We have investigated the chemical composition and the antibacterial activity of the essential oil of Dysphania ambrosioides (L.) Mosyakin & Clemants (Chenopodiaceae) (DA-EO) against a representative panel of cariogenic bacteria. We have also assessed the in vitro schistosomicidal effects of DA-EO on Schistosoma mansoni and its cytotoxicity to GM07492-A cells in vitro. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS) revealed that the monoterpenes cis-piperitone oxide (35.2%), p-cymene (14.5%), isoascaridole (14.1%), and α-terpinene (11.6%) were identified by as the major constituents of DA-EO. DA-EO displayed weak activity against Streptococcus sobrinus and Enterococcus faecalis (minimum inhibitory concentration (MIC) = 1000 μg/ml). On the other hand, DA-EO at 25 and 12.5 μg/ml presented remarkable schistosomicidal action in vitro and killed 100% of adult worm pairs within 24 and 72 h, respectively. The LC values of DA-EO were 6.50 ± 0.38, 3.66 ± 1.06, and 3.65 ± 0.76 μg/ml at 24, 48, and 72 h, respectively. However, DA-EO at concentrations higher than 312.5 μg/ml significantly reduced the viability of GM07492-A cells (IC = 207.1 ± 4.4 μg/ml). The selectivity index showed that DA-EO was 31.8 times more toxic to the adult S. mansoni worms than GM07492-A cells. Taken together, these results demonstrate the promising schistosomicidal potential of the essential oil of Dysphania ambrosioides.
We investigated the gas-phase fragmentation reactions of a series of 2-aroylbenzofuran derivatives by electrospray ionization tandem mass spectrometry (ESI-MS/MS). The most intense fragment ions were the acylium ions m/z 105 and [M+H-C H ] , which originated directly from the precursor ion as a result of 2 competitive hydrogen rearrangements. Eliminations of CO and CO from [M+H-C H ] were also common fragmentation processes to all the analyzed compounds. In addition, eliminations of the radicals •Br and •Cl were diagnostic for halogen atoms at aromatic ring A, whereas eliminations of •CH and CH O were useful to identify the methoxyl group attached to this same ring. We used thermochemical data, obtained at the B3LYP/6-31+G(d) level of theory, to rationalize the fragmentation pathways and to elucidate the formation of E, which involved simultaneous elimination of 2 CO molecules from B.
We report the in vitro schistosomicidal effects of the essential oil obtained from Citrus limonia leaves (CL-EO) and C. reticulata fruit peels (CR-EO), cultivated in Brazil, against Schistosoma mansoni worms. Limonene (29.9%), β-pinene (12.0%), sabinene (9.0%), citronellal (9.0%), and citronellol (5.8%) are the major constituents of CL-EO; limonene (26.5%), γ-terpinene (17.2%), linalool (11.1%), octanal (8.0%), myrcene (6.2%), and capraldehyde (3.9%) predominate in CR-EO. CL-EO displayed moderate lethal concentration 50% (LC ) of 81.7 and 38.9 μg/ml against male and female worms at 24 and 72 h, respectively. At concentrations of 25 and 100 μg/ml, CL-EO separated between 50 and 75% of the coupled worm pairs during the evaluated period. CR-EO presented moderate LC of 81.7 μg/ml against male and female worms at 24 and 72 h. However, this oil separated coupled worm pairs more effectively than CL-EO and displayed lower cytotoxicity to GM07492-A cells (IC = 987.7 ± 88.9 μg/ml) as compared to CL-EO (IC = 187.8 ± 2.9 μg/ml). The enantiomers (+)-(R)-limonene and (-)-(S)-limonene did not affect S. mansoni adult worm pairs significantly. Taken together, these data indicate that CL-EO and CR-EO exhibit moderate in vitro schistosomicidal activity against adult S. mansoni worms.
We evaluated the antimicrobial activity of 25 monoketone curcuminoids (MKCs) against a representative panel of cariogenic bacteria in terms of their minimum inhibitory concentration (MIC) values. Curcumin A (10) displayed promising activity against Streptococcus mutans (MIC = 50 μg/ml) and Streptococcus mitis (MIC = 50 μg/ml) as well as moderate activity against S. sanguinis (MIC = 100 μg/ml), Lactobacillus casei (MIC = 100 μg/ml), and Streptococcus salivarius (MIC = 200 μg/ml). Results indicated higher activity of compound 10 than that of its bis-β-diketone analog. Additionally, compounds 3a (1,5-bis(4-methylphenyl)pentan-3-one) and 7b (1,5-bis(4-bromophenyl)pentan-3-ol) were moderately active against S. mitis (MIC = 100 μg/ml) and S. salivarus (MIC = 200 μg/ml).
The main pathogen underlying citrus variegated chlorosis (CVC), a citrus fruit disease, is Xylella fastidiosa, a Gram‐negative s‐shaped bacterium that blocks water and nutrient circulation. Discovering new pesticides to combat CVC have become a challenge. Research into essential oils (EOs) is crucial because these substances can be potentially useful in pest control. This study aims to determine minimum inhibitory concentrations (MIC), to investigate biofilm inhibition capacities through MBIC50 analysis, and to evaluate synergistic effects with streptomycin of 17 EOs against X. fastidiosa. This study also analyses the chemical profiles of the EOs that provided the best antibacterial activity results. The MIC values of the EOs ranged from 125 to 1,000 µg/ml. Analysis of the MICB50 values of the sandalwood and patchouli EOs revealed biofilm inhibitory activity. No synergistic effects were evident for streptomycin combined with the sandalwood or patchouli EOs: ΣFIC was 1.25 and 1.5, respectively, which denoted indifference. We detected α‐gurjunene (27.6%), patchouli alcohol (21.6%), α‐bulsene (17.3%) and α‐patchoulene (6.3%) as the major patchouli EO constituents. On the basis of our results, the sandalwood and patchouli EOs present antibacterial action and are promising natural sources for the development of new pesticides against X. fastidiosa.
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