Extração de curcuminóides e obtenção in situ de nanopartículas

Abstract

Curcuminoids are phenolic compounds found in Curcuma longa L. rhizomes, which present interesting properties for pharmaceutical and food industries. However, their application is limited due to their poor water solubility. Enhanced solubility and stability of these compounds to external factors may be achieved by encapsulation techniques using biocompatible polymers. Nevertheless, application is still difficult due to high time consumption, resources and high costs when extraction and encapsulation processes are conducted separately. The objective of this work was to produce curcuminoids-loaded polyvinylpyrrolidone (PVP) nanoparticles during their extraction from Curcuma longa L. rhizomes. Optimization of the experimental conditions was performed by the Central Composite Design (CCD) methodology. Temperature, ethanol percentage in the solvent and encapsulant mass (PVP) were selected as independent variables. Quantification of the extracted curcuminoids (curcumin, demethoxycurcumin and bisdemethoxycurcumin) and their water solubility were determined by High Performance Liquid Chromatography. Characterization of nanoparticles obtained under the optimal conditions was performed by Differential Scanning Calorimetry, Fourier Transform Infrared Spectroscopy, Transmission Electron Microscopy and X-Ray Diffraction. The extraction yield and water solubility of the curcuminoids, quantified after the experimental design were fitted to quadratic models resulting in eight statistically significant regressions (p < 0.05). Desirability functions were used for the simultaneous optimization of the responses. The optimized experimental conditions were 29.9°C, 99% ethanol and 15.38 mg PVP. At this point, the predicted responses were 0.0015 mg.mgturmeric-1 for bisdemethoxycurcumin solubility, 0.0014 mg.mgturmeric-1 for demethoxycurcumin solubility, 0.0038 mg.mgturmeric-1 for curcumin solubility and 10.9% extraction yield for total curcuminoids. Characterization of the nanoparticles produced under the optimal conditions revealed that the physical state of curcuminoids was modified from crystalline to amorphous and chemical interactions between curcuminoids and encapsulant were detected, which strongly suggests their encapsulation. Biological assays revealed that curcuminoids nanoparticles significantly inhibited the in vitro activities of acetylcholinesterase (AChE) (12% inhibition for 50 μM) and glutathione S-transferase (GST) (30% inhibition for 5 μM), from rat brain tissue. It was possible to simultaneously extract and encapsulate the curcuminoids from turmeric demonstrating that curcuminoids may act in the cholinergic and endogenous antioxidant systems despite their hydrophobicity.