Estudos químicos e biológicos dos óleos essenciais e extratos de HyEstudos químicos e biológicos dos óleos essenciais e extratos de Hyptis dilatata Benth (lamiaceae), procedentes da Serra do Tepequém - Amajari / Roraimaptis dilatata Benth (lamiaceae), procedentes da Serra do Tepequém - Amajari / Roraima

Abstract

The species of the family Lamiaceae are known in Brazil for being very aromatic and for presenting bioactive properties as antioxidant, bactericide, fungicide and insecticide. In this work was analyzed Hyptis dilatata Benth, found in areas of cerrado in Brazil. The chemical components, the biological activity of the essential oil and extracts of leaves and flowers, considering dry and rainy periods, of specimens of the Serra do Tepequém, in Roraima-Brazil, were studied. The essential oils were extracted from the leaves collected at different times (morning, afternoon and night) and from the flowers in the dry and rainy periods. In relation to the hexane and ethanolic extracts from leaves and flowers, these were extracted from specimens collected during the dry and rainy season. The results of the phytochemical profile, derived from the analysis of the hexane and ethanolic extracts of leaves and flowers, presented different secondary metabolites, being identified coumarin, flavonoids, phenols, saponins, alkaloids, among others. The chemical characterization of the essential oils of leaves and flowers showed as main substances α-pinene, β-pinene, limonene, 3-carene, β-caryophyllene, fenchone and camphor. The essential oil extracted from the flowers in the rainy and dry period inhibited the enzyme acetylcholinesterase, respectively, 93.4% and 92.4%, whereas the essential oil extracted from the leaves, in the dry period and in the morning, showed greater inhibition (96.4%). In the analysis of the cytotoxicity activity performed with larvae of Artemia salina, the essential oil extracted from the leaf collected in the rainy period in the morning, and the essential oil extracted from the flower, collected in the rainy season, presented higher toxicity. The ethanolic extracts of the leaf and the hexane extracts of the flower, both collected during the rainy season, were also more toxic. In the antimicrobial assays, flower oils collected in the rainy and dry period demonstrated greater inhibition against the bacteria Staphylococcus aureus and Bacillus cereus. The Candida albicans yeast only showed inhibition with the essential oils of the flower collected in the dry period. In the rainy season only the essential oil extracted from the leaf collected in the morning and afternoon, showed inhibition against the bacteria S. aureus and B. cereus. Regarding the dry period, the essential oil that showed the highest inhibition in B. cereus bacteria was collected in the afternoon. The hexane extracts of the flower collected in the rainy season showed greater inhibition of S. aureus and in the leaves collected in the rainy season. This extract showed greater toxicity with the bacterium Salmonella typhymurium. In the test against yeast C. albicans, the most toxic hexanic extract was that of the leaf collected in the dry period. In this work the essential oils and extracts of H. dilatata were also tested in larvicidal activities of Aedes aegypti, Anopheles darlingi and adulticides with Ae. aegypti. The essential oil with higher toxicity in the larvicidal activities of Ae. aegypti were extracted from the leaf collected in the rainy season, at night time and from the flower in the rainy season. Only the hexane extracts extracted from the flowers showed toxic activity on the larvae of Ae. aegypti. In larvae of An. darlingi, toxicity predominated with the essential oils of the flowers extracted in the dry period and in the essential oil of the leaf extracted in the same period, in the morning. In the adulticidal assays of Ae. aegypti, leaf oil collected in the rainy season at night showed a mortality of 54.4% to 91.9%, at concentrations of 62.5 μg/mL -1 and 1000 μg/mL-1 respectively in the range of 90 minutes of exposure. The knockdown effect (mosquito immobility) was observed in the test for the development of the product prototype with leaf essential oil, collected in the rainy season and in the morning. For that, the insecticidal activity against the mosquito Ae. aegypti, in 20 minutes at the start of the test, with more than 50% of mosquitoes in knockdown state.