Phytochemical Screening and Antioxidant Activity of the Ethanol Extract of Api-Api Fruit (Avicennia marina) Using the DPPH Method

Avicennia marina is a mangrove species with potential as a natural source of bioactive compounds; however, the utilization of its fruit as a source of antioxidants remains relatively limited. This study aimed to identify the phytochemical profile and evaluate the antioxidant activity of the ethanolic extract of A. marina fruit using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. A. marina fruits collected from a mangrove area in West Kalimantan, Indonesia, were extracted using ethanol. The phytochemical profile was determined through qualitative screening and functional groups were characterized using Fourier-transform infrared (FTIR) spectroscopy, while antioxidant activity was evaluated spectrophotometrically using UV–Vis spectroscopy, with vitamin C as the positive control. Phytochemical screening revealed the presence of flavonoids, saponins, terpenoids, and tannins, whereas alkaloids were not detected. FTIR analysis showed major absorption bands at 3285.33, 2924.89, 1623.20, 1268.28, and 1028.60 cm⁻¹, indicating the presence of O–H, aliphatic C–H, aromatic/conjugated C=C, and C–O functional groups. The DPPH assay at a maximum wavelength of 517 nm showed that the extract at concentrations of 10–50 ppm exhibited radical scavenging activities of 13.75–76.95%, while vitamin C at 1–5 ppm exhibited 22.38–95.40%. Linear regression equations were y = 1.5692x − 2.7204 (R² = 0.9961) for the extract and y = 18.504x + 4.2081 (R² = 0.9985) for vitamin C, yielding IC₅₀ values of 33.60 and 2.47 ppm, respectively. These findings demonstrate that the ethanolic extract of A. marina fruit possesses DPPH radical-scavenging activity, although lower than that of vitamin C, indicating its potential as a natural source of antioxidant compounds for further development.