Síntese e caracterização de compostos multifuncionais obtidos do óleo das sementes de Annona Squamosa L.

Abstract

This research aimed to explore the utilization of oil extracted from Annona squamosa Linn. seeds (ASSO), a byproduct of the food industry, as a raw material for obtaining multifunctional compounds with higher added value. In the first chapter, ASSO was subjected to chemical modification aiming at the synthesis of lubricating esters with potential industrial application. In the second chapter, the oil was used in the development of nanoemulsions (NEs) intended for the encapsulation of carvacrol, with the purpose of improving its pharmacological effect. The polyol esters were obtained by an esterification route, preceded by basic hydrolysis, using the polyols neopentyl glycol (NPG), trimethylolpropane (TMP), and pentaerythritol (PE). Characterization was conducted by Hydrogen Nuclear Magnetic Resonance (1H NMR), Fourier transform infrared spectroscopy (FTIR), physicochemical, thermal (thermogravimetric analysis – TGA and differential scanning calorimetry – DSC), and rheological analyses. Structural analyses confirmed the chemical modification of ASSO. The synthesized polyol esters showed high conversion rates (>90%), low acidity indices (~0.5 mg KOH g-1), and high viscosity indices (>180). Furthermore, according to the kinematic viscosity, the NPG, TMP, and PE derivatives may be classified into ISO VG 32, 46, and 68, and SAE 20, 30, and 40 categories, respectively, demonstrating suitability for use as hydraulic and automotive lubricants. Thermal analyses revealed that the polyol esters showed greater stability compared to the unmodified oil, especially the PE derivative. DSC analysis revealed crystallization and melting events in positive temperature ranges, demonstrating that the polyesters are suitable for applications in tropical climates. The rheological properties obtained demonstrated that the samples exhibited Newtonian fluid behavior up to 40 °C and pseudoplastic behavior above 60 °C. In the second stage, ASSO-based nanoemulsions (NEs) were obtained by the high-energy emulsification method using the ultrasonic irradiation process. The formulations were subjected to physicochemical characterization and evaluation of their pharmacological potential. Cytocompatibility was verified by means of the lactate dehydrogenase (LDH) enzyme release assay, while anti-inflammatory activity was investigated by neutrophil degranulation assays stimulated with phorbol-12-myristate-13-acetate (PMA). In addition, the antifungal activity of the formulations against different species of the Candida genus was evaluated. The NEs showed colloidal stability, with a hydrodynamic diameter in the range of 170 nm, polydispersity index (PDI) values close to 0.1, and a ζ potential greater than |30 mV|. The formulations exhibited high encapsulation efficiency (%EE >99%) and sustained release capacity of the active ingredient, reaching a cumulative release of 26% (745 μg) in 72 h, whose release kinetics fit the Korsmeyer-Peppas model, with a release mechanism denominated super case II. Cytocompatibility assays did not indicate a toxicity effect on human neutrophils, neither for free carvacrol (CARV) nor for the carvacrol-loaded nanoemulsion (CNE). Microbiological tests showed that the antifungal potential of the CNE formulation is considerably superior to the unencapsulated active ingredient. Furthermore, anti-inflammatory assays demonstrated that the NEs were able to potentiate the biological effect of carvacrol, with efficacy at concentrations ten times lower (5 μg mL-1) compared to free CARV (50 μg mL-1). Taken together, the results confirm that both the ASSO-derived polyesters and the developed NEs represent promising alternatives for industrial and pharmacological applications, highlighting the high potential of this natural resource as a renewable base for the development of high value-added products.