Eucommia
Selected from ~100 articles 

Cheung SC. Szeto YT. Benzie IF. Antioxidant protection of edible oils. Plant Foods for Human Nutrition. 62(1):39-42, 2007 The ability of different cooking oils to withstand oxidation was investigated in relation to their native antioxidant capacity [measured as the Ferric Reducing/Antioxidant Power (FRAP) value]. The antiperoxidation effect of the presence of the Chinese herbs, du-zhong (Cortex Eucommia ulmoides) and ginseng (Panax ginseng C.A. Mayer) in corn oil was also investigated over 26 days' storage at 55 degrees C. Results showed that sesame oil had the highest FRAP value (803 microM), followed by canola oil (400 microM), and sunflower, peanut, corn and olive oils (100-153 microM). Oils with higher intrinsic antioxidant content showed higher resistance to oxidation, although this was not statistically significant. Corn oil to which was added the herbs du-zhong, ginseng or both had increased resistance to oxidation (conjugated diene level and lipid peroxide formation) over 26 days. FRAP values of the oil/herb mixtures decreased during this time, implying utilisation of herbal antioxidants. Results have implications for increasing the shelf-life and usage time of cooking oils by addition of herbs which can increase resistance of the oil to oxidation. Results have implications also for health, as it is possible that ingestion of these herbs could increase resistance of polyunsaturated fatty acids of cell membranes and lipoproteins to oxidation within the body. 

Hypoglycemic and hypolipidemic action of Du-zhong (Eucommia ulmoides Oliver) leaves water extract in C57BL/KsJ-db/db mice. Journal of Ethnopharmacology. 107(3):412-7, 2006. The anti-diabetic efficacy of Du-zhong (Eucommia ulmoides Oliver) leaves water extract (WDZ) was investigated in type 2 diabetic animals. The WDZ was given to C57BL/KsJ-db/db mice as a dietary supplement based on 1% dried whole Du-zhong leaves (0.187 g WDZ/100 g standard diet) for 6 weeks. The WDZ supplementation significantly lowered the blood glucose level and enhanced the glucose disposal in an intraperitoneal glucose tolerance test. The plasma insulin and C-peptide levels were significantly higher in the WDZ group than in the control group, while the glucagon level was lower. The hepatic glucokinase activity was significantly higher in the WDZ group, whereas, the glucose-6-phosphatase and phosphoenolpyruvate carboxykinase activities were significantly lower. The WDZ supplementation also significantly lowered the hepatic fatty acid synthase, HMG-CoA reductase and ACAT activities compared to the control group, while it elevated the lipoprotein lipase activity in the skeletal muscle. The WDZ also altered the plasma and hepatic lipid levels by lowering the cholesterol and triglyceride concentrations, while elevating the plasma HDL-cholesterol level. Therefore, these results suggest that WDZ may partly ameliorate hyperglycemia and hyperlipidemia with type 2 diabetes through increasing glycolysis, suppressing gluconeogenesis and the biosynthesis of fatty acid and cholesterol in the liver. 

Lang C. Liu Z. Taylor HW. Baker DG. Effect of Eucommia ulmoides on systolic blood pressure in the spontaneous hypertensive rat. American Journal of Chinese Medicine. 33(2):215-30, 2005. Experiments were conducted to establish the safety and efficacy of Eucommia ulmoides (Du-Zhong) extract in the treatment of hypertension. Pilot experiments using rats demonstrated that E. ulmoides extract was safe to the saturation limits of the compound. The maximum tolerated dose (MTD) was 1200 mg/kg when administered by gastric gavage at a concentration of 1200 mg/ml. Also, rats given 200 mg/kg, 600 mg/kg or 1200 mg/kg doses of E. ulmoides extract daily for 28 days demonstrated no evidence of acute toxicity as determined by clinical appearance, histopathology and serum chemistry evaluation. Lastly, spontaneous hypertensive rats (SHRs) were administered E. ulmoides extract daily for 22 days. Systolic blood pressure (BP) was measured on treatment days 1, 8, 15 and 22 at 0, 1, 2 and 3 hours post-treatment. Beginning on day 8, E. ulmoides extract administered at the mid or high dosages lowered BP in male, but not female, rats. BP declined at a rate of approximately 10 mmHg per hour. The mid dosage of 600 mg/kg was found to be the minimum effective dose. In conclusion, E. ulmoides extract was non-toxic and effective in reducing systolic BP in the SHR. 

Ho JN. Lee YH. Park JS. Jun WJ. Kim HK. Hong BS. Shin DH. Cho HY. Protective effects of aucubin isolated from Eucommia ulmoides against UVB-induced oxidative stress in human skin fibroblasts. Biological & Pharmaceutical Bulletin. 28(7):1244-8, 2005. Ultraviolet-B (UVB) irradiation has been demonstrated to produce reactive oxygen species (ROS) in the cells and skin, which induces the synthesis of matrix metalloproteinases (MMPs), causing skin photoaging. Using the human skin fibroblast HS68 cell line in the present study, we investigated the photoprotective effects of aucubin from Eucommia ulmoides. Pretreatment with aucubin significantly inhibited the production of MMP-1 by 57% when compared to the UVB-irradiated cells. Additionally, the senescence-associated beta-galactosidase (SA beta-gal) activity was markedly decreased in the presence of aucubin, which indicates it as an antiphoto-induced aging compound. As the effect of aucubin was determined against ROS, the inhibited ROS formation and malondialdehyde (MDA) levels, and the increased cell viability and glutathione (GSH) level were observed with aucubin under UVB irradiation. Based upon these results, it was suggested that aucubin might play an important role in the cellular defense mechanism against UV radiation-induced photoaging. An understanding of the antioxidant properties of aucubin could, in part, act to elucidate its protective mechanism on the human skin photoaging. 

Ho JN. Lee YH. Lee YD. Jun WJ. Kim HK. Hong BS. Shin DH. Cho HY. Inhibitory effect of Aucubin isolated from Eucommia ulmoides against UVB-induced matrix metalloproteinase-1 production in human skin fibroblasts. Bioscience, Biotechnology & Biochemistry. 69(11):2227-31, 2005. Of 30 herbal plants tested, the methanol extracts of Eucommia ulmoides (52%), Evodia officinalis (45%), and Pleuropterus multiflorus (41%) each showed a potent inhibitory effect on the matrix metalloproteinase-1 (MMP-1) production in ultraviolet B (UVB)-irradiated human fibroblasts. Aucubin was isolated as the MMP-1 inhibitor from E. ulmoides, and significantly suppressed the production of MMP-1 by nearly 57% compared to the control. It also reduced MMP-1 mRNA expression. These results suggest that aucubin is a photoprotective phytochemical, and could be used as a potential agent in preventing photoaging. 

Lee MK. Kim MJ. Cho SY. Park SA. Park KK. Jung UJ. Park HM. Choi MS. Hypoglycemic effect of Du-zhong (Eucommia ulmoides Oliv.) leaves in streptozotocin-induced diabetic rats. Diabetes Research & Clinical Practice. 67(1):22-8, 2005. The current study investigated whether Du-zhong (Eucommia ulmoides Oliv.) leaves could improve the hyperglycemia in streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were divided into a non-diabetic group (NDM), diabetic group (DM), diabetic group supplemented with powdered Du-zhong leaves (DM-PDZ) and diabetic group supplemented with a water extract of the powdered Du-zhong leaves (DM-WDZ). Diabetes was induced by injecting STZ (70 mg/kg B.W., i.p.). The powdered Du-zhong leaves or its powdered water extract was add to a standard diet based on 1% dried Du-zhong leaves (1 g PDZ/100 g diet and 0.187 g WDZ/100 g diet, respectively) for 3 weeks. Body weight was significantly higher in both types of Du-zhong leaves supplemented groups than in the DM group. The blood glucose levels were significantly lower in the DM-PDZ and DM-WDZ groups than in the DM group (20.05+/-0.88 and 18.96+/-1.23 mmol/l versus 24.42+/-1.07 mmol/l, P<0.05), whereas the plasma insulin and C-peptide levels were significantly higher in the PDZ and WDZ supplemented groups than in the DM group (7.45+/-0.27 and 7.62+/-0.69 microl U/ml versus 3.75+/-0.27 microl U/ml for the plasma insulin, and 224.52+/-14.6 and 239.76+/-15.52 pmol/l versus 166.5+/-10.4 pmol/l for the plasma C-peptide, respectively, P<0.05). The supplementation of PDZ and WDZ also resulted in lower plasma urea nitrogen levels compared to the DM group. Du-zhong leaves supplement seemed to be helpful to preserve the normal histological appearance of pancreatic islets as well as to preserve insulin-positive beta-cells but it did not reverse the effect of STZ to a great extent. Accordingly, the reduction in plasma glucose by the powdered Du-zhong leaves and its water extract is quite small but significant, nevertheless, this was occurred with simultaneous the increase in plasma insulin and C-peptide. They improved hyperglycemia and seemingly enhance the function of pancreatic beta-cells in STZ-induced diabetic rats. 

Lee MK. Cho SY. Kim DJ. Jang JY. Shin KH. Park SA. Park EM. Lee JS. Choi MS. Lee JS. Kim MJ. Du-zhong (Eucommia ulmoides Oliv.) cortex water extract alters heme biosynthesis and erythrocyte antioxidant defense system in lead-administered rats. Journal of Medicinal Food. 8(1):86-92, 2005. This study examined the ameliorative effect of a Du-zhong (Eucommia ulmoides Oliv.) cortex water extract (DzCw) on heme biosynthesis and erythrocyte antioxidant enzyme activities in lead (Pb)-administered rats. Male rats were divided into three groups: normal control group, Pb control group (Pb), and DzCw-administered Pb group (Pb + DzCw). The Pb (25 mg/kg of body weight) was administered orally once a week for 4 weeks, while the DzCw was administered orally at a dosage of 0.139 g of DzCw/kg of body weight/day. DzCw administration significantly lowered plasma Pb concentration compared with the Pb group. Furthermore, the blood hematocrit and hemoglobin levels were significantly higher in the Pb + DzCw group than in the Pb group. Although the blood and hepatic delta-aminolevulinic acid dehydratase (ALAD) activities were significantly lower in the Pb group compared with the normal control group, both ALAD activities was normalized with the administration of DzCw. The erythrocyte superoxide dismutase and catalase activities were significantly higher in the Pb group than in the normal control group, whereas the glutathione peroxidase activity and glutathione level were lowered by Pb administration compared with the normal group. However, the administration of DzCw was found to enhance the antioxidant defense system and significantly lower lipid peroxidation levels in erythrocytes compared with the Pb group. These results indicate that the DzCw administration alleviated the Pb-induced oxidative stress in the erythrocytes through elevating the blood and hepatic ALAD activity and enhancing the antioxidant enzyme activities. 

Kwan CY. Zhang WB. Deyama T. Nishibe S. Endothelium-dependent vascular relaxation induced by Eucommia ulmoides Oliv. bark extract is mediated by NO and EDHF in small vessels. Naunyn-Schmiedebergs Archives of Pharmacology. 369(2):206-11, 2004. The vasorelaxant effects of the aqueous extract prepared from the bark of the Chinese medicinal herb, Eucommia ulmoides Oliv. (also referred to as Tu-Chung or Du-Zhong), which is a common active ingredient in traditional antihypertensive herbal prescriptions in China, have recently been characterized in rat aorta and dog carotid artery. The vasorelaxant effect of eucommia bark extract on these large elastic arteries was found to be entirely endothelium-dependent and nitric oxide (NO)-mediated. Since smaller muscular arteries play a more dominant role in the change of peripheral resistance and thus the regulation of blood pressure, we have now compared the relaxant effects of eucommia bark extract using aorta and the proximal as well as the distal ends of the superior mesenteric arteries from the rat, with a specific objective to investigate whether smaller muscular arteries also elicit endothelium-dependent vascular relaxation (EDVR) in response to eucommia bark extract. We have also determined whether the EDVR, if indeed occurring in the mesenteric arteries, is mediated entirely by NO, or whether it also involves endothelium-derived hyperpolarizing factor (EDHF). We found that all three types of vessel preparations elicit EDVR in response to the eucommia bark extract concentration-dependently in a similar manner to the relaxant responses to carbachol (CCh). Although the NO synthase inhibitor L-NAME totally abolished the EDVR in aorta, it only partial abolished EDVR in mesenteric arteries isolated from each end, the distal end being more resistant to L-NAME. However, the residual L-NAME-resistant relaxation of the rat mesenteric arteries could be further inhibited by preincubation of the vessels with the combination of L-NAME and 15-20 mM KCl (KCl itself at this low concentration caused little or no contraction). Therefore, the EDVR induced by the eucommia extract and CCh in aorta is mediated entirely by NO, and that in mesenteric arteries by NO as well as EDHF, with the EDHF component (inhibited by KCl) larger in the smaller distal end of the rat mesenteric artery. Results of our study offer a plausible mechanistic basis for the vasorelaxing action of Eucommia ulmoides Oliv., which may account for its well-documented antihypertensive action. 

Huang RH. Xiang Y. Tu GZ. Zhang Y. Wang DC. Solution structure of Eucommia antifungal peptide: a novel structural model distinct with a five-disulfide motif. Biochemistry. 43(20):6005-12, 2004. The three-dimensional structure in aqueous solution of Eucommia antifungal peptide 2 (EAFP2) from Eucommia ulmoides Oliv was determined using (1)H NMR spectroscopy. EAFP2 is a newly discovered 41-residue peptide distinct with a five-disulfide cross-linked motif. This peptide exhibits chitin-binding activity and inhibitory effects on the growth of cell wall chitin-containing fungi and chitin-free fungi. The structure was calculated by using torsion angle dynamic simulated annealing with a total of 614 distance restraints and 16 dihedral restraints derived from NOESY and DQF-COSY spectra, respectively. The five disulfide bonds were assigned from preliminary structures using a statistical analysis of intercystinyl distances. The solution structure of EAFP2 is presented as an ensemble of 20 conformers with a backbone RMS deviation of 0.65 (+/-0.13) A for the well-defined Cys3-Cys39 segment. The tertiary structure of EAFP2 represents the first five-disulfide cross-linked structural model of the plant antifungal peptide. EAFP2 adopts a compact global fold composed of a 3(10) helix (Cys3-Arg6), an alpha-helix (Gly26-Cys30), and a three-strand antiparallel beta-sheet (Cys16-Ser18, Tyr22-Gly24, and Arg36-Cys37). The tertiary structure of EAFP2 shows a chitin-binding domain (residues 11-30) with a hydrophobic face and a characteristic sector formed by the N-terminal 10 residues and the C-terminal segment cross-linked through the unique disulfide bond Cys7-Cys37, which brings all four positively charged residues (Arg6, Arg9, Arg36, and Arg40) onto a cationic face. On the basis of such a structural feature, the possible structural basis for the functional properties of EAFP2 is discussed.  

Mwange KN. Hou HW. Cui KM. Relationship between endogenous indole-3-acetic acid and abscisic acid changes and bark recovery in Eucommia ulmoides Oliv. after girdling. Journal of Experimental Botany. 54(389):1899-907, 2003. This study used the alkaline single cell gel electrophoresis assay (comet assay) to investigate the effect of water extracts of roasted cortex and leaves from Du-zhong on DNA damage in lymphocytes induced by H(2)O(2). The results showed that the DNA damage in human lymphocytes increased with an increase in the concentration of H(2)O(2) (0-200 micro;M), but that the water extracts from Du-zhong (0-2 g l(-1)) only slightly affected DNA damage. The inhibitory effect of leaf extract on DNA damage induced by H(2)O(2) in lymphocytes was more significant (P<0.05) than that of roasted cortex. Leaf extract showed a rather significant inhibitory effect in a concentration-dependent manner. At a concentration of 2 g l(-1), the leaf extract inhibited 37.9% DNA oxidative damage in human lymphocytes. In order to elucidate the mechanism of the leaf extract suppression effect on DNA damage induced by H(2)O(2) in lymphocytes, an experiment was divided with six groups (A-F). Group A was used to evaluate the repair ability of the leaf extract for DNA damage; Group B was employed to determine the scavenging ability on H(2)O(2); and Group C was studied to assess the ability of leaf extract to increase the defense capability. Groups D-F were negative controls and blank. The results showed that group B had the best inhibitory effect. Also, leaf extract had significant ability to scavenge H(2)O(2) in an in vitro HRP-phenol red test. Thus, it appears that H(2)O(2) scavenging potency may be the major mechanism whereby leaf extract inhibits oxidative DNA damage induced by H(2)O(2). 

Ha H. Ho J. Shin S. Kim H. Koo S. Kim IH. Kim C. Effects of Eucommiae Cortex on osteoblast-like cell proliferation and osteoclast inhibition. Archives of Pharmacal Research. 26(11):929-36, 2003. Methanol extract (MeOH), n-hexane (Hx), chloroform (CHCl3), ethyl acetate (EA), butanol (BuOH) and aqueous (H2O) fractions of Eucommiae Cortex including geniposidic acid (GA), geniposide (GP) and aucubin (AU) were tested for their therapeutic efficacy on osteoporosis. The contents of GA, GP and AU in the cortex and leaf of Eucommia ulmoides Oliver were quantified by HPLC. The effect of Eucommiae Cortex on the induction of growth hormone (GH) release was studied by using rat pituitary cells. The proliferation of osteoblast-like cells increased by herbal extracts was assayed using a tetrazolium (MTT), alkaline phosphatase (ALP) activity, and [3H]-proline incorporation assays. The inhibition of osteoclast was studied by using the coculture of mouse bone marrow cells and ST-2 cells. As a result, the GA, GP and AU were present in the cortex more than in the leaf of E. ulmoides Oliver. The MeOH (1 mg/mL), Hx, CHCl3 and EA fractions (each 20 microg/mL) had potent induction of GH release. The CHCl3 exhibited the potent proliferation of osteoblasts. The AU, GP and GA were increased proliferation of osteoblasts. In addition, GA (IC50: 4.43 x 10(-7) M), AU and GP were significantly inhibited proliferation of osteoclast. In summary, it is thought that the components in a part of the fractions of Eucommiae Cortex participate in each step of mechanism for activating osteoblast to facilitate osteogenesis, and suppress osteoclast activity to inhibit osteolysis. 

Kwan CY. Chen CX. Deyama T. Nishibe S. Endothelium-dependent vasorelaxant effects of the aqueous extracts of the Eucommia ulmoides Oliv. leaf and bark: implications on their antihypertensive action. Vascular Pharmacology. 40(5):229-35, 2003. The vascular effects of three extract preparations from the Chinese medicinal herb, Eucommia ulmoides Oliv., which is historically an active ingredient commonly used in antihypertensive herbal prescriptions in China, were investigated with isometric contraction using isolated rat aortic and dog carotid rings. Both aqueous extracts isolated from eucommia leaf (L) and bark (B) concentration dependently caused endothelium-dependent relaxation in vessels precontracted with 1 microM phenylephrine (PE), but the methanol extract of the leaf (M) had no effect. Vessels precontracted with KCl and de-endothelialized vessels precontracted with PE were not affected by B or L. The endothelium-dependent relaxation evoked by B and L was either abolished or substantially inhibited by NG-nitro-L-arginine methyl ester (L-NAME) and methylene blue (MB), indicating the involvement of the nitric oxide (NO) synthase pathway in the vasorelaxant action of B and L. The relaxation to the aqueous extract of eucommia bark was not inhibited with 1 microM atropine, but was inhibited by 3-5 mM tetraethylammonium (TEA) and 3 mM 4-aminopyridine. This suggests that the endothelium-dependent, NO-mediated relaxation evoked by the aqueous eucommia extracts was not mediated via the activation of endothelium muscarinic receptors and may involve the activation of K+ -channels. Results in this study have provided the first evidence on the in vitro vasorelaxant action of E. ulmoides Oliv. that forms the pharmacological basis for its well-documented antihypertensive action. 

Huang RH. Xiang Y. Liu XZ. Zhang Y. Hu Z. Wang DC. Two novel antifungal peptides distinct with a five-disulfide motif from the bark of Eucommia ulmoides Oliv. FEBS Letters. 521(1-3):87-90, 2002. Two antifungal peptides, named EAFP1 and EAFP2, have been purified from the bark of Eucommia ulmoides Oliv. Each of the sequences consists of 41 residues with a N-terminal blockage by pyroglutamic acid determined by automated Edman degradation in combination with the tandem mass spectroscopy and the C-terminal ladder sequencing analysis. The primary structurs all contain 10 cysteines, which are cross-linked to form five disulfide bridges with a pairing pattern (C1-C5, C2-C9, C3-C6, C4-C7, C8-C10). This is the first finding of a plant antifungal peptide with a five-disulfide motif. EAFP1 and EAFP2 show characteristics of hevein domain and exhibit chitin-binding properties similar to the previously identified hevein-like peptides. They exhibit relatively broad spectra of antifungal activities against eight pathogenic fungi from cotton, wheat, potato, tomato and tobacco. The inhibition activity of EAFP1 and EAFP2 can be effective on both chitin-containing and chitin-free fungi. The values of IC(50) range from 35 to 155 microg/ml for EAFP1 and 18 to 109 microg/ml for EAFP2. Their antifungal effects are strongly antagonized by calcium ions. 

Deyama T. Nishibe S. Nakazawa Y. Constituents and pharmacological effects of Eucommia and Siberian ginseng. [Review] [90 refs] Acta Pharmacologica Sinica. 22(12):1057-70, 2001. The bark and leaves of Eucommia ulmoides Oliv (Eucommiaceae) and "Siberian ginseng" (Ezoukogi in Japanese) prepared from the root bark or stem bark of Eleutherococcus senticosus Maxim (Acanthopanax senticosus Harms) have been used as tonic and anti-stress drug. The extracts of Eucommia showed anti-hypertensive, anti-complementary, anti-oxidative, and anti-gastric ulcer effects, and promoting collagen synthesis, accelating granuloma formation, and other pharmacological effects. The Siberian ginseng exhibited anti-fatigue, anti-stress, immuno-enhancing effect, CNS activity, and anti-depressive effect. By now, 40, 28, and 10 compounds have been isolated from Eucommia ulmoides bark, Eucommia ulmoides leaves, and Siberian ginseng, respectively, and their structures were elucidated. Their pharmacological activities were mainly due to lignans and iridoid glycosides. 

Hsieh CL. Yen GC. Antioxidant actions of du-zhong (Eucommia ulmoides Oliv.) toward oxidative damage in biomolecules. Life Sciences. 66(15):1387-400, 2000. This study aimed to investigate the antioxidant effect of water extracts of Du-zhong (WEDZ) on oxidative damage in biomolecules such as deoxyribose, DNA, and 2'-deoxyguanosine (2'-dG) as induced by Fenton reaction. The WEDZ used included leaves, raw cortex, and roasted cortex. All of the WEDZ inhibited the oxidation of deoxyribose induced by Fe(3+)-EDTA/H2O2/ascorbic acid in a concentration dependent manner. At a concentration of 1.14 mg/mL, the inhibitory effect of the extracts of leaves, roasted cortex, and raw cortex was 85.2%, 68.0% and 49.3%, respectively. The extract of leaves inhibited the strand-breaking of DNA induced by the Fenton reaction at concentrations of 5 and 10 micrograms/microL. This inhibitory effect was similar to mannitol whereas the extracts of raw cortex and roasted cortex had no inhibitory effect at all. WEDZ also inhibited the oxidation of 2'-dG to 8-OH-2'-dG induced by Fe(3+)-EDTA/H2O2/ascorbic acid. Gallic acid had a prooxidant effect, but trolox and mannitol had an antioxidant effect. The leaf extract had a marked inhibitory effect on Fenton reaction induced oxidative damage in biomolecules. The extract of roasted cortex exhibited modest inhibition while the extract of raw cortex had the least inhibitory effect on oxidative damage in biomolecules. This is in contrast to gallic acid in the same reaction system, whose higher reducing power and weaker chelating ability may contribute to its prooxidant effect. In the present study, leaf extract of Du-zhong had inhibitory effect on oxidative damage in biomolecules. Therefore, drinking of Du-zhong tea (leaf extract) over a long period of time may have anticancer potential. 

Yen GC. Hsieh CL. Reactive oxygen species scavenging activity of Du-zhong (Eucommia ulmoides oliv.) and its active compounds. Journal of Agricultural & Food Chemistry. 48(8):3431-6, 2000. The biologically active compounds and free radical-/ or reactive oxygen species (ROS)-/ scavenging effect of water extract from Du-zhong (WEDZ) were investigated. The WEDZ used included leaves, raw cortex, and roasted cortex. The hot water extract of Du-zhong leaves showed marked activity as a ROS scavenger, and the scavenging effect was concentration dependent. The extract of roasted cortex exhibited a modest scavenging effect on ROS, while the extract of raw cortex had the weakest scavenging effect. The scavenging activity of WEDZ on ROS was correlated to its protocatechuic acid (PCA) content. The content of PCA in Du-zhong determined by HPLC followed the order of leaves (17.17 mg/g) > roasted cortex (2.99 mg/g) > raw cortex (1.16 mg/g). The inhibitory activity of leaf extract of Du-zhong was stronger than that of PCA on the peroxidation of linoleic acid at the same concentration of 0.1 mg/mL. The results presented herein indicated that extract of Du-zhong could possibly act as a prophylactic agent to prevent free radical-related diseases. 

Li Y. Kamo S. Metori K. Koike K. Che QM. Takahashi S. The promoting effect of eucommiol from Eucommiae cortex on collagen synthesis. Biological & Pharmaceutical Bulletin. 23(1):54-9, 2000. The effect of a methanol extract of Eucommiae Cortex on collagen synthesis was investigated in false aged model rats. Granuloma formation and collagen synthesis were significantly increased by the administration of the methanol extract of Eucommiae Cortex. The effective component of Eucommiae Cortex was then discussed by fractionating the methanol extract of Eucommiae Cortex. Eucommiol, a main component in the water fraction of the methanol extract, was found to be an effective compound. In our previous paper, we reported the promoting effect of Eucommia ulmoides OLIVER leaf on collagen synthesis, and found geniposidic acid and aucubin were the main effective compounds in the leaf. Based on our data in this paper, we clarified that the main effective components of the Eucommia ulmoides OLIVER leaf and Eucommiae Cortex were different. Geniposidic acid and aucubin were reported to be contained at a high concentration in the fresh cortex of Eucommia ulmoides OLIVER, but during the drying process and storage, most of them were destroyed by enzymes in the cortex and very little remained in the Eucommiae Cortex. Therefore, we investigated the effect of the methanol extract of fresh cortex of Eucommia ulmoides OLIVER. A stronger effect than Eucommiae cortex was shown, and geniposidic acid, aucubin and geniposide were concluded to be the main effective components. Although geniposide was found to be an effective compound, when the dose was higher than 50 mg/kg/d, toxicity was shown. The pharmaceutical effect of eucommiol was reported for the first time. 

Metori K. Furutsu M. Takahashi S. The preventive effect of ginseng with du-zhong leaf on protein metabolism in aging. Biological & Pharmaceutical Bulletin. 20(3):237-42, 1997. Stimulation of collagen synthesis prevents the aging process. We found such a synergistic effect by using the leaves of Eucommia ulmoides Oliver, Eucomiaceae (Du-Zhong leaf) and the roots of Panax ginseng C. A. MEYER (Ginseng). The formula consists of amounts which exert no effect when used individually. We tested several formula ratios of Ginseng and Du-Zhong leaf, 1:1, 1:2, 1:3 and 1:4, and concluded that the last two formulas were effective. However, we did not observe a significant difference between 1:3 and 1:4. Thus, it was demonstrated that the formula ratio of Ginseng to Du-Zhong leaf of 1:3 was the most effective for the stimulation of collagen synthesis and the prevention of decreased protein metabolism in aging.