Division of Microbiology, CSIR-Central Drug Research Institute, Sector 10, Janakipuram Extension, Sitapur Road, Lucknow 226031, Uttar Pradesh, India.
Translational Health Science and Technology Institute, Faridabad 121001, India.
J Antimicrob Chemother. 2017 Nov 1;72(11):3117-3121. doi: 10.1093/jac/dkx277.
Novel drug discovery against non-tuberculous mycobacteria is beset with a large number of challenges including the existence of myriad innate drug resistance mechanisms as well as a lack of suitable animal models, which hinders effective translation. In order to identify molecules acting via novel mechanisms of action, we screened the Library of Pharmacologically Active Compounds against non-tuberculous mycobacteria to identify such compounds.
Whole-cell growth inhibition assays were used to screen and identify novel inhibitors. The hit compounds were tested for cytotoxicity against Vero cells to determine the selectivity index, and time-kill kinetics were determined against Mycobacterium fortuitum. The compound's ability to synergize with amikacin, ceftriaxone, ceftazidime and meropenem was determined using fractional inhibitory concentration indexes followed by its ability to decimate mycobacterial infections ex vivo. Finally, the in vivo potential was determined in a neutropenic murine model mimicking mycobacterial infection.
We have identified diphenyleneiodonium chloride (DPIC), an NADPH/NADH oxidase inhibitor, as possessing potent antimicrobial activity against non-tuberculous mycobacteria. DPIC exhibited concentration-dependent bactericidal activity against M. fortuitum and synergized with amikacin, ceftriaxone, ceftazidime and meropenem. When tested in a murine neutropenic M. fortuitum infection model, DPIC caused a significant reduction in bacterial load in kidney and spleen. The reduction in bacterial count is comparable to amikacin at a 100-fold lower concentration.
DPIC exhibits all properties to be repositioned as a novel anti-mycobacterial therapy and possesses a potentially new mechanism of action. Thus, it can be projected as a potential new therapeutic against ever-increasing non-tuberculous mycobacterial infections.
新型抗非结核分枝杆菌药物的研发面临着许多挑战，包括存在大量固有耐药机制以及缺乏合适的动物模型，这阻碍了有效的转化。为了鉴定通过新型作用机制起作用的分子，我们对非结核分枝杆菌进行了药理学活性化合物库的筛选，以鉴定此类化合物。
采用全细胞生长抑制试验筛选并鉴定新型抑制剂。对候选化合物进行了对 Vero 细胞的细胞毒性测试，以确定选择性指数，并对偶然分枝杆菌进行了时间杀伤动力学测试。采用部分抑菌浓度指数测定法确定了化合物与阿米卡星、头孢曲松、头孢他啶和美罗培南的协同作用能力，然后测定其在体外消除分枝杆菌感染的能力。最后，在中性粒细胞减少症小鼠模型中模拟分枝杆菌感染，评估其体内潜力。
我们发现二苯并碘鎓（DPIC），一种 NADPH/NADH 氧化酶抑制剂，对非结核分枝杆菌具有很强的抗菌活性。DPIC 对偶然分枝杆菌表现出浓度依赖性杀菌活性，并与阿米卡星、头孢曲松、头孢他啶和美罗培南协同作用。在中性粒细胞减少症小鼠偶然分枝杆菌感染模型中进行测试时，DPIC 可显著降低肾脏和脾脏中的细菌负荷。细菌计数的减少与阿米卡星在低 100 倍浓度下的减少相当。
DPIC 具有作为新型抗分枝杆菌治疗药物的所有特性，并具有潜在的新作用机制。因此，它可以作为一种潜在的新的治疗方法，用于治疗日益增加的非结核分枝杆菌感染。
