Solid state characterization of potential protozoocidal agents - aminoisoxazolylnaphthoquinones

As part of their preformulation evaluation, four in vitro protozoocidal 3,4 -dimethyl-5-isoxazolylnaphthoquinones (ANQ-1-4) were investigated by differ ential scanning calorimetry (DSC), simultaneous differential thermal analys is-thermogravimetry-derivative thermogravimetry (DTA-TG-DTG), and Fourier t ransform infrared spectroscopy (FTIR). X-ray powder diffractometry (XRPD), thermomicroscopy and polarized light microscopy were used as an aid to inte rpret the thermoanalytical curves. The study demonstrated that the compound s are crystalline solids, unaffected by oxygen, safely manipulated at room temperature (RT) and also at higher temperatures as solids; however, all de compose exothermically at about their mp. Polycrystalline mixtures or undes irable solvates were not detected. All the compounds are insoluble in water and n-hexane and slightly soluble in ethanol, indicating that all are cand idates to improve their solubilities in order to avoid formulation problems . (C) 2001 Elsevier Science B.V. All rights reserved.