微生物产生的淀粉酶抑制剂研究Ⅲ淀粉酶抑制剂抑制动力学研究

Ｓ－２－３５淀粉酶抑制剂是一种易溶于水、不溶于有机溶剂的白色粉末，其紫外谱图呈末端吸收，红外谱图在３３９１、１５７２、１４１０、１０３０及９２７ｃｍ￣（－１）处有明显吸收峰。该抑制剂在ｐＨ６．５的条件下对ａ－淀粉酶有明显的抑制作用（ＩＤ＿（５０）为１．７×１０－５ｍｏｌ／Ｌ）．在３７℃，ｐＨ６．５的磷酸缓冲液中，Ｓ－２－３５抑制剂对淀粉酶的抑制作用与抑制剂的浓度关系密切，在抑制剂浓度较小的情况下，抑制剂与酶的结合呈直线关系，随着抑制剂浓度增大，残留活力曲线则出现漂移。根据Ｄｉｘｏｎ图和Ｌｉｎｅｗｅａｖｅｒ－Ｂｕｒｋ图的研究表明，Ｓ－２－３５淀粉酶抑制剂对淀粉酶的结合和底物呈竞争性抑制，抑制常数Ｋ＿ｉ为１．５～１．６×１０￣（－６）ｍｏｌ／Ｌ。     

国外中枢神经系统药物研究进展

近年来国外对中枢神经系统（系统ＣＮＳ）药物的研究开发特别活跃。抗抑郁药是目前ＣＮＳ最大治疗药物类别，约占ＣＮＳ药品市场３４％的份额，年平均增长１６．２％。根据药物的药理作用机制，较新的抗抑郁药可以分４种类型，即５－羟色胺（５－ＨＴ）重吸收抑制剂，５－ＨＴ－去甲蛹 腺素重吸收抑制剂、可逆性单胺氧化酶－Ａ抑制剂以及双重作用于５－ＨＴ环节的抗抑郁药。第二大类别是抗焦虑药，约占ＣＮＳ药品市场２３％的份额。     

5—脂氧合酶抑制剂及其从药用植物中的筛选

近期很多５－脂氧合酶抑制在临床研究上产生明确效果。许多研究工作者从传统药用植物中筛性了这类抑制剂。我国有大量的传统上用于治疗类症等疾病的天然药物，此为筛选５－脂氧合酶抑制剂的宝库。     

微生物产生的淀粉酶抑制研究Ⅲ淀粉酶抑制动力学的研究

Ｓ－２－３５淀粉酶抑制剂是一种易溶于水、不溶于有机溶剂的白色粉末、其紫外谱图呈末端吸收，红外谱图在３３９１、１５７２、１４１０、１０３０及９２７ｃｍ＾－１处有明显吸收峰。该抑制剂在ｐＨ６．５的条件下对α－淀粉酶有明显的抑制作用（ＩＤ５０为１．７×１０＾－５ｍｏｌ／Ｌ）。在３７℃，ｐＨ６．５的磷酸缓冲液中，Ｓ－２－３５抑制剂对淀粉酶的抑制作用与抑制剂的浓度关系密切，在抑制剂浓度较小的情况下，抑制剂与     

抗哮喘药物的研究进展

支气管哮喘是一种气道慢性炎症疾病。主要概述了新的支气管扩张剂，如磷酸二酯酶ＩＶ抑制剂等；炎性介质抑制剂，如白三烯拮抗剂、血栓烷素拮抗剂、５－脂氧酶抑制剂、血小板激活因子拮抗剂、神经肽受体拮抗剂等；以及甾体类抗炎药物和免疫抑制剂等作为抗哮喘药物的研究状况。     

用于治疗良性前列腺增生的激素类药物

对良性前列腺增生的发病机制以及５α－还原酶抑制剂、芳构化酶抑制剂及抗雄激素等药物在治疗良性前列腺增生方面的应用研究进行了概述，同时也介绍了部分研究中的新药。     

生物活性物质的筛选与新药研究

首先介绍生物活性物质的筛选与新药开发的研究方法，对筛选模型的发展作简单描述；主要介绍本实验室近几年筛选和研究微生物来源的生物活性物质取得的成果，表现在五个方面，即胆固醇生成合成酶抑制剂、Ｎａ＾＋－ＡＴＰａｓｅ抑制剂和抗虫化合物，５α－还原酶抑制剂、免疫抑制剂和抗肿瘤抗生素的研究，共发现１６个有活性的化合物，其中两个化合物已经成为临床药物。     

选择性5-羟色胺回收抑制剂在抑郁症治疗中的应用

本文介绍了选择性５＿羟色胺回收抑制剂的作用机制、药物动力学、临床疗效、不良反应和药物相互作用。     

选择性5—羟色胺回收抑制剂在报郁症治疗中的应用

本文介绍了选择性５－羟色胺回收抑制剂的作用机制、药物动力学、临床疗效、不良反应和药物相互作用。     

4—氨基—1—甲基—3—丙基吡唑—5—甲酰胺的合成

以２－戊酮和草酸二乙酯为起始原料,经缩合,环合、甲基化、水解、硝化、氨解、还原等７步反应合成了新型磷酸二酯酶５型（ＰＤＥ５）抑制剂西地那非的关键中间体－４－氨基－１－３－丙基吡唑－５－甲酰胺。     

In Vitro Study of Isoflavones and Isoflavans as Potent Inhibitors of Human 12‐ and 15‐Lipoxygenases

In this study, we have investigated 16 isoflavone and isoflavan derivatives as potential inhibitors of human lipoxygenase (platelet 12‐lipoxygenase, reticulocyte 15‐lipoxygenase‐1, and epithelial 15‐lipoxygenase‐2). The flavonoid baicalein, a known lipoxygenase inhibitor, was used as positive control. Four compounds, 6,7‐dihydroxy‐3′‐chloroisoflavone ( 1c ), 7‐hydroxy‐8‐methyl‐4′‐chloroisoflavan ( 5a ), 7,8‐dihydroxy‐4′‐methylisoflavan ( 5b ), and 7,8‐dihydroxy‐3′‐methylisoflavan ( 5c ), were effective inhibitors of 12‐lipoxygenases and 15‐lipoxygenase‐1 with IC₅₀'s <10 μm , while 6,7‐dihydroxy‐4′‐nitroisoflavone ( 1b ) was a selective inhibitor of 12‐lipoxygenases. Docking studies, antioxidant assays, and kinetic measurements were carried out for the three best inhibitors ( 1b , 5b , 5c ). The results showed that a catechol group in ring A is critical for the antioxidant properties of these compounds, and probably essential for their inhibitory activity. Kinetic assays showed that compounds 1b , 5b , and 5c are competitive inhibitors with K_i values in the range of 0.3–3 μm .     

Novel 3-aryl-5-substituted-coumarin analogues: Synthesis and bioactivity profile

Eighteen 3-aryl-5-substituted-coumarins—six 5-acetyloxy-derivatives, six 5-hydroxy-derivatives, and six 5-geranyloxy-derivatives—were synthesized, structurally characterized and their antioxidant activity, lipoxygenase inhibitory ability, as well as their cytotoxic activity against human neuroblastoma SK-N-SH and HeLa adenocarcinoma cell lines were evaluated. The 5-acetyloxy-compounds 3a - 3f were found to be the best cytotoxic agents among all the compounds studied. The bromo-substituted coumarins 3a and 3b were remarkably active against HeLa cell line showing IC₅₀ 1.8 and 6.1 μM, respectively. Coumarin 5e possessing a geranyloxy-chain on position 5 of the coumarin scaffold presented dual bioactivity, while 5-geranyloxy-coumarin 5f was the most competent soybean lipoxygenase inhibitor of this series (IC₅₀ 10 μM). As shown by in silico docking studies, the studied molecules present allosteric interactions with soybean lipoxygenases.     

Discovery of potent and selective inhibitors of human platelet-type 12- lipoxygenase

We report the discovery of novel small molecule inhibitors of platelet-type 12-human lipoxygenase, which display nanomolar activity against the purified enzyme, using a quantitative high-throughput screen (qHTS) on a library of 153607 compounds. These compounds also exhibit excellent specificity, >50-fold selectivity vs the paralogues, 5-human lipoxygenase, reticulocyte 15-human lipoxygenase type-1, and epithelial 15-human lipoxygenase type-2, and >100-fold selectivity vs ovine cyclooxygenase-1 and human cyclooxygenase-2. Kinetic experiments indicate this chemotype is a noncompetitive inhibitor that does not reduce the active site iron. Moreover, chiral HPLC separation of two of the racemic lead molecules revealed a strong preference for the (-)-enantiomers (IC(50) of 0.43 ± 0.04 and 0.38 ± 0.05 μM) compared to the (+)-enantiomers (IC(50) of >25 μM for both), indicating a fine degree of selectivity in the active site due to chiral geometry. In addition, these compounds demonstrate efficacy in cellular models, which underscores their relevance to disease modification.     

The Novel Ketoprofen Amides – Synthesis and Biological Evaluation as Antioxidants,Lipoxygenase Inhibitors and Cytostatic Agents

The novel amides of ketoprofen and its reduced derivatives (5a–f, 4a–n, 6a–g) with aromatic and cycloalkyl amines or hydroxylamines were prepared and screened for their reducing and cytostatic activity as well as for their ability to inhibit soybean lipoxygenase and lipid peroxidation. 1,1-Diphenyl-picrylhydrazyl test for reducing ability revealed that ketoprofen amides were more potent antioxidants than the amides of the reduced ketoprofen derivatives. The most active compound was benzhydryl ketoprofen amide 5f. Lipoxygenase inhibition of the tested compounds varied from strong to very weak. The most potent compound was benzhydryl derivative 6f (IC₅₀ = 20.5 μm ). Aromatic and cycloalkyl amides 4 and 5 were more potent lipoxygenase inhibitors than derivatives with carboxylic group. Aromatic amides of series 4 and 5 showed excellent lipid peroxidation inhibition (92.2–99.9%). On the other hand, the most pronounced cytostatic activity was exerted by O-benzyl derivative 4i, although in general all tested reduced and non-reduced lipophilic derivatives showed similar activity.     

Interactions of sulfhydryl agents and soybean lipoxygenase inhibitors

The enzymic conversion of 5,8,11,14-eicosatetraenoic acid to the corresponding hydroperoxy fatty acids by soybean lipoxygenase (lineolate: oxygen oxidoreductase E.C. 1.13.11.12.) was investigated and a simple selective extraction method was introduced. The known inhibition of the lipoxygenase pathway by phenidone, mercuric chloride, methylmercuric chloride, methylmercuric iodide, 1,5-dihydroxynaphthalene and acetone phenylhydrazone was influenced by thiol compounds in different ways. (1) A total reactivation of lipoxygenase activity was achieved when several thiol compounds, especially gluthatione, were preincubated with the inhibitor mercuric chloride and the enzyme. (2) A remarkable reduction of the inhibitory potency of phenidone against soybean lipoxygenase was seen when thiol compounds were preincubated with the enzyme before the addition of the inhibitor. When phenidone was preincubated with lipoxygenase first, sulfhydryl agents did not restore the enzyme activity. (3) No interaction was seen, when glutathione or other thiol compounds and the lipoxygenase inhibitors 1,5-dihydroxynaphthalene, nordihydroguaiaretic acid and acetone phenylhydrazone were tested against the enzyme.Therefore, we suggest that soybean lipoxygenase inhibitors may act via different modes of action. It is important to study the mechanisms of lipoxygenase inhibitors, since mammalian lipoxygenase and their products are known to be involved in the inflammatory response.     

Soybean lipoxygenase inhibition: Studies with the sulphasalazine metabolites N-acetylaminosalicylic acid, 5-aminosalicylic acid and sulphapyridine

Summary Soybean lipoxygenase inhibition has been proposed as an in vitro biochemical model for the antiinflammatory action of certain drugs used in the treatment of ulcerative colitis. In an extension of a recent study which showed that therapeutically active compounds, such as sulphasalazine and its colonic metabolite 5-aminosalicylic acid were soybean lipoxygenase inhibitors, it has now been shown that N-acetylaminosalicylic acid, the principal metabolite of 5-aminosalicylic acid, also inhibits soybean lipoxygenase in a dose dependent and noncompetitive manner (K_i 3.0×10^–8M, IC₅₀ 250 µM). Sulphapyridine, the other major metabolite of sulphasalazine, which has been demonstrated to be inactive in the treatment of ulcerative colitis, did not inhibit the lipoxygenase activity. The findings further support the hypothesis that only the therapeutically active compounds are soybean lipoxygenase inhibitors.     

Prostaglandin synthesis inhibitors: effect on angiotensin II- and oxytocin-induced contractions in rat uterine smooth muscle.

1 Eicosatetraynoic acid, the acetylene analogue of arachidonic acid, which inhibits both the cyclo-oxygenase and lipoxygenase pathways, reduced the contractile response of rat uterine smooth muscle to either angiotensin II or oxytocin. 2 Indomethacin, an inhibitor of cyclo-oxygenase, did not reduce the response to angiotensin II but did abolish the contractile response to low doses of oxytocin. 3 Nordihydroguaiaretic acid, a lipoxygenase inhibitor, totally abolished the uterine response to either oxytocin or angiotensin II. 4 The contractile response to carbachol, a cholinoceptor agonist, was unaffected by pretreatment with any of the cyclo-oxygenase or lipoxygenase inhibitors. 5 From these findings, it can be implied that some product of the arachidonate lipoxygenase pathway augments peptide-induced contractions of the rat uterus.     

The effect of some flavonoids on non-enzymatic lipid oxidation and enzymatic oxidation of arachidonic acid

Twenty flavonoids isolated from plants or transformed into methyl or acetyl derivatives were tested with regard to their influence on cyclooxygenase from the ram seminal vesicle microsomes and lipoxygenase from soya beans. Moreover, their antioxidant properties were evaluated by estimating the amount of the malonylaldehyde formed from arachidonic acid. Only rhamnetin and myricetin inhibited the soybean lipoxygenase. Most of the tested flavonoids stimulated cyclooxygenase at a high (100 microM) substrate concentration, myricetin being the most potent. Rhamnetin was the strongest antioxidant, while myricetin was about ten times weaker. Structural requirements for the cyclooxygenase stimulation, lipoxygenase inhibition and antioxidant properties were different in the case of the twenty tested flavonoids.     

Influence of some inhibitors of arachidonic acid metabolism on oxytocin contractions in the isolated testicular capsule of the rat

Oxytocin (50-750 nM) contracted the isolated testicular capsule of the rat. Mepacrine, a phospholipase A2 inhibitor (3 X 10(-5) M) and the lipoxygenase inhibitor nordihydroguaiaretic acid (10(-5) M) inhibited this response whereas the cyclooxygenase inhibitor, diclofenac sodium (10(-5) M), and the thromboxane synthetase inhibitor imidazole (10(-5) M) did not. It appears that metabolites of arachidonic acid dependent on lipoxygenase are involved in the contractile response of the rat testicular capsule to oxytocin.     

Regulation of leukocyte and platelet lipoxygenases by hydroxyeicosanoids

During allergic and inflammatory reactions, arachidonic acid is oxidized by lipoxygenases to a variety of biologically active products, including leukotrienes. The mechanisms for regulation of the different lipoxygenase activities are not well defined. We report here that [14C]arachidonic acid metabolism by the 5- and 15-lipoxygenase activities in rabbit leukocytes and the 12-lipoxygenase in rabbit platelets is inhibited by various hydroxyeicosatetraenoic acids (HETEs). 15-HETE was the most effective inhibitor of the 5- and 12-lipoxygenases, whereas similar inhibitory potencies were observed for 5-HETE and 12-HETE acting on the 15-lipoxygenase. These three enzyme pathways were all least sensitive to their own products HETEs. To determine which structural characteristics of 15-HETE are essential for inhibition of the 5-lipoxygenase, various derivatives were prepared and purified by high pressure liquid chromatography, and their structures were confirmed by gas chromatography-mass spectrometry. The inhibitory potencies of 15-HETE analogs with different degrees of unsaturation were in the order of three double bonds greater than 4 greater than 2 greater than 0. 15-Hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE) was four times more potent than 15-HETE. The 15-acetoxy, 15-keto and methyl ester derivatives were of comparable activity to 15-HETE, and the 15-acetoxy methyl ester derivative was less potent. Based upon the observed patterns of inhibition, we postulate that complex interregulatory relationships exist between the various lipoxygenases, and that cells containing these lipoxygenases may interact with each other via their lipoxygenase metabolites.