| The genus of Dioscorea, belonging to Dioscoreaceae, consists of over 650 species in the world. About 30 species contain diosgenin and glycoside dioscin in their rhizome. Diosgenin is chief raw material of the steroid hormone production in pharmaceutical industry, and the supply is unable to fit the need in the international market up to now.Dioscorea nipponica Makino, which distributes widely in China, its rhizome has long been used as a folk herb. It is known that diosgenin and dioscin content in its rhizome is higher than other species. So it has been widely planted in China to provide diosgenin and dioscin. The resource of aerial parts of D. nipponica is abundant compared with the rhizome because aerial parts can be harvest every year and to get rhizomes needs at least 4 years. We noticed that no research about the aerial parts of D. nipponica is reported up to now. To utilize this kind of medical plant sufficiently we studied the chemical constituents and its pharmacological activities of the aerial parts of D. nipponica.Air-dried aerial parts of D. nopponica was cut into small pieces and then extracted with 70% EtOH at reflux 3 times (3h/t), and the filtrate was evaporated to relative density to 1.12. Then it was subjected to solvent-solvent partitioning, to yield petroleum ether, CHCl3, EtOAc, n-butanol soluble phases. Separate and purified the trichlormethane and acetoacetate extracts by column chromatography of a silica gel, resversed phase silica column, semipreparative high performance liquid chromatography, recrystallization, etc. Twenty-five compounds are obtained. Structures are identified according to their physico-chemical properties and spectra evidence (1H NMR, 13C NMR, DEPT, HMBC, HMQC, HRMS, etc). The structures of the 25 compounds are as following: 4, 6-dihydroxy-2, 3, 7-trimethoxy-9, 10-dihydrophenanthrene (1); 1-(4,7-dihydroxy-2,6-dimethoxy-9,10-dihydrophenanthrenyl)-4,7-dihydroxy-2, 6-dimethoxy-9, 10-dihydrophenanthrene (2); 7-hydroxy-2, 3, 5-trimethoxy-9, 10-dihydrophenanthrene (3); 2, 7-dihydroxy-3, 5-dimethoxy-9, 10-dihydro- phenanthrene (6-methoxycoelonin, 4); 4, 7-dihydroxy-2, 3, 6-trimethoxyphen- anthrene (5); 3, 7-dihydroxy-2, 4, 6-trimethoxyphenanthrene (6); 1-(2, 7- dihydroxy-4, 6-dimethoxyphenanthrenyl)-2, 7-dihydroxy-4, 6-dimethoxyphen- anthrene (7); 7-hydroxy-2, 6-dimethoxy-1, 4-phenanthraquinone (dioscoreanone, 8); 2-ethoxy-7-hydroxy-6-methoxy-1, 4-phenanthraquinone (9); 3′, 5-dihydroxy-3, 4′-dimethoxybibenzyl (10); 4, 4′-dihydroxy-3, 3′-dimethoxy-trans-stilbene (11); 1, 7-bis(4-hydroxyphenyl)-1, 4 ,6- heptatrien-3-one (12); 1, 7-bis(4-hydroxyphenyl)-4, 6-heptabien-3-one (13); 6, 8-dihydroxy-3-phenyl-3, 4-dihydroisocoumarin (montroumarin, 14); kaempferol (15); kaempferol-3-O-β-D-glucopyranoside (16); kaempferol-3-O-β-rutinoside (17); quercetin-3-O-rutinoside (rutin, 18); 4-hydroxyphenethylol- 4-O-β-D-glucopyranoside (icariside D2, 19); 3,4-dihydroxybenzoic acid (20); 4-hydroxy-3-methoxybenzoic acid (vanillic acid, 21); 4-hydroxybenzoic acid (22); pyrocatechol (23); daucosterol (24); D-mannitol (25)。And among them compoun 1, 2, 3, 7and 9 are new, compound 1-12 and 17-19 are isolated from the genus Dioscorea for the first time.The effects of aerial parts of D. nipponica on blood lipid metabolism were investigated in experimental hyperlipidemia mice. ICR mice were randomly allocated to the control, positive drug control group, 100mg/kg, 200mg/kg, 400mg/kg total saponin fraction groups, 400mg/kg total water extract group. The drugs were daily given by gavage administration for 14 days. All the mice were fasted for 16 hours after the last time of treatment. Then the retrobulbar blood was taken and separated the serum from the blood. The sera were treated according to the instruction of reagent kits and lipids content were measured with the automatic Biochemistry Analysors.The result showed that high dose group of the total saponin fraction can remarkably antagonize the disorder of lipids metabolism in experimental hyperlipidemic mice. Decrease the contents of total cholesterol (TC) and low density lipoprotein (LDL-C)(P<0.05), and increase the contents of High density lipoprotein (HDL-C) (P<0.05), as well as decreased the value of TC /HDL-C(P<0.05). The total water extract effects are similar. It also can decrease the contents of TC and LDL-C(P<0.01), and increase the contents of HDL-C (P<0.01), and decreased the value of TC /HDL-C(P<0.05).LDL-C is the main form of transferring endogenous Ch to periphery tissues. HDL-C can transfer the Ch from the periphery tissues to the liver and then excreted out of the body. The studies indicated that the total saponin fraction and total water extract of aerial parts of D. nipponica possessed hypolipidemic effect on experimental hyperlipidemia mice.The hyperlipidemia is one of the common illness in middle and old aged people. The results of our studies provided evidence for the futher research on the aerial parts of D. nipponica.
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