BIOACTIVITY GUIDED ISOLATION OF A NOVEL ANTI-INFLAMMATORY AND ANTIBACTERIAL FLAVONOL AND OXYCHROMONE FROM THE PLANT PILIOSTIGMA RETICULATUM (SCHUM)
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Date
2008
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
Piliostigma reticulatum (Schum) is a plant used throughout tropical Africa in treating varieties of ailments, which includes ulcers, cough, wounds, chest pains, gingivitis, fever, gonorrhea etc.In a screening of fifteen plant species from an inventory of some African medicinal plants for anti-inflammatory activity, \textit{Piliostigma reticulatum} leaf extract was found to possess highly moderate but specific prostaglandin synthesis inhibitory activity. The plant extract was also found to exhibit antibacterial activity against \textit{Staphylococcus aureus} NCTC 10788, \textit{Escherichia coli} NCTC 9001, \textit{Bacillus subtilis} NCTC 8236 and \textit{Proteus vulgaris} NCTC 4175. This observation prompts in looking into the constituents present in \textit{Piliostigma reticulatum} leaves with its widespread ethnomedicinal uses. A total of Ten compounds were isolated and their structures were unambiguously established by spectroscopic methods including infrared and ultraviolet spectroscopy, high-resolution mass spectrometry and Nuclear magnetic resonance spectrometry. Four of the isolated compounds were Novels. This includes the first ever \textit{P1}C-Methyl-p-phenoxychromonol (Piliostigmol), \textit{P2} 6,8-Di-C-Methylquercetin 3,7,3$^\prime$-trimethyl ether, \textit{P3} 6,8-Di-C-Methylquercetin 3,3$^\prime$-dimethyl ether and the \textit{P4} 6,8,3$^\prime$-tri-C methylquercetin 3,7-dimethyl ether. Four known C-Methyl flavonols were also isolated from \textit{P. reticulatum} for the first time and were \textit{P7} 6-C-Methylquercetin 3-methyl ether, \textit{P8} 6-C-Methylquercetin 3,7,3$^\prime$-trimethyl ether, \textit{P9} 6,8-Di-C-methylkaempferol 3-methyl ether and \textit{P10} 6,8-Di-C-methylkaempferol 3,7-dimethyl ether. All of the isolated compounds were tested for their ability to inhibit prostaglandin synthesis and 6-CMethylquercetin 3,7,3$^\prime$-trimethyl ether was found to be the most active (IC =6.58 mM) being about 300 times as 50 potent as aspirin.
Description
Author Institution: Department of Chemistry, Obafemi Awolowo University, Adeyemi; Campus, P.M.B 520, Ondo, Ondo State Nigeria; Department of Chemistry,University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa