Magnolia Officinalis Medicinal Value Research

Houpo (Magnolia Officinalis Cortex), the bark of stem, root or branch of Magnolia officinalis Rehd et Wils. or Magnolia officinalis Rehd et Wils. var. biloba Rehd et Wils., was first recorded in "Shennong Bencaojing". It has been used in traditional Chinese medicine for the treatment of abdominal distention and dyspepsia, and this crude drug is one of the important components of the prescriptions. At present, the number of the leaves of M. officinalis is so huge for many trees are planted in major producing areas, but most of them has been wasted.On the foundation of the group’s former work, the medicinal value of the leaves of M. officinalis was studied in this paper, including chemical constituents, pharmacological effects and the dynamic variation of quercitrin. The major achievements and creative points were as followed.1. The paper first reported the contraction activity of alcoholic extract and chloroform extract of the leaves of M. officinalis on rabbit aortic rings with or without endothelium in vitro. They might exert action through the long lasting voltage operated Ca2+channels and alpha-receptors, because the effect could be inhibited by both calcium channel blocker and alpha-blocker. Whereas, the n-Butyl alcohol extract of the leaves of M. officinalis exhibited relaxant effect on the arteries induced by NE, but the mechanism was unclear.2. From the chloroform extract and n-Butyl alcohol extract of the leaves of M. officinalis,36compounds were isolated and26of which were identified based on spectral techniques. All these compounds were composed of flavonoids, phenylpropanoids, lignans and so on.22compounds were isolated from the leaves of Magnolia officinalis for the first time,14compounds were isolated from Magnolia officinalis for the first time and8compounds were isolated from the genus Magnolia for the first time. 3.8compounds were highly-contained among the identified compounds, they were also assayed on isolated rabbit arteries in vitro in order to initially elucidate efficacious material basis of it. The data indicated that all the8compounds were ineffective on the aortic rings, but quercitrin and afzelin which isolated from the n-Butyl alcohol extract could dose-dependently relax the rabbit arteries induced by NE. The endothelium-independent relaxation effect of quercitrin might be mediated by vascular smooth muscle cell. On the contrary, the excellent vasodilation of afzelin was endothelium-dependent, which was associated with NO-GC-cGMP pathway and cyclooxygenase pathway. In addition, rutin was also been reported of its relaxation on the isolated arteries. Therefore, the efficacious material basis of the leaves of M. officinalis was quercitrin, afzelin and rutin.4. As the main active ingredient of the leaves of M. officinalis, quercitrin was used as reference standards to analyze the content changes of it in the different harvest time through HPLC method for the first time. The research showed that the content of quercitrin changed regularly, it was highest in the middle of June and the fallen leaves contained little quercitrin after November. Consequently, taking quercitrin as index, the optimum time of the leaves of M. officinalis to harvest was the middle of June.The findings suggested that the leaves of M. officinalis could modulate the tension of isolated blood vessels, especially vasodilatation, it reminded that the leaves of M. officinalis might be used as cardiovascular drug or antihypertensive drug.The study was supported by the Ph. D. Programs Foundation of Ministry of Education of China---"Study on the Medicinal Value of the Leaves of M. officinalis’"(No:200806330006). and the National Science and Technology Support Project (2009BAI84B03) from Ministry of Science.