The Study On Purification Of Emodin And Its Application To Synthesis Hypericin

Emodin is a kind of 1,8-dihydroxy-anthraquinone derivative.It exists in many kinds of herba medicine just like Rhubarb,Polygonum cuspistum and Radix polygoni multiflori. Emodin has many pharmacological functions such as immunoregulation,antibacterial, diminishing inflammation and killing tumours.Hypericin is one of the most important active components in hypericum pefforatum L.Hypericin has significant effect such as antidepression, anticancer and so on.Hypericin exists rarely in Hypericum Perforatum L.The method of extraction and isolation is so incomplete,as to little hypericin has been obtained.To solve those problems,hypericin was synthesized from emodin in the experiment.It is significant to produce hypericin using the method of chemosynthesis.Under the consinderation of saving rude materials,decreasing production cost and improving production ability,in this paper,crude emodin powder was used as the experimental material.The purification of emodin and the synthesis of hypericin starting from emodin had been studied.The main research is as follows.(1)The optimum purification condition was confirmed.The optimum purification process was studied by using the orthogonal design and the uniform design of four factors,respectively. The optimum purification conditions obtained from the orthogonal design were adding 12 times amount of acetone,refluxing and extracting for three times,and 60 minutes per time under 60℃.The content of emodin in the product was 62.18%and the extraction ratio was 47.62%. The optimum extracting conditions obtained from the uniform design were adding 14 times amount of acetone,refluxing and extracting for three times and 60 minutes per time under 55℃. The content of emodin in the product was 65.04%,and the extraction ratio was 50.52%.(2)The existence of anthraquinone compounds that are structurally similar to emodin in raw product limits the use of emodin.The low content emodin could not meet the needs of the market.Therefore,the paper conducted the research to get high-purity emodin.Three methods: extraction with ethanol,recrystalization,and extraction with 5%Na₂CO₃ were used for purifying emodin,respectively.The method of extracting with ethanol and recrystalization required that the content of emodin must reach 50%.The method of extraction with 5%Na₂CO₃ was firstly put forward in this paper.The content of emodin after extraction was 85.65%,and the extraction ratio was 62.13%.After the recrystalization,the content of emodin in the product reached 92.28%.The simple,fast,efficient purification and extraction of emodin was constructed.(3)two methods of synthesis hypericin with emodin was studied in this paper.â‘ Emodin was heated and catalysts were hydroquinone and potassium hydroxide with illumination,the ultimate product was hypericin.The yield of hypericin was 51.36%and the content of hypericin after purification was 70.16%.â‘¡The emodin was deoxidized to anthrone.Then the latter was used to synthesis hypericin directly,where the catslysts were pyridine and FeSO₄.The yield of hypericin was 26.51%and the content of hypericin after purification was 34.16%.The configuration and content of product were confirmed and detected by infrared spectrum and spectrophotometry.Result showed that the first process is better than the second method.It was concluded that the scheme of synthesis hypericin with emodin can offer guidance for chemosynthesis of hypericin.