Liquid Chromatography-Mass Spectrometric Analyses of Potential Antioxidant Constituents from Zanthoxylum zanthoxyloides Leaves: Probing into the Role of Alkaloids

Thecla O. Ayoka1*, Ngwu Nwachukwun2, Aloysius C. Ene2, Chidi U. Igwe2, Charles O. Nnadi3

1Department of Science Laboratory Technology (Biochemistry Unit), Faculty of Physical Science, University of Nigeria, Nsukka, Nigeria
2Department of Biochemistry, School of Biological Sciences, Federal University of Technology, Owerri, Nigeria
3Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmacy, University of Nigeria, Nsukka, Nigeria

Corresponding Author: thecla.ayoka@unn.edu.ng; Tel: +2348037982401
Recieved Date: September 03, 2020; Accepted Date: October 29, 2020; Published Date: 02 November 2020
Citation: Ayoka TO, Nwachukwun N, Ene AC, Igwe CU, Nnadi CO. Liquid Chromatography-Mass Spectrometric analyses of Potential Antioxidant Constituents from Zanthoxylum zanthoxyloides Leaves: Probing into the Role of Alkaloids. Trop J Nat Prod Res. 2020; 4(10):817-823. https://doi.org/10.26538/tjnpr/v4i10.26
Copyright: © 2020 Ayoka et al This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
ABSTRACT

Zanthoxylum zanthoxyloides is a plant used traditionally as food and in medicine, with known antioxidant properties. The study aimed to prepare n-butanol fractions of Z. zanthoxyloides leaves and evaluate their in-vitro antioxidant potential. Vacuum liquid chromatography (VLC) was used to separate the constituents of the n-butanol fraction using gradients of binary mixtures of dichloromethane in methanol (1L) sequentially in the ratios; 9:1 (BF1), 7:3 (BF2), 5:5 (BF3), 3:7 (BF4), and 1:9 (BF5). Three standard antioxidant assay models were adopted for the in-vitro antioxidant activity. Ascorbic acid (53.60%) exhibited superior antioxidant activity relative to the n-butanol sub-fractions; (BF1 14.51%, BF2 24.76%, BF3 10.90%, BF4 6.19% and BF5 23.38%). Meanwhile, BF3 displayed superior reducing potential relative to ascorbic acid using both the TAC and FRAP method (TAC 2.320 ± 0.002; FRAP 2.27 ± 0.002 versus TAC 0.298 ± 0.000; FRAP 0.274 ± 0.002). BF1, BF2, BF4 and BF5 displayed lower reducing potential: TAC 0.202 ± 0.001; FRAP 0.199 ± 0.000, TAC 0.162 ± 0.001; FRAP 0.153 ± 0.001, TAC 0.186 ± 0.002; FRAP 0.174 ± 0.002 and TAC 0.262 ± 0.000; FRAP 0.223 ± 0.003, respectively when compared to ascorbic acid. Several known potential antioxidants were tentatively characterized in the n-butanol sub-fractions by liquid chromatography-mass spectrometry (LC-MS) dereplication. However, a significant number of alkaloids and phenolic compounds unknown for any role in radical scavenging activity (RSA) were detected in n-butanol sub-fractions. Our findings also further probed the possible role of alkaloids in antioxidant cascade.

Keywords: Zanthoxylum zanthoxyloides, Antioxidant, Phytochemical, Dereplication, Liquid Chromatography-mass spectrometry, Radical scavenging activity.
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