Some Observations on the Saponin Accumulation in Oat Seedlings and on the Transformation of the Avenacosides to the Antibiotic 26-Desgluco-avenacosides

The accumulation o f the steroidal saponins avenacoside A and B in oat was investigated in green and etiolated seedlings and was found to be strictly bound to the growth o f the seedlings. N o significant differences were detected between green and etiolated seedlings, showing that there is no relation between saponin accumulation and plastid development. As the role o f the oat saponins has to be seen as a protective device against fungi and bacteria, the transformation o f the inactive avenacosides to their corresponding antibiotic 26-desgluco-avenacosides was tested in dependence o f pH and temperature. During disruption o f leaves, transformation occurs almost completely over a wide pH-range (pH 4 —pH 10); the degree o f transformation exhibits no distinct temperature optimum but a drastic decrease at 70 °C.