- Polar compounds isolated from the leaves of albertisia delagoensis (menispermaceae)
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Aqueous infusions of the leaves of the shrub Albertisia delagoensis (Menispermaceae) are used in South Africa in traditional Zulu medicine to alleviate a variety of symptoms, including fever, and intestinal problems. We report the analysis of such an aqueous extract using the HPLC-NMR technique. A number of polar compounds were identified, including proto-quercitol, nicotinic acid, allantoic acid, 3,4-dihydroxybenzoic acid, phthalic acid and the aporphine alkaloid derivative roemrefidine. Allantoic acid and roemrefidine have been fully characterised by 1H- and 13C-NMR and mass spectrometry. Earlier reports of antiplasmodial activity of roemrefidine and of A. delagoensis extracts are correlated with this study and with the antipyretic properties of neutral aqueous extracts.
- Hawkes, Geoffrey E.,De Wet, Helene,Li, Jia
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- THE MECHANISM FOR THE CONVERSION OF URIC ACID INTO UROXANATE AND ALLANTOIN A NEW BASE-INDUCED 1,2-CARBOXYLATE SHIFT
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Alkaline permanganate oxidation of uric acid (1), particularly the late stages of the transformation into uroxanate (7) and allantoin (3), was studied by means of isotope-position labelling.A clear-cut degradation procedure developed for distinguishing among carbonyl and α-aminal carbon atoms in these products demonstrated conclusively that the carboxylic carbon of 7 and the 4-carbonyl carbon of 3 have their origin in C(5) of uric acid (1).None of the mechanisms that have been proposed for this reaction would have predicted this result.Isotope-labelling evidence, in combination with other data, revealed the sequence of events and identities of species involved in oxidative transformation of 1; the carbon-skeleton rearrangement of the first transient intermediate 4 must occur by a 1,2-carboxylate shift to give allanatoin-5-carboxylate (6) which either decarboxylates to allantoin (3) or else undergoes hydrolytic ring opening to uroxanate (7).
- Poje, M.,Sokolic-Maravic, Lea
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p. 6723 - 6728
(2007/10/02)
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