FIG 1.

Levels of total GSH in M. tuberculosis (M. tb)-infected macrophages treated with first-line antibiotics in the presence and absence of NAC. The GSH assay was performed by the colorimetric method using an assay kit from Arbor Assays. Corrections were made to the total amount of protein measured by use of a bicinchoninic acid protein assay kit from Thermo Scientific. GSH and total protein levels were measured from the cellular lysates. There was a notable decrease in the levels of GSH when THP-1 cells were infected with the Erdman strain of M. tuberculosis. There was a significant increase in the levels of GSH when M. tuberculosis-infected samples were treated with NAC. A significant increase in the levels of GSH was also observed when M. tuberculosis-infected macrophages were treated with INH, INH plus NAC, RIF, RIF plus NAC, EMB plus NAC, PZA, and PZA plus NAC. Data represent the means ± SE from 6 trials. *, significant difference between the antibiotic- and NAC-treated group and the group treated with antibiotic alone and between the infected NAC-treated group and the infected control group; §, significant difference between the infected control group and the uninfected control group; #, significant difference between any group and the infected control group.