RESUMEN
Aaptos sp. can be developed and utilized as a new antioxidant source. This study aims to investigate the antioxidantactivity and its acute toxicity of acetone ASE stands for Aaptos sp. Extract and its isolates. Aaptos sp. was extractedby acetone, followed by fractionating with vacuum liquid chromatography, liquid–liquid partition, and radialchromatography. Each step was intervened with thin-layer chromatography. Isolates identified by comparing theirphysical properties and 1H and 13C NMR stands for Nuclear Magnetic Resonance spectrum with literature data.Antioxidant activity assayed qualitatively and quantitatively, and the acute toxicity assayed with brine shrimp lethalitytest. Isolates of ASE (44 g) obtained were AS1 (50 mg), AS2 (23 mg), AS3 (8.3 mg), and AS4 (22 mg). AS1 isidentified as cholestanol. Antioxidant activity assayed qualitatively showed that ASE, AS1, AS2, and AS5 wereshowing as antioxidant activity, only ASE had IC50 values 16.10 µg/ml. LC50 of ASE, AS1, AS2, and AS5 were 1,041.5µg/ml; 1,488.33 µg/ml; 681,87 µg/ml; and 783,21 µg/ml, respectively. In conclusion, there are four isolates from theASE although only cholestanol (AS1) successfully identified. ASE, AS1, AS2, and AS5 have antioxidant activity butonly IC50 of ASEwas measured and they are regarded as safe with LC50 > 1,000 for ASE and LC50 > 200 for its isolates.