ANTIOXIDANT ACTIVITY OF COMPOUNDS ISOLATED FROM PYCNANTHUS ANGOLENSIS (WELW.) WARB AND BYROPHYLLUM PINNATUM (LAM.) OKEN

Oladimeji Oladimeji,Augustine A Ahmadu

doi:10.17628/ecb.2019.8.96-100

Abstract

Pycnanthus angolensis (Welw.) Warb and Byrophyllum pinnatum (Lam.) Oken are two herbal recipes employed in native medicine for the treatment /management of gastrointestinal disorders, skin infections and more especially cancers, wounds and many other inflammatory conditions. Before now, seven compounds ( NG-1b, NG-2 , NG-3b, NG-4c, NG-5a , KF - 1a and KF - 2) have been obtained from the extracts of these plants by column and /or preparative thin - layer chromatographies. The search for new and more active antioxidant agents necessitated the screening of these compounds for potential activity. Generally the isolates gave (IC 50 ) of between 0.50and 0.60 μg mL -1 .However, NG-1b demonstrated a significant activity at 0.48 μg mL -1 which compare favourably with that shown by Vitamin A (a standard antioxidant drug) at 0.49 μg mL -1 . These compounds, most especially NG-1b could be further worked on with the aim of improving on the observed antioxidant activity through in-vitro structural activity relationship studies (SARS) and probably in-vivo clinical trials.

Highlights

Free radicals occur in the human body in the forms of reactive oxygenated species (ROS), super-oxides, peroxides, hydroxyl and nitrogenous species
The crude extracts and resultant sub-fractions were separately put through silica chromatographic separations and the exercises led to the isolation of compounds coded as NG-1b, NG-2, NG-3b, NG-4c, NG-5a, KF-1a and KF-2 respectively
NG-1b=ethyl cinnamate; NG-2=3ethoxy-3,7-dimethyl-1,6-octadiene; NG-3b=9oximino-2,7-diethoxyfluorene (2,7-diethoxy-9H-fluoren-9-one oxime); NG-4c=1,2-benzenedicarboxylic acid diethyl ester; NG-5a = ethyl 1,6-dihydro-2-methyl-4-hydroxy-6-oxo3-pyridine carboxylic acid, ethyl ester (1,6-dihydro-2-methyl-4hydroxy-6-oxo-3-nicotinic acid, ethyl ester; KF-1a=1-ethoxy-2hydroxy-4-prophenyl guaethol; KF-2 = 17-spiro(1ʹ-cyclobutan)-2ʹone-3-hydroxy)-(3β, 17β)-androst-5-ene; RSA % (PI %) = Radical scavenging activity (Percentage inhibition); IC50 = concentration at which 50 % of DPPH is scavenged or inhibited; NR=Not regressed

Summary

Introduction

Free radicals occur in the human body in the forms of reactive oxygenated species (ROS), super-oxides, peroxides, hydroxyl and nitrogenous species. Previous studies by the lead author and co-workers have led to seven compounds namely, ethyl cinnamate (cinnamic acid, ethyl ester) (NG-1b), 3-ethoxy-3,7-dimethyl-1,6-octadiene (ethyl linalool) (NG-2), 9-oximino-2,7-diethoxyfluorene (2,7diethoxy-9H-fluoren-9-one oxime) (NG-3b), 1,2benzenedicarboxylic acid diethyl ester (diethyl phthalate) (NG-4c), ethyl 1,6-dihydro-2-methyl-4-hydroxy-6-oxo-3pyridine carboxylic acid, ethyl ester (1,6-dihydro-2-methyl4-hydroxy-6-oxo-3-nicotinic acid, ethyl ester (NG-5a), 1ethoxy-2- hydroxy-4-prophenyl guaethol (KF-1a) and 17-(1ʹcyclobutan)-2ʹ-one-3-hydroxy)-(3β,17β)-spiro(andorst-5-ene, (KF-2) from the plants.12-15 This present study was done by subjecting the crude extracts and the seven isolated compounds to antioxidant tests with a view of confirming or disproving the reported uses in ethno-medicine for the treatment/management of inflammatory conditions which arise from the debilitating incidence of free-radicals.

Results

Conclusion