Avaliação de condições de extração de compostos com atividade antioxidante e determinação do perfil fitoquímico da própolis de Scaptotrigona depilis (Abelha canudo)

Abstract

Propolis produced by stingless bees has attracted increasing scientific interest due to its diverse chemical composition and the therapeutic potential associated with its bioactive compounds. However, propolis from lesser-studied species, such as cks in-depth investigations regarding its chemical constituents and the most efficient methods for extracting its metabolites. In this context, the present study aimed to understand how the concentration of the solvent mixture (ethanol:water) and the extraction time influence the recovery of phenolic and antioxidant compounds from the propolis of this species, using ultrasound-assisted extraction (UAE) and advanced statistical tools such as Central Composite Rotational Design (CCRD). Samples were collected from a meliponary located in the municipality of Verê, in the southwestern region of Paraná State. The samples were subjected to different combinations of ethanol/water solvent ratios (0, 15, 50, 80 and 100%) and sonication times (30, 130, 300, 513 and 600 seconds). The use of ultrasound was essential, as it accelerates mass transfer through the cavitation phenomenon, allowing concentrated extracts to be obtained in significantly shorter times compared to traditional extraction methods. The results revealed significant variations in total phenolic content (TPC) and antioxidant activity measured by the ABTS, DPPH and FRAP assays. The extracts exhibited a wide range of responses: TPC varied from 0.48 to 21.3 mg GAE g ¹, demonstrating that solvent polarity strongly influences the extraction of these compounds. Solvents with higher ethanol content favored the release of phenolics, while very low concentrations or the use of water alone resulted in low yields. Antioxidant activity ranged from 9.5 to 57.4 mmol TE g ¹ (ABTS), 9.13 to 216.3 mmol TE g ¹ (DPPH), and 6.30 to 180.9 mmol Fe² g ¹ (FRAP). Evaluating antioxidant activity using multiple analytical methods is essential, since each method relies on distinct reaction mechanisms. Phytochemical characterization by HPLC-DAD identified three major phenolic compounds: p-coumaric acid, ferulic acid and trans-cinnamic acid. Among them, ferulic acid exhibited the highest concentration (11.2 mg g ¹). The study also showed that each compound has its own optimal extraction conditions, reflecting differences in their structures and solubilities. Response surface analysis and Pareto diagrams demonstrated that both solvent concentration and extraction time influence extraction efficiency, although not always equally. For some responses, such as DPPH, extraction time played a more pronounced role, whereas for others, such as FRAP and TPC, solvent concentration was the main factor. Overall, solvent concentrations between 50% and 85% ethanol were found to favor the extraction of most bioactive compounds evaluated. Based on the mathematical equations generated by the model, it was possible to propose optimized extraction conditions for each variable analyzed. Furthermore, principal component analysis (PCA) revealed clear clustering among the extracts, as observed in treatments T8, T9, T10 and T11, which showed a positive influence on the responses of the phenolic acids identified by HPLC-DAD. The results of this study demonstrate that the propolis of Scaptotrigona depilis possesses significant functional potential and that its extraction can be optimized quickly and efficiently through ultrasound-assisted extraction. This species exhibits promising chemical profiles, reinforcing the importance of future research to expand its applications in the pharmaceutical, food and nutraceutical fields.