Antioxidative Activities of Natural Hydroxy-Bearing Cinnamaldehydes and Cinnamic Acids: A Comparative Study

Hong Jiang², Sheng-Ling Sun³, Chao Zhang², Erdong Yuan¹, Qing-Yi Wei^1*, Zhen Zeng²

¹College of Light Industry and Food Science, South China University of Technology, Guangzhou 510640, ²Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan 430070, ³State Key Laboratory of  Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

*For correspondence: Email: feweiqingyi@scut.edu.cn; Tel: +86-020-87112594; Fax: +86-020-87112594    

Received: 2 November 2013                                  Revised accepted: 9 October 2013

Tropical Journal of Pharmaceutical Research, December 2013; 12(6): 1017-1022

Purpose: To determine the potent antioxidants among six hydroxy-bearing cinnamaldehyde compounds and their corresponding acids.

Methods: The antioxidative activities were evaluated by scavenging 2, 2’-diphenyl-1-picrylhydrazyl (DPPH) free radicals and anti-hemolysis of human red blood cells (RBCs). Fourier transform infrared spectrometry（FT-IR, nuclear magnetic resonance (NMR）and mass spectrometer(MS) evaluations were used to determine the synthesized compounds.

Results: The scavenging ability of the compounds on DPPH radicals was in the following rank order: caffeic aldehyde (F) ≈ caffeic acid (C) > vitamin C (Vc) > o-coumaraldehyde (D) > p-coumaric acid (B) > p-coumaraldehyde (E) ≈o-coumaric acid. Inhibitory ability against 2′-Azobis(2-methylpropionamidine) dihydrochloride (AAPH)-induced erythrocyte hemolysis was ranked as follows: o-coumaraldehyde (D) > p-coumaraldehyde (E) ≈ caffeic aldehyde (F) > caffeic acid (C) ≈o-coumaric acid (A) > p-coumaric acid (B) > Vitamin C. The corresponding inhibition time (t_inh ) of D and Vc was 63.6, and 23.7 min, respectively.

Conclusion: Cinnamaldehydes demonstrated superior antioxidative activities to their corresponding acids. DPPH scavenging ability correlated directly with the number of hydroxyl groups on the catechol ring while the degree of lipophilicity of the compounds may be proportional to their anti-hemolytic activity.