Licorice Flavonoids In Vitro Antioxidant Activity Of Research

Since superoxide dismutase was found in 1968, the studies on free radical have gained rapid development, and have obtained great achievement. Now, free-radical biology and free-radical medicine research are experiencing another climax due to the study on nitrous oxide free radical won the 1998' Nobel Prize in physiology or Medicine. Free radical has important biologic function, but on the other hand it can bring many kinds of illness, such as cardiovascular disease, senile dementia, tumor and sugar diabetes and so on when the free radical in body is imbalance. Numerous researches found that taking preventions, especially taking antioxidant or free radical scavenger reasonably can effectively keep above diseases from happening, and meanwhile exerts free radical's function. In the last century, the antioxidant BHT and BHA were artificial synthesized, and were widely used in food industry. However, a plenty of experimental data indicated that these synthetics could cause cancer. So, crude antioxidant has got people's favor again, because of its extensive source, strong antioxidant activity and excellent security. Therefore, filtering the crude antioxidant will become the new study hotspot of food chemistry eara.This paper introduced the general situation of resource, chemical constitutes and pharmacologic function of flavonoids about Glycyrrhizae radix. We hope that through our serial researches can provide references for the exploiture and utilization of Glycyrrhizae radix. The results we have got as follows:1. Extraction of Glycyrrhizae radix total flavone: The concentration of ethanol is 60%, the extraction temperature is 70℃, the ratio of solid to liquid is 1:20, and the extraction time is 2 hours (twice), respectively. The extraction rate of rude total flavone of Glycyrrhizae radix (LF₀) is 1.28%. The contents of total flavone and total glucose were measured with colorimetry and phenol-sulfuric acid methods.2. Purification of Glycyrrhizae radix total flavone: First, LF₀ were extracted with equivalent volume ethyl acetate three times, then, the extraction obtained was applied to AB-8 resin column which was equilibrated with 10% ethanol. LF₀ was eluted with 70% ethanol. The flavone-containing fractions (LF₁) were pooled and concentrated. Then the sample obtained was used to component and content assay. We found that the content of total flavone increased and total glucose of LF₁ reduced obviously.3. The content of liquiritin in Glycyrrhizae radix was determined by HPLC (waters Nova-Pak C₁₈ column, size: 150×3.9mm). The technological method as following: the mobile phase consisted of acetonitrile-0.5% acetic acid (1:4); the flow rate employed was 0.8mL·min^-1; The ultraviolet detection wavelength was 276nm and column temperature was room temperature. The results showed that the content of liquiritin in Glycyrrhizae radix was 12.7%. The RSD of recovery and stability was 2.5% and 1.08%, respectively.4. The study on antioxidant and antiradical activity of Glycyrrhizae radix. The antioxidant and antiradical activity of LF₀ and LF₁ were evaluated by superoxide anion (·O₂^- ) , 1, 1-diphenyl-2-picrylhydrazyl (DPPH·) radical, NBT-NADH-PMS system, 2-deoxy-D-ribose methods andβ-carotene linoleate model system assays. The results showed that Glycyrrhizae radix flavone has strong radical ing activity towards·O₂, DPPH·and hydroxyl radical, and their scavenging ablity depend on their content. All in all, the study indicates that Glycyrrhizae radix flavone is a good crude antioxidant.5. The protective effect of LF₀ and LF₁ on rat liver mitochondria injury: First, rat liver mitochondria injury was induced by Fe²⁺+Vc, and the effect of LF₀ and LF₁ on mitochondria ATPase activity, swelling and contents of protein carbonyl was measured. Then, rat liver mitochondria injury was induced by Fe²⁺+ H₂O₂ to analyze the influence of LF₀ and LF₁ on content of MDA. Last, the NBT method was used to evaluated the function of LF₀ and LF₁ inhibiting the superoxide anion producing. The result exhibited that LF₀ and LF₁ can restrain mitochondria ATPase activity decreasing and swelling caused by mitochondria oxidative damage, reduce the carbonyl ate level, scavenge superoxide anion producing and extremely inhibit oxidative damage of rat liver mitochondria. These studies indicate that LF₀ and LF₁ can effectively protect rat liver mitochondria.In sum, the Glycyrrhizae radix flavone is a good crude antioxidant, and it can effectively protect rat liver mitochondria. The study offered the reference for the study of pharmacological function and for the exploiture and utilization of Glycyrrhizae radix.