X-ray and DFT Study of Glaucocalyxin A Compound with Cytotoxic Activity
- Received Date: 2008-11-02
Abstract: The title compound glaucocalyxin A (1) (7α,14β-dihydroxy-ent-kaur-16-en-3,15-dione) isolated from the leaves of isodon excisoides was characterized by IR, 1H NMR, 13C NMR,1H-1H COSY, HMQC, HMBC, and EIMS, and its crystal structure was determined by singlecrystal X-ray diffraction. The X-ray crystal structure revealed that the molecular backbone of the chosen crystal is a tetracyclic system, including three six-membered rings and a five-membered ring, and the three six-membered rings are in a chair-like conformation. The five-membered ring adopts a twisted envelope-like conformation, and its geometrical parameters were compared with theoretical calculations at the B3LYP and HF level of theory. The molecules form extensive networks through the intra- and intermolecular hydrogen bonds.The experimental NMR data were interpreted with the aid of magnetic shielding constant calculations, by means of the GIAO (gauge-lncluding atomic orbitals) method. Calculated and experimental results were compared with a satisfactory level of agreement. Molecular electrostatic potential map was used in an attempt to identify key features of the diterpenoid glaucocalyxin A that is necessary for its activity. Calculations of molecular electrostatic potential and stabilization energies suggest that the protonation of glaucocalyxin A will be able to occur on carbonyl oxygen atoms.
|Citation:||Fu-dong Wang, Tao Wang, An-an Wu, Lan Ding, Han-qing Wang. X-ray and DFT Study of Glaucocalyxin A Compound with Cytotoxic Activity[J]. Chinese Journal of Chemical Physics , 2009, 22(3): 275-284. doi: 10.1088/1674-0068/22/03/275-284|