Anthocyanins in Bananas

Abstract

The bracts of wild banana species are pigmented by glycosides (probably 3-diglucosides) of four combinations of anthocyanidins: cyanidin-pelargonidin; cyanidin-delphinidin; delphinidin-petunidin-cyanidin-malvidin-peonidin; mal-vidin-peonidin. The proportions of the various components are slightly variable as between clones of one species and even between samples, but the general pattern is characteristic of a species and is therefore of considerable taxonomic value. In Musa acuminata a cline in bract colour is related to variation in oxidation and methylation of the anthocyanidins. Yellowness of (i.e. absence of antho-cyanin in) the bracts of a strain of the same species is probably caused by a single recessive gene. The bracts of edible bananas have, broadly, the pigments expected on taxonomic and genetic grounds but show an (unexplained) tendency towards a generally lower level of methylation of the anthocyanidins. Leucoanthocyanins are present in most parts of the banana plant; they yield delphinidin and cyanidin in proportions that vary approximately with overall intensity. In discussion, the taxonomic interest of the results and the technically favourable nature of bananas for investigation of the leucoanthocyanins and the biogenesis of the visible pigments are emphasized.