In Vitro Effect of Aqueous Extract of Garlic (Allium Sativum) on the Growth and Viability ofCryptococcus Neoformans

Antifungal activity of liriodenine on clinical strains of Cryptococcus neoformans and Cryptococcus gattii species complexes

Background:

Cryptoccocal meningitis continues to present high incidence among AIDS patients. The treatment of choice is the synergistic combination of flucytosine (5-FC) with amphotericin B deoxycholate (AmBd) or its lipid formulations. However, 5-FC is unavailable in many countries and AmB demands hospitalization. The combination of AmB with the fungistatic fluconazole (FLC) or the use of high FLC daily doses alone became the choice. Nonetheless, sterilization of cerebrospinal fluid is delayed with FLC monotherapy, mainly with high fungal burden. These findings suggest the search for new antifungal compounds, such as liriodenine.

Methods:

Liriodenine antifungal activity was evaluated by three procedures: determining the minimum inhibitory concentration (MIC) on 30 strains of the Cryptococcus neoformans (C. neoformans) complex and 30 of the Cryptococcus gattii (C. gattii) complex, using EUCAST methodology and amphotericin B deoxycholate as control; performing the time-kill methodology in two strains of the C. neoformans complex and one of the C. gattii complex; and injury to cryptococcal cells, evaluated by transmission electron microscopy (TEM). Liriodenine absorption and safety at 0.75 and 1.50 mg.kg^-1 doses were evaluated in BALB/c mice.

Results:

Liriodenine MICs ranged from 3.9 to 62.5 μg.mL^-1 for both species complexes, with no differences between them. Time-kill methodology confirmed its concentration-dependent fungicidal effect, killing all the strains below the limit of detection (33 CFU.mL^-1) at the highest liriodenine concentration (32-fold MIC), with predominant activity during the first 48 hours. Liriodenine induced severe Cryptococcus alterations - cytoplasm with intense rarefaction and/or degradation, injury of organelles, and presence of vacuoles. Liriodenine was better absorbed at lower doses, with no histopathological alterations on the digestive tract.

Conclusion:

The fungicidal activity confirmed by time-kill methodology, the intense Cryptococcus injury observed by TEM, the absorption after gavage administration, and the safety at the tested doses indicate that the liriodenine molecule is a promising drug lead for development of anticryptococcal agents.

S-ethyl ethanethiosulfinate, a derivative of allicin, induces metacaspase-dependent apoptosis through ROS generation in Penicillium chrysogenum

Allicin can be used as fumigant to protect food and cultural relics from fungal contamination because of its strong antifungal activity and the characteristics of high volatility and no residues. However, the obvious disadvantages such as high minimal inhibitory concentration and instability prevent it from wide application. In this study, a stable derivative of allicin, S-ethyl ethanethiosulfinate (ALE), was synthesized. We further explored its antifungal activity and apoptosis-inducing effect, as well as the underlying mechanism. ALE had an excellent capability of inhibiting spore germination and mycelial growth of Penicillium chrysogenum observed by inverted microscope and scanning electron microscopy. XTT colorimetric assay indicated ALE could reduce the cell viability obviously and IC₅₀ was 0.92 μg/ml, only 1/42 of allicin (38.68 μg/ml). DHR 123 ROS Assay Kit, flow cytometry assay and confocal immunofluorescence revealed intercellular ROS generation and metacaspase-dependent apoptosis triggered by ALE, while antioxidant tocopherol could reverse ALE-induced cytotoxicity effect and metacaspase activation. These results indicate that ALE induces metacaspase-dependent apoptosis through ROS generation, thus possesses an effective antifungal activity. This new derivative of allicin might be developed as a high efficient alternative to the conventional fungicides for food storage and cultural relic protection.

A quantitative assessment of the antimicrobial activity of garlic (Allium sativum)

An aqueous extract of freeze-dried garlic (Allium sativum), when incorporated into growth media, inhibited many representative bacteria, yeasts, fungi and a virus. All microorganisms tested were susceptible to garlic. Quantitative assessment of the minimum inhibitory concentrations for bacteria and yeasts showed values ranging from 0.8 to 40.0 mg garlic ml(-1). Fungal radial colony growth was inhibited by at least 25% at concentrations as low as 2.0 mg garlic ml(-1). The 50% endpoint neutralization titre for rotavirus was 2.4 to 2.8 μg ml(-1). Lactic acid bacteria were the least sensitive microorganisms to the inhibitory effects of garlic. In mixed culture studies of Lactobacillus acidophilus and Escherichia coli, garlic prevented the establishment of E. coli, although the final outcome of competition was not affected.

Echinacea purpurea and Allium sativum as immunostimulants in fish culture using Nile tilapia (Oreochromis niloticus)

The study was conducted to evaluate the efficiency of echinacea (E) and garlic (G) supplemented diets as immunostimulant for tilapia (Oreochromis niloticus). Seven treatments were designed including a control (C). Fish were fed on 35% protein diet at a rate of 3% body weight per day. Echinacea (1.0 ppt) and garlic (3%) were incorporated in the feed, which was administered for periods of 1, 2 and 3 months (summer season), followed by basal diet for 4 more months (winter season). Neutrophil adherence and haematocrit values increased in both supplemented groups with prolonging period of application. The neutrophils adherence was significantly increased in all treatments except group administered echinacea for 1 month. The lymphocytic counts were significantly (p < 0.004) elevated that resulted in a significant increase in the total leucocytic count in groups administered echinacea for 1 and 2 months when compared with the control and/or other treatments. The gain in the body weight and specific growth rate was significantly increased in all supplemented groups (p < 0.004) during summer, but remained without any significant increase after winter. The survival rate was significantly high (>85%) in all the supplemented groups. The percentage of protection, after challenge infection using pathogenic Aeromonas hydrophila was the highest in groups supplemented with echinacea and garlic for 3 months after summer and winter seasons. It could be concluded that echinacea and garlic improve the gain in body weight, survival rate and resistance against challenge infection. Both compounds showed extended effects after withdrawal and improved resistance to cold stress during the winter season. However, a full commercial cost benefit analysis is necessary before recommending their application in aquaculture.

Self-inflicted garlic burns: our experience and literature review

BACKGROUND

Throughout history, garlic has been used to treat a large variety of illnesses. One of garlic's adverse local effects is contact dermatitis.

METHODS

We present three patients treated in the Department of Plastic Surgery for suspected self-inflicted lower extremity burns.

RESULTS

The burns had unique features, not consistent with the etiology first claimed by the patients. All were soldiers with low motivation who confessed to using garlic to cause the burns.

CONCLUSIONS

Garlic application usually results in local inflammation, but, if applied under a pressure bandage, or if there is poor wound care or a secondary infection, it can cause a severe dermal reaction and a deep chemical burn. We present these cases to increase physician awareness of the characteristics of self-inflicted garlic burns, and review the dermatotoxic effect.

Effect of Oral Administration of Crude Aqueous Extract of Garlic on Pharmacokinetic Parameters of Isoniazid and Rifampicin in Rabbits

AIM

To study the effect of oral administration of crude aqueous extract of garlic for 14 days on pharmacokinetic parameters of isoniazid and rifampicin.

MATERIALS AND METHODS

Crude extract was prepared according to the method described by Fromtling and Bulmer. The study was done on 16 New Zealand white rabbits, divided into two groups of 8 animals each for two drugs. Baseline pharmacokinetic parameters for single-dose isoniazid and rifampicin were calculated from plasma drug concentrations obtained at various time intervals after dosing. The animals were given garlic extract orally for 14 days. Pharmacokinetic parameters were calculated again as done previously.

OBSERVATIONS

Administration of crude aqueous extract of garlic significantly altered the pharmacokinetic parameters for isoniazid. C(max) was reduced from 15.4 +/- 5.6 to 5.4 +/- 3.3 microg/ml. AUC((0-24)) was reduced from 76.7 +/- 25.0 to 34.3 +/- 19.2 microg/ml.h. No significant change in T(max), k(el) and AUC((0-)(alpha)) was seen. Pharmacokinetic parameters of rifampicin were not significantly altered by administration of garlic extract.

CONCLUSIONS

Oral administration of garlic extract decreased the bioavailability of isoniazid significantly with no change in rate of elimination. Bioavailability of rifampicin is not significantly altered by garlic extract.

Bioactive S-alk(en)yl cysteine sulfoxide metabolites in the genus Allium: the chemistry of potential therapeutic agents

S-Alk(en)yl cysteine sulfoxides are odourless, non-protein sulfur amino acids typically found in members of the family Alliaceae and are the precursors to the lachrymatory and flavour compounds found in the agronomically important genus Allium. Traditionally, Allium species, particularly the onion (Allium cepa) and garlic (A. sativum), have been used for centuries in European, Asian and American folk medicines for the treatment of numerous human pathologies, however it is only recently that any significant progress has been made in determining their mechanisms of action. Indeed, our understanding of the role of Allium species in human health undoubtedly comes from the combination of several academic disciplines including botany, biochemistry and nutrition. During tissue damage, S-alk(en)yl cysteine sulfoxides are converted to their respective thiosulfinates or propanethial-S-oxide by the action of the enzyme alliinase (EC 4.4.1.4). Depending on the Allium species, and under differing conditions, thiosulfinates can decompose to form additional sulfur constituents including diallyl, methyl allyl, and diethyl mono-, di-, tri-, tetra-, penta-, and hexasulfides, the vinyldithiins and (E)- and (Z)-ajoene. Recent reports have shown onion and garlic extracts, along with several principal sulfur constituents, can induce phase II detoxification enzymes like glutathione-S-transferases (EC 2.5.1.18) and quinone reductase (QR) NAD(P)H: (quinine acceptor) oxidoreductase (EC 1.6.99.2) in mammalian tissues, as well as also influencing cell cycle arrest and apoptosis in numerous in vitro cancer cell models. Moreover, studies are also beginning to highlight a role of Allium-derived sulfur compounds in cardiovascular protection. In this review, we discuss the chemical diversity of S-alk(en)yl cysteine sulfoxide metabolites in the context of their biochemical and pharmacological mechanisms.

Antidermatophytic activity of garlic (Allium sativum) in vitro

BACKGROUND

Interest in herbal medicine is enjoying a renaissance at present. Garlic (Allium sativum) is an intriguing herb with a long history of medicinal use for a variety of diseases including ringworm infections.

METHODS

Antidermatophytic activity of the aqueous extract of garlic (A. sativum) was investigated against 88 clinical isolates of dermatophytes by an agar dilution technique. The isolates included Microsporum canis (50), M. audouinii (5), Trichophyton rubrum (6), T. mentagrophytes (5), T. violaceum (12), T. simii (5), T. verrucosum (1), T. erinacei (1), and Epidermophyton floccosum (2). The results were compared with the minimal inhibitory concentrations of ketoconazole.

RESULTS

The aqueous extract of garlic, diluted 1:150 and 1:100, had inhibited 50 and 90% of the isolates tested, whereas the respective values for ketoconazole were 1 and 2.5 micrograms/mL.

CONCLUSIONS

Garlic (A. sativum) could be used as an effective antidermatophytic agent. Further purification and extraction of the active principle of garlic would give a true antidermatophytic activity comparable to standard antifungal drugs.

Automatic evaluation of antifungal volatile compounds on the basis of the dynamic growth process of a single hypha

An automatic analysing system was developed and employed for the evaluation of antifungal activity of volatile compounds in the gas phase. Aspergillus niger was inoculated on agar medium in the reaction vessel. The reaction vessel was incubated at 28 degrees C for 24 h and then a volatile compound was introduced into the vessel either in a batch or flow manner. The antifungal activity of the respective compounds estimated in situ was expressed by the dynamic response parameters of a single hypha. All volatiles tested in the present system inhibited hyphal growth, except linalyl acetate: Limone and geraniol were the most inhibitory. In contrast, linalyl acetate promoted hyphal growth. By definition of the parameters, the fungicidal and fungistatic effects could be distinguished.