IN-VITRO ANTIOXIDANT ACTIVITIES OF HYDROMETHANOLIC STEM EXTRACT OF Costus afer KER GAWL. (COSTACEAE) AND ITS RESIDUAL AQUEOUS FRACTION
ABDULFATAI ADETUNJI JIMOH1,*, BILKISU BELLO MAIHA2 , BEN AHMED CHINDO1 , JANET
IFEAKANWA EJIOFOR2 , DANJUMA MALLAM1 , AHMED AHMED DANBALA1
- Department of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, Kaduna State University, Kaduna.
Nigeria.
- Department of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, Ahmadu Bello University, Zaria.
Nigeria.
Afr. J Pharm Res Dev; Volume 13(3): 235-244 (2021)
ABSTRACT
Costus afer Ker Gawl (Costaceae) is used traditionally for the treatment of various diseases in several countries in tropical Africa. The antioxidant activities of the hydromethanolic stem extract of this plant and its residual aqueous fraction were investigated in in-vitro studies using spectroscopic methods against 2,2-Diphenyl-1-picryl-hydrazyl-hydrate (DPPH), hydrogen peroxide, Ferric ion Reducing Antioxidant Power (FRAP) and Total Antioxidant Activity Capacity (PM) assays. Total phenols and flavonoids were also determined to assess their effects on the antioxidant activities of this plant. The DPPH free radical scavenging activities of the extract and its residual aqueous fraction were concentration dependent with IC50 values of 23.60 ± 1.00 and 49.40 ± 1.20 µg/ml respectively, while ascorbic acid had the most potent action (IC50 = 1.04 ± 0.10 µg/ml). The scavenging activities of the extract and its residual aqueous fraction against hydrogen peroxide non-free radical decreased with increasing concentration with IC50 values of 31.60 ± 2.30 and 63.10 ± 3.50 µg/ml respectively. There were concentration dependent increases in reducing power of the extract, residual aqueous fraction and ascorbic acid when absorbances were measured at 700 nm against a blank sample. In the PM assay, the total antioxidant activity of the extract was similar to that of ascorbic acid. The total phenolic content of the hydromethanolic extract was 129.8 mg tannic acid equivalent, TAE/g of extract as against 70.2 mg TAE/g of residual aqueous fraction. The total flavonoid contents were 254.9 mg quercetin equivalent, QE/g of extract and 152.9 mg QE/g of residual aqueous fraction. A positive linear correlation was observed between these polyphenols and the free radical scavenging activities. The results indicate that Costus afer stem is a potential source of natural antioxidants.
Email of correspondence: abdulfataijimoh@gmail.com
KEYWORDS: Antioxidant activity; Costus afer; In vitro; Total flavonoid content; Total phenols.