Novel natural products from four annonaceae species
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Date
2001
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University of Dar es Salaam
Abstract
This Thesis reports on phytochemical investigations of four plants of the family Annonaceae, namely Monodora angolensis Welw., Isolona cauliflora Verdc., Uvaria puguensis D.M. Johnson and Lettowianthus stellatus Diels, whereby two known cytotoxic and antimalarial monoprenylated indoles 6-(3-methyl-2-butenyl)-1H-indole and 6-(3-methylbuta-l,3-dienyl)-1H-indole, 4-(indoyl-6-yl)-3-buten-2-one, 3-geranylindole and the hitherto unreported 5-formylindole, 2-indolelactam and annonidine G were isolated from M. angolensis. From I. cauliflora, the monoprenylated indoles 5-(3-methyl-2-butenyl)-1H-indole and 5-(3-methylbuta-l,3dienyl)-1H-indole, the diprenylated indoles caulidine A and caulidine B, and Diels Alder type adducts of monoprenylated indoles were obtained, together with the pentitol ribitol that occurred only in the flower stalks. The stem bark of the newly described Uvaria puguensis D.M. Johnson yielded the hitherto unreported phenanthrenoid 6-hydroxy-3-methoxy-4-oxapyren-5-one, the C-benzyldihydrochalcone 5'-methyluvaretin and known antimalarial C-benzyldihydrochalcones. The root bark of Lettowianthus stellatus Diels from Tanzanian coastal forests yielded two hitherto unreported telisatin type aporphine alkaloids, liriodenine, 3,4,5-trimethoxyphenol, 7-octadecen-9-ynoic acid, the insect juvenile hormone III [methyl (2E,6E,lOR)-10,11-epoxy-3,7,11-trimethyl-2,6dodecadienoate] together with its diol derivative and the new guaiane sesquiterpene 11-hydroxyguaia-4,6-dime. These results indicated that the genus Lettowianthus has only one species, viz. L. stellatus, whose fruits also yielded six hitherto unreported non-cytotoxic and non-antimalarial geranylated quinone derivatives, insect juvenile hormone III, an unidentified C t g acetylenic fatty acid and an aporphine alkaloid. Structures of all the compounds were determined by extensive spectroscopic and chemical methods.
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Keywords
Natural products, Medicinal plants, Botanical drugs, Annonaceae
Citation
Makangara, J. J. (2001) Novel natural products from four annonaceae species, Doctoral dissertation, University of Dar es Salaam. Available at (http://41.86.178.3/internetserver3.1.2/detail.aspx)