Inhibition of the Activities of Pro-inflammatory Enzymes and Total Phenolic Contents of Leaf Extracts of Strychnos spinosa
Adamu I. Isa *
Department of Physiology, Faculty of Medicine, University of Bisha, Kingdom of Saudi Arabia and Phytomedicine Programme, Faculty of Veterinary Sciences, University of Pretoria, Private Bag X04, Ondersterpoort, 0110, South Africa
Adebayo S. Adeniyi
Phytomedicine Programme, Faculty of Veterinary Sciences, University of Pretoria, Private Bag X04, Ondersterpoort, 0110, South Africa and Department of Biomedical Sciences, Faculty of Science, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa
Dzoyem J. Paul
Phytomedicine Programme, Faculty of Veterinary Sciences, University of Pretoria, Private Bag X04, Ondersterpoort, 0110, South Africa and Department of Biochemistry, Faculty of Science, University of Dschang, P.O.Box 67, Dschang, Cameroon
Jacobus N. Eloff
Phytomedicine Programme, Faculty of Veterinary Sciences, University of Pretoria, Private Bag X04, Ondersterpoort, 0110, South Africa
*Author to whom correspondence should be addressed.
Abstract
Aims: Strychnos spinosa Lam. is a deciduous tree used in folkloric medicine to treat inflammatory-related conditions. The aim of this study was to establish the effect of leaf extracts of S. spinosa on the activity of pro-inflammatory cyclooxygenase (COX) enzymes and to determine the total phenolic contents of S. spinosa leaves.
Study Design: An in vitro study.
Place and Duration of Study: Department of Paraclinical Sciences, Faculty of Veterinary Sciences, University of Pretoria, Pretoria between June 2013 and November 2013.
Methodology: Extracts were obtained by maceration with acetone, methanol and dichloromethane/methanol (1/1). Fractions were prepared by liquid–liquid fractionation of the acetone extract. COX activity was evaluated using a COX inhibitor screening assay kit, Cayman, MI, USA. The total phenolic content of the extracts were determined using the Folin–Ciocalteau method.
Results: The extracts significantly (P = .05) inhibited COX enzyme activity. The n-butanol, water and hexane fractions selectively inhibited COX-1, with IC50 values of 14.66 ± 0.01, 15.25 ± 0.20 and 14.93 ± 0.01 pg/mL, respectively. The dichloromethane/methanol extract (Dcm/MetE) and methanol extract (MetE) selectively inhibited COX-2, with IC50 values of 15.51 ± 0.05 and 14.47 ± 0.12 pg/mL, respectively. The alkaloid fraction inhibited both COX-1 and COX-2, with IC50 values of 15.42 ± 0.01 and 14.81±0.11 pg/mL, respectively. The water fraction had the highest phenolic content (78 ± 3.71 mg/g galic acetone extract , and the acetone extract had the lowest (8.0 ± 0.01 mg GAE/g).
Conclusion: The selective inhibition of COX-1 and COX-2 by the extracts point to the potential of S. spinosa as a potent anti-inflammatory agent. The results support the use of leaf extracts of S. spinosa in traditional medicine for the treatment of inflammation-related conditions.
Keywords: Strychnos spinosa, anti-inflammatory, cyclooxygenase, phenolics