Study On Content And Molecular Weight Distrbution Of Gutta-Percha From Eucommia Ulmoides Leaves

Eucommia ulmoides Oliv is the Chinese native valuable medicinal species, it is also the most adaptable gutta-percha source tree around the world, which is widepreadly planted from sub-tropic zones to worm-temperate zones in China.The bark of Eucommia ulmoides Oliv is a unique rare medicinal herb. It is in the first category of Chinese herbal medicine, which can make physique muscular, benefit for liver as well as for kidney, and prevent from aging after long time taking. The present research of pharmacology revealed that the leaf has the same chemical constituents and pharmacological action as the bark. The pericarp, bark and leaf contain gutta-percha, which are the precious natural rubber resources in China. Furthermore, the unique function of duality of "plasticity and elasticity" and shape memory of gutta-percha high-elastomer makes it a quite foreground for industrializations.Dealt with Eucommia leaves, the gutta-percha contents, molecular-weight, molecular-weight distribution and their dynamic change of different clones were studied in order to explore the genetic variation and synthesis rule of gutta-percha. The amounts of gutta-percha were determined from Eucommia leaves treated with different exogenous hormone at variant concentration, and the best kind and density of pexogenous hormone, the best treat time and harvest time for promoting gutta-percha content were confirmed. The molecular-weight and molecular-weight distribution of gutta-percha were analyzed by GPC to explor the effect of exogenous hormone on molecular-weight and molecular-weight distribution of gutta-percha. Meanwhile a coulorless oiled compound was isolated from Eucommia leaves and identified as eucommiol. The content determination of eucommiol was setup.The research on the contents of gutta-percha in different clones' leaves revealed that there was significant difference among clones. Clone G3 has the highest concentration of gutta-percha, and Clone L41 has the lowest concentration of gutta-percha. Four clones (G3, X18, L11 and L49) had more than 4.0 percent of gutta-percha, which were defined as high concentration clones.The study on the molecular-weight and molecular-weight distrbition of gutta-percha in different clones' leaves showed that there was significant difference among clones. Clones L23 and L33 have the maximum molecular-weight and L49 has the minimum molecular-weight. The molecular-weight distribution of the gutta-percha showed a typical bimodal distribution. But all of the clones the lower molecular-weight fractions are large, and the higher molecular-weight fractions are small.The dynamic change of the content, molecular-weight, molecular-weight distribution of gutta-percha were studied. The results showed that in generally, from June to August and to October, the content of gutta-percha increased, but the molecular-weight of gutta-percha decreased, which were contrasted to the content of gutta-percha. The reason for this decreasing trend is undoubtedly due to the degradation of the polymers. And the molecular-weight distribution of gutta-percha decreased, which was parallel to the values of molecular-weight. It was noteworthy that the distribution of the higher molecular-weight fractions and the lower molecular-weight fractions are very different. For all the higher concentration of the clones the higher molecular-weight fractions and the low molecular-weight fractions were almost equal in June, whereas in August and October, the lower molecular-weight fractions were much larger than the higher molecular-weight fractions.The amounts of gutta-percha were determined from Eucommia leaves treated with different exogenous hormone at variant concentration were assayed, the results indicated that the four exogenous hormones all have positive effects on promoting the contents of gutta-percha. The best one is GA3, the second is 2, 4-D, 6-BA and NAA were followed. The difference of variant concentration of the same hormone is significant. The best density of GA3 is 300ppm, 2, 4-D is 0.1ppm, 6-BA is 0.5ppm and NAA is 0.01ppm.Study on the spray time of hormones revealed that spray time is important for increasing the contents of gutta-percha. Sprayed in early July, all of the hormones can promote the amount, but sprayed in early August some play a role of increasing and some decreasing. So the best spray time of hormones for promoting gutta-percha amount is early July.Study on the harvest time of Eucommia leaves after sprayed hormones showed that the harvest time affected the effect of the hormones on gutta-percha amount. Harvest in August, the contents of gutta-percha in the samples treated with all the hormones were promoted greatly. Harvest in September, some samples increased, some samples decreased. After September, the contents decreased. So, the best harvest time is August.The results of the research on the molecular-weight and molecular-weight distribution of gutta-percha after sprayed hormones revealed that the molecular-weight and molecular-weight distribution were affected by all the exogenous hormones. Some hormones increased the molecular-weight and molecular-weight distribution, but some hormones decreased the molecular-weight and molecular-weight distribution. The mechanics are unknown.A coulorless oiled compound was isolated from Eucommia leaves and identified as eucommiol. And the content of eucommiol was measured by HPLC and the chromatographic conditions were determined. The chromatogram column was ODS, the elution was MeOH: H₂O (10: 90), the detect wave was 210 nm and the velocity of flow was 1ml/min. The main factors influenced the extracting of eucommiol were anaysized. The best extracting conditions were determined. The materials shattered and were supplied with 10 times water, then was heated 2 hours at 80℃twice.The dynamic change of eucommiol in Eucommia leaves was studied. The results indiced that in different harvest time the amount of eucommiol was varied. The content of eucommoil in leaves reached its first maximum in July, and then decreased in August and reached its second maximum in September, which was the highest of the whole year. From August to October the content of eucommoil was at the stable and high standard. So the conclusion can be arrived that the best harvest time for eucommiol is September.