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PHOTOCHEMICAL STUDIES ON CARALLUMA TUBERCULATA, CARALLUMA EDULIS AND PHARMACOLOGICAL STUDIES ON SIDE PAKISTANICA

Muhammad, Tanweer Alam (1999) PHOTOCHEMICAL STUDIES ON CARALLUMA TUBERCULATA, CARALLUMA EDULIS AND PHARMACOLOGICAL STUDIES ON SIDE PAKISTANICA. PhD thesis, University of Karachi, Karachi.

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Abstract

Three natural drugs of medicinal importance were investigated scientifically and two of them Caralluma tuberculata and Caralluma edulis very well known traditional antidiabetics were subjected to chemical examination and the other an indigenous plant Sida pakistanica was evaluated from the bioactivity point of view. Caralluma tuberculata and Carallull1a edulis showed positively the presence of steroid type of molecules and chemical methodology led to the isolation of nine pregnane type of compounds. The different compounds so separated physico-chemically and chromatographically were designated as caratuberoside A, caratuberoside B, caratuberoside C, caratuberoside D, caratuberoside E, caratuberoside F, caratuberoside G, caratuberoside B1 and caratuberoside A2. Structures of these isolates were determined by chemical and spectroscopic techniques including mass, proton and carbon magnetic resonance, as well as 2D-NMR and NOE experiments. The ambigious assignments of new caratuberosides were resolved through molecular modelling comparisons. Consequently, it was inferred that these glycosidic constituents basically consist of pregnane type of derivative aglycone or the genin to which are attached different type of sugar moieties in C-O linkage fashion, therefore, it will be appropriate to refer all these compounds as caratuberoside, thus specifying the said linkage. The different caratuberosides can be categorized into two major groups based on various aglycones or genin structures of pregnane class or on the basis of aglycone and glycone linkage. The aglycone comprised of ketonic group (C-17 position), hydroxyl group (C-20 position), ether linkage (between C-12 and C-20), and double bond (between C-5 and C-6). The aglycone and aglycone linkage exhibit at either C-3 or C-14 of aglycones of different caratuberosides having only two well-defined sugar either digitalose and glucose. A hypothetical biogenetic scheme of these caratuberosides is also presented. The biological study of the ethanolic extract of Sida pakistanica was executed for the possible presence of spasmogenic and spasmolytic constituents at the dose of 0-1-5.0 mg/ml caused spasmogenic effects both in isolated guinea-pig ileum and rabbit jejunum. In the presence of atropine (0.1 uM), Sida pakistanica did not exhibit spasmogenic effect, instead spasmolytic activity was enhanced at similar doses. When tested against K+ induced contraction, Sida pakistanica caused a dose dependent relaxation in the concentration range of O.3-IO mg/ml, suggestive of the involvement of calcium channel blockade (CCB). The crude extract was subjected to activity - directed fractionation to separate spasmogenic (cholinergic) and spasmolytic (CCB) constituents. The results revealed the spasmogenic component was separated in the aqueous fraction whereas, the spasmolytic component was concentrated in the ethyl acetate fraction. The potent CCB effect of the ethyl acetate fraction was confirmed when the pre-treatment or tissue with Sida pakistanica (0.03-0.3 mg/ml) shifted Ca++ dose-response

Item Type:Thesis (PhD)
Uncontrolled Keywords:caralluma tuberculata, caralluma edulis, side pakistanica, antidiabetics, caratuberoside
Subjects:Biological & Medical Sciences (c) > Biological Sciences(c1) > Biology (c13)
ID Code:1250
Deposited By:Mr. Muhammad Asif
Deposited On:19 Jan 2007
Last Modified:04 Oct 2007 21:05

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