After chewing a few leaves of Gymnema sylvestre, the ability to taste sweet substances-e.g., sucrose, sodium saccharin, and sodium cyclamate-is suppressed for a few hours. Earlier investigations detected the acidic and glycosidic nature of the active principle which was called gymnemic acid. More recently some components of this material, which appeared to be a mixture, were isolated.The major component, gymnemic acid A1( which still possesses the antisweet property, has been shown to be a D-glucuronide of a new hexahydroxytriterpene (esterified with different acids). On the basis of physical and chemical data the structure of the new triterpene could nearly be established.V)The leaves of the tropical plant Gymnema sylvestre R.Br. possess a strange property. After chewing one or two leaves one is unable to detect the sweet taste, and the bitter taste is also suppressed to some extent. Drinking sweet tea one can fully appreciate the aroma

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Aus der Latex von C. procera werden neben einer Reihe von Cardenoliden, die als Inhaltsstoffe der Pflanze bereits bekannt sind, z.B. Uscharin (I), drei weitere Verbindungen isoliert: Uzarigenin (II), Syriogenin [für das die frü‐ her angegebene Struktur (III) vermutlich nicht zutrifft] und das neue Glykosid Procerosid (IV).

Die CD‐ und z.T. die ORD‐Kurven von 44 Sesquiterpenlactonen, wie z.B. (I), und der Cotton‐Effekt der Pyrazolin‐Addukte solcher Lactone, wie z.B. (II), wird untersucht.

Aus den Blättern von Marsdenia erecta R. Br.