Study On The Accumulation And Distribution Of Cadmium In The Effect Of Ophiopogon Japonicas, Houttuynia Cordata And Duchesnea Indica (ANDR.) Focke

The accumulation and distribution of cadmium in three Chinese herbal medicines——Ophiopogon japonicas, Houttuynia cordata and Duchesnea indica (Andr.) were studied by pot experiments with simulatively polluted soil containing different amount of cadmium. The physiological and biochemical indicators such as soluble total sugar, total flavonoid, and the activity variation of antioxidant enzyme of the three Chinese herbal medicines were systematically investigated, the cadmium tolerance ability of the three plants was evaluated. The main research results are as follow:1、As direct determination of cadmium in plants is very difficult due to low content, a method for determination of trace cadmium in Chinese herbs by catalytic polarography after separation and enrichment using sulfhydryl cotton with ultrasonication assistance was developed. It was found that sulfhydryl cotton was of good performance in adsorption of trace cadmium in herbal medicine extracts with ultrasonication assistance; the absorbed cadmium could be quantitatively eluted from sulfhydryl cotton using acetic acid and phosphoric acid, respectively. Based on this, a new method for catalytic determination of trace cadmium in Chinese herbs was proposed. Under the optimum experimental conditions, the detection limit was 0.52 ng·mL-1, standard addition recovery was 97.5～102%. This method was used to determination of trace cadmium in ophiopogon and cordate houttuynia with satisfactory results.2、The content of cadmium in Ophiopogon japonicus was positively correlated with that in soil; the distribution of cadmium in Ophiopogon japonicus:root>leaf. With the increase in cadmium concentration in the pollution treatment solution and the pollution time, the physiological and biochemical indicators of Ophiopogon japonicus showed various variations:the content of soluble total sugar and total flavonoid were lower than that of control group; the antioxidant enzyme activities of the leaf decreased slowly, while the antioxidant enzyme activities of the root increased firstly and then decreased.3、The cadmium content in soil and Houttuynia cordata increased with the increase in cadmium concentration of pollution solution. The distribution of cadmium in Houttuynia cordata:stem>root>leaf. The content of soluble total sugar of leaf and root increased firstly and then decreased, the content of soluble total sugar in stem decreased obviously; the content of total flavonoid and the antioxidant enzyme activities of leaf and stem increased firstly and then decreased, the content of total flavonoid and the antioxidant enzyme activities of root decreased quickly.4、With the increase in the cadmium concentration of pollution solution, cadmium content in soil and Duchesnea indica (Andr.) Focke increased. The distribution of cadmium in Duchesnea indica (Andr.) Focke:root> stem> leaf. The content of soluble total sugar, total flavonoid and the antioxidant enzyme activities of Duchesnea indica (Andr.) Focke demonstrated a decreasing trend, indicating that small amount of cadmium can damage Duchesnea indica (Andr.) Focke.