Investigations on Hoya Species. I

Abstract

In Hoya australis latex free triterpenols as well as their esters are present in a ratio of about 1 :7. Main free alcohols are: β–amyrin, α–amyrin, cyclo–artenol and 24–methylene–cycloartanol; esterification occurs mainly with cinnamic acid and to a lesser extent with acetic acid. In addition to triterpenols the sterol β–sitosterol and the 4α–methylsterols obtusifoliol and cycloeucalenol were identified. The composition of latex taken from different individuals or from different parts within an individual plant appeared highly identical. Once outside the plant, however, photochemical changes such as conversion of cycloartenylacetate and trans–cis isomerisation of the cinnamic acid part of the triterpene cinnamates occurred.

Key Word Index

Hoya australis - Asclepiadaceae - Latex Lipids