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In vitro antioxidant activity of crude extracts of Harpagophytum zeyheri and their anti-inflammatory and cytotoxicity activity compared with diclofenac

  • Ncube, Sibonokuhle F.1
  • McGaw, Lyndy J.2
  • Njoya, Emmanuel Mfotie2, 3
  • Ndagurwa, Hilton G. T.1, 4
  • Mundy, Peter J.1
  • Sibanda, Samson1
  • 1 National University of Science and Technology,
  • 2 University of Pretoria,
  • 3 Martin Luther University,
  • 4 University of the Witwatersrand,
Published Article
BMC Complementary Medicine and Therapies
BioMed Central
Publication Date
Sep 23, 2021
DOI: 10.1186/s12906-021-03407-x
PMID: 34556115
PMCID: PMC8461911
PubMed Central
  • Research


Background This study evaluated the in vitro antioxidant activity and comparison of anti-inflammatory and cytotoxic activity of Harpagopytum zeyheri with diclofenac. Methods In vitro assays were conducted using water, ethanol, and ethyl acetate extracts of H.zeyheri . The antioxidant activity was evaluated using the 2,2′-diphenyl-1-picrylhydrazy (DPPH) and 2,2′- azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. The anti-inflammatory activity was determined by measuring the inhibition of nitric oxide (NO) on lipopolysaccharide (LPS)-induced RAW 264.7 mouse macrophages as well as cytokine (TNF-α and IL-10) expression on LPS-induced U937 human macrophages. For cytotoxicity, cell viability was determined using the 3-(4, 5-dimethylthiazol- 2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Results The ethyl acetate extract had the lowest IC50 values in the DPPH (5.91 μg/ml) and ABTS (20.5 μg/ml) assay compared to other extracts. Furthermore, the ethyl acetate extracts effectively inhibited NO and TNF-α and proved to be comparable to diclofenac at some concentrations. All extracts of H. zeyheri displayed dose-dependent activity and were associated with low levels of human-IL-10 expression compared to quercetin. Furthermore, all extracts displayed low toxicity relative to diclofenac. Conclusions These findings show that H. zeyheri has significant antioxidant activity. Additionally, similarities exist in the inflammatory activity of H. zeyheri to diclofenac at some concentrations as well as low toxicity in comparison to diclofenac.

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