Euphorbia abyssinica (Camel Slipper plant) is an important medicinal herb in East African traditional
medicine, reputed for treating inflammatory, infectious, and dermatological conditions. While its biological
activities are attributed to various secondary metabolites, a detailed phytochemical profile of its phenolic
fraction remains underexplored. This study aimed to systematically extract, characterize, and evaluate the
antioxidant potential of phenolic compounds from E. abyssinica leaves. An optimized ultrasonic-assisted
extraction using a hydroethanolic solvent (70:30 ethanol/water) at pH 3 was employed. The phenolic
composition was analyzed via Reverse-Phase High-Performance Liquid Chromatography with Photodiode
Array detection (RP-HPLC-PDA). Total phenolic content (TPC) was quantified using the Folin-Ciocalteu
assay, and in vitro antioxidant activity was assessed via the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical
scavenging assay, with results expressed as Gallic Acid Equivalents (GAE) and efficient concentration
(EC). HPLC analysis identified and quantified five major phenolics: chlorogenic acid (45.9 μg/mL),
kaempferol (9.18 μg/mL), caffeic acid (7.25 μg/mL), vanillic acid (3.81 μg/mL), and syringic acid (3.77
μg/mL). The extract exhibited a high TPC of 79.33 mg GAE/100 mL. It demonstrated potent DPPH radical
scavenging activity, with inhibition rates up to 77%, and an EC range of 10.65–11.55 mg GAE/100 mL. The
results confirm that E. abyssinica leaves are a rich source of bioactive phenolics, with chlorogenic acid as
the dominant constituent. The strong correlation between TPC and antioxidant activity provides a scientific
basis for the plant's ethnomedicinal uses in managing oxidative stress-related pathologies and supports its
potential for development into standardized nutraceutical or cosmetic products.