Efecto del aceite esencial de Minthostachys mollis Kunth en la estabilidad oxidativa de aceite de sachainchi (Plukenetia hayllabambana)

RESUMEN El aceite de sachainchi, es considerado un alimento de alto valor nutritivo por su elevado contenido en ácidos grasos poliinsaturados, tocoferoles y esteroles. Sin embargo, al igual que otros aceites de su categoría, es muy susceptible a la oxidación lipídica durante el almacenamiento. El objetivo fue evaluar el efecto del aceite esencial de Minthostachys mollis en la estabilidad oxidativa de aceite de sachainchi (Plukenetia huayllabambana). Se mezcló aceite esencial (AE) de M. mollis con 1, 2, 4, 6 y 8 g/kg de aceite de sachainchi y dos aceites controles (sin AE y con 0,02 g/kg de antioxidante comercial BHT). Todos los tratamientos fueron almacenados a T° ambiente (17 °C promedio). Se midió el índice de peróxido de los tratamientos a los 2, 5, 10 y 15 días de almacenamiento. Se encontró que dosis de 1, 2 y 4 g/kg de AE de M. mollis estabilizaron la oxidación lipídica del aceite de sachainchi hasta por 10 días de almacenamiento con igual efectividad que el antioxidante comercial BHT. Aunque este trabajo revela el potencial que tiene el AE de M. mollis como antioxidante natural en alimentos, es necesario evaluaciones con menores dosis y mayor tiempo de almacenamiento para fortalecer esta primera aproximación.

ABSTRACT Sacha inchi oil is considered a food of high nutritional value, due to its high content of polyunsaturated fatty acids, tocopherols and sterols. However, like other oils in its category, it is very susceptible to lipid oxidation during storage. The objective was to evaluate the effect of Minthostachys mollis essential oil on the oxidative stability of sacha inchi oil (Plukenetia huayllabambana). Essential oil (EO) of M. mollis was applied with 1, 2, 4, 6 and 8 g/kg of sacha inchi oil and two controls (without EO and with 0.02 g/kg of commercial antioxidant BHT). All treatments were stored at room temperature (17 °C average) and the peroxide value of the treatments was measured at 2, 5, 10 and 15 days of storage. It was found that doses of 1, 2 and 4 g/kg of M. mollis EO could stabilize lipid oxidation of sacha inchi oil for up to 10 storage days with equal effectiveness to the commercial antioxidant BHT. Although this work reveals the potential of M. mollis EO as a natural antioxidant in food, evaluations with lower doses and longer storage times are necessary to strengthen this first approximation.

Larvicidal effect of Clinopodium macrostemum essential oil extracted by microwave-assisted hydrodistillation against Culex quinquefasciatus (Diptera: Culicidae)

Abstract INTRODUCTION: In the present study, we determined the chemical composition of Clinopodium macrostemum essential oil obtained by microwave-assisted hydrodistillation and its effect on the growth and development of Culex quinquefasciatus mosquito larvae. METHODS: The essential oil compounds were identified by gas chromatography-mass spectrometry analysis, and bioassays were conducted to evaluate the influence on the developmental stages of early second instar larvae of Cx. quinquefasciatus until the emergence of adults, using essential oil concentrations of 50, 100, 200, 400, and 800mg/L. RESULTS: The gas chromatography-mass spectrometry analyses revealed that the leaf essential oil of C. macrostemum contained 32 compounds and the major chemical compounds identified were linalool (55.4%), nerol (6.4%), caryophyllene (6.25%), menthone (5.8%), geraniol acetate (4.1%), terpineol (3.7%), and pulegone (2.8%). The essential oil yield obtained by microwave-assisted hydrodistillation was 0.8% at 20 min. The treatments showed lethal concentrations (LC50 and LC90) of 22.49 and 833.35mg/L, respectively, after the final measurement of the total number of dead larvae (second, third, and fourth instars), and LC50 and LC90 of 6.62 and 693.35mg/L, respectively, at the end of the experimental period. The essential oil inhibited the growth and development of the mosquito larvae by 32% (relative growth index = 0.68) at 50mg/L, and up to 47% (relative growth index = 0.53) at 800mg/L. CONCLUSION: The present study demonstrated the larvicidal effect of C. macrostemum essential oil on Cx. quinquefasciatus, which can be attributed to the oxygenate compounds obtained by the extraction method.

Essential oils of Cunila galioides and Origanum majorana as anesthetics for Rhamdia quelen: efficacy and effects on ventilation and ionoregulation

This study evaluated anesthetic efficacy and possible effects of the essential oils (EOs) of Cunila galioides (EOC) and Origanum majorana (EOO) on ventilatory rate (VR) and ionoregulation in Rhamdia quelen. In the anesthesia assessments, 50, 100, 200 and 300 μL L-1 EOC and 50, 100, 200, 300, 400 and 500 μL L-1 EOO were tested, and time for induction to sedation and anesthesia stages, as well as recovery, were taken. A second trial employed lower concentrations of both EOs, 10, 25, 50 and 100 μL L-1, in order to verify VR and Na+, K+ and Cl- whole body net fluxes. Sedation was achieved with both oils at 100 µL L-1, and anesthesia at ≥ 200 µL L-1. There was no significant difference between control and EO-treated groups regarding VR, but all fish subjected to 100 µL L-1 EOC died within 2 h of exposure. Overall, ionic loss declined in the presence of the EOs. The EOC at 200 - 300 μL L-1 and EOO at 400 - 500 μL L-1 present the potential to promote fast anesthesia in R. quelen.(AU)

No presente estudo foi avaliada a eficácia da anestesia e possíveis efeitos dos óleos essenciais (EOs) de Cunila galioides (EOC) e Origanum majorana (EOO) sobre a taxa ventilatória (VR) e regulação iônica em Rhamdia quelen. Nas avaliações de anestesia, as concentrações de 50, 100, 200 e 300 μL L-1 EOC e 50, 100, 200, 300, 400 e 500 μL L-1 EOO foram testadas, e os tempos para a indução às fases de sedação e de anestesia, assim como recuperação, foram mensurados. Um segundo ensaio empregou concentrações mais baixas de ambos EOs: 10, 25, 50 e 100 μL L-1 a fim de verificar a VR e o fluxo líquido corporal dos íons Na+, K+ and Cl- . A sedação foi alcançada para ambos os óleos em 100 μL L-1, e a anestesia em concentrações ≥ 200 µL L-1. Não houve diferença significativa entre o controle e grupos tratados com EOs em relação a VR, mas todos os peixes submetidos a 100 µL L-1 do EOC morreram dentro de 2 h de exposição. No geral, a perda iônica declinou na presença dos EOs. O EOC em 200 - 300 μL L-1 e o EOO em 400 - 500 μL L-1 apresentam potencial para anestesia rápida em R. quelen.(AU)