Chemical and antimicrobial analysis of husk fiber aqueous extract from Cocos nucifera L.

Cocos nucifera L. (Arecaceae) is a widely distributed species around the tropical areas. Popular uses have been reported in the treatment of arthritis and diarrhea. This study evaluates the antimicrobial activity of husk fiber aqueous extract from C. nucifera and performed the identification of some biological active substances. The minimal inhibitory concentration (MIC) against human pathogen microorganisms was determined. Chromatographic and spectrometric procedures were also performed to isolate and identify the components present in the extract. In the MIC assay of crude aqueous extract, only the methicillin sensible and the resistant (MRSA) Staphylococcus aureus strains were susceptible at 156 μg/mL. The ethyl acetate partition taken from crude extract was more promising (MIC of 78 μg/mL). No fungal growth inhibition was observed. Catechin, epicatechin, two procyanidin dimers and condensed tannins were found in the organic phase. In addition, gallic and ellagic acids were detected for the first time in C. nucifera husk fiber. Gallic acid showed MIC of 39 μg/mL and minimal bactericidal concentration (MBC) at 78 μg/mL. Ellagic acid was not active against the tested strains, as well as catechin and epicatechin. Additionally catechin, epicatechin, two procyanidin dimers and condensed tannins were also detected. The antimicrobial activity observed was selective to S. aureus strains.Keywords: Antimicrobial analyses, Cocos nucifera, arecaceae, ellagic acid, gallic acid, procyanidins, Staphylococcus aureus strainsAfrican Journal of Biotechnology Vol. 12(18), pp. 2478-248

Does the essential oil of Lippia sidoides Cham. (pepper-rosmarin) affect its endophytic microbial community?

Background: Lippia sidoides Cham., also known as pepper-rosmarin, produces an essential oil in its leaves that is currently used by the pharmaceutical, perfumery and cosmetic industries for its antimicrobial and aromatic properties. Because of the antimicrobial compounds (mainly thymol and carvacrol) found in the essential oil, we believe that the endophytic microorganisms found in L. sidoides are selected to live in different parts of the plant. Results: In this study, the endophytic microbial communities from the stems and leaves of four L. sidoides genotypes were determined using cultivation-dependent and cultivation-independent approaches. In total, 145 endophytic bacterial strains were isolated and further grouped using either ERIC-PCR or BOX-PCR, resulting in 76 groups composed of different genera predominantly belonging to the Gammaproteobacteria. The endophytic microbial diversity was also analyzed by PCR-DGGE using 16S rRNA-based universal and group-specific primers for total bacteria, Alphaproteobacteria, Betaproteobacteria and Actinobacteria and 18S rRNA-based primers for fungi. PCR-DGGE profile analysis and principal component analysis showed that the total bacteria, Alphaproteobacteria, Betaproteobacteria and fungi were influenced not only by the location within the plant (leaf vs. stem) but also by the presence of the main components of the L. sidoides essential oil (thymol and/or carvacrol) in the leaves. However, the same could not be observed within the Actinobacteria. Conclusion: The data presented here are the first step to begin shedding light on the impact of the essential oil in the endophytic microorganisms in pepper-rosmarin

Synergism effect of the essential oil from Ocimum basilicum var. Maria Bonita and its major components with fluconazole and its influence on ergosterol biosynthesis

The aim of this study was to evaluate the activity of the EO and its major components of Ocimum basilicum var. Maria Bonita, a genetically improved cultivar, against the fluconazole sensitive and resistant strains of Candida albicans and Cryptococcus neoformans. Geraniol presented better results than the EO, with a low MIC (76 mg/mL against C. neoformans and 152 mg/mL against both Candida strains). The combination of EO, linalool, or geraniol with fluconazole enhanced their antifungal activity, especially against the resistant strain (MIC reduced to 156, 197, and 38 mg/mL, resp.). The ergosterol assay showed that subinhibitory concentrations of the substances were able to reduce the amount of sterol extracted. The substances tested were able to reduce the capsule size which suggests they have an important mechanism of action. Transmission electron microscopy demonstrated cell wall destruction of C. neoformans after treatment with subinhibitory concentrations. In C. albicans ultrastructure alterations such as irregularities in the membrane, presence of vesicles, and cell wall thickening were observed. The biofilm formation was inhibited in both C. albicans strains at MIC and twice MIC. These results provide further support for the use of O. basilicum EO and its major components as a potential source of antifungal agents

Growth inhibition of sulfate-reducing bacteria in produced water from the petroleum industry using essential oils

Strategies for the control of sulfate-reducing bacteria (SRB) in the oil industry involve the use of high concentrations of biocides, but these may induce bacterial resistance and/or be harmful to public health and the environment. Essential oils (EO) produced by plants inhibit the growth of different microorganisms and are a possible alternative for controlling SRB. We aimed to characterize the bacterial community of produced water obtained from a Brazilian petroleum facility using molecular methods, as well as to evaluate the antimicrobial activity of EO from different plants and their major components against Desulfovibrio alaskensis NCIMB 13491 and against SRB growth directly in the produced water. Denaturing gradient gel electrophoresis revealed the presence of the genera Pelobacter and Marinobacterium, Geotoga petraea, and the SRB Desulfoplanes formicivorans in our produced water samples. Sequencing of dsrA insert-containing clones confirmed the presence of sequences related to D. formicivorans. EO obtained from Citrus aurantifolia, Lippia alba LA44 and Cymbopogon citratus, as well as citral, linalool, eugenol and geraniol, greatly inhibited (minimum inhibitory concentration (MIC) = 78 µg/mL) the growth of D. alaskensis in a liquid medium. The same MIC was obtained directly in the produced water with EO from L. alba LA44 (containing 82% citral) and with pure citral. These findings may help to control detrimental bacteria in the oil industry