X-ray diffraction and infrared spectroscopy of N,N-dimethylformamide and dimethyl sulfoxide solvatomorphs of betulonic acid

X-ray diffraction and infrared spectroscopy measurements for the N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) solvatomorphs of betulonic acid (BA) were investigated. BA [3-oxolup-20(29)-en-28-oic acid, C30H46O3] exhibits a wide spectrum of biological activities and is considered to be a promising natural agent for the treatment of various cancer diseases. BA as a noncrystalline substance was obtained by oxidation of betulin. Crystal structures and the spectral data allowed analysis of hydrogen bonding (H-bonding), molecular conformation, and crystal packing differences in the solvatomorphs. Crystals of BA solvates were grown from the DMFacetone (1:10, v/v) and DMSOwater (9:1, v/v) solutions. BADMF (1:1) solvate crystallizes in the monoclinic P21 space group, Z = 2. The unit cell parameters are as follows: cell lengths a = 13.2458(5) angstrom, b = 6.6501(2) angstrom, c = 17.9766(7) angstrom, and beta = 110.513(4)degrees. BADMSO (1:1) solvate crystallizes in the orthorhombic P212121 (Z = 4) space group with the following unit cell parameters: a = 6.6484(4) angstrom, b = 13.3279(8) angstrom, and c = 32.6821(19) angstrom. Conformational analysis of the six-membered rings, cyclopentane ring, and isopropenyl group showed differences in comparison with other betulin derivatives examined earlier. For both solvates, the intermolecular packing arrangement was governed mainly by H-bonds. The shortest H-bonds with D...A distances of 2.604 and 2.657 angstrom, and almost linear DH...A connection occurred between OH of carboxylic group of BA and oxygen atoms from O?C and O?S groups of DMF and DMSO, respectively. (c) 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 101:44584471, 2012