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.

Umbelliferone (7-hydroxycoumarin): A non-toxic antidiarrheal and antiulcerogenic coumarin.

Gastrointestinal diseases are very common problems; available treatments are very limited and come with a range of side effects. Coumarins are an extensive class of phenolic compounds that can be found in plants, fungi and bacteria. The 7-hydroxycoumarin, also known as umbelliferone (UMB), is a compound that comes from coumarin and has been showing biological activities in other studies. As of this scenario, the present study was designed to evaluate the acute oral toxicity, mutagenic, antidiarrheal, anti-bacterial, and antiulcerogenic effects, and antioxidant capacity of UMB. An investigation was conducted through the hippocratic screening method and through histopathological analysis in animals to evaluate the effects of acute oral administration of a dose of 50, 100 and 200 mg/kg of UMB. A micronucleus test on peripheral blood of Swiss mice, which were orally treated with three doses (50, 100 and 200 mg/kg), was conducted to evaluate mutagenic activities. The antiulcerogenic activity was accomplished through the ethanol-induced damage method. Antidiarrheal activities were tested for inducing diarrhea with castor oil and evaluating intestinal transit duration; additionally, the antimicrobial effect against some enteropathogenic bacteria was analyzed. Finally, the antioxidant capability was determined by the capacity of the UMB sample to kidnap the stable radical 2,2-diphenyl-1-picrylhydrazyl. Of the evaluated doses, signs of toxicity after acute administration of the compound were not observed. UMB presented antiulcerogenic activity (100 and 200 mg/kg), which was explained because of its antioxidant capacity. A gastro protective effect was similar to the positive control, and the UMB was able to significantly reduce intestinal transit, and also diarrheal symptoms. Furthermore, UMB had an anti-bacterial effect with minimum inhibitory concentration fluctuating between 62.5 and 1000 µg/mL. Based on these findings, we can suggest that UMB has important biological activities in vivo and in vitro and is not toxic under the evaluated circumstances, which demonstrates its large potential for pharmacological use.