ABSTRACT
Objective: To evaluate the essential oils (EO) composition, antimicrobial and antioxidant power of a local plant, Daucus gracilis (D. gracilis). Methods: The aerial parts of D. gracilis were subjected to hydro distillation by a Clevenger apparatus type to obtain the EO which had been analyzed by gas chromatography and gas chromatography coupled with mass spectrometry, and screened for antimicrobial activity against five bacteria and three fungi by agar diffusion method. The mechanism of action of the EO was determined on the susceptible strains by both of time kill assay and lysis experience. The minimal inhibitory concentrations were determined by agar macro-dilution and micro-dilution methods. Anti-oxidative properties of the EO were also studied by free diphenyl-2-picrylhydrazyl radical scavenging and reducing power techniques. Results: The EO yielded 0.68 (v/w). The chemical analysis presented two dominant constituents which were the elemicin (35.3%) and the geranyl acetate (26.8%). D. gracilis EO inhibited the growth of Bacillus cereus and Proteus mirabilis significantly with minimal inhibitory concentrations of 17.15 μg/mL by the agar dilution method and 57.05 μg/mL and 114.1 μg/mL, respectively by liquid micro-dilution. A remarkable decrease in a survival rate as well as in the absorbance in 260 nm was recorded, which suggested that the cytoplasm membrane was one of the targets of the EO. The EO showed, also, important anti-oxidative effects with an IC
ABSTRACT
Objective: To evaluate the essential oils (EO) composition, antimicrobial and antioxi-dant power of a local plant, Daucus gracilis (D. gracilis). Methods: The aerial parts of D. gracilis were subjected to hydro distillation by a Cle-venger apparatus type to obtain the EO which had been analyzed by gas chromatography and gas chromatography coupled with mass spectrometry, and screened for antimicrobial activity against five bacteria and three fungi by agar diffusion method. The mechanism of action of the EO was determined on the susceptible strains by both of time kill assay and lysis experience. The minimal inhibitory concentrations were determined by agar macro-dilution and micro-dilution methods. Anti-oxidative properties of the EO were also studied by free diphenyl-2-picrylhydrazyl radical scavenging and reducing power techniques. Results: The EO yielded 0.68 (v/w). The chemical analysis presented two dominant constituents which were the elemicin (35.3%) and the geranyl acetate (26.8%). D. gracilis EO inhibited the growth of Bacillus cereus and Proteus mirabilis significantly with minimal inhibitory concentrations of 17.15 mg/mL by the agar dilution method and 57.05 mg/mL and 114.1 mg/mL, respectively by liquid micro-dilution. A remarkable decrease in a survival rate as well as in the absorbance in 260 nm was recorded, which suggested that the cytoplasm membrane was one of the targets of the EO. The EO showed, also, important anti-oxidative effects with an IC50 of 0.002 mg/mL and a dose-dependent reducing power. Conclusions: D. gracilis EO showed potent antimicrobial and anti-oxidative activities and had acted on the cytoplasm membrane. These activities could be exploited in the food industry for food preservation.
ABSTRACT
The present study describes the chemical composition, antifungal and antioxidant activity of Pelargonium graveolens essential oil. The essential oil profile was determined by GC and GC-MS. The main compounds were citronellol (24.54%), geraniol (15.33%), citronellyl formate (10.66%) and linalool (9.80%). Minimal inhibitory concentrations (MIC) and minimal fungicidal concentrations (MFC) were recorded using the microdilution and macrodilution methods. Commercial antimycotic bifonazol was used as a control. The concentration of 0.25-2.5 mg/ml showed fungicidal activity. The most resistant fungi were Mucor mucedo and Aspergillus species. The antioxidant activity of pure essential oil was evaluated by means of the 2,2-diphenyl-1-picrylhydrazil (DPPH) radical assay. The essential oil of P. graveolens was able to reduce DPPH radicals into the natural DPPH-H form, and this activity was dose-dependent. The oil exhibited antioxidant activity and reduced DPPH to 50% at EC50 value of 0.802 mg/ml of oil solution.
ABSTRACT
Várias pesquisas vêm sendo desenvolvidas e direcionadas no descobrimento de novos agentes antimicrobianos provenientes de extratos de plantas e outros produtos naturais, para serem aplicados em produtos farmacêuticos e cosméticos. Atualmente, existem vários métodos para avaliar a atividade antibacteriana e antifúngica dos extratos vegetais. Os mais conhecidos incluem método de difusão em ágar, método de macrodiluição e microdiluição. A proposta dessa revisão é apresentar diferentes métodos comumente utilizados na pesquisa de novos agentes antimicrobianos, provenientes de extratos vegetais, e elucidar os principais fatores interferentes. Dessa maneira, contribuir como fonte de pesquisa para o desenvolvimento de futuros trabalhos relacionado ao estudo de atividade antimicrobiana de produtos naturais.
Several researches have been developed to search for new antimicrobial agents from extracts of plants and other natural products to be used in pharmaceutical and cosmetic products. Nowadays there are many methods to evaluate the antibacterial and antifungal activity of the plant extracts. The most known assays have been based on diffusion in agar; and micro and macrodilution methods. The purpose of this review is to describe the different methods commonly used for the determination of new antimicrobial agents from the plants extracts and elucidate the main interference factors. Moreover, this contributes as research source for future development of investigations related to the study of antimicrobial activity from natural products.
ABSTRACT
BACKGROUND: Although standardized broth dilution methods for antifungal susceptibility testing are available, easier testing procedures are desirable. We evaluated the E-test (AB disk, Sweden) as a possible alternative instead of NCCLS (National Committee for Clinical Laboratory Standards) broth macrodilution method. METHODS: Fifty-two bloodstream isolates of Candida spp. (including 11 C. albicans, 13 C. tropicalis, 18 C. parapsilosis, 1 C. glabrata, 4 C. krusei, 2 C. pelliculosa, 2 C. lipolytica, and 1 C. guilliermondii) were tested. Amphotericin B and fluconazole MICs for each isolate were determined by both NCCLS broth macrodilution method and E-test. The results of E-test for Candida spp. were compared with those of NCCLS macrodilution method. For selecting plating media for E-test, we compared E-test results in two different media (RPMI and Casiton medium) using five ATCC Candida strains. RESULTS: As E-test media, we selected RPMI medium for amphotericin B and Casitone medium for fluconazole because of higher agreement with NCCLS method. The E-test and NCCLS method of 52 Candida spp. yielded a very narrow range of MICs (0.064-2.0 microgram/mL) for amphotericin B and a broad range of MICs (0.5-64 microgram/mL) for fluconazole. The agreements of E-test within one doubling dilutions of the macrodilution reference were 90.4% (24h and 48h) for amphotericin B, and 90.4% (24h) and 96.2% (48h) for fluconazole. CONCLUSION: The E-test is a valuable alternative to the NCCLS macrodilution method for amphotericin B and fluconazole susceptibility testing of Candida species.