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. 2018 Dec 16:7:1937.
doi: 10.12688/f1000research.17165.2. eCollection 2018.

Nrf2-Mediated Antioxidant Activity of the inner bark extracts obtained from Tabebuia rosea (Bertol) DC and Tabebuia chrysantha (JACQ) G. Nicholson

Sandra C Garzón-Castaño  1   2 , Iván A Lopera-Castrillón  1 , Francisco J Jiménez-González  3 , Fernando Siller-López  2 , Luz A Veloza  3 , Juan Carlos Sepúlveda-Arias  1
Affiliations

Nrf2-Mediated Antioxidant Activity of the inner bark extracts obtained from Tabebuia rosea (Bertol) DC and Tabebuia chrysantha (JACQ) G. Nicholson

Sandra C Garzón-Castaño et al. F1000Res. .

Abstract

Background: Several ethnobotanical and ethnopharmacological studies have shown the therapeutic potential of plants from the genus Tabebuia, which have long been used in traditional medicine in rural areas of South America, for the treatment of several human diseases. This study aimed to evaluate the Nrf2-mediated antioxidant activity of the inner bark extracts obtained from Tabebuia rosea and Tabebuia chrysantha. Methods: The antioxidant activity of extracts obtained from the inner bark of T. rosea and T. chrysantha was evaluated using the Oxygen radical absorbance capacity (ORAC) technique. The effect of extracts on the viability of HepG2 cells was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method. The translocation of Nrf2 to the nucleus after exposure of HepG2 cells to the extracts and controls (α-lipoic acid, curcumin and hydrogen peroxide) was evaluated using the Nrf2 transcription factor kit. Induction of the Nrf2-mediated antioxidant response gene ( NQO1) was evaluated by real-time PCR. Results: The ethyl acetate extract obtained from both species displayed the highest ORAC activity (12,523 and 6,325 µmoles Eq Trolox/g extract). In addition, the extracts had the ability to activate and to translocate Nrf2 to the nucleus, as well as to induce the expression of NQO1. Conclusion: These results indicate that the ethyl acetate extracts obtained from the inner bark of T. chrysantha and T. rosea have an important antioxidant effect mediated by Nrf2 activation, and could be used as a new source of natural antioxidants.

Keywords: Bignoniaceae; Nrf2; Tabebuia chrysantha; Tabebuia rosea; antioxidant agents.; extracts.

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Conflict of interest statement

No competing interests were disclosed.

Figures

Figure 1.
Figure 1.. Nrf2 levels in cytosol (C) and nucleus (N) after 0 (white bars) and 4 hours (black bars) exposure to 50 mM ALA, 15 mM CUR, ethyl acetate extracts from T. chrysantha (0.5 μg/mL) and T. rosea (1 µg/mL) and induction of oxidative stress with 0.6 mM H 2O 2.
Kruskal Wallis ** p<0.01, *** p<0.001. ALA: Alpha-lipoic acid; CUR: Curcumin.
Figure 2.
Figure 2.. Relative NQO1 mRNA levels with 0, 6 and 12 hours post-exposure to 50 mM ALA, 15 mM CUR, ethyl acetate extracts from T. chrysantha (0.5 μg/mL) and T. rosea (1 µg/mL) and induction of oxidative stress with 0.6 mM H 2O 2.
Kruskal Wallis * p<0.05. ALA: Alpha-lipoic acid; CUR: Curcumin.
See this image and copyright information in PMC

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