amphotericin-b and allicin

Reports about the safe and successful intravenous (i.v.) use of garlic derivatives in China against invasive fungal infections have been made, but little has been done to seriously investigate the in vivo use of these derivatives in the West. Laboratories have demonstrated impressive in vitro MICs using allitridium, one of these derivatives, against a range of medically important fungi. In addition, it has been demonstrated that allitridium shows in vitro synergy with amphotericin B, one of the main i.v. antifungal agents. Some of the breakdown products of allicin, the main parent antifungal compound in garlic, have been investigated for their general antimicrobial, anticancer and anticholesterol properties, and it appears that there is a common mode of action that underlies these activities. It appears that these small molecules have the ability to cross cell membranes and combine with sulfur-containing molecular groups in amino acids and proteins, thus interfering with cell metabolism. It has been suggested that the reason human cells are not poisoned by allicin derivatives is that they contain glutathione, a sulfur-containing amino acid that combines with the allicin derivative, thus preventing cell damage. In addition to their biochemical mechanism, these derivatives appear to stimulate cellular immunity, an important ability lacking in conventional antifungal chemotherapy. These derivatives appear to be safe, cheap, wide-spectrum and immunostimulatory, as well as possibly synergistic with conventional antifungal therapy, making them ideal candidates for investigation into their use as prophylactic antifungal agents.

Topics: Amphotericin B; Antifungal Agents; Disulfides; Drug Synergism; Drug Therapy, Combination; Fungi; Humans; Immunity, Cellular; Mycoses; Sulfinic Acids

Current monotherapy against visceral leishmaniasis has serious side effects, and resistant Leishmania strains have been identified. Amphotericin B (AmB) has shown an extraordinary antileishmanial efficacy without emergence of resistance; however, toxicity has limited its general use. Results obtained showed, using a fixed-ratio analysis, that the combination of diallyl thiosulfinate (allicin) and AmB ranged from moderately synergic to synergic at low concentrations (0.07 μM AmB plus 35.45 μM allicin induced 95% growth inhibition). None of the treatments, alone or in combination, had noticeable adverse effects on macrophages (M) in the concentration range examined (allicin, 0.5, 1, 5 and 10 μM; AmB, 0.05, 0.075, and 0.1 μM). Allicin, AmB, or the combination did not affect the infection rate (percentage of infected M) of Leishmania. Allicin enhanced the activity of AmB on intracellular amastigotes of Leishmania donovani and L. infantum (ca. 45% reduction of amastigote burden with 0.05 μM AmB plus 10 μM allicin); this represented nearly a 2-fold reduction in the 50% inhibitory concentration (IC50) of the antibiotic added alone. Results point toward the possible utility of testing this combination in vivo to reduce the toxicity associated with monotherapy with AmB.

Topics: Amphotericin B; Animals; Disulfides; Dose-Response Relationship, Drug; Drug Synergism; Female; In Vitro Techniques; Leishmania donovani; Leishmania infantum; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Sulfinic Acids; Trypanocidal Agents

To evaluate the efficacy of the combination of allicin and amphotericin deoxycholate (AmB) in the chemotherapy of Leishmania infantum infection with the final aim of reducing the dose of AmB in the chemotherapy of visceral leishmaniasis.. Hamsters were intraperitoneally (ip) infected with L. infantum (10(7) stationary phase promastigotes). On day 45 post-infection animals were treated ip with AmB (1 or 5 mg/kg/day), allicin (5 mg/kg/day) or a combination of AmB (1 mg/kg/day) + allicin (5 mg/kg/day) for 5 days. Animals were clinically and biopathologically monitored and the antibody response (IgG, IgG1, IgG2) was determined. Parasite burdens were estimated by limiting dilution and AmB biodistribution was determined by HPLC in plasma, kidney, spleen and liver.. No clinical signs or liver and kidney alterations were observed. AmB (1 mg/kg/day) did not clear the Leishmania infection and no parasites were detected in two animals treated with 5 mg/kg/day allicin. Combination therapy (5 mg/kg allicin + 1 mg/kg AmB) reduced the L. infantum burden by >95%. Antileishmanial activity of the combination was comparable (P < 0.05) to the standard AmB treatment (5 mg/kg).. Allicin alone (5 mg/kg/day for 5 days) significantly reduced the Leishmania burden in spleen and liver of infected hamsters. Co-administration of allicin (5 mg/kg/day for 5 days) and AmB (1 mg/kg/day for 5 days) showed a partial additive effect on the reduction of leishmanial burden in both target organs.

Topics: Amphotericin B; Animal Structures; Animals; Antiprotozoal Agents; Chromatography, High Pressure Liquid; Cricetinae; Disease Models, Animal; Disulfides; Drug Therapy, Combination; Female; Leishmania infantum; Leishmaniasis, Visceral; Parasite Load; Plasma; Sulfinic Acids; Treatment Outcome

The antifungal activity of allicin and its synergistic effects with the antifungal agents flucytosine and amphotericin B (AmB) were investigated in Candida albicans (C. albicans). C. albicans was treated with different conditions of compounds alone and in combination (allicin, AmB, flucytosine, allicin + AmB, allicin + flucytosine, allicin + AmB + flucytosine). After a 24-hour treatment, cells were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM) to measure morphological and biophysical properties associated with cell death. The clearing assay was conducted to confirm the effects of allicin. The viability of C. albicans treated by allicin alone or with one antifungal drug (AmB, flucytosine) in addition was more than 40% after a 24-hr treatment, but the viability of groups treated with combinations of more than two drugs was less than 32%. When the cells were treated with allicin alone or one type of drug, the morphology of the cells did not change noticeably, but when cells were treated with combinations of drugs, there were noticeable morphological changes. In particular, cells treated with allicin + AmB had significant membrane damage (burst or collapsed membranes). Classification of cells according to their cell death phase (CDP) allowed us to determine the relationship between cell viability and treatment conditions in detail. The adhesive force was decreased by the treatment in all groups compare to the control. Cells treated with AmB + allicin had a greater adhesive force than cells treated with AmB alone because of the secretion of molecules due to collapsed membranes. All cells treated with allicin or drugs were softer than the control cells. These results suggest that allicin can reduce MIC of AmB while keeping the same efficacy.

Topics: Amphotericin B; Antifungal Agents; Candida albicans; Disulfides; Drug Synergism; Flucytosine; Microbial Sensitivity Tests; Microscopy, Atomic Force; Microscopy, Electron, Scanning; Sulfinic Acids

In this study, the polyene macrolide antibiotics amphotericin B (AmB), nystatin and filipin III were evaluated for their fungicidal activity and their ability to produce vacuole disruption as well as enhancement of these activities by allicin using Saccharomyces cerevisiae. Nystatin has a macrocyclic lactone ring analogous to AmB and their fungicidal activities were both increased by allicin, an allyl-sulfur compound, whereas filipin III, a pentaene macrolide, did not show an increase in fungicidal activity in the presence of allicin. Vacuole staining with the fluorescent probe FM4-64 showed that both AmB and nystatin induced vacuole membrane disintegration at their lethal concentrations; in addition, the vacuole disruptive effect was also enhanced by allicin. In contrast, filipin III did not affect vacuole morphology and addition of allicin had no effect despite filipin III localising to the cell cytoplasm. Isolated S. cerevisiae vacuoles were disrupted following treatment both with nystatin and AmB, though this activity was not potentiated in the presence of allicin. In contrast, filipin III had little effect on the vacuole architecture. This study reveals differential effects of polyene antibiotics on vacuoles in S. cerevisiae, which may be due to differences in the structure of the macrocyclic ring.

Topics: Amphotericin B; Antifungal Agents; Disulfides; Filipin; Fluorescent Dyes; Lactones; Microbial Viability; Microscopy; Microscopy, Fluorescence; Nystatin; Polyenes; Pyridinium Compounds; Quaternary Ammonium Compounds; Saccharomyces cerevisiae; Staining and Labeling; Sulfinic Acids; Vacuoles

Allicin selectively enhances the fungicidal activity of amphotericin B (AmB). It also accelerates AmB-induced vacuole disruption but does not affect AmB-induced potassium ion efflux in Saccharomyces cerevisiae and Candida albicans. The fungicidal activity of AmB alone or combined with allicin was further evaluated based on the relationship among cell viability, vacuole disruption and potassium ion efflux in S. cerevisiae. Lethality and vacuole disruption caused by AmB alone were completely restricted when K(+) and Mg(2+) were added to the growth medium. On the other hand, in identical conditions, the combination of AmB and allicin induced both lethality and vacuole disruption. S. cerevisiae Δerg6 cells, which lack ergosterol in plasma membrane, were mostly resistant to AmB as well as the combination of AmB and allicin against both lethality and vacuole disruption. The incorporation of AmB into the cytoplasm of Δerg6 cells was significantly reduced in comparison with that in parent cells, regardless of the presence of allicin. Our results suggest that the fungicidal activity of AmB combined with allicin is involved in vacuole disruption but not in potassium ion efflux, and that the expression of allicin-mediated activity of AmB requires the presence of ergosterol in the plasma membrane.

Topics: Amphotericin B; Antifungal Agents; Cell Membrane; Disulfides; Drug Synergism; Ergosterol; Potassium; Saccharomyces cerevisiae; Sulfinic Acids; Vacuoles

In Saccharomyces cerevisiae, ergosterol was visible in the plasma membrane of untreated cells and was enriched in the vacuole membrane in response to amphotericin B (AmB) treatment at a non-lethal concentration. The simultaneous addition of allicin was inhibitory to AmB-induced ergosterol enrichment in the vacuole membrane, resulting in increased sensitivity of the organelles to the disruptive action of AmB. Allicin was also inhibitory to ergosterol enrichment in the vacuole membrane that was achieved by its external addition to cells. The combined fungicidal activity of AmB and allicin was suppressed together with suppression of vacuole membrane damage in cells where ergosterol had been fully enriched in the vacuole membrane. AmB caused direct disruptive damage of the isolated vacuoles, but the antibiotic was apparently less effective in disrupting the organelles that were isolated after ergosterol enrichment. These findings suggest that allicin enhances AmB-induced vacuole membrane damage by inhibiting ergosterol trafficking from the plasma membrane to the vacuole membrane.

Topics: Amphotericin B; Antifungal Agents; Cell Membrane; Cell Survival; Disulfides; Ergosterol; Garlic; Intracellular Membranes; Plant Extracts; Saccharomyces cerevisiae; Sulfinic Acids; Vacuoles

Amphotericin B (AmB) is the gold standard of antifungal treatment for the most severe invasive mycoses. In addition to the interaction of AmB with ergosterol in the fungi cell membrane, several studies have demonstrated oxidative damage involved in the fungicidal activity of AmB. In this study, allicin, an allyl sulphur compound from garlic, was shown to enhance significantly the effect of AmB against Candida albicans in vitro and in vivo, although allicin did not exert a fungicidal effect. Further study first demonstrated that allicin-mediated oxidative damage, such as phospholipid peroxidation in the plasma membrane, via influencing the defence of C. albicans against oxidative damage may be the cause of the synergistic interaction between allicin and AmB. We envision that a combination of AmB with allicin may prove to be a promising strategy for the therapy of disseminated candidiasis.

Topics: Amphotericin B; Animals; Antifungal Agents; Candida albicans; Candidiasis; Colony Count, Microbial; Disulfides; Drug Synergism; Female; Mice; Mice, Inbred BALB C; Microbial Viability; Sulfinic Acids

In this study, the vacuole disruptive activity was evaluated as a cause of amphotericin B (AmB) lethality against the pathogenic fungus Candida albicans in terms of its enhancement by allicin, an allyl-sulfur compound from garlic. Vacuole disruption was observed in parallel to AmB-induced cell death when the antibiotic was used at a lethal concentration and at a non-lethal concentration in combination with allicin. Allicin did not enhance AmB-induced cell death and the accompanying vacuole disruption when the cells were incubated with exogenous ergosterol for its enrichment in the vacuole. The vacuoles isolated from intact cells could be directly disrupted by the action of AmB to the same extent in the absence and presence of allicin, whereas the organelles isolated from ergosterol-enriched cells were resistant to its direct disruptive action. AmB was similarly incorporated into the fungal cytoplasm in cells with or without ergosterol enrichment, supporting the fact that AmB-induced vacuole disruption depends on its direct disruptive action on the organelle. In agreement with these findings, allicin was found to inhibit ergosterol transport from the plasma membrane to the cytoplasm, which is considered to be a cellular protective response to AmB-induced vacuole disruption in S. cerevisiae. Our study suggests that AmB lethality against C. albicans depends at least in part on its vacuole disruptive activity under the physiological condition permissive for invasive growth of the fungus.

Topics: Amphotericin B; Antifungal Agents; Biological Transport; Candida albicans; Colony Count, Microbial; Disulfides; Drug Synergism; Ergosterol; Garlic; Microbial Viability; Molecular Structure; Sulfinic Acids; Vacuoles

Amphotericin B (AmB) is a representative antibiotic for the control of serious fungal infections, and its fungicidal activity was greatly enhanced by allicin, an allyl-sulfur compound from garlic. In addition to the plasma membrane permeability change, AmB induced vacuole membrane damage so that the organelles were visible as small discrete particles. Although allicin was ineffective in promoting AmB-induced plasma membrane disability, this compound enhanced AmB-induced structural damage to the vacuolar membrane even at a non-lethal dose of the antibiotic. Allicin could also enhance the antifungal activity of AmB against the pathogenic fungus Candida albicans and against Aspergillus fumigatus. In contrast, allicin did not enhance the cytotoxic activity of AmB against cells of human promyelocytic leukemia (HL-60), a vacuole-less organism.

Topics: Amphotericin B; Antifungal Agents; Aspergillus fumigatus; Candida albicans; Cell Membrane Permeability; Disulfides; Drug Synergism; Garlic; Intracellular Membranes; Saccharomyces cerevisiae; Sulfinic Acids; Vacuoles