The genus Allium--Part 3

Investigating the therapeutic potential of Allium cepa extract in combating pesticide exposure induced ocular damage

The ocular surface is subject to a range of potentially hazardous environmental factors and substances, owing to its anatomical location, sensitivity, and physiological makeup. Xenobiotic stress exerted by chronic pesticide exposure on the cornea is primarily responsible for ocular irritation, excessive tear production (hyper-lacrimation), corneal abrasions and decreased visual acuity. Traditional medicine hails the humble onion (Allium cepa) for its multi-faceted properties including but not limited to anti-microbial, antioxidant, anti-inflammatory and wound healing. However, there is a lacuna regarding its impact on the ocular surface. Thereby, the current study investigated whether topical application of crude extract of Allium cepa aided in mitigating pesticide-induced damage to the ocular surface. The deleterious effects of pesticide exposure and their mitigation through the topical application of herbal extract of Allium cepa were analysed initially through in vitro evaluation on cell lines and then on the ocular surface via various in-vivo and ex-vivo techniques. Pathophysiological alterations to the ocular surface that impacted vision were explored through detailed neurophysiological screening with special emphasis on visual acuity wherein it was observed that the murine group treated with topical application of Allium cepa extract had comparable visual capacity to the non-pesticide exposed group. Additionally, SOD2 was utilized as an oxidative stress marker along with the expression of cellular apoptotic markers such as Bcl-xL to analyse the impact of pesticide exposure and subsequent herbal intervention on oxidative stress-induced corneal damage. The impact on the corneal epithelial progenitor cell population (ABCG2 and TERT positive cells) was also flowcytometrically analysed. Therefore, from our observations, it can be postulated that the topical application of Allium cepa extract might serve as an effective strategy to alleviate pesticide exposure related ocular damage.

Garlicnin B1, an Active Cyclic Sulfide from Garlic, Exhibits Potent Anti-Inflammatory and Anti-Tumor Activities

This study aimed to investigate the pharmacological activities of garlicnin B1, a cyclic sulfide compound found abundantly in garlic and structurally similar to onionin A1, which has been shown to possess strong anti-tumor effects. In vitro studies demonstrated that garlicnin B1 significantly reduced intracellular reactive oxygen species triggered by hydrogen peroxide in colon cancer cells. In a mouse colitis model induced by dextran sulfate sodium, garlicnin B1 at a low dose (5 mg/kg) remarkably ameliorated the symptoms and pathological progression. Additionally, garlicnin B1 exhibited considerable tumoricidal activity with an IC50 value of ~20 μM, as observed in cytotoxicity assays. In vivo experiments using the mouse sarcoma S180 transplanted model and the azoxymethane (AOM) or DSS-induced colon cancer model showed that garlicnin B1 effectively suppressed tumor growth in a dose-dependent manner, with marked inhibition at 80 mg/kg. These results suggest that garlicnin B1 has diverse functions that could be achieved by carefully manipulating the dosing regimen. We anticipate that garlicnin B1 has the potential to be used beneficially in the future for the treatment of cancer and inflammatory diseases, although further studies are warranted to elucidate its mechanisms of action.

Biosynthesis and Metabolism of Garlic Odor Compounds in Cultivated Chinese Chives (Allium tuberosum) and Wild Chinese Chives (Allium hookeri)

Chinese chives is a popular herb vegetable and medicine in Asian countries. Southwest China is one of the centers of origin, and the mountainous areas in this region are rich in wild germplasm. In this study, we collected four samples of germplasm from different altitudes: a land race of cultivated Chinese chives (Allium tuberosum), wide-leaf chives and extra-wide-leaf chives (Allium hookeri), and ovoid-leaf chives (Allium funckiaefolium). Leaf metabolites were detected and compared between A. tuberosum and A. hookeri. A total of 158 differentially accumulated metabolites (DAM) were identified by Gas Chromatography—Mass Spectrometry (GC-MS) and Liquid Chromatography—Mass Spectrometry (LC-MS), among which there was a wide range of garlic odor compounds, free amino acids, and sugars. A. hookeri contains a higher content of fructose, garlic odor compounds, and amino acids than A. tuberosum, which is supported by the higher expression level of biosynthetic genes revealed by transcriptome analysis. A. hookeri accumulates the same garlic odor compound precursors that A. tuberosum does (mainly methiin and alliin). We isolated full-length gene sequences of phytochelatin synthase (PCS), γ-glutamyltranspeptidases (GGT), flavin-containing monooxygenase (FMO), and alliinase (ALN). These sequences showed closer relations in phylogenetic analysis between A. hookeri and A. tuberosum (with sequence identities ranging from 86% to 90%) than with Allium cepa or Allium sativum (which had a lower sequence identity ranging from 76% to 88%). Among these assayed genes, ALN, the critical gene controlling the conversion of odorless precursors into odor compounds, was undetected in leaves, bulbs, and roots of A. tuberosum, which could account for its weaker garlic smell. Moreover, we identified a distinct FMO1 gene in extra-wide-leaf A. hookeri that is due to a CDS-deletion and frameshift mutation. These results above reveal the molecular and metabolomic basis of impressive strong odor in wild Chinese chives.

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.

Short report: Aqueous extract of chives (Allium schoenoprasum L.) plant impairs erythrocyte deformability in sickle cell patients

Sickle cell anemia (SCA) is a genetic disorder characterized by chronic hemolysis and the presence of erythrocytes with low deformability, which may trigger vaso-occlusive crises. We tested the in-vitro effects of aqueous extract of vhives (Allium schoenoprasum L.) on erythrocyte deformability of SCA patients. Blood samples from 6 apparently healthy volunteers and 5 SCA patients were collected into heparin coated tubes. Both apparently healthy and SCA patient blood samples were incubated with 80μg/mL chives plant aqueous extract at 37°C for 60 min and erythrocyte deformability was measured by ektacytometry (3 Pa and 30 Pa; 37°C). Results of incubation of apparently healthy blood samples with plant extract showed that incubation did not alter erythrocyte deformability significantly. However, for SCA blood samples, erythrocyte deformability decreased significantly with plant extract exposure at 3 Pa (p <  0.043) and 30 Pa (p <  0.043). In conclusion, although ex-vivo incubation with plant extract does not fully model gastrointestinal processing of onions, the decrease in SCA erythrocyte deformability following incubation with aqueous chives should stimulate further studies to test the in-vivo effects of this diet in sickle cell mice.

Effect of hydroalcoholic Allium atroviolaceum L. on the pathology of testicular tissue in cyclophosphamide-treated mice

Background

The most important side effects of Cyclophosphamide, as an anticancer broad-spectrum drug, are the negative effects on the reproduction and fertility because of oxidative stress. Considering the antioxidant properties of medicinal plants, especially those of the Allium genus, this paper studied the effect of hydroalcoholic extract of Allium atroviolaceum L. on the pathology of testicular tissue in CP-treated mice.

Methods

Groups of this experimental study consisted of normal saline recipients; three groups receiving A. atroviolaceum extract at 50, 100, 200 mg/kg; three groups receiving A. atroviolaceum extract at 50, 100, and 200 mg/g and 6.6 mg/kg of Cyclophosphamide; and a group given Cyclophosphamide at 1.6 mg/kg. All injections were performed intra-peritoneally. After 30 days, the testicular histological profile as well as the number of spermatozoa, the number of primary and round spermatocytes, and the number of spermatogonia were investigated.

Results

Cyclophosphamide treatment significantly reduced the lumen diameter, the seminiferous tubule diameter, the epithelial thickness, as well as decreased the quantity of spermatozoa and round and primary spermatocytes compared to the control group. Cyclophosphamide groups treated with A. atroviolaceum extract at 50, 100 and 200 mg/kg in a significant manner improved these variables (P < 0.001).

Conclusion

A. atroviolaceum extract can significantly improve Cyclophosphamide-induced toxicity and pathological process on testicular tissue. It seems that this plant, with high antioxidant capacity, can be considered a complementary therapy for Cyclophosphamide to prevent undesirable effects on the reproductive system.

Formation, nutritional value, and enhancement of characteristic components in black garlic: A review for maximizing the goodness to humans

Black garlic (BG) is essentially a processed food and obtained through the transformation of fresh garlic (FG) (Allium sativum L.) via a range of chemical reactions (including the Maillard reaction) and microbial fermentation. This review provides the up-to-date knowledge of the dynamic and complicated changes in major components during the conversion of FG to BG, including moisture, lipids, carbohydrates (such as sugars), proteins, organic acids, organic sulfur compounds, alkaloids, polyphenols, melanoidins, 5-hydroxymethylfurfural, vitamins, minerals, enzymes, and garlic endophytes. The obtained evidence confirms that BG has several advantages over FG in certain product attributes and biological properties (especially antioxidant activity), and the factors affecting the quality of BG include the type and characteristics of FG and processing technologies and methods (especially pretreatments, and processing temperature and humidity). The interactions among garlic components, and between garlic nutrients and microbes, as well as the interplay between pretreatment and main manufacturing process, all determine the sensory and nutritional qualities of BG. Before BG is marketed as a novel snack or functional food, more research is required to fill the knowledge gaps related to quantitative monitoring of the changes in metabolites (especially those taste-active and/or biological-active substances) during BG manufacturing to maximize BG's antioxidant, anticancer, antiobesity, anti-inflammatory, immunostimulatory, anti-allergic, hepatoprotective, cardioprotective and oxidative stress-/hangover syndrome-reducing functions, and beneficial effects on memory/nervous systems. Assessments of the quality, efficacy, and safety of BG should be performed considering the impacts of BG production conditions, postproduction handling, and intake methods.

Insecticidal activity of garlic essential oil and their constituents against the mealworm beetle, Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae)

This study evaluated the insecticidal activity of garlic, Allium sativum Linnaeus (Amaryllidaceae) essential oil and their principal constituents on Tenebrio molitor. Garlic essential oil, diallyl disulfide, and diallyl sulfide oil were used to compare the lethal and repellent effects on larvae, pupae and adults of T. molitor. Six concentrations of garlic essential oil and their principal constituents were topically applied onto larvae, pupae and adults of this insect. Repellent effect and respiration rate of each constituent was evaluated. The chemical composition of garlic essential oil was also determined and primary compounds were dimethyl trisulfide (19.86%), diallyl disulfide (18.62%), diallyl sulfide (12.67%), diallyl tetrasulfide (11.34%), and 3-vinyl-[4H]-1,2-dithiin (10.11%). Garlic essential oil was toxic to T. molitor larva, followed by pupa and adult. In toxic compounds, diallyl disulfide was the most toxic than diallyl sulfide for pupa > larva > adult respectively and showing lethal effects at different time points. Garlic essential oil, diallyl disulfide and diallyl sulfide induced symptoms of intoxication and necrosis in larva, pupa, and adult of T. molitor between 20–40 h after exposure. Garlic essential oil and their compounds caused lethal and sublethal effects on T. molitor and, therefore, have the potential for pest control.

Chemical and biochemical mechanisms underlying the cardioprotective roles of dietary organopolysulfides

Foods that are rich in organosulfides are highly regarded for their broad range of functions in disease prevention and health promotion since ancient time yet modern scientific study, particularly clinical studies could not agree with traditional wisdom. One of the complexities is due to the labile nature of organosulfides, which are often transformed to different structures depending on the processing conditions. The recent evidence on polysulfides as H₂S donors may open up a new avenue for establishing structure and health promotion activity relationship. To put this development into perspective, we carried out a review on the recent progress on the chemistry and biochemistry of organopolysulfides with emphasis on their cardioprotective property. First, we briefly surveyed the foods that are rich in polysulfides and their structural diversity. This is followed by in-depth discussion on the chemical transformations of polysulfides under various processing conditions. We further reviewed the potential action mechanisms of polysulfides in cardioprotection through: (a) hydrogen sulfide releasing activity; (b) radical scavenging activity; and (c) activity in enzyme inhibition and intervention of gene regulation pathways. Based on the literature trend, we can conclude that the emerging concept of organopolysulfides as naturally occurring H₂S donors is intriguing and warrants further research to establish the structure and activity relationship of the organopolysulfides as H₂S donors.

Garlic and onions: their cancer prevention properties

The Allium genus includes garlic, onions, shallots, leeks, and chives. These vegetables are popular in cuisines worldwide and are valued for their potential medicinal properties. Epidemiologic studies, while limited in their abilities to assess Allium consumption, indicate some associations of Allium vegetable consumption with decreased risk of cancer, particularly cancers of the gastrointestinal tract. Limited intervention studies have been conducted to support these associations. The majority of supportive evidence on Allium vegetables cancer-preventive effects comes from mechanistic studies. These studies highlight potential mechanisms of individual sulfur-containing compounds and of various preparations and extracts of these vegetables, including decreased bioactivation of carcinogens, antimicrobial activities, and redox modification. Allium vegetables and their components have effects at each stage of carcinogenesis and affect many biologic processes that modify cancer risk. This review discusses the cancer-preventive effects of Allium vegetables, particularly garlic and onions, and their bioactive sulfur compounds and highlights research gaps.

Effects of onion juice on the normal flora of eyelids and conjunctiva in an animal model

Background:

Traditional medicine/complementary alternative medicine may suggest new ideas to modern medicine in order to face new challenges however these concepts should be acknowledged based on experimental studies.

Objectives:

We aimed to study the effects of onion (Allium cepa) juice on the normal flora of conjunctiva and eye lids, and to follow the histopathology changes of conjunctiva in an animal study.

Materials and Methods:

Twenty-four rabbits were randomly classified into three equal groups. Groups 1, 2 and 3 received fresh red onion juice, as an eye drop, into the right eye twice daily for; one week, one month, and two months, respectively. Microbiological sampling by sterile swabs was performed before and after the intervention. Cultural characteristics, including the growth rate and the kind of organisms, are reported. At the end of the study, pathological samples were collected from the inferior fornix.

Results:

After the intervention, the number of positive cultures in the samples, collected from both the conjunctiva and eyelid, had decreased. Group 3 demonstrated the lowest amount of growth after the administration of the onion juice and the bacterial isolation rates from each organism had decreased. All pathological samples revealed some degree of inflammation. There was no evidence of metaplasia or dysplasia. There was no significant difference between the growth rates of organisms in the experimental groups using statistical analysis.

Conclusions:

According to our experiment, onion has an inhibitory effect on the growth of normal eye flora; although the duration of onion juice instillation did not show any significant effect on the group results. Hence, this finding is an initiating point for further investigations into the antimicrobial properties of this herb to treat common eye infections, including conjunctivitis and blepharitis.

Preliminary sensory evaluation of edible flowers from wild Allium species

BACKGROUND

The use of edible flowers as an aesthetic and flavour component of specific dishes is gaining popularity, and their production is becoming an interesting niche market activity for growers. Allium is an important genus of flowering plants, also including traditional wild food species. The combination of tradition with the new uses of flowers is appealing, requiring, however, explorative acceptance assays for its exploitation.

RESULTS

The flowers of the native Mediterranean species Allium neapolitanum, A. roseum and A. triquetrum were subject to hedonic visual, smell and flavour evaluation. Panellists also indicated specific flavour notes and their opinion about the more suitable uses. All the species were positively rated. A. roseum was preferred for all respects; A. triquetrum obtained the lowest visual rating, whereas A. neapolitanum had the lowest flavour rating. A spicy note was the main determinant of high flavour ratings. Dishes retaining the visual appearance of flowers were indicated as more suitable to combine with Allium flowers.

CONCLUSION

This is the first attempt at sensory evaluation of Allium flowers. Nutritional and health promotion properties and toxicity risks do not represent major issues for these products, because of potentially low consumption levels. The main constraint for a wider use of Allium flowers is represented by the absence of a consolidated consumption habit and regular supply.

Dietary spices as beneficial modulators of lipid profile in conditions of metabolic disorders and diseases

Spices are valued for their medicinal properties besides their use as food adjuncts to enhance the sensory quality of food. Dietary garlic, onion, fenugreek, red pepper, turmeric, and ginger have been proven to be effective hypocholesterolemics in experimentally induced hypercholesterolemia. The hypolipidemic potential of fenugreek in diabetic subjects and of garlic and onion in humans with induced lipemia has been demonstrated. Capsaicin and curcumin - the bioactive compounds of red pepper and turmeric - are documented to be efficacious at doses comparable to usual human intake. Capsaicin and curcumin have been shown to be hypotriglyceridemic, thus preventing accumulation of fat in the liver under adverse situations by enhancing triglyceride transport out of the liver. Capsaicin, curcumin, fenugreek, ginger, and onion enhance secretion of bile acids into bile. These hypocholesterolemic spices/spice principles reduce blood and liver cholesterol by enhancing cholesterol conversion to bile acids through activation of hepatic cholesterol-7α-hydroxylase. Many human trials have been carried out with garlic, onion, and fenugreek. The mechanism underlying the hypocholesterolemic and hypotriglyceridemic influence of spices is fairly well understood. Health implications of the hypocholesterolemic effect of spices experimentally documented are cardio-protection, protection of the structural integrity of erythrocytes by restoration of membrane cholesterol/phospholipid profile and prevention of cholesterol gallstones by modulation of the cholesterol saturation index in bile.

Efficacy of aqueous garlic extract on growth, aflatoxin B1 production, and cyto-morphological aberrations of Aspergillus flavus, causing human ophthalmic infection: topical treatment of A. flavus keratitis

By using agar well diffusion assay, antifungal activity of aqueous extract prepared from Egyptian garlic (Allium sativum L.) was evaluated in vitro against two strains of Aspergillus flavus (OC1 and OC10) causing human ocular infection. The recorded minimum inhibitory concentration (MIC) for growth inhibition of both strains was 3.60 mg/ml. Aqueous garlic extract (AGE) was used in successive in vivo tests as an attempt to cure rabbit's fungal keratitis caused by A. flavus OC1. Findings showed that diluted preparation of AGE was effective topical antifungal agent and succeeded to cure severe A. flavus keratitis in a time course less than 10 days without any observable side effects. Microscopic examination showed that AGE induced deleterious cyto-morphological aberrations in A. flavus target cells. AGE applied to Czapek's broth via contact method was more effective on growth, spores and aflatoxin B1 production than AGE applied to the same broth at the same concentration via fumigation method.

Higher bioaccessibility of iron and zinc from food grains in the presence of garlic and onion

Bioavailability of micronutrients iron and zinc is particularly low from plant foods. Hence there is a need to evolve a food-based strategy to improve the same to combat widespread deficiencies of these minerals in a population dependent on plant foods. Dietary sulfur-containing amino acids have been reported to improve the mineral status of experimental animals. Our objective was to examine whether sulfur compound-rich Allium spices have a similar potential of beneficially modulating the mineral bioavailability. In this context, we examined the influence of exogenously added garlic and onion on the bioaccessibility of iron and zinc from food grains. Two representative cereals and pulses each were studied in both raw and cooked condition employing two levels of garlic (0.25 and 0.5 g/10 g of grain) and onion (1.5 and 3 g/10 g of grain). The enhancing effect of these two spices on iron bioaccessibility was generally evidenced in the case of both the cereals (9.4-65.9% increase) and pulses (9.9-73.3% increase) in both raw and cooked conditions. The two spices similarly enhanced the bioaccessibility of zinc from the food grains, the extent of increase in cereals ranging from 10.4% to 159.4% and in pulses from 9.8% to 49.8%. Thus, both garlic and onion were evidenced here to have a promoting influence on the bioaccessibility of iron and zinc from food grains. This novel information has the potential application in evolving a food-based strategy to improve the bioavailability of trace minerals and hence contributes to the human health benefit.

Hypolipidemic and antioxidant efficacy of dehydrated onion in experimental rats

Hypolipidemic and antioxidant potency of a dehydrated onion product was evaluated in experimental rats maintained for 6 weeks at 5 and 10% dietary levels. Serum cholesterol especially low-density lipoprotein was significantly reduced by dietary dehydrated onion in hypercholesterolemic rats. This was associated with an increase in high density lipoprotein cholesterol. Blood triglyceride concentration in hypercholesterolemic rats was lower in onion supplemented diet group. Glutathione, ascorbic acid and α-tocopherol in the blood of hypercholesterolemic rats were higher in onion treatment, while lipid peroxides were lower. Hepatic α-tocopherol concentration was higher in rats maintained on onion diets, while lipid peroxides were reduced. Thus, this study has proved significant cholesterol lowering and antioxidant effect of dehydrated onion product.

In vitro evaluation of the amoebicidal activity of garlic (Allium sativum) extract on Acanthamoeba castellanii and its cytotoxic potential on corneal cells

Free-living protozoa of the genus Acanthamoeba can cause one of the most severe, potentially sight-threatening infections of the eye, the so-called A. keratitis. A. keratitis is difficult to treat because, under adverse conditions, the amoeba encyst and medical therapy is often less effective against cysts than against trophozoites. The aim of this study was to investigate evaluate the in vitro effect of the nonpolar subfraction of the methanol extract of garlic (Allium sativum) on the growth of A. castellanii trophozoites and cysts and also its cytotoxicity on corneal cells in vitro. Extract was evaluated for its amoebicidal activity, using an inverted light microscope. The effect of the nonpolar extract with the concentrations, ranging from 0.78 to 62.5 mg/mL on the proliferation of A. castellanii trophozoites and cysts, were examined in vitro. For the determination of cytotoxicity of the extract on corneal cells, agar diffusion tests were performed. The present study demonstrates the in vitro effectiveness of the garlic against the A. castellanii growth curve. Evaluations revealed that garlic inhibits trophozoite growth in dose- and time-dependent ways. In the case of the cyctotoxic acitivities, it showed no cytotoxicity for the cornea cells in the concentration of 3.90 mg/mL. These findings indicate that nonpolar subfraction of the methanol extracts of garlic has amoebicidal, as well as its cysticidal, properties on Acanthamoeba trophozoites and cysts. Garlic alone, and in combination with other amoebicidal agents, may be used in clinical practices after further investigations.

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.

Effects of garlic oil and two of its major organosulfur compounds, diallyl disulfide and diallyl trisulfide, on intestinal damage in rats injected with endotoxin

Garlic and its active components are known to possess antioxidant and antiinflammatory effects. The present study investigated the effects of garlic oil and its organosulfur compounds on endotoxin-induced intestinal mucosal damage. Wistar rats received by gavage 50 or 200 mg/kg body weight garlic oil (GO), 0.5 mmol/kg body weight diallyl disulfide or diallyl trisulfide, or the vehicle (corn oil; 2 ml/kg body weight) every other day for 2 weeks before being injected with endotoxin (i.p., 5 mg/kg body weight). Control rats were administered with corn oil and were injected with sterile saline. Samples for the measurement of proinflammatory cytokines were collected 3 h after injection, and all other samples were collected 18 h after injection. The low dose of GO suppressed endotoxin-induced inducible nitric oxide synthase (iNOS) activity, ulceration, and apoptosis in the intestinal mucosa (P < 0.05). The high dose of GO significantly lowered the peripheral level of nitrate/nitrite and endotoxin-induced iNOS activity in the intestinal mucosa (P < 0.05) but worsened intestinal mucosal damage accompanied by elevated peripheral proinflammatory cytokines. Diallyl trisulfide but not diallyl disulfide showed similar toxic effect as that of high-dose GO. These results suggest the preventive effect and possible toxicity of garlic oil and its organosulfur compounds in endotoxin-induced systemic inflammation and intestinal damage.

Synthesis of 3-alkylthio-6-allylthiopyridazine derivatives and their antihepatocarcinoma activity

The allylthio group of allicin and other organosulfur compounds, isolated from garlic, is considered a pharmacophore, and a key structure component of the molecule, which affords biological activities. In the foregoing studies, various 3-alkoxy-6-allylthiopyridazine derivatives (K-compounds) were synthesized, and their biological activities tested in animals. As expected, the various derivatives showed good hepatoprotective activities on carbon tetrachloride-treated mice and aflatoxin B1-treated rats, and chemopreventive activities on hepatocarcinoma cells in rats. Other new pyridazine derivatives, with the oxygen atom at the 3-position of the 3-alkoxy-6-allylthiopyridazine displaced by sulfur (S), were synthesized, and their activities tested in vitro. Thio-K6, one of the sulfur-substituted compounds, showed better chemopreventive activity toward hepatocarcinoma cells.

In Vitro Antimicrobial Properties of Aqueous Garlic Extract Against Multidrug-Resistant Bacteria and Candida Species from Nigeria

The antimicrobial effects of aqueous garlic extract (AGE) against 133 multidrug-resistant gram-positive and gram-negative bacterial isolates, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Salmonella typhi, Pseudomonas aeruginosa, Escherichia coli, Shigella spp., and Proteus spp., and against 10 Candida spp. were studied. Antibacterial activity of AGE by well-diffusion and macrobroth dilution method was characterized by inhibition zones of 20.2-22.7 mm for gram-positives and 19.8-24.5 mm for gram-negatives and minimum inhibitory concentration (MIC) ranges of 15.6-48.3 mg/mL and 22.9-37.2 mg/mL, respectively. With the exception of P. aeruginosa, the observed disparity in MIC values at 24 and 48 hours was not significant (P >.05) in these isolates. The anticandidal effect of AGE resulted in a growth inhibition zone of 27.4 +/- 3.7 mm with no significant difference (P >.05) in MIC values at 24 and 48 hours, respectively. Minimum fungicidal concentrations were found to be 14.9 and 15.5 mg/mL, respectively, at these incubation periods. Further analysis revealed the antimicrobial efficacy of AGE to be dose and time dependent, producing five distinct time-kill profiles among the isolates tested. The results of this study support the use of garlic in health products and herbal remedies in Nigeria.

The 26S proteasome in garlic (Allium sativum): purification and partial characterization

The 26S proteasome (multicatalytic protease complex, MPC) was purified from fresh garlic cloves (Allium sativum) to near homogeneity by ion exchange chromatography on DEAE-sephacel, gel filtration on Sepharose-4B, and glycerol density gradient centrifugation. Two alpha-type (20S proteasome "catalytic core") subunits were identified by the direct sequencing of peptide fragments (mass fingerprint analysis, Mass Spectrometry Lab, Stanford University) or the sequencing of a cloned cDNA generated using a garlic cDNA library as the template; these subunits were found to have a high homology to those from other plants. Polyacrylamide gel electrophoresis under denaturing conditions separated the garlic MPC into multiple polypeptides having molecular masses in the range of 21-35 (components of the 20S catalytic core) and 55-100 kDa (components of the 19S regulatory units). The banding pattern of the garlic MCP is similar to that of spinach and rat liver with minor differences in some components; however, polyclonal antibodies against mammalian proteasomes failed to significantly stain the enzyme from garlic. This is the first work to identify the garlic proteasome.

Dual role of organosulfur compounds in foods: a review

Organosulfur compounds present in natural food are generally considered as beneficial for health because of their antioxidant and anticarcinogenic properties. This has led to their excessive and long-term consumption. However, there is also evidence that these compounds demonstrate toxicity and adverse health effects suggesting their potential dual biological roles. Thus, they can act as double-edged biological swords.

Mechanisms by which garlic and allyl sulfur compounds suppress carcinogen bioactivation. Garlic and carcinogenesis

Overall, a host of studies provides compelling evidence that garlic and its organic allyl sulfur components are effective inhibitors of the cancer process. These studies reveal that the benefits of garlic are not limited to a specific species, to a particular tissue, or to a specific carcinogen. Several mechanisms are likely to account for this protection. Notable among these is a depression in nitrosamine formation and a reduction in carcinogen bioactivation. The benefits provided by garlic must be viewed as part of the entire diet, since several dietary constituents can influence the degree of protection. More than one compound is responsible for the anticancer properties associated with garlic. Future research should focus on how genetic variability and daily environmental factors influence the anticancer benefits attributed to garlic and its allyl sulfur components.

A historical perspective on garlic and cancer

Epidemiological and laboratory studies provide insight into the anticarcinogenic potential of garlic and its constituent compounds. Both water- and lipid-soluble allyl sulfur compounds are effective in blocking a myriad of chemically induced tumors. Part of the protection from these compounds probably relates to a block in nitrosamine formation and metabolism. However, blockage in the initiation and promotion phases of the carcinogenicity of various compounds, including polycyclic hydrocarbons, provide evidence that garlic and its constituents can alter several phase I and II enzymes. Their ability to block experimentally induced tumors in a variety of sites including skin, mammary and colon, suggests a general mechanism of action. Changes in DNA repair and in immunocompetence may also account for some of this protection. Some, but not all, allyl sulfur compounds can also effectively retard tumor proliferation and induce apoptosis. Changes in cellular thiol and phosphorylation stains may account for some of these antitumorigenic properties. The anticarcinogenic potential of garlic can be influenced by several dietary components including specific fatty acids, selenium, and vitamin A. Since garlic and its constituents can suppress carcinogen formation, carcinogen bioactivation, and tumor proliferation it is imperative that biomarkers be established to identify which individuals might benefit most and what intakes can occur with ill consequences.

The microaerophilic flagellate Giardia intestinalis: Allium sativum (garlic) is an effective antigiardial

Whole garlic (Allium sativum L.) extract and some of its components were assayed for antigiardial activity. Whole garlic extract gave an IC(50) at 24 h of 0.3 mg ml(-1). Most of the components assayed were inhibitory to the organism, especially allyl alcohol and allyl mercaptan, with IC(50) values of 7 microg ml(-1) and 37 microg ml(-1) respectively. Studies with calcofluor white indicated that whole garlic and allyl alcohol collapse the transmembrane electrochemical membrane potential (Deltapsi) of the organism, as indicated by uptake of the fluorochrome. Electron microscopy allowed the morphological changes that occur with garlic inhibition to be recorded. Both the surface topography and internal architecture of the organism changed during incubation with the biocides. Both whole garlic and allyl alcohol resulted in fragmentation of the disc and an overexpression of disc microribbons, internalization of flagella, vacuole formation and an increase in distended vesicles. Allyl mercaptan, however, only gave an increase in distended vesicles, suggesting that this biocide has a different mode of action.

Health effects of vegetables and fruit: assessing mechanisms of action in human experimental studies

Epidemiologic data support the association between high intake of vegetables and fruits and low risk of chronic disease. There are several biologically plausible reasons why consumption of vegetables and fruit might slow or prevent the onset of chronic diseases. Vegetables and fruit are rich sources of a variety of nutrients, including vitamins, trace minerals, and dietary fiber, and many other classes of biologically active compounds. These phytochemicals can have complementary and overlapping mechanisms of action, including modulation of detoxification enzymes, stimulation of the immune system, reduction of platelet aggregation, modulation of cholesterol synthesis and hormone metabolism, reduction of blood pressure, and antioxidant, antibacterial, and antiviral effects. Although these effects have been examined primarily in animal and cell-culture models, experimental dietary studies in humans have also shown the capacity of vegetables and fruit and their constituents to modulate some of these potential disease-preventive mechanisms. The human studies have relied on intermediate endpoints related to disease risk. Design methodologies used include multiple-arm trials, randomized crossover studies, and more compromised designs such as nonrandomized crossovers and pre- and posttreatment analyses. Length of treatment ranged from a single dose to years depending on the mechanism of interest. Stringency of dietary control varied from addition of supplements to a habitual diet to provision of all food for the duration of a treatment. Rigorously conducted experimental dietary studies in humans are an important link between population- and laboratory-based research.

Amelioration of renal lesions associated with diabetes by dietary curcumin in streptozotocin diabetic rats

Curcumin, the coloring principle of the commonly used spice turmeric (Curcuma longa) was fed at 0.5% in the diet to streptozotocin-induced diabetic Wistar rats for 8 weeks. Renal damage was assessed by the amount of proteins excreted in the urine and the extent of leaching of renal tubular enzymes: NAG, LDH, AsAT, AlAT, alkaline and acid phosphatases. The integrity of kidney was assessed by measuring the activities of several key enzymes of the renal tissue: glucose-6-phosphate dehydrogenase, glucose-6-phosphatase, and LDH (Carbohydrate metabolism), aldose reductase and sorbitol dehydrogenase (polyol pathway), transaminases, ATPases and membrane PUFA/SFA ratio (membrane integrity). Data on enzymuria, albuminuria, activity of kidney ATPases and fatty acid composition of renal membranes in diabetic condition suggested that dietary curcumin brought about significant beneficial modulation of the progression of renal lesions in diabetes. These findings were also corroborated by histological examination of kidney sections. It is inferred that this beneficial ameliorating influence of dietary curcumin on diabetic nephropathy is possibly mediated through its ability to lower blood cholesterol levels.

The antimicrobial properties of chile peppers (Capsicum species) and their uses in Mayan medicine

A survey of the Mayan pharmacopoeia revealed that tissues of Capsicum species (Solanaceae) are included in a number of herbal remedies for a variety of ailments of probable microbial origin. Using a filter disk assay, plain and heated aqueous extracts from fresh Capsicum annuum, Capsicum baccatum, Capsicum chinese, Capsicum frutescens, and Capsicum pubescens varieties were tested for their antimicrobial effects with fifteen bacterial species and one yeast species. Two pungent compounds found in Capsicum species (capsaicin and dihydrocapsaicin) were also tested for their anti-microbial effects. The plain and heated extracts were found to exhibit varying degrees of inhibition against Bacillus cereus, Bacillus subtilis, Clostridium sporogenes, Clostridium tetani, and Streptococcus pyogenes.

Antifungal effects of Allium sativum (garlic) extract against the Aspergillus species involved in otomycosis

Otomycosis due to saprophytic keratolytic fungi represents a small percentage of clinical external otitis. Although there are certain antibacterial and antifungal agents available, they usually are very caustic, potentially ototoxic and cannot be used if the ear drum is perforated. Garlic is utilized as a folk medicine in many countries for its antimicrobial and other beneficial properties. In response to a lack of otic preparations, the authors studied the efficacy of garlic extracts against the fungi belonging to the genus Aspergillus which are the most common cause of this infection. Aqueous garlic extract (AGE) and concentrated garlic oil (CGO) along with various commercial garlic supplements and pharmaceutical prescriptions were used in an in-vitro study. AGE and especially CGO were found to have antifungal activity. These agents showed similar or better inhibitory effects than the pharmaceutical preparations and demonstrated similar minimum inhibitory concentrations.

Effect of alkyl sulfides on diazomethane-induced methylation of DNA in vitro

Organosulfur compounds found in Allium species such as garlic and onions inhibit carcinogenesis induced by alkylating agents. One potential mechanism for this activity involves scavenging of ultimate carcinogenic species by the nucleophilic sulfur atom. Carcinogenic methylating agents such as methyl-nitrosourea produce, among others, O6-methylguanine and N7-methylguanine in DNA both in vivo and in vitro. In the present study we have determined the effect of several alkyl sulfides on the formation of O6-methylguanine and N7-methylguanine in DNA reacted with the methylating agent diazomethane in vitro. Dipropyl sulfide and diallyl sulfide affect guanine methylation by increasing the O6/N7 ratio without drastic alterations in the total amount of adduct formed. Three similar compounds--diallyl disulfide, allyl methyl sulfide and diallyl ether--had no appreciable effect on the amount of alkylation at either position. These data suggest that scavenging of diazomethane-like ultimate carcinogens does not play a major role in the inhibition of carcinogenesis by organic sulfides.