A. A. Craveiro

Larvicidal activity of the essential oil from Lippia sidoides cham. against Aedes aegypti linn

The aim of this work was to study the larvicidal activity of Lippia sidoides essential oil against Aedes aegypti larvae. The essential oil and its hydrolate (saturated solution of essential oil in water) were obtained by vapor extraction and their chemical composition determined by GL-chromatography coupled to mass spectroscopy. Bioassays were run with the essential oil, pure and diluted hydrolate and with their main constituents thymol and carvacrol. The results obtained showed that L. sidoides essential oil and its hydrolate have larvicidal action against the mosquito A. aegypti, causing an almost instantaneous mortality. Thymol, an alkylated phenol derivative and one of the major components of L. sidoides essential oil, was identified as the active principle responsible for the larvicidal action, causing 100% larval mortality at the lowest tested concentration of 0.017% (w/v). These results suggest that the essential oil of L. sidoides is promising as larvicide against A. aegypti and could be useful in the search of newer, more selective, and biodegradable larvicidal natural compounds to be used in official combat programs and at home.

Chemical variation during daytime of constituents of the essential oil of Ocimum gratissimum leaves

Abstract Variation of chemical composition of the essential oil of Ocimum gratissimum eugenol type was studied for 11 h during the daytime. Microwave oven technique was used for the serial extraction and the obtained oils were analysed by GC/MS. A considerable variation was observed in the eugenol yield, 98% at 12.00 am. to 11% at 05.00 p.m. These results show the influence of the solar light on eugenol production and can be useful to indicate the optimal time for collection of the plant.

Essential oil composition of two chemotypes of Lippia alba Grown in northeast Brazil

ABSTRACT Essential oils of six types of Lippia alba (Mill.) N.E. Brown, an aromatic shrub used in folk medicine in northeastern Brazil under the name “cidreira” were analyzed by GC/MS. The results showed neral (27.18–30.40%) and geranial (35.63–40.95%) as the main chemical constituent in three samples, while carvone (42.30–54.69%) was the main constituent in three other samples. These differences allowed for the classification of two chemotypes.

Identification of Some Chemical Components of the Essential Oil from Molasses Grass (Melinis minutiflora Beauv.) and their Activity Against Cattle-Tick (Boophilus microplus)

The essential oil of molasses grass (Melinis minutiflora Beauv.) has shown virtually 100% lethal effect on larvae of the cattle-tick (Boophilus microplus) within 10 min exposure. GC/MS analysis of the essential oil led to the identification of six major components: propionic acid, butyric acid, phenylethyl alcohol, hexanal, 1,8-cineole and 9 -E-eicosene. Two of those components (1,8-cineole and n-hexanal) have also shown individually 100% lethal effect on cattle-tick larvae within 10 min. The presence of 2,6-di-t-butyl-4-methylphenol was assigned to a contaminant from commercially supplied diethyl ether used for the essential oil extraction.

Antioxidant, larvicidal and antiacetylcholinesterase activities of cashew nut shell liquid constituents

Anacardic acid, cardanol and cardol, the main constituents of natural cashew nut shell liquid (CNSL), were obtained by solvent extraction and assayed for antioxidant, larvicidal and antiacetylcholinesterase activity. Their relative percent composition was obtained by HPLC analysis. Antioxidant activity was assessed using the DPPH and ABTS(+) tests, which showed cardanol as the most active, followed by cardol and anacardic acid. The three CNSL components demonstrated good larvicidal activity against Aedes aegypti (LC(50)=12.40 for anacardic acid, 10.22 for cardol and 14.45 for cardanol) and exhibited inhibition zones for acetylcholinesterase enzymes in the TLC test similar to carbachol, which was used as standard. Based on the results, these multipotent compounds represent promising agents in the control of Ae. aegypti, the main dengue vector in Brazil.

Two cleistanthane type diterpenes from Croton sonderianus

Abstract Sonderianol (12-hydroxy-3-oxo-cleistanth-8, 11, 13, 15-tetraene) and 3, 4-seco-sonderianol (methyl 12-hydroxy-3, 4-seco-cleistanth-8, 11, 13, 15, 18(4)-penten-3-oate), two new diterpenes with cleistanthane skeletons, were isolated from heartwood of Croton sonderianus .

Medicinal Plants of Northeast Brazil Containing Thymol and Carvacrol - Lippia sidoides Cham. and L. gracillis H.B.K. (Verbenaceae)

Abstract Lippia sidoides Cham, and L. gracillis H.B.K. (Verbenaceae) are wild aromatic small trees or shrubs of Northeast Brazil vegetation. Chemical analysis of the oils obtained from the two plants by GC/MS revealed that L. sidoides contained thymol (73.1%), while L. gracillis contained carvacrol (47.7%) and p-cymene (19.2%) as main components.

Essential Oil of Mentha x villosa Huds. from Northeastern Brazil

Abstract An oil produced from Mentha x villosa Huds. by steam distillation of plant material collected in Fortaleza was analyzed by GC/MS and retention indices. The oil was found to be rich in piperitenone oxide (55.4%) and γ-muurolene (13.1%).

Volatile constituents of Eugenia uniflora leaf oil from northeastern Brazil

ABSTRACT The leaf oil of Eugenia uniflora L. [syn. Stenocalyx michelii (Berg.) Legrand] was investigated by GC/MS, retention data, and 13C-NMR spectroscopy. The main constituents were selina-1,3,7(11)-trien-8-one (48.52%) and oxidoselina-1,3,7(11)-trien-8-one (17.33%).

Constituents of Brazilian Chamomile Oil

ABSTRACT The constituents of the essential oil obtained from flowerheads of Chamomilla recutita (L.) Rausch. plants growing around Medianeira city, in Parana State, Brazil, were analyzed by GC/MS. The major constituents identified in the oil were similar to those found in oils from other parts of the world. The Brazilian oil contained the following major components: bisabolol oxide B (23%), bisabolol oxide A (17%), (Z)-β-farnesene (16%), α-bisabolol (13%), chamazulene (8%) and chamo-spiroether (5%).