Isoflavone composition, total polyphenolic content, and antioxidant activity in soybeans of different origin.

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.

Determination of trans- and cis-resveratrol in Serbian commercial wines.

Resveratrol (trans-3,5,4'-trihydroxystilbene) is a phytoalexin produced by grapevines in response to fungal infection, particularly to Botrytis cinerea. It has been shown that it possess various biological effects such as prevention of cardiovascular diseases and anti-inflammatory and anticancerogenic properties. Red wines are a primary source of resveratrol. Although a number of investigations have focused on the determination of resveratrol in wines of different countries, there is no similar study about the wines produced in Serbia. As authors are aware, the only study concerning resveratrol content in wine in the Balkan region was conducted in Greece. In this study, the trans- and cis-resveratrol content in samples obtained from 18 commercial Serbian wines (10 red, 7 white, and 1 rose) were analyzed. Analyses were performed after solid-phase extraction by high-performance liquid chromatography with a diode array detection system using an RP-C(18) column with gradient elution [solvent A: acetonitrile-acetic acid-water (20:2:78 v/v), solvent B: acetonitrile-acetic acid-water (90:2:8 v/v)]. Detection of trans- and cis-resveratrol was performed on 306 and 286 nm, respectively. It was clearly established that there was a presence of trans-resveratrol isomers in all analyzed wines (0.11-1.69 mg/L) except in one white wine. Cis-resveratrol was present in 12 from 18 samples in different amounts (0.12-1.49 mg/L).

Solubilization of resveratrol in micellar solutions of different bile acids.

Bile acids are a special group of biological surfactants which can express different physiological and pharmacological effects. Micellar solutions of bile acids can solubilizate poorly soluble organic substances and improve their resorbtion. Above their critical micellar concentration (CMC) values, bile acids can cause interruption of membrane's integrity. Resveratrol (trans-3,5,4'-trihydroxystilbene) is a stilbene phytoalexine and studies reported that it can prevent or reduce diseases such as cancer and coronary heart disease. In this study, we examined affinity of different bile acids (CA, 12-MDCA, 12-MCA, 7-MCA, 7,12-DCA, 3,7,12-TCA) micellar solutions for resveratrol solubilization. CMC values for bile acids were determined by conductivity measurements. Concentration of micellar solutions were 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0 CMC value, for each acid respectively. At the same time, we investigated membranolytical potential of each acid. Solubilizated resveratrol was quantified using HPLC system with UV detection. Membranolytical potential was determined from citrate rabbit blood. Structures of mixed micelles of each bile acid and resveratrol were explained, and multiple linear regression equations for solubilization of resveratrol on different concentrations of bile acids were obtained. Micellar solution of 3,7,12-TCA had the biggest affinity for resveratrol solubilization and then, in decreasing order 7-MCA>7, 12-DCA>12-MCA>12-MDCA>CA. Also, 3,7,12-TCA had the lowest membranolytical potential.