Chemical composition and in vitro schistosomicidal activity of the essential oil from the flowers of Bidens sulphurea (Asteraceae).

In this study, the chemical composition and the in vitro schistosomicidal properties of the essential oil obtained from Bidens sulphurea flowers (Bs-EO) were investigated. Its major constituents were identified as being 2,6-di-tert-butyl-4-methylphenol (44.98%), germacrene D (33.70%) and ß-caryophyllene (10.23%). Bs-EO at 100 µg mL(-1) caused death of all the adult worms and promoted separation of the couple pairs into individual male and female within 48 h, besides leading to a significant decrease in the motility of the parasites. This oil was also responsible for a remarkable reduction in the number of eggs and the percentage of developed eggs produced by adult worms. These results suggest that the Bs-EO can be considered a promising source for the development of new schistosomicidal agents.

Antimicrobial activity of selected essential oils against cariogenic bacteria.

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%), ß-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.