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STUDIES IN THE CHEMICAL CONSTITUENTS OF BOMBAX CEIBA AND CUSCUTA REFLEXA

Versiani, Muhammad Ali (2004) STUDIES IN THE CHEMICAL CONSTITUENTS OF BOMBAX CEIBA AND CUSCUTA REFLEXA. PhD thesis, University of Karachi, Karachi.

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Abstract

The PhD work presented in this thesis consists of two parts. The part A describes the studies in the chemical constituents of Bombax ceiba and part B represents the bioassay directed isolation and structure elucidation studies in the chemical constituents of Cuscuta reflexa. A brief review on the biosynthesis of terpeniods, steroids, cardiotonic glycosides, aromatic compounds and falvonoids is also included Part-A: This part describes the review of earlier researches in the constituents of B. Ceiba and a brief discussion of the present work. Dried leave extracts of the plant was subjected to chemical investigation which led to the isolation of three new (I-III) and one known compound mangiferin (IV) which was obtained in high yield. These compounds are listed below New constituents from B. Ceiba: 4-C-B-D-Glucopyranosyl-1,3,6,8-tetrahydroxy-7-o-(4”-hydroxybenzoyl)-9H-xanthen-9-one (I) 2-C-B-D-Glucopyranosyl-1,6,7-trihydroxy-3-o(4”-hydroxybenzoyl)-9H-xanthen-9-one (II) 4-C-B-D-Glucopyranosyl-1,6,8-trihydroxy-3,7-di-o-(4”-hydroxybenzoyl)-9H-xanthen-9-one (III) Constituents isolated for the first time from B. Ceiba: 4, 2-C-B-D-Glucopyranosyl-1,3,6,7-tetrahydroxy-9H-xanthen-9-one, Mangiferin (IV) In conformity to the structure IV, mangiferin afforded octa (V), hepta (VI), penta (VII) and tetra (VIII) acetylated derivatives, on reaction with acetic anhydride and pyridine. Antimicrobial studies showed that IV, V and VI are active against a few Gram positive and Gram negative bacteria and some fungi. Mangiferin (IV) has significant potency as hypotensive agent and exhibited hypoglycaemic activity and possessed on toxicity. Moreover, a known compound lupeol (IX) has been isolated from the petroleum ether extract of the stem bark of B. ceiba in very large amount Compounds IV and V were found to be inactive in cytotoxic (cancer cell panel of 60 lines) and anti-HIV tests carried out in NCI, (NIH), Bethesda, USA. Extensive spectral .studies UN, IR, EIMS, NMR (H and C) and 2D-NMR (COSY-45, NOESY, HMQC/Hetro COSY, HMBC/COLOC and J-resolved experiments as well as chemical transformation were employed to elucidate the structures of all the isolated compounds. Part-B.4This part provides a review of the earlier contributions made in the chemistry and pharmacology of parasitic plant Cuscuta reflexa and a brief discussion of the present work, with reference to the bioassay directed isolation of anti-cancer and other compounds from the ethanolic extract of C. reflexa. This work led to the isolation of twenty six compounds which were characterized through the spectral studies and chemical transformations. One (II) of them is a new constituent and the remaining twenty five (I, III-XXVI) are known compounds of which twelve are new from the plant C. reflexa. They are listed below. New constituent from C. reflexa, 1. 21-Hydroxy odoroside H (II) Constituents isolated for the first time from C. reflexa 2. Odoroside H (I) 3. Neritaloside (III) 4. Strospeside (IV)

Item Type:Thesis (PhD)
Uncontrolled Keywords:bombax ceiba, cuscuta reflexa, terpeniods, steroids, cardiotonic glycosides, aromatic compounds, falvonoids
Subjects:Physical Sciences (f) > Chemistry(f2)
ID Code:982
Deposited By:Mr. Muhammad Asif
Deposited On:23 Nov 2006
Last Modified:04 Oct 2007 21:03

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