Estudo Químico do Óleo Essencial de Plectranthus Ornatus Codd: Identificação de Compostos Voláteis, Síntese e Caracterização de Complexo de Inclusão em β-Ciclodextrina

Abstract

Plectranthus ornatus Codd (Lamiaceae), popularly known as “boldo pequeno”, is a medicinal plant used to treat ailments that affect the digestive system. This plant is of economic importance, because its essential oil presents antioxidant and antimicrobial activity, besides potentiating the bactericidal effect of antibiotics. However, the bioactivity of the essential oil of P. ornatus (POEO) can be compromised if exposed to ultraviolet light, high temperatures or humidity, making its application in the pharmaceutical area difficult. One of the alternatives to circumvent these disadvantages is the encapsulation of essential oils by β-cyclodextrin (β-CD). In view of this, this TCC sought to perform the chemical study of POEO, aiming the isolation and identification of the volatile profile of this essential oil, as well as the preparation and characterization of its inclusion complex in β-CD. In view of this, the essential oil was isolated from the leaves of P. ornatus by means of hydrodistillation in a bidistilled clevenger apparatus, while to characterize it, the GC-MS technique was used. In addition, with P. ornatus essential oil and β-CD a total of three POEO/β-CD inclusion complexes were prepared by physical mixing (PM), water kneading (KW) and water/ethanol kneading (KWE) methods. These three POEO/β-CD inclusion complexes, POEO and β-CD were characterized by FTIR, in addition to which GC-MS was used to characterize KW and KWE. Docking was also carried out with the four main compounds of POEO through molecular dynamics (DM) method, PM6 semi-empirical method and quantum DFT method (wb97xd). The GC-MS analysis of POEO resulted in the identification of 36 volatile compounds, and the four main compounds of this essential oil were: β-caryophyllene (21.52%), terpinen-4-ol (6.89%), phytol (4.00%), and caryophyllene oxide (3.32%). About the functional groups present in the essential oil, most were sesquiterpenes (48.6%) followed by monoterpenes (31.4%). Furthermore, GC-MS analysis indicated that KWE encapsulated a greater amount of POEO molecules than KW. The FTIR data showed encapsulation in KW, KWE and PM. The docking by PM6 showed that hydrogen bonds are one of the factors contributing to interaction of the main volatile compounds of POEO with β-CD in the encapsulation process. Thus, the chemical composition identified in the POEO provides support for the ethnobotanical use of the plant P. ornatus by the population of northern Tocantins. Finally, it is necessary the collaboration of research groups to have more complete results, which in turn allow the proposition of the inclusion complexes of P. ornatus in β-CD as a possible alternative to synthetic drugs.