Isoflavones-structure, properties, applications

Abstract

Introduction: Isoflavones are a class of organic compounds and biomolecules related to the flavonoids. Isoflavones are produced almost exclusively by the members of the Fabaceae (i.e., Leguminosae, or bean) family. Some are termed antioxidants because of their ability to trap singlet oxygen. Some isoflavones, in particular soy isoflavones, when studied in populations eating the soy protein, have indicated that there is a lower incidence of breast cancer and other common cancers because of its role in influencing sex hormone metabolism and biological activity through intracellular enzymes, protein synthesis, growth factor actions, malignant cell proliferations, differentation and angiogenesis. However some critics claim that isoflavones can increase the incidence of epithelial hyperplasia and cause goitre and hyperthyroidism. Isoflavones remain the subject of many scientific studies, as illustrated by the more than 1700 scientific publications mentioning isoflavones in their title or abstract. Most of these studies show that isoflavones may have some health benefit. Materials and methods: bibliographic study of plants producing isoflavones - soybean (Glycine max L.), green bean (Phaseolus vulgaris L.), alfalfa sprout (Medicago sativa L.), mung bean sprout (Vigna radiata L.), cowpea (Vigna unguiculata L.), kudzu root (Pueraria lobata L.). The analysis of methods used for the separation and standartization of isoflavones: Nuclear Magnetic Resonance (NMR), UV-VIS, MS, high-performance liquid chromatography (HPLC). Results: Most protocols of the sample preparation for isoflavone determination in soymilk and other liquid soybean products involves tedious freeze-drying and time-consuming extraction procedures. Were report a facile and rapid magnetic solid-phase extraction (M SPE) of isoflavones from soymilk for subsequent high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-M S/M S) analysis. The extraction was based on the selective binding of the isoflavones to baicalin-functionalized core-shell magnetic nanoparticles (BMNPs). The HPLC method is the most suitable choice for the identification of flavonoids as separation methods are well established and coupling with the MS is easy. For the isolation of flavonoids from liquid samples (drinks) or of physiological fluids typically are addressed in two ways: the first one is based on liquid-liquid extraction, and the second SPE. An interlaboratory study was conducted to evaluate a method for determining total soy isoflavones in dietary supplements, dietary supplement ingredients, and soy foods. Isoflavones were extracted using aqueous acetonitrile containing a small amount of dimethylsulfoxide (DMSO) and all 12 of the naturally occuring isoflavones in soy were determined by HPLC with UV detection using apigenin as an internal standard. Conclusions: Isoflavones are found in high concentrations in the vegetable, fruit and vegetable flavonols in most of the human diet.