Saponins are a structurally diverse class of compounds occurring in many plant species possessing a number of desirable biological and pharmacological activities. In this work methodology was developed to extract, isolate and purify desirable triterpenoid saponins based on the unusual aglycone backbone hederagenin from the fruits and leaves of common ivy (Hedera helix). The principal saponins obtained from the fruit were monodesmosidic and composed of predominantly a-hederin; the fruit by contrast had a saponin profile consisting of a mixture of monodesmosides and bidesmosides with Hederacoside the principle saponin present. The hydrolysis of these was investigated and procedures designed for the subsequent selective hydrolysis of the glycoside portions of these saponins by acid and base hydrolysis to obtain the aglycone and hemiglycone (monodesmosidic) derivatives. By chemical modification of the glycosides and aglycone, further derivatives have been prepared so as to develop a suite of novel compounds which were used to conduct trials of their biological activities to discover any potentially useful products and identify the best means of optimising these activities. A number of new long and short chain ester derivatives of hederagenin were prepared at the two hydroxyl positions, as well as investigation into the modification of the acid and olefin functionalities of the starting material which showed both of these positions to be significantly sterically hindered and as such exhibit a very low reactivity.
The saponin extracts and hydrolysis products from both the fruit and the folium of H. helix together with the their hydrolysis products were shown to exhibit significant biological activity against a number of microorganisms, particularly fungi, giving rise to the potential to develop triterpene saponin based therapeutic treatments for such conditions. In addition to this, H. helix fruit saponin and hydrolysis products were found to exhibit activity against slugs, potato cyst nematode and potato blight which could signify a potential use of these compounds in crop protection.