Twenty soybean cultivars, originating from the United States, Russia, Serbia, and China, were analyzed for their isoflavone composition, total polyphenolic content, and antioxidant activity. Isoflavones were extracted by aqueous methanol (80%) and analyzed by high-performance liquid chromatography/diode array detection. Precision and linearity of the applied method were within the standard limits of validation. The highest and the lowest total isoflavone contents were 4.59 and 1.45 mg/g of dried soybean weight, respectively. A significant difference ( P < .05) was found in isoflavone concentration among the different cultivars, but it was observed that origin is not a significant factor that could influence isoflavone content in soybeans. Total polyphenolic content varied between 2.13 and 3.45 mg of gallic acid equivalents/g of dried soybean weight. The free radical scavenging activity of soybean extracts assayed by 2,2-diphenyl-1-picrylhydrazyl in terms of 50% inhibitory concentration (IC ₅₀ ) ranged from 1.40 to 3.35 mg/mL. Negative correlation between total polyphenolic content and IC ₅₀ was observed, but there was no correlation between total isoflavone content and IC ₅₀ . On the basis of this study, soybean cultivars with larger potency for biological activity could be recognized.

Herein, a brief overview of the cyclodextrin structure is provided, along with its most important derivatives. The difference between the water molecules in the outer hydration shell of cyclodextrin and those in its hydrophobic cavities is discussed. The structural characteristics of surfactants, along with their structural differences, are presented. An insight into the formation of surfactant micelles was given in aqueous solution. A thermodynamic model for the formation of the inclusion complex between surfactants and cyclodextrin in a solution is presented, explaining the hydrophobic effect, which drives the formation of the inclusion complex at lower and room temperatures. The influence of the size of the cyclodextrin cavity and the structure of surfactants on the stoichiometry of the inclusion complex, as well as on the affinity of the surfactant to the hydrophobic cavity of cyclodextrin, is discussed. The most important experimental methods used to study the cyclodextrin-surfactant inclusion complex are listed.