In-vitro Antioxidant Screening of Ethanol Extracts of Costus afer and Justicia carnea Leaves

This study evaluated the in-vitro antioxidant activity of ethanol extract of Costus afer and Justicia carnea leaves. Ethanol extract of the plant leaves were obtained using standard procedures. The antioxidant parameters of the plants extract studied were 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, Ferric Reducing Antioxidant Power (FRAP) and Nitric oxide. In each case, the result of test was compared with that of a standard Ascorbic Acid (Vitamin C). The antioxidant study showed that Justicia carnea extract had a significantly higher Nitric oxide radical scavenging ability (04.16 ± 0.68) compared with Costus afer (02.15 ± 0.26) at 50 µg/ml concentration while DPPH scavenging ability of the extract of Justicia carnea showed no significant difference with Costus afer (07.63 ± 0.42) and (06.29 ± 0.53) at 50 µg/ml concentrations respectively. For FRAP test, the result indicated that ethanol extract of Costus afer (01.78 ± 0.22) was significantly lower (p<0.05) than that of Justicia carnea (05.12 ± 0.22) at 800 µg/ml concentration. The findings show that ethanol extracts of Costus afer and Justicia carnea could operate as main antioxidants and free radical scavengers. The findings back up local assertions that they can be used to treat malaria in folklore medicine.