Comparative Antioxidant Activities of Selected Apiaceous Plants Using EPR Technique

Introduction: Electron Paramagnetic Resonance (EPR) spectroscopy is a unique technique able to identify and quantify free radicals in the complex biological matrices. In this study, free radical scavenging activity of aqueous and methanol extracts of fruits, shoots and roots of dill and parsley was examined using EPR technique, in addition to the determination of their contents of total polyphenols (TPC) and flavonoids (TFC). Method: The hydroxyl anion scavenging activity (HASA) of the tested extracts was determined using EPR spin trapping technique and hypoxanthine/xanthine oxidase system generating (O•-₂). The TPC and TFC were determined using Folin-Ciocalteu and aluminum chloride colorimetric assays. Results: Both aqueous shoot of dill (ADSh) and methanol root of parsley (MPR) demonstrated the strongest inhibition of HASA. On the contrary, the aqueous extract of dill fruit at a concentration of 0.5 mg/ml was found to be pro-oxidant (49.43 %), but at 10 mg/ml demonstrated potent inhibition of HASA (98.12 %). TPC was found to be the highest in the methanol extract of parsley fruit (MPF, 88.62 ± 0.6 mg GAE/g) and the lowest in MPR (4.34 ± 0.050 mg GAE/g). On the other hand, TFC was the highest in MPF (584.29 ± 2.10 mg GAE/g) and the lowest in the methanol extract of dill fruit (MDF, 1.28 ± 0.02 mg rutin/g). Conclusion: In this study, EPR provided a direct insight that all tested apiaceous plants extracts showed effective HASA except two extracts that proved to be pro-oxidant at 0.5 mg/mL This study confirmed that there is no correlation between antioxidant potential and TPC and TFC.