Encapsulation of genistein in amylose complexes

Introduction Isoflavones are natural bioactives associated with a variety of beneficial health effects including reducing the risk of cardiovascular disease, lowering the rate of some cancers and improving bone health among other claims (Kano et al., 2006). One of the most abundant aglycone form of isoflavones found in soybean is genistein, 4',5,7-trihydroxyisoflavone (Crupi et al., 2007). Genistein bioavailability is limited due to its poor water solubility which limits its efficacy when administered orally (Motlekar et al., 2006). Moreover, its bitter taste is also a drawback (Huang et al., 1982). Therefore, a novel delivery system might help improve its performance. Amylose, a fraction of starch, is known for its ability to form molecular complexes with a variety of ligands (Conde-Petit et al., 2006). These complexes are composed of left handed helices known as V amylose. The exact location of the guest molecules in V-amylose varies (inside the helix cavity, between the helices or in both sites) and so does the number of glucose residues per turn which can be six (V6), seven (V7) or eight (V8) (Biais et al., 2006). This form has recently gained attention as a possible delivery system for various bioactives, however, scarce data exists on the complexation of water-insoluble aromatic bioactives. Thus, the challenge was to induce amylose complexation with genistein, study their structure, their stability in different pH levels and temperatures, and test their functionality in simulated stomach and intestinal conditions.