Liquid and vapour-phase antifungal activities of selected essential oils against candida albicans: microscopic observations and chemical characterization of cymbopogon citratus

<p>Abstract</p> <p>Background</p> <p>Use of essential oils for controlling <it>Candida albicans </it>growth has gained significance due to the resistance acquired by pathogens towards a number of widely-used drugs. The aim of this study was to test the antifungal activity of selected essential oils against <it>Candida albicans </it>in liquid and vapour phase and to determine the chemical composition and mechanism of action of most potent essential oil.</p> <p>Methods</p> <p>Minimum Inhibitory concentration (MIC) of different essential oils in liquid phase, assayed through agar plate dilution, broth dilution & 96-well micro plate dilution method and vapour phase activity evaluated through disc volatilization method. Reduction of <it>C. albicans </it>cells with vapour exposure was estimated by kill time assay. Morphological alteration in treated/untreated <it>C. albicans </it>cells was observed by the Scanning electron microscopy (SEM)/Atomic force microscopy (AFM) and chemical analysis of the strongest antifungal agent/essential oil has been done by GC, GC-MS.</p> <p>Results</p> <p>Lemon grass (<it>Cymbopogon citratus</it>) essential oil exhibited the strongest antifungal effect followed by mentha (<it>Mentha piperita</it>) and eucalyptus (<it>Eucalyptus globulus</it>) essential oil. The MIC of lemon grass essential oil in liquid phase (288 mg/l) was significantly higher than that in the vapour phase (32.7 mg/l) and a 4 h exposure was sufficient to cause 100% loss in viability of <it>C. albicans </it>cells. SEM/AFM of <it>C. albicans </it>cells treated with lemon grass essential oil at MIC level in liquid and vapour phase showed prominent shrinkage and partial degradation, respectively, confirming higher efficacy of vapour phase. GC-MS analysis revealed that lemon grass essential oil was dominated by oxygenated monoterpenes (78.2%); α-citral or geranial (36.2%) and β-citral or neral (26.5%), monoterpene hydrocarbons (7.9%) and sesquiterpene hydrocarbons (3.8%).</p> <p>Conclusion</p> <p>Lemon grass essential oil is highly effective in vapour phase against <it>C. albicans</it>, leading to deleterious morphological changes in cellular structures and cell surface alterations.</p

Antidiarrheal and antimicrobial activities of Stachytarpheta jamaicensis leaves

Objective: To evaluate the antidiarrheal and antimicrobial activity of the extract of Stachytarpheta jamaicensis   leaves. Materials and Methods: The methanolic extract of leaves of S. jamaicensis was prepared, with successive extraction in soxhlet apparatus with 300 ml of methanol for 24 h. The methanol extract of the leaves of S. jamaicensis (250 and 500 mg/kg) was studied for antidiarrheal activity using castor oil and magnesium sulphate-induced diarrhea models in mice. The antimicrobial activity of the extract (10 mg/ml) was determined by disk diffusion method. Results: At the doses of 250 and 500 mg/kg, the methanol extract showed significant antidiarrheal activity (P < 0.05). When tested for antibacterial activity, the methanol extract displayed moderate inhibitory activity against Escherichia coli, Staphylococcus epidermis and Pseudomonas aeruginosa   , with an MIC value of 5.00 mg/ml. Conclusion: On the basis of these findings, it can be assumed that S. jamaicensis leaves could be a potential source for novel ′lead′ discovery for antidiarrheal drug development

Antimicrobial Activities and Toxicity of Crude Extract of the Psophocarpus Tetragonolobus Pods

The extract of the Psophocarpus tetragonolobus pods has been tested for antimicrobial activity in a disk diffusion assay on eight human pathogenic bacteria and two human pathogenic yeasts. The extracts of P. tetragonolobus possessed antimicrobial activity against all tested strains. The ethanolic extract of P. tetragonolobus pods was further tested for in vivo brine shrimp lethality test and in vitro sheep erythrocyte cytotoxic assay. The brine shrimp lethality test exhibited no significant toxicity (LC50=1.88 mg/ml) against Artemia salina, whereas sheep erythrocyte test showed significant toxicity. The reason for haemolysis of erythrocyte was discussed. The P. tetragonolobus extract with high LC50 value signified that this plant is not toxic to human. This result also suggested that the ethanolic extract of P. tetragonolobus pods is potential source for novel antimicrobial compounds