Enzyme Inhibitors as Potential Anticancer and Antiviral

A.蛋白激酶C项目：使用我们不断改进的固相合成方法生成新的DAG-内酯化学库，继续在具有潜在治疗重要性的各个领域产生重要的先导化合物。我们的第一个对RasGRP具有独占选择性的C1域选择性DAG-内酯的结果最近发表了，以及我们关于能够刺激α-分泌酶活性的DAG-内酯的结果。今年发现的另一种DAG-内酯在体内被发现是一种非常有效的放射感受器，当与放射一起使用时，使前列腺特异性抗原(PSA)水平下降到接近零的水平。一些DAG-内酯的大规模合成已经完成，用于体内研究，目前正在研究与IL-12联合使用时干扰素产量的增加。在这些发现的同时，我们继续在分子水平上研究这些DAG-内酯的作用，剖析两个不同的化学基团(sn-1和sn-2)与蛋白质或膜成分的相互作用。2005年底和2006年初发表了涉及这些问题的两篇全文论文。一类新的含芳基的DAG-内酯类化合物的合成最近得到了拓展。去年，由于恒河猴的一种不可预见的毒性，ZeBularine[2(1H)-嘧啶酮核糖苷]的临床进展被终止，当血浆水平达到25微摩尔时，这种毒性是致命的。这与啮齿动物(大鼠和小鼠)完全没有毒性形成鲜明对比，即使在高剂量下也是如此。为了规避药物的毒性并在较低剂量下提高ZeBularine的活性，人们从两个方向进行了努力：(1)合成能够传递5‘-单磷酸(ZMP)的亲脂性ZeBularine前药，并绕过代谢激活和降解。这是与一家德国公司(海德堡制药)和南加州大学的联合努力。为此，与这两个机构签署了一项合作协议，以准备和测试第一个候选药物，以及(2)开发2‘-脱氧泽布林前体药物，其目的是提供2-脱氧泽布林-5’-单磷酸(DZMP)。一些2‘-脱氧泽布拉林前药似乎有效，但只有在添加胸腺嘧啶核苷的情况下才有效。生成的dZMP最有可能抑制两种关键酶，脱氧胞苷脱氨酶和胸苷合成酶，这两种酶对维持正常的胸苷水平都是必不可少的。C.去年发表在《自然》杂志上的一篇论文强调了稳定的NAD类似物β-亚甲基-TAD的使用，该类似物是在过去几年由LMC合成的，用于单-ADP-核糖化毒素(类似于白喉毒素)的高分辨率晶体结构。

A.Protein kinase C project: The generation of novel chemical libraries of DAG-lactones using our constantly improved solid-phase method of synthesis continues to yield important lead compounds in various areas of potential therapeutic importance. The results on our first C1 domain-selective DAG-lactone with exclusive selectivity for RasGRP were published recently, as well as our results on DAG-lactones capable of stimulating alpha-secretase activity. Another DAG-lactone discovered this year was found to function as a very effective radiosentizer in vivo causing prostate-specific antigen (PSA) levels to drop to near zero when administered in conjunction with radiation. Large-scale syntheses of some of DAG-lactones were completed for in vivo studies, which are now in progress to investigate the increase in interferon production in combination with IL-12. In parallel to these findings, we continue to investigate the action of these DAG-lactones at the molecular level dissecting the interaction of the two chemically different carbonyl groups (sn-1 and sn-2) with the protein or membrane components. Two full papers addressing these issues were published late in 2005 and in early 2006. The syntheses of a new family or DAG-lactones containing aryl groups have been recently expanded. B.The progression toward the clinic for Zebularine [2(1H)-pyrimidinone riboside] was brought to an end last year by an unforeseen toxicity in rhesus monkeys, which was lethal when plasma levels reached 25 micromolar. This is in total contrast to the complete lack of toxicity in rodents (rats and mice), even at high doses. Efforts to circumvent the drug's toxicity and to improve the activity of zebularine at lower doses have been channeled in two directions: (1) Synthesis of a lipophilic prodrug of zebularine capable of delivering the 5'-monophosphate (ZMP), and bypassing metabolic activation and degradation. This is a joint effort with a German company (Heidelberg Pharma) and the University of Southern California. To that effect a Collaboration Agreement was signed with these two institutions to prepare and test the first candidate, and (2) The development of pro-drugs of 2'-deoxyzebularine, which are intended to deliver 2-deoxyzebularine-5'-monophosphate (dZMP). A number of 2'-deoxyzebularine prodrugs appear to work but only in the presence of added thymidine. Most likely, the dZMP generated inhibits two key enzymes, deoxycytidine deaminase and thymidylate synthase, and both are essential in maintaining normal thymidine levels.C.The use of stable NAD analogue, beta-methylene-TAD, synthesized at the LMC in years past and used for the high-resolution crystal structure of a mono-ADP -ribosylating toxin (similar to diphteria toxin) was highlighted in a paper published in Nature last year.