Abstract:
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.
