The objective of this work was to evaluate the proximate composition, as well as Daidzein (D) and Genistein (G) contents by HPLC, of BRS 243 RR soybean. Sample preparation for the chromatographic analysis involved the use of hexane to remove lipids. Isoflavones were extracted with 70% ethanol containing 0.1% acetic acid. The optimized chromatographic conditions were: C18 column, mobile phase methanol:5% acetic acid (1:1 v/v), flow rate 0.5 mL/minute, column temperature 30 °C, UV absorbance at 254 nm and volume injected 40 µL. The validation parameters were: linearity of daidzein (y = 11242 x -37433, r = 0.9976) and genistein (y = 18510 x -66761, r = 0.9980); variation coefficients obtained in intra-day precision assays [CV = 5.3% (D), CV = 6.7% (G)] and inter-day precision assays [CV = 8.7% (D), CV = 9.7% (G)]; quantification limit 10 µg.g-1; detection limit 5 µg.g-1 and recovery 95.7%. Therefore, the optimized method was appropriate for the determination of daidzein and genistein in soybean. Carbohydrate (31.4%), protein (35.9%), lipid (20.9%), moisture (6.9%), ash (4.9%), daidzein (44.1 µg.g-1) and genistein (37.4 µg.g-1) contents determined in transgenic soybean were similar to those of conventional soybean determined in other studies.
transgenic soybean; isoflavones; daidzein; genistein; centesimal composition; HPLC
