Caracterização química e atividades biológicas de extrativos obtidos de Nectandra grandiflora Nees e Ocotea lancifolia (Shott) Mez

Abstract

This study aimed to contribute to the chemical knowledge and biological potential of two native trees of the Lauraceae family from Brazil as well as to find applications for the identified extractives. This way, the extractives obtained from Nectandra grandiflora Nees and Ocotea lancifolia (Schott) Mez were studied according to the following: I) Assessment of the N. grandiflora essential oil (EONG) fungicidal potential and its major constituent, (+)-dehydrofukinone (DHF), against wood-rot fungi; II) Verification of the changes on the EO production, chemical composition and antifungal activity in a population of O. lancifolia during one year; III) Characterization of leaf extractives from O. lancifolia and verification of their antioxidant potential as well as their properties as a wood-preserving agent; IV) Evaluation of the influence of three extraction methods on the yields of ethanolic extracts from N. grandiflora, and their chemical and physical properties and V) Assessment of the sedative and anesthetic potential of the N. grandiflora EO and DHF in an animal model. The EO were obtained by hydrodistillation and analyzed through gas chromatography. Multivariate analysis was used to assess the changes on the EO of leaves, inflorescences and fruits from O. lancifolia (EOOL) over a year of collection. The ethanolic extracts were obtained by conventional extraction using Soxhlet, ultrasound and microwave techniques and liquid chromatography (LC-MS), infrared and thermogravimetry were used for main characterization. Isolates of Pycnoporus sanguineus, Gloeophyllum trabeum, Trametes versicolor and Fusarium moniliforme were used for antifungal assays. The extracts antioxidant activity was evaluated by DPPH and ABTS radical reduction methodology. The sedative-anesthetic effects were evaluated in silver catfish juveniles and the tested concentrations were 23-828 mg/L of EONG and 9-160 mg/L of DHF. The EONG (5 μL/mL) promoted micelial inhibition above 70% with IC50 ranged from 0.39 to 1.22 μL/mL for G. trabeum and P. sanguineus, respectively. The DHF (1.25 mg/mL was effective against the both fungi (76.06-79.45%). High yields of leaves EOOL were observed in the spring (1.03%) and in the summer (0.96%), being caryophyllene oxide the predominant constituent, while β-chenopodiol, found in two samples, it is the main chemical difference detected by multivariate analysis. Leaves EOOL presented better antifungal activity against F. moniliforme (67.5%). The LC-MS analysis indicated the presence of quercetin-derivatives in the extracts of both tree species. Among the evaluated extraction methods, the conventional one showed superior yield and thermal stability for N. grandiflora extracts; however, the chemical compositions of different extracts were similar. The antioxidant potential was verified for all assessed extractives. Wood samples treated with 4% of O. lancifolia extractives presented mass loss lower than 8%. Animals exposed to 92-828 mg/L of EONG and 50-160 mg/L reached the anesthesia stage. Analyzing the results, different classes of secondary metabolites were identified in the studied species outlining their promising applications as natural antioxidants, anesthetics for aquatic animals and fungicidal agents.