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STUDIES ON THE CHEMICAL CONSTITUENTS OF RHAZYA AND NIGELLA SATIVA

Malik, Sohail (1985) STUDIES ON THE CHEMICAL CONSTITUENTS OF RHAZYA AND NIGELLA SATIVA. PhD thesis, University of Karachi, Karachi.

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Abstract

Studies on the chemical constituents of the fruits of Rhazya stricta have led to the isolation of four new alkaloids: rhazimanine, bhimberine, RA-l and RA-2. In addition, five more alkaloids have also been reported for the first time from this plant. Modern spectroscopic methods were employed to determine their structures including two-dimensional NMR experiments ego COSY, NOESY and J-resolved. DEPT experiments were carried out to determine the multiplicity of each carbon atom. The stereochemistry of various asymmetric centres was established by extensive NOE difference studies. Biosynthetic routes to the isolated alkaloids are also proposed. Investigations on the chemical constituents of the seeds of Nigella sativa resulted in the isolation of four new alkaloids: nigellicine, nigellimine, nigellimine N-oxide and NS-l. Their structures have been established by extensive NMR studies. Two of these alkaloids possess a novel skeleton which was confirmed by x-ray diffraction. The structures of the other two alkaloids were confirmed by synthesis. Biosynthetic routes to these alkaloids are proposed. As a result of studies on the non-alkaloidal constituents of this plant, a saponin has been isolated and its structure is presented. Antimicrobial testing of various chemical constituents of Nigella sativa has been carried out. Studies on the behavior of 19-5-vindolinine in solution have revealed a remarkable isomerization to 19-R-vindolinine. 13C-solid state CP-MAS spectrum of 19-5 vindolinine is also presented.

Item Type:Thesis (PhD)
Uncontrolled Keywords:rhazya, nigella sativa, rhazimanine, bhimberine, ra-l, ra-2, nigellicine, nigellimine, nigellimine n-oxide, ns-l
Subjects:Physical Sciences (f) > Chemistry(f2)
ID Code:1172
Deposited By:Mr. Muhammad Asif
Deposited On:03 Jan 2007
Last Modified:04 Oct 2007 21:04

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