Protective effects of five compounds from Livistona chinensis R. Brown leaves against hypoxia/reoxygenation, H₂O₂, or adriamycin-induced injury in H9c2 cells

Abstract

Purpose:

Discovering new antimyocardial ischemia drug candidates that are highly efficient, have low toxicity, and originate from natural products is a popular trend for new cardiovascular drug development at present. The ethanol extract of Livistona chinensis leaves showed a favorable antioxidant activity in our preliminary screening test. This study aims to screen out antioxidants from the herb leaves further and evaluate their efficacy in acute myocardial ischemia treatment at the cellular level.

Materials and methods:

Guided with online 1, 1-diphenyl-2-picrylhydrazyl (DPPH)–high-performance liquid chromatography (HPLC) screening, antioxidants were first separated and isolated from the ethanol extract of L. chinensis leaves by preparative-HPLC. Subsequently, offline DPPH approach was used to validate the free radical scavenging activity of the components. Ultimately, the resulting antioxidants were evaluated against the hypoxia/reoxygenation (H/R)-, H₂O₂-, or adriamycin (ADM)-induced injury in H9c2 cells to verify their cardioprotective effects in vitro.

Results:

Five antioxidant ingredients, namely, orientin, isoorientin, vitexin, isovitexin, and tricin, were quickly distinguished and isolated from L. chinensis leaves. The IC₅₀ values of these ingredients were further examined by offline DPPH assay, as follows: 15.51±0.22, 6.64±0.38, 11.86±0.24, 8.89±0.66, and 31.86±0.24 μg/mL, respectively. Out of these ingredients, isoorientin showed the strongest antioxidation, which was equivalent to that of the positive control drug (vitamin C, IC₅₀: 6.99±0.62 μg/mL). Using H/R-, H₂O₂-, and ADM-induced H9c2 cell injury models, the five ingredients had different extents of cardioprotective effects in vitro. In particular, isoorientin showed the strongest protection. All the five ingredients also showed insignificant cytotoxic effect to normal H9c2 cells.

Conclusion:

The ethanol extract of L. chinensis leaves contained five antioxidants with low cardiac cytotoxicity. Isoorientin possessed the strongest antioxidation, which can predominantly account for the myocardial protection effects within the extract.

Keywords:

• effect-directed analysis
• antioxidant
• protective effects
• flavone
• H9c2 cell

Acknowledgments

The authors gratefully acknowledge the financial support of the Fujian Provincial Natural Science Foundation (grant no. 2016J01368), Joint Funds for the Innovation of Science and Technology Fujian Province (grant no. 2017Y9118), and the Natural Science Foundation of Fujian Province in China (grant no. 2016J01767), and Medical Innovation Project of Fujian Province in China (grant no. 2016-CX-44).

Author contributions

Shaoguang Li, Hong Yao, and Xinhua Lin conceived and designed the experiments. Shaohong Luo and Hao Chen performed the experiments. All authors contributed to data analysis, drafting and revising the article, provided final approval of the version to be published, and agreed to be accountable for all the aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.

Supplementary Material

Figure S1 Mass spectrometric data of five compounds.