Development of Natural Product Based Opioid Receptor Ligands

描述（由申请人提供）：尽管半个多世纪的研究旨在确定新的镇痛药，从吗啡中提取的镇痛药继续作为严重疼痛的一线治疗方法。虽然阿片类药物的临床使用很普遍，但它们有一些严重的缺点。除了一些潜在的副作用，上瘾的风险总是存在的。许多患者产生的耐受性进一步加剧了这种风险。为了克服这些问题，有必要确定对三种主要阿片受体具有选择性结合的新化合物。这类化合物也将被证明对设计下一代成瘾疗法有用。据推测，hasubanan生物碱（HB生物碱）可能满足这种长期存在的需求。不幸的是，需要这些天然产物的非自然对映体来充分验证这一假设。因此，必须开发一种高效的合成丁烯- hb生物碱核心的途径。本阶段申请的总体目标是合成和评价具有代表性的丁基血红蛋白生物碱的生物活性。因此，拟议的研究与NIH支持对疾病治疗和治愈至关重要的研究这一使命有关。该倡议的目标将通过追求以下三个具体目标来实现。在第一个目标下，将通过合成两个具有代表性的家族成员来开发和证明HB生物碱的高效合成路线。这种策略将C12-C13和C14-N键的形成与B环和D环的形成结合起来。在第二个目标下，在aim 1中合成的化合物将被评估其作为阿片受体配体的能力。这将通过使用标准的基于细胞的测定来确定受体选择性和配体功能（激动作用或拮抗作用）来完成。在第三个目标下，将调整aim 1中开发的合成路线，以合成具有更高效力和选择性的正hb生物碱衍生物。所提出的类似物的身份是由报道的三种不同阿片受体的x射线晶体结构指导的。这些类似物被设计为加强与结合袋保守区域关键残基的相互作用（以增加效力），并与仅存在于阿片受体中的关键残基建立相互作用（以增加选择性）。这项工作的预期结果将是证明ent-HB生物碱确实对阿片受体具有强大的亲和力。这将对人类健康产生积极影响，因为ent-HB生物碱类似物可以用作一类新的探针分子，用于确定急性疼痛的新治疗方法。通过适当的修饰，这些探针分子也将被证明对药物成瘾的新治疗方法的开发有用。

DESCRIPTION (provided by applicant): Despite well over half a century of research aimed at identifying new analgesics, analgesics derived from morphine continue to serve as the front-line treatment for severe pain. While the clinical use of opiates is widespread, they suffer from a number of serious drawbacks. In addition to several potential side effects, the risk of addiction will always be present. This risk is further exacerbated by tolerance that develops with many patients. In order to overcome these problems, there is a need to identify new compounds that have selective binding toward the three main opioid receptors. Such compounds will also prove useful for designing the next- generation of addiction therapeutics. It has been hypothesized that the hasubanan alkaloids (HB alkaloids) may meet this long-standing need. Unfortunately, the unnatural antipode of these natural products is needed to adequately test this hypothesis. Consequently, an efficient synthetic route to the ent-HB alkaloid core must be developed. The overall objectives of this phased application is to synthesize and evaluate the bioactivity of representative ent-HB alkaloids. Thus, the proposed research is relevant to that part of the NIH's mission that supports research that is fundamental to disease treatment and cure. This PI's objectives will be met by pursuing the following three specific aims. Under the first aim, an efficient synthetic route to the HB alkaloids will be developed and demonstrated by synthesizing two representative family members. This strategy will integrate the formation of the C12-C13 and C14-N bonds with the formation of the B and D rings. Under the second aim, the compounds synthesized in Aim 1 will be evaluated for their ability to function as opioid receptor ligands. This will be accomplished by using standard cell-based assays to determine receptor selectivity and ligand function (agonism or antagonism). Under the third aim, the synthetic route developed in Aim 1 will be adapted in order to synthesis ent-HB alkaloid derivatives with increased potency and selectivity. The identity of the proposed analogs has been guided by the reported X-ray crystal structures of the three different opioid receptors. These analogs have been designed to strengthen interactions with key residues in the conserved region of the binding pocket (to increase potency) and to establish an interaction with a key residue found only in the opioid receptor (to increase selectivity). The expected outcome of this work will be a demonstration that the ent-HB alkaloids do indeed have potent affinity toward the opioid receptors. This will have a positive impact on human health because ent-HB alkaloid analogs can then be used as a new class of probe molecules for identifying new treatments for acute pain. With the proper modifications, these same probe molecules will also prove useful for the development of new treatments for drug addiction.