【作者】 李炜；

【导师】 仇缀百； 唐赟；

【作者基本信息】 复旦大学 ， 药物化学， 2007， 博士

【摘要】 麻醉性镇痛药物研究历史久远、在临床上用于缓解疼痛疗效可靠。第一章简单回顾了镇痛药物二百多年来辉煌曲折的发展历程，分析了当今世界上镇痛药物研究领域的现状和临床止痛策略，并提出进一步探索面临的机遇和挑战。第二章分别从吗啡生物碱及其结构类似物、芳香乙酰乙二胺类、芳基哌啶类和其他结构类型出发，系统整理和归纳了已经发现的非肽类阿片受体κ亚型配基的多种结构类型，着眼于κ配基对受体结合能力（Binding Affinity）的高低，活性（Potency）的强弱，效能（Efficacy）的优劣以及对κ受体的选择性，根据构效关系展开讨论。引入“信使”—“位码”概念，阐述κ“位码”的研究现状，以明确本课题设计的主导思想：选取共同作用的母核，在适当的区域和取向上引入合适的药效基团使化合物产生κ选择性作用，同时保留对μ和δ受体的一定活性，以阻滞激动κ受体引起的焦虑、致幻等副作用。最终达到发现安全、有效且使用方便的低／非成瘾性阿片类先导药物的目的。论文第三章选取了纳曲吲哚和奥维醇两种典型结构类型的稠环吗啡类化合物，运用分子模拟技术和定量构效关系方法并结合其他相关研究的成果，初步探讨了“信使”——“位码”概念的化学本质。认识到Ⅲ∶08的天冬氨酸残基较为保守，是“信使”结构的主要作用部位；外口袋的Ⅵ∶23的非保守性谷氨酸（Glu297）是拮抗型“位码”组分的主要作用部位，具体表现为与配基特定分布的碱性基团相互作用；而位于外口袋Ⅶ∶03的非保守性酪氨酸（Tyr312）则是激动型“位码”组分的主要作用部位，具体表现为与配基特定分布的芳环或氢键供体／受体或其组合相互作用。满足上述条件之一或相互间的组合，都可能成为潜在的κ“位码”组分，发挥配基的对κ受体的选择性作用。第四章在第三章研究的主旨指导下，在具有非选择性作用的蒂巴因母核结构的基础上设计并合成了含有潜在κ“位码”作用的两种结构类型三个系列（苯蒂巴因、奈培酮和奈培醇系列）的稠环吗啡类化合物。苯蒂巴因系列化合物以硝基苯甲醛为原料，通过与丙二酸的Knoevenagel缩合反应、热脱羧、与蒂巴因的Diels-Alder加成反应、硝基还原、胍基亲核取代及脱除Boc保护的反应方法制备。首次发现了蒂巴因与单取代亲二烯试剂在Diels-Alder反应中的两类三个8α-加成副产物并用单晶衍射确定了结构及构型，对该类副产物形成机理的探讨将有助于深化对Diels-Alder的反应机理的理解。对于苯环上含取代基的奈培酮系列化合物，经过尝试无法通过蒂维醇以及经典奈培酮合成法制备。设计了新的合成路线，以硝基苯甲醛为原料，在低温下与乙烯基溴镁试剂发生格氏反应，经Jones氧化、与蒂巴因的Diels-Alder加成、硝基还原、KBH₄还原、格氏反应和胍基亲核取代以及脱除Boc保护基等方法成功制备了取代奈培酮和奈培醇系列化合物。目标化合物经受体亲和力初筛和构效关系讨论，表明8α-苯蒂巴因对μ受体具有较强的亲和力。而能够产生氢键供体／受体作用的三个系列化合物中对κ亲和力高的有四个化合物，其中LQ004C（16）、LQ022C（34）和LQ022D2（39）的结构中都有取代氨苯基的存在，且氨基的空间分布相似。作为探针药效基团，该结构对化合物产生κ亲和力是重要的，此结论与论文第三章QSAR方法对氢键给体场分布的研究结果相对应，发现值得进一步研究的κ“位码”因素，初步实现了本探索性课题的研究目的。氨基取代苯蒂巴因盐酸盐经兔输精管离体组织试验发现：只有对位氨基取代7α-（苯基）-6α，14α-endo-乙烯基-四氢蒂巴因（LQ004C）能够发挥κ“位码”作用，它的盐酸盐对电刺激兔输精管收缩抑制的作用强度与阳性对照药布托啡诺（Butorphanol）相近，且能被κ选择性拮抗剂nor-BNI所阻断。此外在小鼠醋酸扭体和辐射热刺激的动物模型中也发现该化合物具有镇痛活性，比强效镇痛药布托啡诺低十倍，作为典型κ激动剂值得进一步研究。第五章主要研究低成瘾性混合型镇痛药美谱他酚在溶液中的构象异构现象并揭示其药效基团模型。以（+）-美普他酚盐酸盐为例，通过溶液中的核磁共振解析、变温实验以及分子动力学模拟等方法阐明了美普他酚盐类在溶液中存在两种构象。由于美普他酚在生理状态下以氮原子质子化状态存在，探讨了它的药效基团模型上与吗啡类、芳基哌啶类镇痛药物的异同。研究结果表明：美普他酚盐类在溶液中所存在的两种构象都可能是其镇痛活性构象。本研究对于如何理解混合型阿片作用机理的本质与设计理想镇痛药物具有一定的理论指导意义。第六章为化学实验部分，总共涉及超过45个中间体与目标化合物的合成，包括经红外、核磁共振和质谱确证的新化合物28个；苯蒂巴因系列的两个化合物LQ003A（10）和LQ003B（11）还通过单晶衍射测定确定结构及其构型。更多还原

【Abstract】 The researches on opioid analgesics have lasted for more than two centuries, whose history, painful but fantastic, was briefly reviewed in the first chapter. We have to make gains in pain since the researches on traditional opioids was discouraged by analgesic booming against novel potential targets and the reality of failure on R&D ofκopioid selective agonists from arylacetamides.A variety of non-peptidicκligands (e.g. morphine analogs, arylacetamides, arylpiperidines and other structures) were critically reviewed in the second chapter. We focused on some related parameters such as binding affinity, potency and efficacy ofκligands, as well as their SAR (Structure-Activity Relationships) analysis. Then the concepts of "message" and ""address" were introduced intoκopioid investigations, from which the key theme of this thesis was derived. That is. analgesics should specifically bind and activateκopioid receptor to exert their pain-relief functions, but need maintain gentle binding affinities toμorδopioid receptors, which should be helpful to overcome the unacceptable side-effects ofκopioid agonists such as dysphoria and psychoactive effects.In the third chapter two categories of polycyclic morphinanes, namely natrindole analogs and orvinols, were discussed in detail, where molecular modeling and 3D-QSAR analysis were carried out to explore the "message" and "address" components over the morphine skeleton. In addition to good results achieved, the "address" component ofκopioid ligands was suggested to consist of an agonistic type of "address" and an antagonistic type of "address". The former "address" interacts with Tyr312 residue (VII:03) ofκopioid receptor by hydrogen bonds or/and hydrophobic interactions, whereas the latter one forms a salt bridge with Glu297 (VI:23) of the receptor.Based on the enlightened suggestions proposed in Chapter Three, two series of compounds identified as polycyclic morphinanes were designed and prepared in the forth chapter and initial pharmacological assays were conducted.Considering the non-selective thebaine as the skeleton, potentialκ"address" components (e.g. aromatic, hydrogen donor/acceptor or basic groups) were introduced to find analgesic leads throughκopioid acting mechanisms. With nitrobenzaldehyde as the starting material, phenyl thebaine series were prepared successfully by knoevenagel condensation with malonic acid, followed by decarboxylation to afford nitrostyrenes, then thermal cycloaddition with thebaine, the reduction of nitro group, and the substitution of guanidine group. During the Diels-Alder reactions of thebaine with nitrostyrenes, unexpected 8α-adducts, which were not present in the adducts of other single substituted dienophiles, were elucidated and verified by X-ray crystallography techniques. Discussion on the formation mechanism of these side products provided more detailed insights to understand Diels-Alder reactions. Unlike phenyl thebaine series, synthesis forwarded to nepenthone series were tried and failed by thevinols or classical nepenthone preparations. New synthetic routes were schemed and performed in this thesis and they were further validated to be successful to obtain our target molecules on nepenthone series. Synthesis was initiated by Grignard reactions of nitrobenzaldehyde with Bromovinylmagnesium at low temperature, followed by Jones oxidation, then by thermal cycloaddition with thebaine to afford nitronepenthones. And the transformation of nitronepenthones to various substituted nepenthones were investigated by reduction of nitro group with hydrazine/Raney nickel, reduction of carbonyl group with potassium borohydride, Grignard reactions of carbonyl group with iodomethylmagnesium and substitution of guanidine group.Binding affinity assays were conducted on cloned opioid receptors. For phenyl thebaine series, although phenyl thebaine showed low binding profiles against opioid receptors, the binding toμopioid receptor was favored by introduction of 8a-phenyl group with electron demanding properties. The presence of amino group could enhance affinity toκreceptor, which was proposed to be mediated through hydrogen donor/acceptor interactions other than salt bridge interactions. Furthermore, the p-amino substitution was critically required forκagonistic activity. The site onκreceptor involved in this interaction was suggested to be Tyr312 (VII:03). But for nepenthone series, different SARs were observed. The prototype compounds of this series, thevinone and nepenthone, retained someμopioid affinities. Nitronepenthones showed slightly increased binding toμandκreceptors. However, the affinities were almost abandoned by the introduction of amino group except for 2-amino nepenthone. In case of 2-amino nepenthone, the negative electronic effects were neutralized by the interaction of amino group with corresponding site onμandκopioid receptor. Nepenthols showed increasedκbut reducedμreceptor binding affinities as a result of formation of 19S-configuration and additional hydroxyl group. Similar to amino nepenthones, amino nepenthols abandonedκaffinities with slightly increasedμaffinities except for 2-amino nepenthols.Based on the results of RVD assays and rodent antinociceptive models in vivo, the para position of amino group was essential forκagonist potency and thus considered as aκ"address" component in phenyl thebaine series. LQ004C (16) contained this subunit was a kappa opioid agonist with similar activities to the marketed butorphanol which was believed to exert its analgesic potency throughκopioid receptor in RVD assays. Furthermore, LQ004C (16) was found to be an analgesic in vivo, with 10 less fold than butorphanol. And this compound showed desirable profiles for further investigations.In Chapter Five, the conformation of a marketed analgesic meptazinol. categorized as 3-aryl azepines, was investigated thoroughly, because its mixed pharmacological nature was still confusing to date. Our study began with an unexpected phenomenon observed on NMR spectra of meptazinol hydrochloride, followed by elucidation of different conformers in (+)-meptazinol hydrochloride present in solution, and then the mechanism of formation was discussed in detail. The resolved conformers were used for structural comparisons with the known opioid pharmacophores, from which (+)-meptazinol was suggested to be an opioid with different analgesic pharmacophore. The investigation provided heuristic insights for novel analgesic R&D from opioids.As the experimental part of Chapter Four, Chapter Six deal with more than forty five intermediates and target molecules, among which twenty eight compounds were novel. Detailed processes in organic synthesis and physiochemical properties were provided, as well as the data obtained from IR, NMR and MS spectra. Furthermore, the structures of LQ003A and LQ003B from phenyl thebaine series were also examined by X-ray crystallography.更多还原