Isolation, characterization, crystal structure, free radical scavenging- and computational studies of 9-[4-(propan-2-yl)phenyl]-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione from Garcinia kola seeds

A new crystallographic form of a pure xanthenedione derivative (11′), C22H24O3, was isolated from the hexane extract of the seeds of Garcinia kola. The structure of the compound was determined on the basis of FTIR and NMR spectroscopy and confirmed by single-crystal X-ray diffraction analysis. The compound crystallized as C22H24O3 H2O H3O+ Cl−, as the result of the extraction process, adopts monoclinic, space group P21/n (no. 14) and is stabilized by OWH⋯OW, OWH⋯Cl, CH⋯OW, CH⋯Cl intramolecular hydrogen bonds and weak OWH⋯O, CH⋯O, intermolecular interactions forming a 3-D supramolecular structure. The molecular property of the pure xanthene derivative, C22H24O3, has also been investigated using the density functional theory (DFT) method. The calculated IR, 1H and 13C data were found to be in good agreement with experimental values. The compound C22H24O3 showed weak DPPH radical scavenging activity with IC50 value of 2.37 ± 0.08 mg/ml.