Euphorbia calyptrata (L.) is a medicinal plant used in traditional medicine. In the present work, essential oils from Euphorbia calyptrate were studied in terms of chemical composition, antioxidant, antimicrobial, and hemolytic properties. Results showed that Euphorbia calyptrate essential oils possessed promising aforementioned activities thanks to their richness in bioactive compounds.

Abstract

In this work, we sought to validate the use of Euphorbia calyptrata (L.), a Saharan and Mediterranean medicinal plant, in traditional pharmacopeia. GC-MS/MS identified volatile compounds of potential therapeutic interest. Antioxidant tests were performed using β-carotene decolorization, DPPH radical scavenging, FRAP, beta-carotene bleaching, and TAC. The antimicrobial activity was evaluated on solid and liquid media for bacterial and fungal strains to determine the zone of inhibition and the minimum growth concentration (MIC) of the microbes tested. The hemolytic activity of these essential oils was assessed on red blood cells isolated from rat blood. Phytochemical characterization of the terpenic compounds by GC-MS/MS revealed 31 compounds, with alpha-Pinene dominating (35.96 %). The antioxidant power of the essential oils tested revealed an IC₅₀ of 67.28 μg/mL (DPPH), EC₅₀ of 80.25.08±1.42 μg/mL (FRAP), 94.83±2.11 μg/mL (beta carotene) and 985.07±0.70 μg/mL (TAC). Evaluating solid media‘s antibacterial and antifungal properties revealed a zone of inhibition between 10.28 mm and 25.80 mm and 31.48 and 34.21 mm, respectively. On liquid media, the MIC ranged from 10.27 μg/mL to 24.91 μg/mL for bacterial strains and from 9.32 μg/mL to 19.08 μg/mL for fungal strains. In molecular docking analysis, the compounds naphthalene, shogunal, and manol oxide showed the greatest activity against NADPH oxidase, with Glide G scores of −5.294, −5.218 and −5.161 kcal/mol, respectively. For antibacterial activity against E. coli beta-ketoacyl-[acyl carrier protein] synthase, the most potent molecules were cis-Calamenene, alpha.-Muurolene and Terpineol, with Glide G-scores of −6.804, −6.424 and −6.313 kcal/mol, respectively. Hemolytic activity revealed a final inhibition of 9.42±0.33 % for a 100 μg/mL concentration. The essential oils tested have good antioxidant, antimicrobial, and hemolytic properties thanks to their rich phytochemical composition, and molecular docking analysis confirmed their biological potency.