Free radical scavenging activity and oxidative stress inhibition of Dalbergiella welwitschii essential oils: evidence from experimental and computational studies

Abstract Free radicals are a growing public health concern because of their contribution to the development and progression of many diseases. Essential oils from medicinal plants have long displayed antioxidant properties that could be exploited in scavenging free radicals and preventing oxidative stress. This study examines the potential of Dalbergiella welwitschii essential oils to prevent oxidative stress by their ability to scavenge free radicals. Insilco studies on the potential of the major compounds present in the oils to inhibit the overexpression of free radical generating proteins (Human Xanthine Oxidase (XOR), Myeloperoxidase (MPO) and Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX2)) was also conducted. The toxicity of the essential oils and its major compounds were ascertained using the Brine shrimp lethality test and ADMET studies. Aristolone (32.3%) and 13-isopimaradiene (88.13%) dominated the oils of the stems and leaves, respectively. The EC 50 of the leaf oil (0.382 µg/mL) and the stem oil (0.369 µg/mL) indicated that they could effectively inhibit free radicals of DPPH even at minute concentrations. Molecular docking studies showed that 13-isopimaradiene had the highest binding affinity with XOR (-7.6 kcal/mol) and MPO (-7.8 kcal/mol) comparable to the standards Allopurinol (-6.0, -6.4 kcal/mol) Dextromethorphan (-6.2, 7.0 kcal/mol) and Ticlopidine (-7.7, -7.0 kcal/mol). Brine shrimp lethality test revealed that the oils were medium toxic in comparison to cyclophosphamide. The ADMET studies confirmed that the major compounds 13-isopimaradiene and aristolone are non-toxic, have good absorption and solubility hence, could be safely administered as drugs with no toxic side effects. These findings show that the essential oils of Dalbergiella welwitschii could be used as a natural alternative source of antioxidants. The major compounds could also serve as scaffolds in the development of drugs with antioxidant potential that could regulate free radical generation.