Carla Mariana da Silva Medeiros¹, Cicero Alves Lopes Júnior ¹, Edivan Carvalho Vieira¹

The Brazilian Cerrado is home to a wide variety of flora and fauna, including plant species with promising bioactive properties. Sterculia striata is a native species that has traditionally been used for its ethnobotanical properties, such as using the leaves to treat wounds and the bark to make tea. Therefore, investigating the chemical composition of this species is essential to understanding its bioactive potential. The aim of this study was to quantify the total phenolic content (TPC) and optimise the green extraction of phenolic compounds from S. striata fruit peels using natural deep eutectic solvents (NADES) assisted by ultrasound, applying response surface methodology (RSM). Two NADES systems were employed in the ultrasonic probe extraction process: a mixture of choline chloride:glucose (1:2), and a mixture of choline chloride:tartaric (1:2), both containing 20% water. The operating parameters were standardised at 2 minutes of extraction, a temperature of 70 °C, 2 s pulses and an amplitude of 50%. TPC was quantified using the Folin-Ciocalteu method. The resulting analytical curve showed the equation Y = 0.00104x + 0.003, with an R value of 0.99957, and limits of detection and quantification of 4.87 µg/mL and 16.25 µg/mL, respectively. The TPC results were 1,167.44 ± 1.07 and 954.12 ± 4.62 mg EAG/100 g for the choline chloride:glucose (1:2) and choline chloride:tartaric acid (1:2) systems, respectively. The test t showed that the means were statistically different at the 95% confidence level. Given this, the phenolic compounds in the choline chloride:glucose (1:2) system will be optimised using RSM Central Composite Design (CCD). The parameters to be evaluated are the sample/solvent ratio, extraction time and pulse duration, and the responses are total phenolic content and antioxidant activity (AA). This study contributes to the sustainable valorisation of Cerrado flora, highlighting the potential of S. striata as a natural source of bioactive phenolic compounds.

Agradecimentos: Universidade Federal do Piauí, Programa de Pós-graduação em Química, FAPEMA, FAPEPI e CAPES