Tropical Journal of Pharmaceutical Research

Original Research Article | OPEN ACCESS

In Vitro Antioxidant Activity of Chitosan Aqueous Solution: Effect of Salt Form

Natthan Charernsriwilaiwat, Praneet Opanasopit , Theerasak Rojanarata, Tanasait Ngawhirunpat

Faculty of Pharmacy, Silpakorn University, Nakhon Pathom 73000, Thailand;

For correspondence:- Praneet Opanasopit Email: praneet@su.ac.th Tel:+6634255800

Received: 14 January 2011 Accepted: 17 February 2012 Published: 24 April 2012

Citation: Charernsriwilaiwat N, Opanasopit P, Rojanarata T, Ngawhirunpat T. In Vitro Antioxidant Activity of Chitosan Aqueous Solution: Effect of Salt Form. Trop J Pharm Res 2012; 11(2):235-242 doi: 10.4314/tjpr.v11i2.9

© 2012 The authors.
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Abstract

Purpose: To investigate the effect of salt form on the antioxidant activities of chitosan aqueous solution.

Methods: The antioxidant activities of chitosan acetate (CS-acetate), chitosan hydroxybenzotriazole (CS-HOBt), chitosan thiamine pyrophosphate (CS-TPP) and chitosan ethylenediaminetetraacetic acid (CS-EDTA) solution were determined employing various established in vitro system such as superoxide and hydroxyl radicals scavenging, metal ion chelating and reducing power. Their chemical structures were characterized by nuclear magnetic resonance (NMR) and Fourier transform infrared spectrophotometry (FT-IR).

Results: NMR and FT-IR show confirmed formation of chitosan salts. The 50 % inhibition concentration (IC₅₀) of superoxide and hydroxyl radicals was 0.349 – 1.34 and 0.34 – 1.54 mg/mL, respectively. Among the salt forms, CS-acetate (IC₅₀ = 0.349 mg/mL) showed the highest superoxide radical scavenging effect while CS-HOBt (IC₅₀= 0.34 mg/mL) showed the highest hydroxyl radical scavenging effect. With regard to metal ion chelating activity, CS-EDTA showed the highest chelating activity (approx 100 % at 1 mg/mL) while the others showed 20 % activity at a concentration of 1 mg/mL. The results for reducing power indicate that CS-TPP had the highest reducing power.

Conclusion: The results indicate that antioxidant activity varied with the salt form. Thus, CS salts may be used as a source of antioxidants for pharmaceutical applications.

Keywords: Chitosan, Antioxidant, Hydroxybenzotriazole, Thiamine pyrophosphate, Ethylenediaminetetraacetic acid