Volume 19, Issue 44, July - December, 2025

Antioxidant potential of extracts from Ehretia amoena - A Swazi medicinal plant

Manoharan Karuppiah Pillai¹, Noncedo Lomini Sithole¹, Justice Mandlenkhosi Thwala^1♦

¹Department of Chemistry, Faculty of Science & Engineering, University of Eswatini, Kwaluseni Campus, Private Bag 4, Kwaluseni, M201, The Kingdom of Eswatini, Southern Africa

^♦Corresponding author
Justice Mandlenkhosi Thwala; Department of Chemistry, Faculty of Science & Engineering, University of Eswatini, Kwaluseni Campus, Private Bag 4, Kwaluseni, M201, The Kingdom of Eswatini, Southern Africa

ABSTRACT

Ehretia amoena belongs to the Boraginaceae family. E. amoena finds several therapeutic applications in traditional medicine. Nonetheless, its usage in treating human trypanosomiasis (sleeping sickness) and diabetes mellitus is astonishing. The objectives of the present study were to evaluate the antioxidant potential, determine the IC50 value, determine total phenolic contents (TPCs), and determine total flavonoid contents (TFCs) of various solvent extracts from the leaves and stem-bark of E. amoena. Various solvent extracts were obtained by combining maceration and hot solvent extraction techniques. DPPH radical scavenging assay was used to evaluate the antioxidant potential and to determine the IC50 values. Folin-Ciocalteu and aluminium chloride colorimetric methods were employed to estimate the TPCs and TFCs, respectively. At a concentration range of 200-3000 μg/mL, the DPPH radical scavenged by various extracts from leaves and stem-bark and the positive control (ascorbic acid) was in the ranges of 22.00±0.20-65.00±0.10%, 20.85±0.20- 63.04±0.30% and 55.50±0.20-85.20±0.20%, respectively. Similarly, the IC50 values of various extracts from leaves and stem-bark were in the ranges of 691.80- >3000μg/mL and 560.45- >3000μg/mL, respectively. The IC50 value of the positive control was <200 μg/mL. The ethyl acetate extract showed lowest IC50 value of 691.80μg/mL among the extracts from leaves and the acetone extract showed lowest IC50 value of 560.45μg/mL among extracts from stem-bark. The TPCs of various extracts from leaves and stembark were in the ranges of 1.22±0.02-6.61±0.04 and 1.48±0.01-7.45±0.01mg GAE/g DW, respectively. The TFCs of various extracts from leaves and stem-bark were in the ranges of 17.7±0.02-90.0±0.02 and 31.2±0.05-81.6±0.08mg QE/g DW, respectively. We concluded that various leaves and stem-bark extracts from E. amoena showed a moderate to significant radical scavenging activity and possessed a moderate to higher TPCs and TFCs. The ethnomedicinal use of E. amoena is supported from this findings and antioxidant-based therapeutics can be developed.

Keywords: Ehretia amoena, Boraginaceae, antioxidant activity, DPPH radical scavenging assay, IC50 values, total phenolic contents (TPCs), total flavonoid contents (TFCs).

Drug Discovery, 2025, 19(44), e14dd2089

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Published: 03 August 2025