FIGURE 1.

Small molecules protect B. anthracis-infected macrophages and inhibit CD45 phosphatase activity in vitro. A, J774A.1 macrophages preincubated for 1 h with NSC 95397 or NSC 270012 (10 μm) were infected with the B. anthracis Sterne spores for 4 h. The cells were stained with sytox green dye and analyzed by flow cytometry. The percentage of living and dead cells is indicated. Data from a representative experiment, which was repeated three times with similar results, are shown. B, chemical structures of the two most potent compounds, NSC 95397 (2,3-bis(2-hydroxyethylsulfanyl)naphthalene-1,4-dione), and NSC 270012 (4-(1,4-dioxonaphthalen-2-yl)sulfanylbutanamide). C, identified compounds did not exhibit anti-microbial activity. B. anthracis Sterne spores were treated with either DMSO (1%), NSC 95397 (10 μm), or NSC 270012 (10 μm), and at various time intervals growth of the bacteria was monitored at an absorbance of 600 nm. D, the compound NSC 95397 (10 μm) demonstrated the most potent in vitro inhibition of CD45 phosphatase activity when screened against a panel of 16 different phosphatases.