Volatile oils from Olax subscorpioidea Oliv. (Olacaceae): Antioxidant, antibacterial, anticancer activities, and molecular docking

Abstract

Olax subscorpioidea is a medicinal plant from Africa, traditionally used for the management of obesity and metabolic syndrome. This study explored the essential oils from its leaves and roots, assessing their chemical composition and biological properties, including antioxidant, antibacterial, and anticancer activities. Essential oils were extracted via hydrodistillation and analyzed by GC-MS. The toxicity of the oils was carried out using brine shrimp lethality assay (BSLA). Antioxidant capacity was evaluated using DPPH, FRAP, and ORAC assays, while antibacterial activity was tested with the agar well diffusion method. The anticancer potential was determined through sulforhodamine B (SRB) assays on the HT-29 cell line, and molecular docking studies were performed using Chimera software. The leaf oil had eleven components, mainly monoterpene hydrocarbons (76.63 %) and oxygenated monoterpenes (15.10 %). The major compounds found in the leaf oil were Azulene (48.79 %), β-pinene (16.24 %) and α-pinene (7.82 %) whereas azulene (100 %) was only component of the root oil.The leaf and root essential oils of O. subscorpioidea were found to be toxic with LC₅₀ of 0.1771 and 92.642 µg/L, where the leaf oil showed higher toxicity compared to the root oil. The leaf oil demonstrated superior antioxidant activity in FRAP and ORAC assays, while the root oil excelled in DPPH radical scavenging. Additionally, the root oil showed stronger antibacterial effects against Escherichia coli, Streptococcus pyogenes, and Proteus mirabilis. In the cell viability assays, the root oil exhibited better anticancer effects at 24 h, which diminished over 48 h. Molecular docking revealed favorable binding energies (-6.8 to −7.4 kcal/mol) with selected proteins, indicating potential efficacy of O. subscorpioidea oils. In conclusion, the study highlights the toxicity, antioxidant, antibacterial, and anticancer properties of O. subscorpioidea essential oils, suggesting their therapeutic applications as antioxidant, antibacterial, and anticancer agents.