed more frequently for differentiated than undifferentiated gastric cancer.
Conclusion: Combination assay with Hp-IgG titer and pepsinogens may help identify groups at high risk for gastric cancer. Subjects with low Hp-IgG titer and mucosal atrophy were at extremely high risk for gastric cancer, particularly differentiated cancer. Subjects with this background may require ongoing observation and periodic endoscopic examination for early cancer detection.