Analysis of Solvent Concentration Effect and Extraction Method on The Total Phenolic of Syzygium myrtifolium Walp. Leaf Extract

Background: Syzygium myrtifolium Walp., an Indonesian ornamental plant, contains phenolic compounds with antioxidant, anti-inflammatory, and antibacterial activities. The demand for natural antioxidants is rising due to concerns over synthetic alternatives. Objectivity: To determine the total phenolic content (TPC) and antioxidant activity of S. myrtifolium leaf extracts obtained with various solvents (ethanol 60, 70, 80, 96% v/v, ethyl acetate, n-hexane) and two extraction methods (maceration and ultrasonic-assisted extraction, UAE), and to assess the effects of solvent polarity and extraction method. Methods: Leaves were extracted by maceration and UAE. TPC was measured via the Folin–Ciocalteu method (tannic acid equivalents, %) using UV–Vis spectrophotometry. Antioxidant activity was evaluated using the DPPH assay (IC₅₀). Phytochemical screening was also performed. Results: TPC (maceration): 60% ethanol = 18.76%, 96% ethanol = 13.64%, ethyl acetate = 8.33%, n-hexane = 0.83%. TPC (UAE): 60% ethanol = 20.02%, 96% ethanol = 14.04%, ethyl acetate = 10.13%, n-hexane = 0.92%. Solvent type/concentration and extraction method significantly affected TPC (p < 0.05). UAE 96% ethanol showed the strongest antioxidant activity (IC₅₀ ≈ 16.03 ppm), ethyl acetate had moderate activity (≈67–76 ppm), and n-hexane the weakest (≈153–163 ppm). UAE 60% ethanol had the highest TPC but not the strongest activity (IC₅₀ ≈ 88.27 ppm), suggesting antioxidant potency depends on phenolic composition. Conclusion: UAE with 60% ethanol produced the highest TPC, while UAE with 96% ethanol exhibited the strongest antioxidant activity. Further profiling is needed to clarify the phenolic composition–activity relationship.