Oestrogenic Isoflavone Content in Natural Strains of Subterranean Clover (Trifolium subterraneum L.) from Sardinia

Abstract

A collection of subterranean clover (Trifolium subterraneum L.) genotypes from Sardinia was evaluated for the content of oestrogenic isoflavones to assess differences in total and individual compounds. Daidzein, genistein, and their respective 4′-methoxy derivatives biochanin A and formononetin, were detected in leaves and quantified by GC/FID and GC/MS methods. A large variation among genotypes for individual compounds and for the total isoflavone concentration was observed. Total isoflavones were measured in the range 0.8-13.4 mg/g fresh weight (0.3-4.5% dry matter). Daidzein was usually present in lower amount compared to the other isoflavones. Genistein and biochanin A were found in most cases in higher concentration than formononetin. Phyto-oestrogens have been shown to have both oestrogenic and anti-oestrogenic properties, and their effects entail a positive role for the human health. T. subterraneum revealed the presence of higher concentration of isoflavones compared to other sources of these compounds, e.g. soybean (Glycine max (L.) Merrill) and red clover (Trifolium pratense L.). This study provided information on the biodiversity of the natural strains from Sardinia, emphasizing the importance of these genetic resources for their variation in the amount of total and individual isoflavones.