THE EFFECTS OF FAR-INFRARED IRRADIATION ON THE ANTIOXIDANT ACTIVITY OF LICORICE (GLYCYRRHIZA URALENSISFISCH) ROOT

Abstract

Licorice (Glycyrrhiza uralensis Fisch) roots (LR) powders were far-infrared (FIR)-irradiated for 30 min at 120∼200C. After irradiation, a 50% ethanol extract of LR (LRE) (0.5 g/50 mL) was prepared, and total phenolic content (TPC), total flavanol content (TFC) and radical scavenging activity (RSA) were determined. The antioxidant activities of the LRE were significantly affected by FIR irradiation. For example, the FIR irradiation of LR at 120C increased the TPC, TFC and RSA of the LRE from 22.85 to 29.81 mg/g, 5.61 to 13.31 mg/g and 24.59 to 52.24%, respectively, as compared with the nonirradiated control. The main functional chemical components of LR such as glycyrrhizin, glycyrrhetic acid and liquiritin, were also significantly affected by irradiation. These results indicate that the FIR irradiation of LR affected the antioxidant activities and important chemical compositions of LRE and FIR irradiation can be used to improve the quality of LR. PRACTICAL APPLICATIONS Licorice root (LR) has been widely used in traditional oriental medicine to treat bronchitis, cough, arthritis, adrenal insufficiency, and allergies. In this article, we report appropriate far-infrared (FIR) irradiation can increase antioxidant activity and functional chemical components of LR. For example, when LR was FIR irradiated at 120C increased the total phenolic content, total flavanol content and radical scavenging activity of the LR ethanol extract from 22.85 to 29.81 mg/g, 5.61 to 13.31 mg/g and 24.59 to 52.24%, respectively, as compared with the nonirradiated control. The results indicated that appropriate FIR-irradiation could be applied to increase quality of LR.