Chemistry and bioactivity of some Sri Lankan Menispermaceae and Rubiaceae
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Date
2003
Authors
Jayasooriya, J. A. C. P.
Journal Title
Journal ISSN
Volume Title
Publisher
University of Peradeniya
Abstract
This thesis includes two parts. Part I describes the chemistry and bioactivity studies of the leaves of Diploclisia glaucescens of the family Menispermaceae and part Il describes antimicrobial activity studies of thirteen Sri Lankan plant species of family Rubiaceae.
Part I
Diploclisia glaucescens is a creeper climbing up about twenty-five meters high and is totally glabrous. It is distributed in the mid country regions of South India and Sri Lanka. It has been reported that the leaves of this plant are used to treat biliousness and venereal diseases.
Chromatographic separation of the ethyl acetate extract yielded three ecdysteroids low polar than 20-hydroxyecdysone, which is generally considered as the moulting hormone in insects. They were identified as makisterone A, dihydrorubrosterone and epi-pterosterone. This is the first report of dihydrorubrosterone and epi-pterosterone from the family Menispermaceae. Makisterone A has been previously reported from the seeds of D. glaucescens.
Chemical investigation of the n-hexane extract of the leaves of Diploclisia glaucescens furnished stigmasterol.
Chromatographic separation of the methanol extract afforded two ecdysteroids, 20-hydroxyecdysone and a new ecdysteroid, 3-deoxy-1-β20- dihydroxyecdysone and three saponins, β-sitosterol-D-glucoside, 3-O-β-D- glucopyranosyl-(1->3)-β-D-glucopyranosyl ~28-O-β-D-glucopyranosyloleanolic acid and 3-O-β-D-xylopyranosyl-(1—>2)-β-D-glucopyranosyl-28-O-β-D-glucopy -ranosyloleanolic acid. Latter two triterpenoidal saponins are reported for the first time from the family Menispermaceae.
Structure elucidation of the isolates was mainly based on spectroscopic techniques such as NMR, HMBC, HMQC, H-H COSY, NOE, etc and chemical methods such as acid hydrolysis, acetylation etc.
All isolates were tested for their antifungal activity against Cladosporium cladosporioides using TLC bioautography method. None of them showed any activity.
Part II
Ninety solvent extracts (n-hexane, dichloromethane and methanol) obtained from the leaves and bark of thirteen Sri Lankan Rubiaceae plants; Benkara malabarica, Canthium coromandelicum, Canthium dicoccum, Haldina cordifolia, Ikora calycina, Morinda tinctoriya, Mussaenda frondosa, Psychotria gardneri, Psychotria nigra, Psychotria stenophylla, Saprosma foetens, Tarenna asiatica and Wendlandia bicuspidata were tested for antibacterial activity against Escherichia coli (Gram-), Micrococcus luteus (Gram+), Bacillus subtilis (Gram+), Bacillus cereus (Gram+) and antifungal activity against Saccharomyces cerevisiae, Ustilago maydis and Aspergillus niger by Disk diffusion method.
Morinda tinctoriya, Mussaenda frondosa, Psychotria gardneri and Psychotria stenophylla displayed the widest spectrum of antibacterial activity.
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Keywords
Chemistry , Bioactivity