¹Department of Pharmacy, Faculty of Mathematics and Natural Sciences, Universitas Sriwijaya, Indralaya (OI) Sumatera Selatan 30662, Indonesia
²Phytopharmaceutical Research Center (PRC), Department of Pharmacy, Faculty of Mathematics and Natural Sciences, Universitas Sriwijaya, Indralaya (OI) Sumatera Selatan 30662, Indonesia
³Department of Pharmacy, STIKES ‘Aisyiyah Palembang, Sumatera Selatan 30152, Indonesia
⁴Biomaterials and Drug Delivery System (BiDDS) Research Group, STIKES 'Aisyiyah Palembang, Sumatera Selatan 30152, Indonesia DOI : 10.29228/jrp.889 Robusta coffee fruit peel contains many polyphenolic compounds, so the antioxidant activity is high. These compounds require special extraction techniques to obtain optimal results. This study aims to determine the optimal extraction process conditions for producing polyphenol compounds (flavonoids and anthocyanins) with strong antioxidant activity. The robusta fruit peel extraction process uses the ultrasoundassisted extraction (UAE) method and is analyzed using the full factorial design (FFD) application. Factors in determining the optimal extract consist of extraction time (10-45 minutes), extraction temperature (25-50°C), and solvent pH (2-5). The observed responses included percent yield, total flavonoids, anthocyanin levels, and antioxidant activity. The results of the extraction optimization yielded the optimal extract at an extraction time of 45 minutes, an extraction temperature of 50°C, and a pH of 2. The optimum extract has a yield value of 17.25%, TFC 242.26 mgCE/g, anthocyanins 367.04 mg/100 g, and IC50 22.11 μg/mL. Extract optimization results show a good value with desirability of 0.997. The optimum extract contains 0.21% water content and 0.26% dry shrinkage. The optimum results of the phytochemical screening of the extract contained phenolic compounds, flavonoids, tannins, saponins, and alkaloids. The optimum extract verification results obtained yield percent values of 17.10%, TFC 250.28 mgCE/g, anthocyanins 391.20 mg/100 g, and antioxidant activity 24.54 μg/mL. The response results show values supporting verification, as evidenced by 95% CI and 95% TI range values. Keywords : Factorial design; polyphenol; antioxidant; robusta coffee fruit peel; ultrasound-assisted extraction