Isolation of 4-Hydroxyphthalide from Oat Grain

Abstract

A NUMBER of substituted phthalide derivatives have been isolated from plant material¹ and most of these compounds carry either an alkyl substituent at position-3 (I) or an oxygen function at positions-5 and/or -7. Some of the latter group of compounds also carry a hydroxyl group at position-3 (for example, gladiolic acid (II)). It has been postulated² that all phthalides with an even number of carbon atoms or no alkyl group at position-3 have an oxygen function at position-7 and are derived from an even number of acetate units. On the other hand, phthalides with an uneven number of carbon atoms at position-3 (for example, eleutherol (III)) were considered to be related to 4-hydroxyphthalide by way of condensation of an odd number of acetate units. The isolation of 4-hydroxyphthalide from oat grain reported here offers an opportunity for further investigation of the origin of this group of compounds.