Abstract:The in vitro schistosomicidal effects of the essential oil obtained from Tagetes erecta L. Asteraceae, leaves (TE-EO) collected in Brazil against Schistosoma mansoni worms are reported in this paper. The oil caused a significant decrease in the motor activity at 50 μg/mL as minimal concentration after 24 h. This oil also caused death of all the parasites and the separation of coupled pairs into individual male and female at 100 μg/mL after 24 h. The viability of adult worm groups treated with the TE-EO at 100 μg/mL was similar to that of groups treated with praziquantel (positive control). In addition, the oil promoted the inhibition of eggs development at all the tested concentrations. These data indicate that the TE-EO could be considered as a promising source for the development of new schistosomicidal agents.

The fragmentation of six plumeran indole alkaloids (PIAs) previously isolated from Aspidosperma spruceanum has been investigated by electrospray ionization tandem mass spectrometry (ESI-MS/MS) in the positive ion mode. The fragmentation pathways have been established on the basis of MS/MS experiments using fragment ions generated in-source and deuterium-labeled alkaloids as precursor ions and on the basis of accurate mass measurements. Our results demonstrated that the fragmentation routes observed for the protonated PIAs are essentially derived from a pericyclic reaction and from the opening of rings D and E, followed by 1,4-hydrogen rearrangements. Product ions resulting from radical eliminations were also observed, contrary to the 'even-electron rule'. Our data reveals that some product ions from protonated PIAs provide crucial information for the characterization of the acyl substituent at N-1, the methoxyl and hydroxyl groups at the aromatic moiety, and give evidence of an ether bridge between C-18 and C-21. The data reported here were used for the dereplication of these compounds in a stem bark methanolic extract of Aspidosperma spruceanum.

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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.

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