https://dx.doi.org/10.4314/jpb.v19i2.8 Journal of Vol. 19 no. 2, pp. 116-127 (May 2022) PHARMACY AND http://ajol.info/index.php/jpb BIORESOURCES Isolation of pentacyclic triterpene, phenolic content and antioxidant activity of root bark of Irvingia gabonesis Baill. (Irvingiaceae) Aliyu NUHU 1* , Ezzeldin M. ABDURAHMAN 1 , Umar H. DANMALAM 1 , Muhammed U. KAWU 2 , Sadam A. ADEBAYO 3 , Musa BASHIR 4 1 Departmentof Pharmacognosy and Drug Development; 3 Department of Pharmaceutical and Medicinal Chemistry; Faculty of Pharmaceutical Sciences, Ahmadu Bello University, Zaria. Nigeria. 2 Departmentof Veterinary Physiology, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria. Nigeria. 4 Centre for Dryland Agriculture, Bayero University, Kano State, Nigeria. Received 27 th December 2021; Accepted 27 th February 2022 ______________________________________________________________________________ Abstract The aim of this study was to investigate the phytochemical constituents and antioxidant potentials of the ethanol extract and fractions of Irvingia gabonensis root bark in order to establish the scientific basis and rationale for its folkloric use. The powdered root bark of I. gabonensis was macerated with 70% ethanol and then partitioned with different solvents based on their polarity to afford 4 fractions. The extract and fractions were subjected to phytochemical analysis. The in vitro antioxidant activity was evaluated using DPPH assay. The quantitative phytochemical determination showed that ethyl acetate fraction of I. gabonensis root bark (EFIGR) had the highest content of tannins (154.44 mg/GAE g), phenol (106.26 mg/GAE g and flavonoid (76.07 mg/QE g). The in vitro antioxidant activity of the extract and the fractions had IC50 values of 76.0±0.03, 27.0± 0.05, 39.0±0.07 and 28.0±0.10 μg/mL for Ethanol extract, EFIGR, Butanol fraction and Aqueous fraction respectively while the standard had 29.0±0.03 μg/mL.Further fractionation of EFIGR led to the isolation of hederagenin which was characterized using 1D-NMR and mass spectrometric data. The present study revealed that root bark of I. gabonensis is a potential source of natural antioxidant which justified its uses in the traditional medicine. Keywords: Irvingia gabonensis; Qualitative; Quantitative; Hederagenin; Natural antioxidant ______________________________________________________________________________ INTRODUCTION The use of plants in the management and treatment of diseases started with life. In more recent years, with considerable research, it has been found that many plants do indeed have medicinal value [1]. Medicinal plants contain phytochemicals that are mainly primary and secondary metabolites which can be utilized as drug [2]. These phytochemicals * Correspondence. E-mail: aliyunuhu@abu.edu.ng Tel: +234-8032872875. ISSN 0189-8442 2022. Published by Faculty of Pharmaceutical Sciences, University of Jos, Nigeria. Under Creative Commons Attribution-Non-Commercial 4.0 International License. https://creativecommons.org/licenses/by-nc/4.0/ are naturally occurring and biologically active plant compounds that have potential disease inhibiting properties [3]. Plant phytochemicals are potent antioxidants against reactive oxygen species and have several health benefits [4]. Free radicals are chemically unstable species containing unpaired electrons that can cause damage to lipid cells, proteins and DNA as a result of imbalance between the generation of