A B C
Z. Naturforsch. 2013, 68b, 1041 – 1048
doi:10.5560/ZNB.2013-3096
Isolation and Characterization of Limonoids from Kigelia africana
Bushra Jabeen1, Naheed Riaz1, Muhammad Saleem1, Muhammad Akram Naveed1, Maqsood Ahmed1, Muhammad Nawaz Tahir2, Gennaro Pescitelli3, Muhammad Ashraf4, Syeda Abida Ejaz5, Irshad Ahmed5, and Abdul Jabbar1
1 Department of Chemistry, Baghdad-ul-Jadeed Campus, The Islamia University of Bahawalpur, Bahawalpur 63100, Pakistan
2 Department of Physics, University of Sargodha, Sargodha, Pakistan
3 Department of Chemistry, University of Pisa, via Risorgimento 35, I-56126, Pisa, Italy
4 Department of Biochemistry and Biotechnology, Baghdad-ul-Jadeed Campus, The Islamia University of Bahawalpur, Bahawalpur 63100, Pakistan
5 Department of Pharmacy, Khawaja Fareed Campus, The Islamia University of Bahawalpur, Bahawalpur 63100, Pakistan
Reprint requests to N. Riaz. E-mail: nrch322@yahoo.com or nrch322@hotmail.com
Received April 19, 2013 / published online September 4, 2013
Two new limonoids, 1-O-deacetyl-2α-methoxykhayanolide (1) and kigelianolide (2), together with deacetylkhayanolide E (3), 1-O-deacetyl-2α-hydroxykhayanolide E (4) and khayanolide B (5) were isolated from the ethyl acetate-soluble fraction of the methanolic extract of Kigelia africana. The structures of these limonoids (15) were elucidated by the combination of 1D (1H and 13C NMR) and 2D (HMQC, HMBC and COSY) NMR spectroscopy and mass spectrometry (EIMS, HREIMS), and in comparison with literature data of related compounds. The structure of compound 1 was further confirmed by X-ray crystallography, and the absolute stereochemistry of compounds 1 and 2 was determined by electronic circular dichroism (ECD) spectroscopy. Limonoids 15 showed weak inhibitory activities against the enzymes acetylcholinesterase (AChE), butyrycholinesterase (BChE) and lipoxygenase (LOX) in a concentration-dependent manner with IC50 values in the ranges 137.5–225.2 μm for AChE, 185.4–241.5 μm for BChE and 281.2–189.6 μm for LOX.
Key words: Kigelia africana, Methanolic Extract, Limonoids, Solid-state ECD/TDDFT Method, Enzyme Inhibition
Full-text PDF