[Show abstract][Hide abstract] ABSTRACT: The silverleaf whitefly Bemisia tabaci (Genn.) biotype B (Hemiptera: Aleyrodidae) is an economically important pest of tomatoes Solanum lycopersicum (L.), causing irregular ripening on fruits and transmitting several plant pathogenic geminiviruses. The management of this pest is commonly based on repetitive spraying with syn-thetic pesticides, causing serious environmental damages and increase of resistance by insect population. In the present study, essential oils from the leaves of Artemisia camphorata Vill., Ageratum conyzoides L., Foeniculum vulgare Mill., Lippia alba (Mill.) N. E. Br., Plectranthus neochilus Schltr., and Tagetes erecta L. were investigated for their possible repellent and oviposition-deterrent effects against B. tabaci biotype B on tomato. In a multi-choice assay, P. neochilus essential oil was the most active repellent and oviposition deterrent. Essential oils of A. conyzoides and T. erecta significantly deterred the female B. tabaci biotype B from laying eggs on treated tomato leaflets compared with the control. (E)-Caryophyllene (30.67 %) and the monoter-penes α-pinene (15.02 %) and α-thujene (11.70 %) were identified as the major constituents of the essential oil of P. neochilus. Our findings demonstrated the potential of essential oil of P. neochilus and other oils in the reduction of settlement and oviposition of B. tabaci biotype B on tomato.
[Show abstract][Hide abstract] ABSTRACT: 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.
Full-text · Article · Dec 2012 · Natural product research
[Show abstract][Hide abstract] ABSTRACT: 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 β-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.
Full-text · Article · Mar 2012 · Natural product research
[Show abstract][Hide abstract] 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.
Full-text · Article · Feb 2012 · Revista Brasileira de Farmacognosia
[Show abstract][Hide abstract] ABSTRACT: The in vitro schistosomicidal effects of the essential oil of Ageratum conyzoides L. (Ac-EO) against adult worms of Schistosoma mansoni is reported in this paper. Concerning this activity, Ac-EO was considered to be active, but less effective than the positive control (praziquantel, PZQ) in terms of separation of coupled pairs, mortality, decrease in motor activity, and tegumental alterations. However, Ac-EO caused an interesting dose-dependent reduction in the number of eggs of S. mansoni. Precocene I (74.30%) and (E)-caryophyllene (14.23%) were identified as the two major constituents of Ac-EO. These compounds were tested individually and were found to be much less effective than Ac-EO and PZQ. A mixture of the two major compounds in a ratio similar to that found in the Ac-EO was also less effective than Ac-EO, thus revealing that there are no synergistic effects between these components. These results suggest that the essential oil of A. conyzoides is very promising for the development of new schistosomicidal agents.
[Show abstract][Hide abstract] ABSTRACT: The chemical composition and the in vitro schistosomicidal effects of the essential oil of Plectranthus neochilus (PN-EO) grown in Southeast Brazil was studied. β-Caryophyllene (1; 28.23%), α-thujene (2; 12.22%), α-pinene (3; 12.63%), β-pinene (4; 6.19%), germacrene D (5; 5.36%), and caryophyllene oxide (6; 5.37%) were the major essential oil constituents. This chemical composition differed from that previously reported for specimens harvested in Africa. Concerning the in vitro schistosomicidal activity against adult Schistosoma mansoni worms, PN-EO was considered to be active, but less effective than the positive control praziquantel (PZQ) in terms of separation of coupled pairs, mortality, decrease in the motor activity, and tegumental alterations. However, PN-EO caused an interesting dose-dependent reduction in the number and the percentage of developed S. mansoni eggs. These results suggest that PN-EO might be very promising for the development of new schistosomicidal agents.
Full-text · Article · Nov 2011 · Chemistry & Biodiversity
[Show abstract][Hide abstract] ABSTRACT: In this paper, cercariae, schistosomula, and adult Schistosoma mansoni worms were incubated in vitro with the essential oil of Piper cubeba (PC-EO) at concentrations from 12.5 to 200 μg/mL, and the viability was evaluated using an inverted microscopy. The effects of PC-EO at 100 and 200 μg/mL on the stages of S. mansoni were similar to those of the positive control (PZQ at 12.5 μg/mL), with total absence of mobility after 120 h. However, at concentrations from 12.5 to 50 μg/mL, PC-EO caused a reduction in the viability of cercariae and schistosomula when compared with the negative control groups (RPMI 1640 or dechlorinated water) or (RPMI 1640 + 0.1% DMSO or dechlorinated water + 0.1% DMSO). On the other hand, adult S. mansoni worms remained normally active when incubated with PC-EO at concentrations of 12.5 and 25 μg/mL, and their viabilities were similar to those of the negative control groups. In addition, at concentrations ranging from 50 to 200 μg/mL, separation of all the coupled adult worms was observed after 24 h of incubation, which is related to the fact of the reduction in egg production at this concentration. The main chemical constituents of PC-EO were identified by gas chromatography-mass spectrometry as being sabinene (19.99%), eucalyptol (11.87%), 4-terpineol (6.36%), β-pinene (5.81%), camphor (5.61%), and δ-3-carene (5.34%). The cytotoxicity of the PC-EO was determined, and a significant cytotoxicity was only obtained in the concentration of 200 μg/mL after 24 h treatment. The results suggest that PC-EO possesses an effect against cercariae, schistosomula, and adult worms of the S. mansoni.
Full-text · Article · Oct 2011 · Parasitology Research
[Show abstract][Hide abstract] ABSTRACT: 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.
Full-text · Article · Feb 2010 · Rapid Communications in Mass Spectrometry
[Show abstract][Hide abstract] ABSTRACT: This work reviews the current literature about the chemical constituents and the biological activities of the subtribe Lychnophorinae (Vernonieae, Asteraceae). The notable secondary metabolites are sesquiterpene lactones of furanoheliangolide (goyazensolide and eremantholide types) and flavonoids. Some of its most investigated activities include its anti-inflammatory, analgesic, antimicrobial and cytotoxic activities, specially for the Lychnophora and Eremanthus species. The data presented on this paper not only displayed the role played by the Lychnophorinae species as a source of bioactive compounds, but also reinforced the need of further studies involving the species of such subtribe.