City Research Online

Abstract

It has been shown that the prosaponin mixture isolated from the fruit of Phytolacca dodecandra (Phytolaccaceae) may be converted to a molluscicide by saponification. The molluscicide, which may be formulated as a water soluble solid, is active against the schistosomiasis transmitting water-snail, Biomphalaria glabrata and against the fascioliasis transmitting snail Lymnaea truncatula. It may be produced in high yields, is non-toxic towards mammals at molluscicidal concentrations and possesses most of the characteristics recommended in a recent World Health Organisation report on molluscicides. The constitution of the molluscicide has been investigated by chromatography and it has been shown that the polarity of the sugar moieties significantly affects the activity of the molluscicidal saponins. It has also been demonstrated that the saponin sugars play an additional role besides that of rendering the sapogenins water soluble. Molluscicides of high activity were produced from samples of fruit obtained from several different localities within East Africa.

The prosaponins isolated from the fruit of P. clavigera, P. acinosa and Diploclisia glaucescens (Menispermaceae) did not afford a molluscicide on saponification. The major sapogenins were isolated and shown to be the C-20 methoxycarbonyl pentacyclic triterpenoids, serjanic acid and a new compound, diploclisolic acid (the 30-methoxycarbonyl derivative of 3β,23-dihydroxy-olean-12-en-28-oic acid); the major sapogenin in P. dodecandra had been shown by previous workers to be oleanolic acid. The chemical and physical properties of serjanic acid, diploclisolic acid and their derivatives have been investigated; the use of nuclear magnetic resonance spectroscopy and mass spectrometry to determine the nature of the C-4, -28 and -30 substituents is reported.

The sapogenins isolated from the genus Phytolacca are recorded and the future isolation of 28,3β,23-trihydroxy-olean-12-en-28,30-dioic acid is anticipated.

The isolation of triterpenoid saponins from the fruit of Cocculus macrocarpus supports the suggestion by Forman that this plant should be reclassified as Diploclisia glaucescens.

The sapogenin, swartziagenin, which had previously been isolated from the pods of Swartzia madagascariensis has been shown to be a mixture of oleanolic acid and its 3β-acetyl derivative.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QD Chemistry
Departments:	School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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