Cycloart-23-ene-3-oxo-26-oic acid or Mangiferolic acid (C30H48O3), compound 1 and Cycloart-23-ene-3β,25-diol (C30H50O2) compound 2, were isolated from the bark of Mangifera indica. The structures of both compounds 1 and 2 were established by spectral and X-ray diffraction studies. Compound 1 crystallizes in the monoclinic space group P21 with unit cell parameters a = 8.416(1), b = 20.638(2), c = 17.203(2) Å, β = 91.779(2)°, Z = 2. Compound 2 crystallizes in the monoclinic space group C 2 with unit cell parameters a = 33.824(9), b = 7.413(2), c = 11.136(3) Å, β = 98.347(4)°, Z = 4. Both structures (1 and 2) were solved by direct methods and refined to R = 0.0511 and 0.0588, respectively. For compound 1, there are two independent molecules (1A and 1B) per asymmetric unit and one disordered trichloride methane molecule. For compound 2, there is positional disorder of the side chain at C17 beginning from C23 up to C27. All the rings of both steroid skeletons are trans connected. For structures 1A, 1B and 2, the six-membered rings A, B and C have a deformed chair, deformed chair and sofa conformations. The five-membered rings D adopt a half-chair conformation. In structure 1, there are two types of hydrogen bonds, the first type, the molecules 1A and 1B are linked by pairs of O(3A)–H···O(1B) and O3B H3B···O1A hydrogen bonds. In addition, both O(1A)–H and O(1B)–H hydroxyl groups participate in a second type of hydrogen bond involving the atoms O(2A) and O(2B) of adjacent molecules, respectively. In structure 2, there is a characteristic pattern observed in packing diagram is that both hydroxyl groups (O1–H and O2–H) participate as hydrogen bond donors and acceptors. In both structures 1 and 2, the hydrophobic part of the steroid nucleus is stabilized by C–H···O interactions and van der Waals forces.
Index Abstract
A total of 8 cycloartane type triterpenoids were isolated from Mangifera indica. The crystal structures of two and their absolute configuration is discussed. The new crystal structures of two cycloartane type compounds were obtained by X-ray diffraction techniques from suitable single crystals.