Novel Metallo-beta-lactamase Inhibitors

描述(申请人提供)：细菌感染是人类死亡的头号原因，每年全球约有600万人死亡。即使在发达国家，如美国，由于广泛的获得性耐药性，细菌感染再次被认为是对公共健康的重大威胁。？-内酰胺类抗生素，如青霉素和头孢菌素是最常用的抗菌剂之一。细菌对β-内酰胺类抗生素耐药最普遍的机制是产生能水解药物的β-内酰胺酶，从而使药物失活。虽然克拉维酸和舒巴坦可用于灭活丝氨酸内酰胺酶，但目前还没有对许多不同的金属内酰胺酶(MBL)具有广泛活性的抑制剂。MBLS现在已被认为是一种新的临床威胁，因为这些酶不同于丝氨酸内酰胺酶，能够水解几乎所有的β-内酰胺类抗生素，包括碳青霉烯类(例如亚胺培南)，这是治疗几种多重耐药革兰氏阴性细菌感染的最后手段药物。此外，许多MBLs(如IMPS和VIMS)是由质粒上的可转移金属内酰胺酶基因编码的，这些基因在全球范围内迅速传播。假单胞菌和不动杆菌属的部分多重耐药菌株由于MBL基因，已经显示出对亚胺培南的显著耐药性，并且几乎没有可用的选择来治疗这些感染。然而，由于MBLS之间的氨基酸序列同源性很低，目前抑制物的活性谱在不同的酶之间有很大的差异。显然，迫切需要设计和开发具有广泛和有效的抗MBLS活性的新型抑制剂。此类抑制剂的成功开发将为流行性耐药革兰氏阴性细菌感染提供新的治疗选择。针对具体目标1，我们将设计和开发一系列基于噻唑烷MBL抑制剂的化合物，这是我们在初步研究中最有效的化合物，重要的是，它满足我们两个假设的要求：(1)该化合物具有很强的锌(II)螯合基团，(2)模仿青霉素的结构。将测试这些化合物对多个MBLs的活性，分析(定量)结构活性关系(SAR)，并用于设计具有更高活性的化合物。新型MBL抑制剂恢复耐β-内酰胺类细菌敏感性的能力也将得到测试。此外，还将对金属内酰胺酶IMP-1和BLA2与新型抑制剂的络合进行X射线结晶学研究。对于具体目标2，将在初步研究中确定的第二大有效化合物的基础上设计和开发另一系列化合物。此外，在上述两个假设的基础上，我们建议设计和合成新的双环化合物，这些化合物不仅与β-内酰胺类化合物结构相似，而且具有已知的锌离子结合基团。 与公共卫生相关：许多细菌现在对碳青霉烯类抗生素产生了抗药性，碳青霉烯类抗生素被用作最后的药物，因为它们获得了一种名为金属β-内酰胺酶的蛋白质。这项拟议的研究旨在开发新的潜在辅助抗生素，这种抗生素可以抑制这种蛋白质的活性，从而恢复这些细菌对碳青霉烯类抗生素的敏感性。

DESCRIPTION (provided by applicant): Bacterial infections are the number one cause of human deaths, killing ~6 million people each year worldwide. Even in developed countries, such as the US, bacterial infections are once again recognized as a significant threat to public health because of widespread, acquired drug resistance. ?-Lactam antibiotics such as penicillins and cephalosporins are among the most often used antimicrobial agents. The most prevalent mechanism of bacterial resistance to ?-lactam antibiotics is the production of ?-lactamases that are able to hydrolyze and thereby inactivate the drugs. Although clavulanic acid and sulbactam are available for inactivation of serine ?-lactamases, no inhibitors are available that are broadly active against the many distinct metallo-?-lactamases (MBL). MBLs have now been recognized as an emerging clinical threat in that these enzymes, unlike serine ?-lactamases, are able to hydrolyze essentially all ?-lactams, including carbapenems (e.g., imipenem) which are last resort drugs for several multidrug resistant Gram-negative bacterial infections. In addition, many MBLs (e.g., IMPs and VIMs) are encoded by transferable metallo-?-lactamase genes on plasmids that have disseminated quickly worldwide. Some multidrug resistant strains of Pseudomonas and Acinetobacter spp. have already demonstrated significant resistance against imipenem due to MBL genes and there are few options available to treat these infections. However, due to low amino acid sequence homology among MBLs, the spectrum of activity of current inhibitors varies considerably among enzymes. It is apparent that a pressing need exists to design and develop novel inhibitors that have broad and potent activity against MBLs. The successful development of such inhibitors would offer new treatment options for epidemic drug resistant Gram-negative bacterial infections. For Specific Aim 1, we will design and develop a series of compounds based on a thiazolidine MBL inhibitor, which is our most potent compound in Preliminary studies and, importantly, meets both requirements of our two hypotheses: (1) the compound has a strong Zn(II) chelating group and (2) mimics the structure of penicillin. The activity of these compounds against a number of MBLs will be tested and (quantitative) structure activity relationships (SAR) be analyzed and used to design compounds with improved activity. The ability of the novel MBL inhibitors to restore the susceptibility of ?-lactam resistant bacteria will also be tested. In addition, x-ray crystallographic studies of metallo-?-lactamases, IMP-1 and Bla2, complexed with the novel inhibitors will be performed. For Specific Aim 2, another series of compounds will be designed and developed based on the second most potent compound identified in preliminary studies. In addition, based on the two hypotheses stated above, we propose to design and synthesize novel bicyclic compounds that not only closely mimic the structures of ?-lactams, but have a known Zn2+-binding group. PUBLIC HEALTH RELEVANCE: Many bacteria have now become resistant to carbapenems, a class of penicillin-like antibiotics used as last resort drugs, because they have acquired a protein called metallo-beta-lactamase. The proposed research is designed to lead to new potential adjuvant antibiotics that can inhibit the activity of this protein and thus restore the susceptibility of these bacteria to carbapenems.