The Species Analysis Of Metal Elements In Mulberry Leaves, Branches And Root Barks

Mulberry is one of traditional Chinese medicine(TCM). Mulberry is used as medical treatment that is record in many ancient classical works such as "Shennong’s Herbal Classic", "Compendium of Materia Medica". In recent years, more and more people are concerned about the medical and food value of mulberry. Many researchers focus on systematic study of drug activity and mechanism. More attention is payed to the relationship between the species of trace elements in Chinese herbal medicine and its efficacy and biological activity. It is believed that the key of the efficacy of some TCM lies in the natural complex of trace metal elements. Therefore, the study of trace metal elements and their coordination complex has important practical significance.According to the process of the primary and secondary species analysis of TCM, inductively coupled plasma mass spectrometry(ICP-MS) was used to detect the content of metal elements in sterile 711 mulberry varieties of leaves, branches and root bark, and Xinjiang drug mulberry root bark. 12 kinds of elements(Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb) were detected in primary species analysis, and 9 elements(Mg, K, Ca, Mn, Fe, Co, Ni, Cu, Zn) were detected in secondary species analysis. 4 kinds of elements(Mn, Fe, Cu, Zn) were were detected in advanced species analysis. High performance liquid chromatography combined with inductively coupled plasma mass spectrometry(HPLC-ICP-MS)and electrospraytandem mass spectrometry(ESI-MS/MS) were applied to qualitatively analyzing the specific forms of existence of these elements.The main results of this paper are the following:1. A method using ICP-MS was developed for studying the primary species analysis of 12 kinds of metal elements(Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb) in mulberry leaves, branches, root bark and drug mulberry root bark. The results showed that 4 kinds of analytes were rich in constant elements(Mg, K, Ca) and the content of harmful heavy metals(Cr, Cd, Pb) is very low. The extraction rate of K in all analytes was more than 50%. However, the extraction rate of other elements was generally not high, which indicated that the utilization of metal elements in all analytes is low using traditional decoction method. The content of elements(Ca, Mn, Fe, Ni, Cu) in drug mulberry root barkwas higher than that in sterile 711 mulberry root bark and the sterile 711 mulberry root bark had higher content in K, Zn. The total extraction rate of elements as well as the utilization of elements in drug mulberry root bark was generally less than that in sterile 711 mulberry root bark.2. The soluble liquid of 4 kinds of analytes obtained in primary species analysis was treated by the cation exchange resin, chloroform extraction and chelating resin respectively. The 9 kinds of metal elements(Mg, K, Ca, Mn, Fe, Co, Ni, Cu, Zn) in the soluble liquid were separated into free and non-free state, inorganic and organic state as well as steadystate and non-steady state. The constant elements(Mg, K, Ca) and Mn in all soluble liquid existed in the form of free state, and other elements had higher proportion in non-free state. Most of metal elements in all soluble liquid existed in the form of inorganic state, especially the constant elements(Mg, K, Ca). In all soluble liquid, constant elements(Mg, K, Ca) were mainly in the form of non-steady state. Other elements occupied a certain proportion in the steady state, especially Zn, which occupied the highest proportion in the steady state of all soluble liquid.3. The HPLC-ICP-MS and ESI-MS/MS were applied to investigating the specific forms of existence of 4 kinds of metal elements(Mn, Fe, Cu, Zn) in the steady state obtained from the secondary species analysis. The results indicated that compounds containing many hydroxyl groups were identified at the possible location of metal complex, such as glycosides, alkaloids and multi-hydroxyl acids, which easily combined with metal ions to form metal complex. It was assumed that the polyhydroxy compounds were probably the ligand of the metal elements.