The chemical composition of the essential oils from leaves, bark and wood of Cassia
bakeriana Craib. was determined by gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). Alcohols, aldehydes and fatty acids were the major components in leaf and bark oil, while wood essential oil was rich in fatty acids. Terpenes such as linalool, (E)-nerolidol and phytol were present in low concentrations. The antimicrobial activity against aerobic and anaerobic oral bacteria was evaluated using the microdilution method, as was the cell viability test carried out with Vero cells. The oils from leaves and bark showed high antimicrobial activity, with minimum inhibitory concentrations between 62.5 and 125 µg·mL−1 for most of the tested bacteria, including Streptococcusmutans, the main etiological agent of dental caries. Leaves oil displayed the lowest cytotoxic effect (EC50 of 153 µg·mL−1), while wood oil exhibited the highest toxicity to Vero cells. C.
bakeriana oils are thus a source of biologically active compounds against aerobic and anaerobic oral microorganisms. This study is the first report on the chemical composition, antimicrobial activity and cytotoxicity of C.bakeriana.
Many essential oils (EOs) of different plant species possess interesting antimicrobial effects on buccal microorganisms and cytotoxic properties. EOs of Kielmeyera coriacea Mart. & Zucc. were analyzed by gas chromatography coupled to mass spectrometry (GC-MS). The EO from leaves is rich in sesquiterpenes hydrocarbons and oxygenated sesquiterpenes. The three major compounds identified were germacrene-D (24.2%), (E)-caryophyllene (15.5%), and bicyclogermacrene (11.6%). The inner bark EO is composed mainly of sesquiterpenes hydrocarbons and the major components are alpha-copaene (14.9%) and alpha-(E)-bergamotene (13.0%). The outer bark EO is composed mainly of oxygenated sesquiterpenes and long-chain alkanes, and the major components are alpha-eudesmol (4.2%) and nonacosane (5.8%). The wood EO is mainly composed of long-chain alkanes and fatty acids, and the major components are nonacosane (9.7%) and palmitic acid (16.2%). The inner bark EO showed the strongest antimicrobial activity against the anaerobic bacteria Prevotella nigrescens (minimum inhibitory concentration-MIC of 50 µg mL−1). The outer bark and wood EOs showed MICs of 100 µg mL−1 for all aerobic microorganisms tested. The EOs presented low toxicity to Vero cells. These results suggest that K. coriacea, a Brazilian plant, provide initial evidence of a new and alternative source of substances with medicinal interest.
S. dublin and S. infantis, showed low to moderate resistance profiles to most antimicrobial drugs. Nalidixic acid and tetracycline were the most and the least effective drugs, respectively, in the disk diffusion tests. We encountered changes in salmonellosis epidemiology in this geographical region.
The antibacterial activity of nine selected essential oils (EOs) against a panel of oral pathogens was investigated in terms of their minimum inhibitory concentrations (MICs) by using the broth microdilution method. Most of the EOs displayed weak activity or were inactive against the selected oral pathogens, with MIC values ranging from 500 to 4000 μg/mL. However, the EO obtained from the leaves of Bidens sulphurea (Asteraceae) was found to display moderate activity against Streptococcus mutans (MIC = 250 μg/mL) and significant activity against Streptococcus mitis (MIC = 31.25 μg/mL). Germacrene D (38.3%), trans-caryophyllene (18.0%), β-elemene (13.9%) and bicyclogermacrene (13.1%) were identified as the main chemical components of this oil. 2,6-Di-tert-butyl-4-methylphenol, previously described as the major constituent in the EO from the flowers of B. sulphurea, was not detected in this study.
The quality of mineral water commercialized in Brazil regarding the microbial content was analyzed and the results were compared with the standards established by the current legislation. Results demonstrated there was no bacterial contamination, but several types of fungi were found. Therefore, bottled mineral water could be considered a possible route for the transmission of filamentous fungi and yeasts.
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