Tropical Journal of Pharmaceutical Research

Original Research Article | OPEN ACCESS

Isolation and characterization of antioxidant constituents of the fruit of Telfairia occidentalis Hook F (Cucurbitaceae)

Olorunfemi A Eseyin¹ , Uduak Benedict², Paul S Thomas², Iweh Etim¹, Emmanuel Essien³, Ekarika Johnson¹, Aniekan Ebong¹, Zubaid Munavvar⁴, Ashfaq Ahmad⁵, Afzal Sheryar⁴, Ukeme Akpan⁶

¹Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmacy, University of Uyo, Uyo, Nigeria; ²Department of Pharmacognosy and Natural Medicine, Faculty of Pharmacy; ³Department of Chemistry, Faculty of Science, University of Uyo, Uyo, Nigeria; ⁴Faculty of Pharmacy, Mahsa University, Kuala Langat, Selangor, Malaysia; ⁵Department of Pharmacology, Virginia Commonwealth University, Richmond, USA; ⁶Department of Inspection and Enforcement, National Environmental Standards and Regulations Enforcement Agency, Abuja, Nigeria.

For correspondence:- Olorunfemi Eseyin Email: olorunfemieseyin.pharm.lect@uniuyo.edu.ng Tel:+2348065161478

Accepted: 9 September 2018 Published: 31 October 2018

Citation: Eseyin OA, Benedict U, Thomas PS, Etim I, Essien E, Johnson E, et al. Isolation and characterization of antioxidant constituents of the fruit of Telfairia occidentalis Hook F (Cucurbitaceae). Trop J Pharm Res 2018; 17(10):1953-1960 doi: 10.4314/tjpr.v17i10.9

© 2018 The authors.
This is an Open Access article that uses a funding model which does not charge readers or their institutions for access and distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0) and the Budapest Open Access Initiative (http://www.budapestopenaccessinitiative.org/read), which permit unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited..

Abstract

Purpose: To evaluate the antioxidant property of the fruit of Telfairia occidentalis and isolate the components responsible for the antioxidant activity.

Methods: The fruit pericarp was macerated with methanol and the extract obtained successively partitioned with n-hexane, dichloromethane and ethyl acetate. The in vitro antioxidant activity of the extract and fractions was evaluated using 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging, reducing power, nitric oxide scavenging, total antioxidant and hydrogen peroxide scavenging assays. The n-hexane fraction, which had the highest DPPH scavenging and total antioxidant activities, was subjected to column and thin layer chromatography to isolate the components. The isolated compounds were identified by ultraviolet-visible (UV), nuclear magnetic resonance (NMR), Fourier transform infra-red (FTIR) spectroscopy and mass spectrometry.

Results: Among the fractions tested, n-hexane had the best total antioxidant activity of 99.44 % at 20 mg/ml (p < 0.05) compared to ascorbic acid at 99.71 % of 20 mg/ml. This fraction also had the highest DPPH radical scavenging activity of all the fractions (p < 0.05) at all test concentrations. For nitric oxide scavenging activity, the whole extract, and the chloroform and aqueous fractions exhibited activity ranging from 92.29 to 97.66 % compared to 98.93 % for ascorbic acid. The hydrogen peroxide scavenging activity of the extract and fractions ranged from 92.60 to 96.23 % compared with of the standard, ascorbic acid (101.68 %). The major components of the n-hexane fractions were α- amyrin and β-amyrin.

Conclusion: The fruit pericarp of Telfairia occidentalis possesses good DPPH radical scavenging activity. This is the first time the antioxidant activity of the fruit (pericarp) and the presence of α- and β-amyrins in Telfairia occidentalis have been reported.

Keywords: Telfairia occidentalis, Fluted pumpkin, Amyrin, Antioxidants