Thermal degradation of allicin in garlic extracts and its implication on the inhibition of the in-vitro growth of Helicobacter pylori

Efficient removal of allicin from the stalk of Allium fistulosum for dietary fiber production

The stalk of Allium fistulosum contains dietary fibers with complicated monosaccharide composition and glycosidic bond linkages, which renders it a better dietary fiber supplement. However, the unfavorable odor, majorly contributed by allicin, limits its applications. Although many physical and chemical methods have been developed to remove allicin, there is currently no comparison between their efficiencies. Here, we comprehensively compare all these methods of eliminating allicin in the Allium stalk by starting with optimization of the allicin extraction method. Results indicate that incubation of the chopped Allium stalk with water for 20 min and extraction with 75% ethanol reached a maximal extraction yield. Different methods of allicin elimination are examined, and physical removal of allicin by blanching at 100 °C reaches a maximal clearance rate of 73.3%, rendering it the most efficient and effective method eliminating allicin from the stalk of Allium fistulosum for the preparation of a totally green dietary fiber.

Gastric microbiota: an emerging player in gastric cancer

Gastric cancer (GC) is a common cancer worldwide with a high mortality rate. Many microbial factors influence GC, of which the most widely accepted one is Helicobacter pylori (H. pylori) infection. H. pylori causes inflammation, immune reactions and activation of multiple signaling pathways, leading to acid deficiency, epithelial atrophy, dysplasia and ultimately GC. It has been proved that complex microbial populations exist in the human stomach. H. pylori can affect the abundance and diversity of other bacteria. The interactions among gastric microbiota are collectively implicated in the onset of GC. Certain intervention strategies may regulate gastric homeostasis and mitigate gastric disorders. Probiotics, dietary fiber, and microbiota transplantation can potentially restore healthy microbiota. In this review, we elucidate the specific role of the gastric microbiota in GC and hope these data can facilitate the development of effective prevention and therapeutic approaches for GC.

Allicin-Loaded Hydroxyapatite: Enhanced Release, Cytocompatibility, and Antibacterial Properties for Bone Tissue Engineering Applications

Allicin, the active compound of garlic extract, is a naturally sourced biomolecule, which promotes a vast range of health benefits. However, the limited stability of allicin restricts its applications in tissue engineering. Additionally, the detailed effects of allicin in bone health are yet to be explored. Our work reports on the fabrication of a novel allicin-loaded hydroxyapatite drug delivery system with enhanced biological properties. The fabricated system shows excellent antibacterial efficiency against S. aureus after 36 h of bacterial interaction with a sample. The allicin release kinetics are enhanced with polycaprolactone (PCL). The obtained results after 20 days of drug release study indicate that PCL coating leads to an increase in cumulative allicin release from ~ 35% to 70% at a physiological pH of 7.4. These scaffolds maintain stability during the whole period of drug release. Cytocompatibility of tested compositions with osteoblasts indicates enhanced cell viability and good filopodial attachment on the sample surface at day 7. These allicin-loaded antibacterial and cytocompatible scaffolds can find applications as localized delivery vehicles for bone tissue engineering.

Allicin Facilitates Airway Surface Liquid Hydration by Activation of CFTR

Airway epithelium plays critical roles in regulating airway surface liquid (ASL), the alteration of which causes mucus stasis symptoms. Allicin is a compound released from garlic and harbors the capacity of lung-protection. However, the potential regulatory effects of allicin on airway epithelium remain elusive. This study aimed to investigate the effects of allicin on ion transport across airway epithelium and evaluate its potential as an expectorant. Application of allicin induced Cl⁻ secretion across airway epithelium in a concentration-dependent manner. Blockade of cystic fibrosis transmembrane conductance regulator (CFTR) or inhibition of adenylate cyclase-cAMP signaling pathway attenuated allicin-induced Cl⁻ secretion in airway epithelial cells. The in vivo study showed that inhaled allicin significantly increased the ASL secretion in mice. These results suggest that allicin induces Cl⁻ and fluid secretion across airway epithelium via activation of CFTR, which might provide therapeutic strategies for the treatment of chronic pulmonary diseases associated with ASL dehydration.

Effects of an Optimized Aged Garlic Extract on Cardiovascular Disease Risk Factors in Moderate Hypercholesterolemic Subjects: A Randomized, Crossover, Double-Blind, Sustainedand Controlled Study

The consumption of aged black garlic (ABG) has been related to improvements in several cardiovascular disease (CVD) risk factors. However, the extent of the beneficial effects depends on the garlic aging process and the amount and type of chemical compounds accumulated. The main objective of this study was to assess the effect of daily intake of a well-characterized ABG extract with a standardized S-allyl-L-cysteine (SAC) yield in combination with dietary recommendations regarding CVD risk factors in individuals with moderate hypercholesterolemia. Sixty-seven hypercholesterolemic individuals with low-density lipoprotein cholesterol levels ≥115 mg/dL were randomized in a crossover, double-blind, sustained, and controlled intervention study. The participants consumed 250 mg (1.25 mg SAC)/tablet/day ABG or a placebo for 6 weeks, with 3 weeks of washout. Blood and pulse pressure and other CVD risk biomarkers were determined at the beginning and end of each intervention. At 6 weeks, ABG extract reduced diastolic blood pressure (DBP) (mean (95% CI) −5.85 (−10.5; −1.3) mm Hg) compared to the placebo, particularly in men with a DBP > 75 mm Hg. The consumption of an improved ABG extract with 1.25 mg of SAC decreased DBP, particularly in men with moderate hypercholesterolemia. The potential beneficial effects of ABG may contribute to obtaining an optimal DBP.

Antibacterial Properties of Organosulfur Compounds of Garlic (Allium sativum)

Garlic (Allium sativum), a popular food spice and flavoring agent, has also been used traditionally to treat various ailments especially bacterial infections for centuries in various cultures around the world. The principal phytochemicals that exhibit antibacterial activity are oil-soluble organosulfur compounds that include allicin, ajoenes, and allyl sulfides. The organosulfur compounds of garlic exhibit a range of antibacterial properties such as bactericidal, antibiofilm, antitoxin, and anti-quorum sensing activity against a wide range of bacteria including multi-drug resistant (MDR) strains. The reactive organosulfur compounds form disulfide bonds with free sulfhydryl groups of enzymes and compromise the integrity of the bacterial membrane. The World Health Organization (WHO) has recognized the development of antibiotic resistance as a global health concern and emphasizes antibiotic stewardship along with the urgent need to develop novel antibiotics. Multiple antibacterial effects of organosulfur compounds provide an excellent framework to develop them into novel antibiotics. The review provides a focused and comprehensive portrait of the status of garlic and its compounds as antibacterial agents. In addition, the emerging role of new technologies to harness the potential of garlic as a novel antibacterial agent is discussed.

Flavor components, precursors, formation mechanisms, production and characterization methods: garlic, onion, and chili pepper flavors

There is an enormous demand in the food industry to shift toward natural flavors. However, most flavor molecules are significantly unstable outside their original sources. Moreover, limited studies are focused on the flavor formation mechanisms, regeneration methods, and stability, which could help facilitate this replacement by establishing a link between food processing conditions and flavor generation.This scoping review summarizes major findings related to the identification of garlic, onion, and chili pepper flavors and their precursor molecules, formation mechanisms, generation of flavors and precursors, characterization methods, and precursor stability under thermal food processing conditions. The findings confirmed that the allium flavors could be generated by alliin and isoalliin precursors through thermal processing. Also, the literature lacks detailed knowledge about chili pepper flavor's precursors, and only capsaicinoids have been reported as a thermally stable chili pepper flavor.Although numerous studies have focused on this area, there is still a lack of detailed applicable knowledge. Future investigations can be framed into (1) Development of efficient methods to generate flavors during food processing; (2) Improvement of flavors' stability; (3) Understanding the interactions of flavors and their precursors with other food ingredients and additives; and (4) Characterization of the organoleptic properties of flavors.

The Potential Application of Allium Extracts in the Treatment of Gastrointestinal Cancers

Herbal medicine is currently widely practiced, since natural resources are reported to alleviate side effects during oncological treatment while modifying cancer cell responses at the same time. Allium vegetables and their constituents have recently been extensively investigated due to the numerous possible beneficial properties, establishing them as an additional treatment modality in different cancers. According to the epidemiological evidence, as well as many in vivo and in vitro studies, the abovementioned substances seem to be effective in the prevention and inhibition of the progression of carcinogenesis. Due to high concentrations of organosulfur compounds, which exhibit anticarcinogenic, antimicrobial, as well as anti-inflammatory properties, Allium constituents are believed to constitute a promising prevention and supportive therapy for oncological patients. Besides, it was demonstrated that a combination of Allium extracts with chemotherapy provided satisfactory clinical outcomes while at the same time being cost-effective. The aim of this review was to present and discuss currently investigated Allium extracts and their effects on several gastrointestinal cancers including gastric, colon, liver, esophageal, and pancreatic cancer.

Comparative study of allicin-containing quadruple therapy vs. bismuth-containing quadruple therapy for the treatment of Helicobacter pylori infection: a prospective randomized study

BACKGROUND

Bismuth has antimicrobial activity and can improve the efficacy of triple Helicobacter pylori (H. pylori) therapy. Allicin added to conventional therapy for H. pylori infection also improves H. pylori eradication rates. Thus, this study aims to evaluate and compare the efficacy, safety and tolerability of allicin-containing quadruple therapy and bismuth-containing quadruple therapy and to investigate the factors that affect the eradication rates.

METHODS

Two hundred twenty H. pylori-infected patients were included and randomly (1:1) assigned to 14-day quadruple therapy: ilaprazole (5 mg bid), doxycycline (100 mg bid), and furazolidone (100 mg bid) with an allicin soft capsule (40 mg of DATS tid) (IDFA) or colloidal bismuth tartrate (220 mg of elemental bismuth bid) (IDFB). Eradication was confirmed by urea breath tests. Symptom improvement, adverse events, and adherence were assessed by a questionnaire.

RESULTS

In the intention-to-treat and per-protocol analysis, the eradication rates for IDFA and IDFB groups were 87.5% (70/80) vs. 86.3% (69/80, P = 0.815) and 91.9% (68/74) vs. 91.8% (67/73, P = 0.980) as first-line therapies; 83.3% (25/30) vs. 83.3% (25/30, P = 1) and 89.3% (25/28) vs. 88.9% (24/27, P = 1) as second-line therapies. Symptom improvement rates were 96.1% and 97.0% for IDFA and IDFB (P = 1). The adverse event rates were 10.9% in IDFA and 14.5% in IDFB groups (P = 0.418). Nausea occurred frequently in IDFB than IDFA (1.8% vs. 8.2%, P = 0.030). Smoking and sharing utensils significantly affected the efficacy.

CONCLUSION

Allicin-containing quadruple therapy might be regarded as a promising alternative to bismuth-containing quadruple therapy in H. pylori eradication.

Cost Effective Use of a Thiosulfinate-Enriched Allium sativum Extract in Combination with Chemotherapy in Colon Cancer

In this work, we sought to investigate the effects of a thiosulfinate-enriched garlic extract, co-administered with 5-fluorouracil (5-FU) or oxaliplatin chemotherapy, on the viability of colon cancer cells (Caco-2 and HT-29). We also addressed the economic feasibility of a new combined treatment of this thiosulfinate-enriched garlic extract, with oxaliplatin that could reduce the dosage and costs of a monotherapy. The thiosulfinate-enriched garlic extract not only enhanced the impact of 5-FU and oxaliplatin (500 µM) in decreasing Caco-2 and HT-29 viability, but also showed a higher effect than standard 5-FU and oxaliplatin chemotherapy as anti-cancer agents. These results provided evidences for the combination of lyophilized garlic extract and 5-FU or oxaliplatin as a novel chemotherapy regimen in colon cancer cells that may also reduce the clinical therapy costs.

Allicin modulates diclofenac sodium induced hepatonephro toxicity in rats via reducing oxidative stress and caspase 3 protein expression

PURPOSE

This study was designed to evaluate the protective effects of allicin against diclofenac sodium induced hepatonephro toxicity in rats.

METHODS

Sixty male Wister albino rats were assigned into six groups. The control group received calcium carbonate and corn starch. 2^nd group received diclofenac sodium (2 mg/kg bw orally) for 30 days. 3^rd group received allicin (45 mg/kg bw orally) for 30 days. 4^th group administrated diclofenac sodium as in the 2^nd group and allicin (15 mg/kg bw orally) for 30 days. 5^th group received diclofenac sodium as in the 2^nd group and allicin (30 mg/kg bw orally) for 30 days. 6^th group received diclofenac sodium as 2^nd and allicin (45 mg/kg bw orally) for 30 days.

RESULTS

Diclofenac sodium significantly elevated activities of serum aspartate aminotransferase and alanine aminotransferase and serum levels of creatinine and urea. In addition, it induced hyperglycemia, lipid peroxidation, pathological alteration and caspase 3 protein expression in hepatic and renal tissues. However, it decreased reduced glutathione concentration and proliferating cell nuclear antigen protein expression in hepatic tissues. In contrast, allicin modulated the diclofenac sodium induced alteration in liver and kidney functions and structures dose dependently.

CONCLUSION

This study indicated that allicin had potential preventive effects against diclofenac sodium induced hepatonephro toxicity in rats.

Electrospun nanofibers of polyelectrolyte-surfactant complexes for antibacterial wound dressing application

The development of polyelectrolyte-surfactant complexes (PESCs) has attracted extensive research interest in different fields of applications. However, the liquid state of PESCs has limited their utility in applications where solid materials are required. In this study, novel antibacterial fibers were fabricated via electrospinning PESCs in the solid state without any additives. The PESCs were prepared in aqueous mixtures of pre-hydrolyzed polyacrylonitrile (HPAN), a polyelectrolyte, and cetyltrimethyl ammonium chloride (CTAC), an antibacterial cationic surfactant, by taking advantage of the self-aggregation behavior of the polyelectrolyte and surfactant, which increased the antibacterial agent loading ability and, thus, the antibacterial activity of polymers. By release-killing and contact-killing mechanisms, the as-spun PESC nanofibrous membranes exhibited strong antibacterial ability against both Gram-positive and Gram-negative bacteria, killing 5 log CFU of E. coli and S. aureus within a contact time as short as 30 min. Furthermore, PESCs were blended with polycaprolactone (PCL) to prepare composite nanofibrous membranes as a novel wound dressing, which showed excellent antibacterial activity and favorable cytocompatibility, with the mechanical strength high enough to satisfy the clinical application requirements. The PESC fibers with durable antibacterial activity presented in the current work would be promising for medical applications.

Effect of Topical Garlic on Wound Healing and Scarring: A Clinical Trial

BACKGROUND

Historically, garlic containing compounds have been used on wounds to improve healing and ward off infection. Researchers have tested many of these ancient ointments, discovering that garlic is a common ingredient in those that are effective.

OBJECTIVE

To determine the efficacy of topical garlic on surgical wounds compared with Vaseline by analysis of visual analog scales and digital photograph analysis.

MATERIALS AND METHODS

Seventeen patients with 2 skin excisions applied a 30% garlic ointment to one surgical wound and Vaseline to the other surgical wound twice daily. They were followed up at 2 weeks and 4 weeks post-op. Digital photographs were taken of the sites, and wound visual analog scales were filled out by the patient and the physician.

RESULTS

Patients and the onsite physician stated the garlic site healed better in 59% and 65% of the wounds, respectively, at 2 weeks. At 4 weeks, the patients and the onsite physician stated the garlic site healed better in 76% and 88% of wounds, respectively. Digital photograph analysis revealed less erythema at the garlic sites (p-value = .02).

CONCLUSION

Surgical wounds treated with 30% garlic ointment healed with more cosmetically appealing scars than the Vaseline-treated sites.

Antibacterial activity against Staphylococcus aureus of chitosan/chondroitin sulfate nanocomplex aerogels alone and enriched with erythromycin and elephant garlic (Allium ampeloprasum L. var. ampeloprasum) extract

The antibacterial activity against Staphylococcus aureus of aerogels fabricated from colloidal suspensions of chitosan/chondroitin sulfate nanocomplexes is analyzed. Upon freeze-drying the colloidal suspensions, the aerogels presented a porous structure made of microsheets and microfibers. The aerogels could, in addition, be loaded with antimicrobial agents. Loaded with the antibiotic erythromycin, the aerogels showed crystalline deposits, affecting the topography of the samples as well as their mechanical properties, showing a decrease on the apparent Young’s modulus and hardness at 40% deformation. Loaded with elephant garlic (Allium ampeloprasum L. var. ampeloprasum) extract, the aerogels showed texturization of the microsheets and microfibers, and the higher relative mass allowed an increase on the apparent Young’s modulus and hardness at 40% deformation with respect to pristine aerogels. Unloaded aerogels showed activity against Staphylococcus aureus, including a methicillin-resistant strain. The release of erythromycin from the aerogels to an agar environment is governed by equilibrium forces with the polysaccharides, which allow modulating the load of antibiotic and its concomitant diffusion from the material. The diffusion of the active components of the elephant garlic extract did not show a dependence on the polysaccharide content, revealing a week interaction. The elephant garlic extract resulted active against the methicillin-resistant Staphylococcus aureus strain, while resistance was found for the antibiotic, revealing the therapeutic potential of the natural extract. The antimicrobial aerogels may be used for several therapeutic purposes, such as healing of infected chronic wounds.

Non-pharmacological treatment of Helicobacter pylori

Many food and plant extracts have shown in vitro anti-Helicobacter pylori (H. pylori) activity, but are less effective in vivo. The anti-H. pylori effects of these extracts are mainly permeabilitization of the membrane, anti-adhesion, inhibition of bacterial enzymes and bacterial grown. We, herein, review treatment effects of cranberry, garlic, curcumin, ginger and pistacia gum against H. pylori in both in vitro, animal studies and in vivo studies.

Allicin Induces Calcium and Mitochondrial Dysregulation Causing Necrotic Death in Leishmania

Background

Allicin has shown antileishmanial activity in vitro and in vivo. However the mechanism of action underlying its antiproliferative effect against Leishmania has been virtually unexplored. In this paper, we present the results obtained in L.infantum and a mechanistic basis is proposed.

Methodology/Principal Finding

Exposure of the parasites to allicin led to high Ca²⁺ levels and mitochondrial reactive oxygen species (ROS), collapse of the mitochondrial membrane potential, reduced production of ATP and elevation of cytosolic ROS. The incubation of the promastigotes with SYTOX Green revealed that decrease of ATP was not associated with plasma membrane permeabilization. Annexin V and propidium iodide (PI) staining indicated that allicin did not induce phospholipids exposure on the plasma membrane. Moreover, DNA agarose gel electrophoresis and TUNEL analysis demonstrated that allicin did not provoke DNA fragmentation. Analysis of the cell cycle with PI staining showed that allicin induced cell cycle arrest in the G₂/M phase.

Conclusions/Significance

We conclude that allicin induces dysregulation of calcium homeostasis and oxidative stress, uncontrolled by the antioxidant defense of the cell, which leads to mitochondrial dysfunction and a bioenergetic catastrophe leading to cell necrosis and cell cycle arrest in the premitotic phase.

Leishmaniasis is a vectorial parasitic disease caused by flagellate organisms from the genus Leishmania. Infection is present in over 80 countries and visceral forms are the second most fatal human parasitic disease. Control relies on chemotherapy but available drugs have important shortcomings such as toxicity, side effects, unaffordable price of the safest presentations and increasing reports of parasite resistance and clinical failures. Thus, new drugs are needed. Allicin, a molecule obtained from garlic, has shown antiproliferative effect against different cancer cells, bacteria, fungi and Protista including Leishmania. Insofar its mechanism of action is poorly known. Our results with L.infantum point towards allicin inducing high levels of intracellular calcium, redox inbalance, and mitochondrial dysfunction with reduction of ATP. These events lead to cell necrosis without evidence of apoptotic-like markers. The proposed model suggests the potential use of allicin against leishmaniasis, alone or in combination with other drugs with different mechanisms of action.

Food Processing and the Mediterranean Diet

The benefits of the Mediterranean diet (MD) for protecting against chronic disorders such as cardiovascular disease are usually attributed to high consumption of certain food groups such as vegetables, and low consumption of other food groups such as meat. The influence of food processing techniques such as food preparation and cooking on the nutrient composition and nutritional value of these foods is not generally taken into consideration. In this narrative review, we consider the mechanistic and epidemiological evidence that food processing influences phytochemicals in selected food groups in the MD (olives, olive oil, vegetables and nuts), and that this influences the protective effects of these foods against chronic diseases associated with inflammation. We also examine how the pro-inflammatory properties of meat consumption can be modified by Mediterranean cuisine. We conclude by discussing whether food processing should be given greater consideration, both when recommending a MD to the consumer and when evaluating its health properties.

Influence of pH, concentration and light on stability of allicin in garlic (Allium sativum L.) aqueous extract as measured by UPLC

BACKGROUND

Garlic is one of the most important bulb vegetables and is mainly used as a spice or flavoring agent for foods. It is also cultivated for its medicinal properties, attributable to sulfur compounds, of which allicin is the most important. However, the stability of allicin in garlic extract is not well understood. In this study, using UPLC, the stability of allicin extracted in water from garlic was evaluated in phosphate buffer at different temperatures under light and dark conditions.

RESULTS

At room temperature, allicin in aqueous extract was most stable at pH 5-6 but degraded quickly at lower or higher pH. It began to degrade within 0.5 h and was not detectable after 2 h when the pH was higher than 11 or lower than 1.5. It degraded quickly when the temperature was higher than 40 °C and especially higher than 70 °C. At room temperature, allicin in water could be stored for 5 days without obvious degradation. Higher concentrations of allicin in solution were somewhat more stable than low concentrations.

CONCLUSION

Allicin extract was sensitive to pH and temperature of storage but not to light. Higher-concentration allicin solution was more stable.

The defense substance allicin from garlic permeabilizes membranes of Beta vulgaris, Rhoeo discolor, Chara corallina and artificial lipid bilayers

BACKGROUND

Allicin (diallylthiosulfinate) is the major volatile- and antimicrobial substance produced by garlic cells upon wounding. We tested the hypothesis that allicin affects membrane function and investigated 1) betanine pigment leakage from beetroot (Beta vulgaris) tissue, 2) the semipermeability of the vacuolar membrane of Rhoeo discolor cells, 3) the electrophysiology of plasmalemma and tonoplast of Chara corallina and 4) electrical conductivity of artificial lipid bilayers.

METHODS

Garlic juice and chemically synthesized allicin were used and betanine loss into the medium was monitored spectrophotometrically. Rhoeo cells were studied microscopically and Chara- and artificial membranes were patch clamped.

RESULTS

Beet cell membranes were approximately 200-fold more sensitive to allicin on a mol-for-mol basis than to dimethyl sulfoxide (DMSO) and approximately 400-fold more sensitive to allicin than to ethanol. Allicin-treated Rhoeo discolor cells lost the ability to plasmolyse in an osmoticum, confirming that their membranes had lost semipermeability after allicin treatment. Furthermore, allicin and garlic juice diluted in artificial pond water caused an immediate strong depolarization, and a decrease in membrane resistance at the plasmalemma of Chara, and caused pore formation in the tonoplast and artificial lipid bilayers.

CONCLUSIONS

Allicin increases the permeability of membranes.

GENERAL SIGNIFICANCE

Since garlic is a common foodstuff the physiological effects of its constituents are important. Allicin's ability to permeabilize cell membranes may contribute to its antimicrobial activity independently of its activity as a thiol reagent.

Antimicrobial activity of natural products against Helicobacter pylori: a review

Throughout the genetic and physiological evolution of microorganisms, the microbiological sciences have been expanding the introduction of new therapeutic trials against microbial diseases. Special attention has been paid to the bacterium Helicobacter pylori, which induces gastric infections capable of causing damage, ranging from acute and chronic gastritis to the development of gastric cancer and death. The use of compounds with natural origins has gained popularity in scientific research focused on drug innovation against H. pylori because of their broad flexibility and low toxicity. The aim of this study was to describe the use of natural products against H. pylori in order to clarify important parameters for related fields. The study demonstrated the vast therapeutic possibilities for compounds originating from natural sources and revealed the need for innovations from future investigations to expand the therapeutic arsenal in the fight against H. pylori infection.

Allicin: chemistry and biological properties

Allicin (diallylthiosulfinate) is a defence molecule from garlic (Allium sativum L.) with a broad range of biological activities. Allicin is produced upon tissue damage from the non-proteinogenic amino acid alliin (S-allylcysteine sulfoxide) in a reaction that is catalyzed by the enzyme alliinase. Current understanding of the allicin biosynthetic pathway will be presented in this review. Being a thiosulfinate, allicin is a reactive sulfur species (RSS) and undergoes a redox-reaction with thiol groups in glutathione and proteins that is thought to be essential for its biological activity. Allicin is physiologically active in microbial, plant and mammalian cells. In a dose-dependent manner allicin can inhibit the proliferation of both bacteria and fungi or kill cells outright, including antibiotic-resistant strains like methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, in mammalian cell lines, including cancer cells, allicin induces cell-death and inhibits cell proliferation. In plants allicin inhibits seed germination and attenuates root-development. The majority of allicin's effects are believed to be mediated via redox-dependent mechanisms. In sub-lethal concentrations, allicin has a variety of health-promoting properties, for example cholesterol- and blood pressure-lowering effects that are advantageous for the cardio-vascular system. Clearly, allicin has wide-ranging and interesting applications in medicine and (green) agriculture, hence the detailed discussion of its enormous potential in this review. Taken together, allicin is a fascinating biologically active compound whose properties are a direct consequence of the molecule's chemistry.

Dietary fiber intake reduces risk for gastric cancer: a meta-analysis

BACKGROUND & AIMS

The association between dietary fiber intake and gastric cancer risk has been investigated by many studies, with inconclusive results. We conducted a meta-analysis of case-control and cohort studies to analyze this association.

METHODS

Relevant studies were identified by searching PubMed and Embase through October 2012. We analyzed 21 articles, which included 580,064 subjects. Random-effects models were used to estimate summary relative risks. Dose-response, subgroup, sensitivity, meta-regression, and publication bias analyses were performed.

RESULTS

The summary odds ratios of gastric cancer for the highest, compared with the lowest, dietary fiber intake was 0.58 (95% confidence interval, 0.49-0.67) with significant heterogeneity among studies (P < .001, I(2) = 62.2%). Stratified analysis for study design, geographic area, source and type of fiber, Lauren's classification, publication year, sample size, and quality score of study yielded consistent results. Dose-response analysis associated a 10-g/day increment in fiber intake with a significant (44%) reduction in gastric cancer risk. Sensitivity analysis restricted to studies with control for conventional risk factors produced similar results, and omission of any single study had little effect on the combined risk estimate.

CONCLUSIONS

In a meta-analysis, we show that dietary fiber intake is associated inversely with gastric cancer risk; the effect probably is independent of conventional risk factors. The direction of the protective association of dietary fiber was consistent among all studies, but the absolute magnitude was less certain because of heterogeneity among the studies. Further studies therefore are required to establish this association.

Effect of allicin on promastigotes and intracellular amastigotes of Leishmania donovani and L. infantum

Anti-leishmanial activity of allicin (=diallyl thiosulphinate) has been tested in vitro against promastigotes and intracellular amastigotes of Leishmania donovani and Leishmania infantum. Macrophage infections have been carried out in vitro in the murine cell line J774 and ex vivo with peritoneal macrophages from BALB/c mice with a modified method to isolate metacyclic promastigotes. The compound has shown a significant in vitro effect on the multiplication of promastigotes of L. donovani and L. infantum in a time- and dose-dependent manner. It has been shown for the first time the inhibition of multiplication of intracellular amastigotes of Leishmania by allicin. Inhibitory concentrations of the compound were in the micromolar range (10-30 μM) for both Leishmania species. Antileishmanial effect of allicin apparently was not related to products of degradation of the molecule as assessed by mass spectrometry analysis. Inhibitory activity of allicin against promastigotes and intracellular amastigotes increased when the compound was added to the cultures every 24 h. Two administrations of 5 μM allicin inhibited by ca. 50% the proliferation of Leishmania amastigotes. Low toxicity for mammalian cells of this compound suggests the interest of exploring the value of allicin in combined therapy against leishmanial infections.

Release test of alliin/alliinase double-layer tablet by HPLC-Allicin determination

A simple, precise and accurate method was developed and validated for the determination of allicin release from alliin/alliinase double-layer tablets. According to Appendix XC II of Chinese Pharmacopoeia 2010 edition Volume II, a small glass-method was adopted at the rotational speed of 100 r/min using 100 mL phosphate buffer (pH 6.8) as release medium. The release amount was determined by HPLC with a C₁₈ column (250 mm×4.6 mm, 5 μm) using the mobile phase consisting of methanol −0.4% carboxylic acid (65:35) at a flow rate of 1 mL/min and UV detection at 242 nm. The current method demonstrates good linearity over the range 4.052–405.2 μg/mL (r²=0.9999) with an average recovery of 105.5%(RSD=1.25%). The accumulative release of alliin/alliinase double-layer tablets had good homogeneity for within- and between-batches. The method established is simple, accurate and repeatable for the determination of allicin release from alliin/alliinase double-layer tablets.

Consumption of large amounts of Allium vegetables reduces risk for gastric cancer in a meta-analysis

BACKGROUND & AIMS

The chemopreventive effects of Allium vegetables (onions, garlic, shallots, leeks, chives, and so forth) have been studied extensively, although their effect on gastric cancer risk is controversial. We performed a meta-analysis of cohort and case-control studies to analyze this association.

METHODS

We searched MEDLINE for studies of Allium vegetable consumption and gastric cancer that were published in any language, from January 1, 1966, to September 1, 2010. We analyzed 19 case-control and 2 cohort studies, of 543,220 subjects. We pooled the relative risks from individual studies using a random-effects model and performed dose-response, heterogeneity, and publication bias analyses.

RESULTS

In a pooled analysis of all studies, consumption of large amounts of Allium vegetables (in a comparison of the highest and lowest consumption groups) reduced the risk for gastric cancer (odds ratio, 0.54; 95% confidence interval, 0.43-0.65). Specific analyses for onion, garlic, leek, Chinese chive, scallion, garlic stalk, and Welsh onion yielded similar results, except for onion leaf. The estimated summary odds ratio for an increment of 20 g/day of Allium vegetables consumed (approximately the average weight of 1 garlic bulb) was 0.91 (95% confidence interval, 0.88-0.94), based on case-control studies from the dose-response meta-analysis.

CONCLUSIONS

In a meta-analysis, consumption of high levels of Allium vegetables reduced the risk for gastric cancer risk. Because of potential confounding factors and exposure misclassification, further studies are required to establish this association.

Onion dehydration: a review

Onion (Allium cepa), a very commonly used vegetable, ranks third in the world production of major vegetables. Apart from imparting a delicious taste and flavour due to its pungency in many culinary preparations, it serves several medicinal purposes also. Processing and preservation of onion by suitable means is a major thrust area since a long time. The various kinds of treatments followed for dehydration of onion such as convective air drying, solar drying, fluidized bed drying, vacuum microwave drying, infrared drying and osmotic drying are reviewed here. These techniques are mainly used for preservation and value addition of onion. Several researchers have tried for decades to model the drying kinetics and quality parameters, which are also compiled here briefly.

Diet before pregnancy and the risk of hyperemesis gravidarum

Hyperemesis gravidarum (hyperemesis), characterised by severe nausea and vomiting in early pregnancy, has an unknown aetiology. The aim of the present study was to investigate food and nutrient intake before pregnancy and the risk of developing hyperemesis in women participating in the Norwegian Mother and Child Cohort Study. From 1999 to 2002, a total of 7710 pregnant women answered a FFQ about their diet during the 12 months before becoming pregnant and a questionnaire about illnesses during pregnancy, including hyperemesis. Only women who were hospitalised for hyperemesis were included as cases. Nutrient intakes during the year before pregnancy did not differ between the ninety-nine women who developed hyperemesis and the 7611 who did not. However, the intake of seafood, allium vegetables and water was significantly lower among women who developed hyperemesis than among women in the non-hyperemesis group. Relative risks of hyperemesis were approximated as OR, and confounder control was performed with multiple logistic regression. Women in the upper tertile of seafood consumption had a lower risk of developing hyperemesis than those in the lower tertile (OR 0·56, 95 % CI 0·32, 0·98), and women in the second tertile of water intake had a lower risk of developing hyperemesis than those in the first tertile (OR 0·43, 95 % CI 0·25, 0·73). The findings suggest that a moderate intake of water and adherence to a healthy diet that includes vegetables and fish are associated with a lower risk of developing hyperemesis.

Allicin disrupts the cell's electrochemical potential and induces apoptosis in yeast

The volatile substance allicin gives crushed garlic (Allium sativum) its characteristic odor and is a pro-oxidant that undergoes thiol-disulfide exchange reactions with -SH groups in proteins and glutathione. The antimicrobial activity of allicin is suspected to be due to the oxidative inactivation of essential thiol-containing enzymes. We investigated the hypothesis that at threshold inhibitory levels allicin can shunt yeast cells into apoptosis by altering their overall redox status. Yeast cells were treated either with chemically synthesized, pure allicin or with allicin in garlic juice. Allicin-dependent cell oxidation was demonstrated with a redox-sensitive GFP construct and the shift in cellular electrochemical potential (E(hc)) from less than -215 to -181mV was calculated using the Nernst equation after the glutathione/glutathione disulfide couple (2GSH/GSSG) in the cell was quantified. Caspase activation occurred after allicin treatment, and yeast expressing a human antiapoptotic Bcl-XL construct was rendered more resistant to allicin. Also, a yeast apoptosis-inducing factor deletion mutant was more resistant to allicin than wild-type cells. We conclude that allicin in garlic juice can activate apoptosis in yeast cells through its oxidizing properties and that this presents an alternative cell-killing mechanism to the previously proposed specific oxidative inactivation of essential enzymes.

The antibacterial mode of action of allitridi for its potential use as a therapeutic agent against Helicobacter pylori infection

Eradication of Helicobacter pylori with traditional therapy often fails in clinical treatment. As a result, a novel efficacious therapeutic agent is strongly needed. Allitridi, a proprietary garlic derivative, has been successfully used to treat both systemic fungal and bacterial infections in China. Our previous study has shown a dose-dependent inhibitory effect of allitridi on H. pylori growth. However, the antibacterial mode of action of allitridi is still unclear. Proteomic analysis was used to study the global protein alterations induced by allitridi. A total of 21 protein spots were identified to be differentially expressed. Our results indicated that the bacteriostatic mechanism of allitridi in H. pylori can be attributed to its multitarget inhibitory effects in energy metabolism and biosynthesis including amino acid biosynthesis, protein synthesis, mRNA synthesis and fatty acid biosynthesis. Allitridi can also disturb the expression of antioxidant proteins and decrease the production of virulence factors. Western blot analysis showed that allitridi at subinhibitory concentrations can potently suppress the production of CagA and VacA. Our investigations on the antibacterial mode of action of allitridi provide an insight into the potential use of allitridi as a therapeutic agent against H. pylori infection.

Garlic: nature's protection against physiological threats

Currently reliance on natural products is gaining popularity to combat various physiological threats including oxidative stress, cardiovascular complexities, cancer insurgence, and immune dysfunction. The use of traditional remedies may encounter more frequently due to an array of scientific evidence in their favor. Garlic (Allium sativum) holds a unique position in history and was recognized for its therapeutic potential. Recent advancements in the field of immunonutrition, physiology, and pharmacology further explored its importance as a functional food against various pathologies. Extensive research work has been carried out on the health promoting properties of garlic, often referred to its sulfur containing metabolites i.e. allicin and its derivatives. Garlic in its preparations are effective against health risks and even used as dietary supplements such as age garlic extract (AGE) and garlic oil etc. Its components/formulations can scavenge free radicals and protect membranes from damage and maintains cell integrity. It also provides cardiovascular protection mediated by lowering of cholesterol, blood pressure, anti-platelet activities, and thromboxane formation thus providing protection against atherosclerosis and associated disorders. Besides this, it possesses antimutagenic and antiproliferative properties that are interesting in chemopreventive interventions. Several mechanisms have been reviewed in this context like activation of detoxification phase-I and II enzymes, reactive oxygen species (ROS) generation, and reducing DNA damage etc. Garlic could be useful in preventing the suppression of immune response associated with increased risk of malignancy as it stimulates the proliferation of lymphocytes, macrophage phagocytosis, stimulates the release of interleukin-2, tumor necrosis factor-alpha and interferon-gamma, and enhances natural killer cells. In this paper much emphasis has been placed on garlic's ability to ameliorate oxidative stress, core role in cardiovascular cure, chemopreventive strategies, and indeed its prospective as immune booster.

Utilização do óleo de alho e da amoxilina, metronidazol e omeprazol no controle de Helicobacter spp. em cães

Avaliaram-se a eficácia do óleo de alho e da terapia tripla (amoxicilina, metronidazol e omeprazol) no tratamento de 21 cães infectados por Helicobacter spp., que apresentavam alterações histológicas nas biopsias endoscópicas da mucosa gástrica e reação positiva ao teste de urease. Os animais foram distribuídos, aleatoriamente, em três grupos de sete cães, os quais receberam os seguintes tratamentos: grupo 1 - cápsulas vazias; grupo 2 - 500mg de óleo de alho em cápsulas, diariamente, por um período de 30 dias; grupo 3 - amoxicilina, metronidazol e omeprazol, respectivamente, nas doses de 20mg/kg a cada 12 horas, 25mg/kg e 20mg/kg a cada 24 horas, durante 15 dias. Ao final dos tratamentos, os cães foram submetidos à endoscopia com realização de biopsias da mucosa gástrica. O tratamento com amoxicilina, metronidazol e omeprazol resultou em erradicação de Helicobacter spp. tanto na região fúndica quanto na pilórica. No grupo 2, houve redução da degeneração glandular na região fúndica em dois animais e em outros dois na pilórica. O tratamento com óleo de alho não foi eficaz em erradicar Helicobacter spp., apenas reduziu a sua colonização em quatro dos animais tratados.

Allicin, a major component of garlic, inhibits apoptosis in vital organs in rats with trauma/hemorrhagic shock

OBJECTIVE

Allicin is believed to be the main component responsible for the biological activity of garlic. The regulation of cell apoptosis may have therapeutic potential for trauma/hemorrhagic shock, and previous studies have demonstrated that allicin exerts protective effects against tissue ischemia-reperfusion injury. Therefore, this study examined the effects of allicin on apoptosis-related organ damage, induced by trauma/hemorrhagic shock.

METHODS

Studies were performed on an in vivo model of spontaneously breathing rats with induced trauma/hemorrhagic shock; the left lower lobe of the lungs, left kidney, and intestine were resected, and the rats were subjected to femur fracture, ischemia for 30 mins, and reperfusion for 20 mins. Allicin (30 microg/kg) was administered during reperfusion.

RESULTS

Allicin administered during reperfusion markedly attenuated injury and apoptosis of the lungs, kidneys, and intestine and decreased the concentrations of lactic acid and creatinine, the number of in situ TdT-mediated dUTP nick-end labeling-positive cells, and the activity and expression of caspase-3 and -9 (as determined by Western blot). Furthermore, immunohistochemistry and Western blot performed 24 hrs after reperfusion revealed increases in the levels of nuclear factor kappaB, phosphorylated p38, and extracellular signal-regulated kinase 1 mitogen-activated protein kinase in the allicin-untreated group when compared with the sham rats. Allicin treatment downregulated the levels of nuclear factor kappaB and phosphorylated p38 mitogen-activated protein kinase but did not modify those of phosphorylated extracellular signal-regulated kinase 1 mitogen-activated protein kinase.

CONCLUSION

Allicin attenuates tissue injury and inhibits trauma/hemorrhagic shock- and reperfusion-induced apoptosis in several important organs via the p38 mitogen-activated protein kinase signal transduction pathway that functions to stimulate the activation of nuclear factor-kappaB, caspase-3 and -9, but not of extracellular signal-regulated kinase 1 mitogen-activated protein kinase.

Effects of Heating, Storage, and Ultraviolet Exposure on Antimicrobial Activity of Garlic Juice

This study was designed to investigate the effect of heating, storage, and ultraviolet exposure on antimicrobial activity of garlic juice and its bacteriocidal activity against common human pathogens. Antimicrobial activity of fresh garlic juice was tested against Escherichia coli, Staphylococcus aureus, Streptococcus hemolyticus B, S. hemolyticus A, Klebsiella sp., Shigella dysenteriae, and Candida albicans using the disc method. The dilution method was performed by addition of garlic juice to broth media to obtain 1-100% concentrations as vol/vol or wt/vol. Garlic juice was used after 24 hours of storage at 4 degrees C, heating to 100 degrees C for 5 minutes, 10 minutes, 30 minutes, and 60 minutes, heating to 80 degrees C for 60 minutes, and 4 hours of exposure to ultraviolet light. Re-culture of specimens taken from garlic-induced negative media was performed in fresh broth free of garlic juice. Results showed that all the isolates were sensitive to fresh garlic juice; the most sensitive was C. albicans, and the least sensitive was S. hemolyticus A. Heating to 100 degrees C for 30 and 60 minutes completely abolished the antimicrobial activity, while heating for 5 and 10 minutes, storage for 24 hours, and 4 hours of ultraviolet exposure decreased it. Garlic juice was bactericidal at concentrations of 5% and more. Thus garlic juice has marked antimicrobial activity that makes it a potential agent to be tested in clinical trials. The antimicrobial activity was compromised by storage and heating; therefore it is advisable to use fresh garlic and avoid boiling it for more than 5 minutes during cooking.

Allicin, a major component of garlic, inhibits apoptosis of macrophage in a depleted nutritional state

OBJECTIVE

Allicin is believed to be the main component responsible for the biological activity of garlic. The regulation of cell death might have therapeutic potential in many diseases, and previous studies have demonstrated that allicin stimulates the functional activity of macrophages. Therefore, this study examined the effects of allicin on the apoptosis of macrophages induced by serum- and amino acid-free culture.

METHODS

The apoptosis of peritoneal macrophages was examined after pretreating them with allicin and incubating them in a depleted nutritional state. The rate of apoptosis was determined using propidium iodide staining analysis using flow cytometry, DNA fragmentation, and a caspase-3 assay. Western blot analysis was used to examine the changes in the pro- or antiapoptotic protein expression levels.

RESULTS

DNA fragmentation and propidium iodide staining analyses revealed that allicin decreased the malnutrition-induced apoptosis of macrophages. The level of Bax expression, the amount of cytochrome-c released from the mitochondria, and the caspase-3 activity were also lower in the allicin-treated macrophages than in the untreated macrophages in a depleted nutritional state. Moreover, the MEK (mitogen-activated protein kinase/extracellular signal-regulated kinase-kinase) inhibitor suppressed the allicin-induced inhibition of apoptosis in a depleted nutritional state and allicin increased the level of ERK1/2 phosphorylation.

CONCLUSION

Allicin inhibits the apoptosis of macrophages in a depleted nutritional state through the MEK/extracellular signal-regulated kinase pathway.

Ratio of entropy to enthalpy in thermal transitions in biological tissues

Thermal transitions in biological tissues that have been reported in the literature are summarized in terms of the apparent molar entropy (DeltaS) and molar enthalpy (DeltaH) involved in the transition. A plot of DeltaS versus DeltaH for all the data yields a straight line, consistent with the definition of free energy, DeltaG=DeltaH+TDeltaS. Various bonds may be involved in cooperative bond breakage during thermal transitions; however, for the sake of description, the equivalent number of cooperative hydrogen bonds can be cited. Most of the tissue data behave as if 10 to 20 hydrogen bonds are cooperatively broken during coagulation, with one transition, the expression of heat shock protein, involving 90 cooperative hydrogen bonds. The data are consistent with DeltaS=a+bDeltaH, where a=-327.5 J(mol K) and b=31.47 x 10(-4) K(-1). If each additional hydrogen bond adds 19 x 10(3) Jmol to DeltaH, then each additional bond adds 59.8 J(mol K) to DeltaS. Hence, the dynamics of irreversible thermal transitions can be described in terms of one free parameter, the apparent number of cooperative hydrogen bonds broken during the transition.

Bactericidal and anti-adhesive properties of culinary and medicinal plants against Helicobacter pylori

AIM

To investigate the bactericidal and anti-adhesive properties of 25 plants against Helicobacter pylori (H. pylori).

METHODS

Twenty-five plants were boiled in water to produce aqueous extracts that simulate the effect of cooking. The bactericidal activity of the extracts was assessed by a standard kill-curve with seven strains of H. pylori. The anti-adhesive property was assessed by the inhibition of binding of four strains of FITC-labeled H. pylori to stomach sections.

RESULTS

Of all the plants tested, eight plants, including Bengal quince, nightshade, garlic, dill, black pepper, coriander, fenugreek and black tea, were found to have no bactericidal effect on any of the isolates. Columbo weed, long pepper, parsley, tarragon, nutmeg, yellow-berried nightshade, threadstem carpetweed, sage and cinnamon had bactericidal activities against H. pylori, but total inhibition of growth was not achieved in this study. Among the plants that killed H. pylori, turmeric was the most efficient, followed by cumin, ginger, chilli, borage, black caraway, oregano and liquorice. Moreover, extracts of turmeric, borage and parsley were able to inhibit the adhesion of H. pylori strains to the stomach sections.

CONCLUSION

Several plants that were tested in our study had bactericidal and/or anti-adhesive effects on H. pylori. Ingestion of the plants with anti-adhesive properties could therefore provide a potent alternative therapy for H. pylori infection, which overcomes the problem of resistance associated with current antibiotic treatment.

Non-antibiotic therapies for Helicobacter pylori infection

Despite years of experience with Helicobacter pylori treatment, the ideal regimen for treating the infection has not been found. The most effective eradication treatment is the combination of a proton pump inhibitor with antibiotics, but 10-20% of the patients fail to obtain eradication of the infection. Antibiotic resistance is a major factor affecting the outcome of treatment. Non-antibiotic therapies, including phytomedicines, probiotics, and antioxidants, have been increasingly investigated as potential alternatives for the treatment of H. pylori. In this article, we review the non-antibiotic therapies for H. pylori infection.