排序方式: 共有37条查询结果,搜索用时 15 毫秒
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对瑞香狼毒(Stellera chamaejasme L.)的化学成分进行研究,采用硅胶色谱、凝胶色谱、高效液相色谱等多种色谱手段对瑞香狼毒的乙酸乙酯提取物进行分离纯化,利用NMR、MS波谱分析鉴定3个木质素、1个二萜原酸酯、3个双黄酮、2个黄酮。枇杷素(5)、异落叶松树脂醇(7)和(-)-落叶松树脂醇(8)为首次从该植物中分离得到。PC-12细胞活性试验表明,双黄酮类化合物(狼毒色原酮(2),新狼毒素B(3),异新狼毒素A(4))对NGF依赖的PC-12细胞突起生长有较强的抑制活性(P<0.05)。 相似文献
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在单锅中探讨了以芥子酸为底物,经酯化和氧化偶合两步反应合成芥子酸甲酯二聚体酯的方法.研究结果表明,此合成方法操作简便,反应条件温和(室温反应),无须分离中间体,且产率较高(收率高达66.58%).还探讨了时间、原料比、催化剂的用量等对一锅法产率的影响及氧化偶合机理. 相似文献
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By bioactivity-guided isolation, two labdane diterpenes (1 and 2) have been isolated from the bulbs of Fritillaria ebeiensis. Their structures were elucidated as 6α,7β-dihydroxy-labda-8(17),12(E),14-triene (1) and 6-oxo-2α-hydroxy-labda-7,12(E), 14-triene (2), on the basis of spectroscopic data analysis (IR, ESI-MS, HR-ESI-MS, 1D and 2D NMR). Both of the isolates showed neuroprotective effects against MPP+-induced neuronal cell death in human dopaminergic neuroblastoma SH-SY5Y cells. 相似文献
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Plants have always been an exemplary source of drugs and many of the currently available medicines have been directly or indirectly derived from them. For this reason, the research, development and use of natural products as therapeutic agents, especially those derived from plants, have been increasing in recent years. A great deal of attention has focused on the naturally occurring antispasmodic phytochemicals as potential drugs for the treatment of cardiovascular diseases. Arterial hypertension is a common and progressive disorder that poses a major risk for cardiovascular and renal diseases. Recent data have revealed that the global burden of hypertension is an important and increasing public health problem worldwide and that the level of awareness, treatment and control of hypertension varies considerably among countries. The research on naturally occurring blood pressure-lowering agents is rapidly expanding due to the high potential of such molecules as new antihypertensive drugs. Recently, a great number of plant-derived substances, such as diterpenoids, have been evaluated as possible antihypertensive agents. Naturally occurring diterpenes such as forskolin and stevioside, exhibit vasorelaxant action and inhibit vascular contractility by different mechanisms of action. In this review we will discuss the mechanisms underlying the hypotensive action displayed by diterpenes and their potential use in human hypertension. We will also discuss the use of these compounds in the treatment of glaucoma, which is characterized by increased intraocular pressure (IOP). 相似文献
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Bioassay-guided partition of the extract of the Red Sea sponge Pseudoceratina arabica and HPLC purification of the active fraction gave a psammaplysin dimer, psammaceratin A (1), along with psammaplysin A (2). The dimer comprises two units of psammaplysin A (2) connected via the terminal amines with an unprecedented (2Z,3Z)-2,3-bis(aminomethylene)succinamide moiety, and it represents the first dimer to be identified among the psammaplysin family. Data from 1D- and 2D-NMR and HRMS supported the chemical structures of the compounds. Psammaceratin A (1) and psammaplysin A (2) exhibited significant growth inhibition of HCT 116, HeLa, and MBA-MB-231 cells down to 3.1 μM. 相似文献
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Guoliang Zhou Xiaomin Zhang Mudassir Shah Qian Che Guojian Zhang Qianqun Gu Tianjiao Zhu Dehai Li 《Marine drugs》2021,19(2)
Six undescribed polyhydroxy p-terphenyls, namely asperterphenyllins A–F, were isolated from an endophytic fungus Aspergillus candidus LDJ-5. Their structures were determined by NMR and MS data. Differing from the previously reported p-terphenyls, asperterphenyllin A represents the first p-terphenyl dimer connected by a C-C bond. Asperterphenyllin A displayed anti-influenza virus A (H1N1) activity and protein tyrosine phosphatase 1B (PTP1B) inhibitory activity with IC50 values of 53 μM and 21 μM, respectively. The anti-influenza virus A (H1N1) activity and protein tyrosine phosphatase 1B (PTP1B) inhibitory activity of p-terphenyls are reported for the first time. Asperterphenyllin G exhibited cytotoxicity against nine cell lines with IC50 values ranging from 0.4 to 1.7 μM. Asperterphenyllin C showed antimicrobial activity against Proteus species with a MIC value of 19 μg/mL. 相似文献
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GnRH类似物疫苗免疫去势效果的影响因素 《畜牧与饲料科学》2019,40(11):61-64
利用GnRH类似物疫苗主动免疫动物机体可达到与手术去势类似的效果,同时避免了手术去势对动物机体产生的影响。抗原、佐剂、免疫次数、免疫剂量以及免疫时间都会对其免疫效果产生影响。采用GnRH类似物疫苗免疫动物通常需要有力的佐剂以及多次加强免疫来克服个体反应的差异性。 相似文献
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Shingo Kawai Yosuke Kobayashi Makoto Nakagawa Hideo Ohashi 《Journal of Wood Science》2006,52(4):363-366
Nonphenolic β-O-4 lignin substructure model dimer, 1,3-dihydroxy-2-(2,6-dimethoxyphenoxy)-1-(4-ethoxy-3-methoxyphenyl)propane (I) was degraded by horseradish peroxidase (HRP) in the presence of hydrogen peroxide and 1-hydroxybenztriazole (HBT). 4-Ethoxy-3-methoxybenzoic
acid (II), 1-(4-ethoxy-3-methoxyphenyl)-3-hydroxypropanone (III), 2,3-dihydroxy-1-(4-ethoxy-3-methoxyphenyl)-1-formyloxypropane (IV), 2,3-dihydroxy-1-(4-ethoxy-3-methoxyphenyl)propanone (V), 1-(4-ethoxy-3-methoxyphenyl)-1,2,3-trihydroxypropane (VI), 1-(4-ethoxy-3-methoxyphenyl)-1,2,3-trihydroxypropane-2,3-cyclic carbonate (VII), and 1-(4-ethoxy-3-methoxyphenyl)-1,2,3-trihydroxypropane-1,2-cyclic carbonate (VIII) were identified as degradation products by gas chromatography-mass spectrometry. These degradation products were qualitatively
the same as those of substrate I in the laccase/HBT system, but the yield of the products was apparently different. The products catalyzed by the HRP/H2O2/HBT system contained large amounts of the aromatic ring cleavage products IV, VII, and VIII compared with those catalyzed by the laccase/HBT system, while the amount of Cα-Cβ cleavage product II is relatively low. These results suggest that the role of HBT is not in a simple one-electron transfer between the enzymes
and substrates. 相似文献