Discovery of OJT008 as a Novel Inhibitor of Mycobacterium tuberculosis

Despite recent progress in the diagnosis of Tuberculosis (TB), the chemotherapeutic management of TB is still challenging. Mycobacterium tuberculosis (Mtb) is the etiological agent of TB, and TB is classified as the 13th leading cause of death globally [WHO 2021]. 558,000 people were reported to develop multi-drug resistant TB globally [WHO 2020]. Our research focuses on targeting Methionine Aminopeptidase (MetAP), an essential protein for the viability of Mtb. MetAP is a metalloprotease that catalyzes the removal of N-terminal methionine (NME) during translation of protein [Giglione et al., 2003]. This essential role of MetAPs makes this enzyme an auspicious target for the development of novel therapeutic agents for the treatment of TB. Mtb possesses two MetAP1 isoforms: MtMetAP1a and MtMetAP1c, which are vital for Mtb viability, hence a promising chemotherapeutic target for Mtb infection [Zhang et al., 2009; Olaleye et al., 2010; Griffin et al., 2011; Vanunu et al., 2019]. In our study, we cloned, overexpressed recombinant MtMetAP1c, and investigated the in vitro inhibitory effect of OJT008 on cobalt and nickel ion activated MtMetAP1c. The compound’s potency against replicating and multidrug-resistant (MDR) Mtb strains was also investigated. The induction of the overexpressed recombinant MtMetAP1c was optimized at hours with a final concentration of 1mM Isopropyl β-D-1-thiogalactopyranoside. The average yield for MtMetAP1c was 4.65 mg/L of Escherichia coli culture. A preliminary MtMetAP1c metal dependency screen showed optimum activation with nickel and cobalt ions at 100µM. The half-maximal inhibitory concentration (IC50) values of OJT008 against MtMetAP1c activated with CoCl2 and NiCl2 were in the micromolar range. Our in silico study showed OJT008 strongly binds to both metal activated MtMetAP1c, as evidenced by strong molecular interactions and higher binding score thereby corroborating our result. Thus, validating the pharmacophore’s metal specificity. The potency of OJT008 against both active and multidrug-resistant (MDR) Mtb was in the low micromolar concentrations, correlating well with our biochemical data on MtMetAP1c inhibition. These results suggest that OJT008 is a potential lead compound for the pre-clinical development of novel small molecules for the therapeutic management of TB

Powder properties of binary mixtures of chloroquine phosphate with lactose and dicalcium phosphate

A study was conducted on the packing and cohesive properties of chloroquine phosphate in binary mixtures with lactose and dicalcium phosphate powders. The maximum volume reduction due to packing as expressed by the Kawakita constant, a, and the angle of internal flow, &#952;, were the assessment parameters. The individual powders were characterized for their particle size and shape using an optical microscope. Binary mixtures of various proportions of chloroquine phosphate with lactose and dicalcium phosphate powders were prepared. The bulk and tapped densities, angles of repose and internal flow, as well as compressibility index of the materials were determined using appropriate parameters. The calculated and determined values of maximum volume reduction for the binary mixtures were found to differ significantly (P< 0.05), with the Kawakita plot being more reliable in determining the packing properties. Diluent type was found to influence the flow properties of the mixtures, with dicalcium phosphate giving predictable results while mixtures containing lactose were anomalous with respect to flow. The characterization of the packing and cohesive properties of the binary mixtures of chloroquine with lactose and dicalcium phosphate would be useful in the production of powders, tablets, capsules and other drug delivery systems containing these powders with desirable and predictable flow properties.Realizou-se estudo das propriedades de empacotamento e de coesão do fosfato de cloroquina em misturas binárias com lactose e fosfato dicálcico em pó. O volume máximo de redução devido ao empacotamento, segundo expresso pela constante de Kawakita, a, e o ângulo de fluxo interno, &#952;, foram os parâmetros de avaliação. Os pós individuais foram caracterizados por seu tamanho e forma de partículas, utilizando microscópio óptico. Prepararam-se misturas binárias de várias proporções de fosfato de cloroquine e lactose e fosfato dicálcico em pó. As densidades de bulk and tapped, os ângulos de repouso e de fluxo interno e o índice de compressibilidade dos materiais foram determinados utilizando-se parâmetros apropriados. Os valores calculados e determinados do volume máximo de redução para as misturas binárias mostraram-se significativamente diferentes (P< 0,05), sendo o traçado de Kawakita mais confiável na determinação das propriedades de empacotamento. O tipo de diluente influenciou as propriedades de fluxo das misturas com fosfato dicálcico, dando resultados previsíveis, enquanto as misturas contendo lactose mostraram-se anômalas com relação ao fluxo. A caracterização das propriedades de empacotamento e de coesão das misturas binárias de cloroquina com lactose e fosfato dicálcico seria útil na produção de pós, comprimidos, cápsulas e outros sistemas de liberação de fármacos contendo esses pós com propriedade de fluxo desejada e previsível