Comparative Study on Antioxidant Activity in Taraxacum officinale, Phyllanthus amarus, and Leucas zeylanica

Abstract

Background: An imbalance between free radicals and antioxidants causes oxidative stress. Natural plant-based antioxidants have gained significant attention due to their potential in managing diseases such as atherosclerosis, Alzheimer's disease, Parkinson's disease, and various cancers. While Taraxacum officinale (Family: Asteraceae; Common name: Dandelion), Leucas zeylanica (Family: Lamiaceae; Common name: Ceylon slitwort), and Phyllanthus amarus (Family: Phyllanthaceae; Common name: Bhumi Amla) plants have known medicinal uses, such as; anti-inflammatory, hepatoprotective, diuretic, antimicrobial, and hepatoprotective effects, comprehensive scientific validation of their antioxidant potential remains limited. Understanding their antioxidant efficacy contributes to knowledge on natural antioxidants and their potential application in healthcare and pharmaceutical industries. Objectives: To evaluate and compare the antioxidant activities of the methanolic extracts of the above selected medicinal plants Methods: The crude extracts from each dried plant were obtained using the maceration technique. A concentration series of each methanolic extract was assessed using the ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, and IC₅₀ values were obtained for each plant in both assays and their antioxidant activities were analysed using GraphPad Prism 10. Ascorbic acid was used as the reference compound for both antioxidant assays. Due to the small sample size and non-parametric distribution of data, Kruskal- Wallis H test was performed using SPSS to compare the IC₅₀ values across plant species. A significant level of p<0.05 was applied. Results: The methanolic extract of Phyllanthus amarus showed strong antioxidant activity with IC₅₀ values of 32.33±18.60 mg/mL in the FRAP assay and 6.024±19.83 mg/mL in the DPPH assay. In contrast, Leucas zeylanica (IC₅₀: 165.5 ± 37.83 mg/mL FRAP, 219.0 ± 27.17 mg/mL DPPH) and Taraxacum officinale (IC₅₀: 180.1± 96.27 mg/mL FRAP, 82.85±27.53 mg/mL DPPH) exhibited comparatively weaker antioxidant activities. Ascorbic acid, used as the reference standard, demonstrated IC₅₀ values of 41.27±27.70 mg/mL (FRAP) and 2.096±23.96 mg/mL (DPPH). Statistical analysis indicated no statistically significant difference in the distribution of IC₅₀ values among the three plant extracts (p=0.142). Conclusions: Although the differences in IC₅₀ values were not statistically significant, the data suggest that Phyllanthus amarus has superior antioxidant potential compared to the methonolic extract of other tested plants. These findings warrant further investigation with larger sample sizes and biological replicates to confirm the observed trend