Correlation between structure and diverse biological activities of "half-mustard type" phenothiazines

The structure and activity relationship of fifteen "half-mustard type" phenothiazines and related compounds were investigated. These compounds did not show any direct bactericidal activity, possibly due to the lack of radical generation activity. Pretreatment with phenothiazines significantly reduced the lethality of Escherichia coli GN2411 infection, possibly due to activation of the host defense mechanism. Higher concentrations of these compounds showed cytotoxic activity against several cultured tumor cell lines. However, no clear-cut relationship was established between biological activity and two dipole moments (mu g, mu e).