Extração e quantificação por CLAE-DAD de metilxantinas em cacau em pó comercial: avaliando o potencial extrativo de solventes eutéticos

Abstract

In the midst of studying the chemical composition and medicinal properties of plants, there are still many species that have not been investigated. In this context, southern Bahia has much of its area covered by the Atlantic Forest and contains numerous plants with bioactive potential, with Theobroma cacao being a potential source of substances with therapeutic effects in the treatment of diseases. Conventional techniques for extracting these substances use volatile organic solvents such as chloroform, ethanol, methanol, hexane, and propanol. Despite their efficiency in these processes, they may exhibit high toxicity, flammability, and/or high costs. Given this, eutectic solvents, also known as green solvents, present themselves as an alternative. These solvents are often formed by solid materials with high melting points, which result in a liquid mixture at room temperature. In addition to their high capacity to extract bioactive chemical compounds, they also offer low production costs, low melting and boiling points, and, from a sustainability perspective, they have low toxicity, low volatility, and high biodegradability, reducing environmental impact. In this context, this study aims to evaluate the extraction potential of green solvents for the extraction of caffeine, theobromine, and theophylline from a commercial cocoa powder sample, compared to conventional extraction methods. The eutectic solvents were prepared using a heating method with stirring under specific conditions. Choline chloride was used as the hydrogen bond acceptor, and tartaric acid and urea were used as the hydrogen bond donors. The characterization was performed using Fourier Transform Infrared Spectroscopy (FTIR), and the procedure involved diluting the eutectic solvent precursors in acetonitrile. Additionally, the cocoa powder extracts from different solvents underwent an initial pre-treatment step to separate the solid phase using a C18 cartridge, followed by High-Performance Liquid Chromatography with Diode Array Detection (HPLC-DAD) to quantify the methylxanthines and compare the extractions. As a result, the synthesis and characterization of the eutectic solvents were successful, and both proved effective, outperforming ethanol- and methanol-based solvents. Particularly, the choline chloride and urea-based solvent stood out. Thus, the green solvents demonstrated a strong extraction capacity in the process of obtaining methylxanthines, potentially offering a cleaner and more efficient alternative to toxic conventional solvents.