Small Molecule Alanine Racemase Inhibitors as Novel Therapeutics for Tuberculosis

描述(申请人提供)：结核病曾经被认为是在下降，但今天仍然是一个主要的全球健康问题。据估计，每年有800万新病例和200万人死亡，结核病是一种传染病的主要死亡原因。多药耐药结核病(MDR-TB)的出现进一步加剧了这种情况，这种结核病无法用现有的抗生素进行治疗。迫切需要新的抗结核药物来对抗结核分枝杆菌的多药耐药株，结核分枝杆菌是NIAID的优先病原体，也是多药耐药结核病的病原体。这项提案的目标是确定治疗一般结核病，特别是耐多药结核病的新候选药物。为此，我们建议识别阻止分枝杆菌细胞壁合成的小分子，这是一个对细菌生存至关重要的有效靶点。具体的靶标是关键的细菌酶丙氨酸消旋酶。该酶催化L-丙氨酸外消旋合成D-丙氨酸，为合成肽聚糖提供了必需的D-丙氨酸前体。使用从结核分枝杆菌提纯的丙氨酸消旋酶，将首先优化现有的酶分析方法以进行高通量筛选。然后，该分析将用于筛选专有的天然化合物和化学化合物文库，以寻找抑制该酶催化活性的小分子。以这种方式确定的HIT将被严格评估其在培养中抑制结核分枝杆菌生长的能力。该项目的成功完成预计将产生一种或更多化合物，以便在随后的第二阶段研究中进一步开发为治疗结核病和耐多药结核病的候选药物。每年约有300万人死于结核病。约有5000万人感染了对现有抗生素不敏感的结核病细菌。这项研究的目标是开发新的抗生素来治疗耐药结核病。

DESCRIPTION (provided by applicant): Once thought to be on the decline, tuberculosis (TB) still remains a major global health problem today. With an estimated 8 million new cases and 2 million deaths annually, TB is the leading cause of death from an infectious disease. This situation is further exacerbated by the emergence of multi-drug resistant form of TB (MDR-TB), which is refractory to treatment by available antibiotics. New anti-tubercular drugs are urgently needed to combat MDR strains of Mycobacterium tuberculosis, a NIAID priority pathogen and the causative agent of MDR-TB. The objective of this proposal is to identify new drug candidates for the treatment of TB in general and MDR-TB in particular. To this end, we propose to identify small molecules that prevent the synthesis of the mycobacterial cell wall, a validated target that is essential for the survival of the bacterium. The specific target is the key bacterial enzyme, alanine racemase. This enzyme catalyzes the racemization of L-alanine to D-alanine, and provides the necessary D-alanine precursor for peptidoglycan synthesis. Using purified alanine racemase enzyme from M. tuberculosis, an existing enzymatic assay will be first optimized for high-throughput screening. The assay will then be used to screen proprietary natural and chemical compound libraries in search of small molecules that inhibit the catalytic activity of this enzyme. Hits identified in this manner will be critically evaluated for their ability to inhibit the growth of M. tuberculosis in culture. Successful completion of this project is anticipated to yield 1 or more compounds for further development as drug candidates for the treatment of TB and MDR-TB in ensuing Phase II studies. Approximately 3 million people die of tuberculosis (TB) every year. About 50 million people are infected with TB bacteria that are not susceptible to available antibiotics. The goal of this research is to develop new antibiotics to treat drug-resistant TB.