New chemical constituents from some endemic flora of Sri Lanka
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Date
1981-10
Authors
Surendrakumar, S.
Journal Title
Journal ISSN
Volume Title
Publisher
University of Peradeniya
Abstract
This thesis is composed of three parts. The first part consists of the isolation And structure clucidation of a new class of some novel polyphenols of resveratrol Origin (3,5,4'=trihydroxy— stilbene) from some endemic Dipterocarpaceae. The presumed formation of these compounds by phenolic coupling reaction And their viosynthesis is also ty discussed. Data obtained in this study also uzgest that these oligomers of resveratrol have pronounced antibacterial activity and could be used as taxonomic markers on a familial Level to Dipterocarpaceae, 13 nell.er. data of these compounds are interpreted and thelr unique mass spectral fragmentation are studied as far as possible, The second part describes the isolation and characterization of some new constituents from some endemic species of the family Moraceae. ‘The isolation and structure clucidation of two new chromenodihydro= benzoxanthones from_Artocarpus nobilis Thw. are the first examples of the presence of benzoxanthones in pienis. These two new natural products further enlightene a route to the biosynthesis of xanthones from flavonoids which still remain obscure. ‘he structure is also ieoposed for a new prenylated flavonoid from this species. Te presence of resorcinol in this species is reported for the first time and making it the third Artocarpus Species showing the presence of this compound. Three New minor alkaloids have been isolated from Broussonetia : Zgeylanica and two of them have been shown to Have a 8-hydroxy~quinoline moiety and the other Is a bipyridine diol. As a completion of the endemic survey Of this Temily the chemicel constituents of endemic Ficus species are also studied in this part. Part three is based on the chemical investigation Of Caloohylluin calaba L. var. worthingtonii Stevens a plant Belonging to the family Guttiferae. A Giprenyloted trioxygenated xanthone, isolated, Is found to be the precursor of the major xanthone in this species.
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Keywords
Chemistry , Endemic flora