Larvicidal activity of hexane extract, fatty acids, and methyl esters from Tecoma stans pericarps against Culex quinquefasciatus.

Culex quinquefasciatus (Diptera: Culicidae) is responsible for the transmission of lymphatic filariasis. The search for natural sources of new insecticides to control mosquitoes has intensified in recent years. Tecoma stans is an exotic species in Brazil, known as 'ipê de jardim'. T. stans pericarps were extracted with hexane in Soxhlet apparatus, and fatty acids (FA) and methyl esters (FAME) were obtained by transesterification reaction of hexane extract (HE). HE, FA, and FAME were evaluated against 3rd. and 4th. instar larvae of Culex quinquefasciatus. Analysis by gas chromatography-mass spectrometry (GC/MS) identified the hydrocarbon nonacosane (81.69%) as the major compound in HE, and linolenic (16.89%), linoleic (16.83%), and palmitic acids (21.00%) were predominant in FA. FA and HE, at a concentration of 250 µg/mL, promoted mortality of 81.67% and 68.66% of larvae, respectively. HE and FA obtained from T. stans pericarps have larvicidal potential for the control of C. quinquefasciatus.

Chemical composition, antioxidant and cytotoxic activities of extracts from the pericarp of Tecoma stans (L.) Juss. Ex Kunth (Bignoniaceae).

Tecoma stans (L.), popularly known as ipê-mirim, is used in traditional medicine for the treatment of diabetes and digestive problems. The components of the hexane (HE) and methanol (ME) extracts obtained from the pericarp of T. stans were identified by gas chromatography-mass spectrometry (GC-MS) in their methyl ester forms (FAME). The antioxidant and cytotoxic activities of extracts, fatty acids, and methyl esters were evaluated. Methyl linolenate, methyl linoleate, and methyl palmitate were the major compounds in the HE, while methyl hexacosanoate was the main component in the ME. The samples exhibited significant antioxidant potential by DPPH assay. In the Artemia salina larvae bioassay, FAME (HE) and FAME (ME) were considered toxic. This study showed, for the first time to our knowledge, the chemical composition of the hexane and methanol extracts from T. stans pericarp, as well as the antioxidant and cytotoxic activities of the extracts, fatty acids, and methyl esters.