Obtenção de compostos bioativos das folhas do guaranazeiro (Paullinia cupana) utilizando diferentes métodos de extração

Abstract

The Guaraná plant (Paullinia cupana) is a native species widely cultivated in Brazil, especially in the state of Amazonas. Despite the diverse uses of the plant, the bioactive compounds present in its leaves remain poorly explored. This study presents a novel investigation of these compounds, using different extraction techniques with the purpose of adding value to the Guaraná production chain. The dry leaf extracts were obtained through four methods: extraction by maceration (MA) and extraction by shaker (SH), both for 24 hours; extraction by Soxhlet (SO), for 6 hours; and extraction by ultrasound (US), for 5, 10, and 15 minutes. Each technique was performed with three solvents (100 % ethanol, 50 % ethanol, and water), except Soxhlet, which was carried out only with 100 % ethanol. The analyses included proximate composition, total phenolic content, antioxidant activity, Fourier-transform infrared spectroscopy (FTIR), and ultrahigh-performance liquid chromatography coupled with mass spectrometry (UHPLC-ESI-QTOF-MS/MS). The extracts showed 16.30±0.68% proteins, 72.02±1.24% carbohydrates, and an energy value of 380.28 ± 2.48 kcal/ g. Ultrasound extraction (15 min) and maceration, both with 50 % ethanol, resulted in the highest yields (34.33 % and 33.72 %), as well as the highest total phenolic contents (2906.21 ± 4.91 and 2794.70 ± 4.91 mg GAE/100 g) and significant antioxidant activity (90.79 ± 1.95 % and 89.23 ± 1.56 % DPPH radical inhibition), respectively. FTIR revealed more intense peaks in the extracts obtained by ultrasound (15 min), shaker, Soxhlet (100 % ethanol), and maceration (50 % ethanol), allowing the identification of important functional groups such as hydroxyl (–OH), carbonyl (C=O), aromatic rings (C=C), nitrogen-containing compounds (C–N), and the presence of organic compounds such as aromatic hydrocarbons (C–H). Chromatographic analysis was performed with the extract obtained by maceration using 50 % ethanol, which showed the best peak distribution, enabling the identification of 17 ionized compounds, including alkaloids (theobromine, caffeine), flavonoids (catechin, epicatechin), and condensed tannins (procyanidin dimers and trimers of types A and B, with the latter being the most abundant). These results highlight the biotechnological potential of Guaraná leaves for applications in the food, cosmetic, pharmaceutical, and supplement industries, to strengthen the bioeconomy of the State of Amazonas.