Abstract:
γ-Oryzanol is mainly composed of esters of trans-ferulic acid(trans-hydroxycinnamic acid)with phytosterols(sterols and triterpenic alcohols).Among these, cycloartenyl ferulate, 24-methylenecycloartenyl ferulate, campestanyl ferulate and
β-sitosteryl ferulate are the main four components of
γ-oryzanol, accounting for about 95%.UV spectrophotometry can only determine the total amount of
γ-oryzanol, but high performance liquid chromatography can separate and determine the components of
γ-oryzanol.In this work, a high performance liquid chromatography-ultraviolet detection method was developed for the determination of four main components of
γ-oryzanol in a simulation system.The mixture of
γ-oryzanol standards was used as an external standard for quantification and the sample was dissolved in isopropanol.Diphenyl ether and paraffin liquid(1∶1,
V/V)were mixed as the simulated system.
γ-Oryzanol was mixed in this system according to the mass ratio of 3%.The column was Waters Symmetry C18(4.6 mm×250 mm, 5 μm), and the mobile phase was methanol: acetonitrile(1∶1,
V/V).Flow rate was 0.8 mL/min.Detection time was 50 min.The UV detection wavelength was set at 325 nm.The results showed that the method showed good linearity in the concentration range of 20-1 000 μg/mL.The standard curve equation of cycloartenyl ferulate was
y=34 889
x-63 757, the standard curve equation of 24-methylenecycloartenyl ferulate was
y=34 813
x-112 228, the standard curve equation of campestanyl ferulate was
y=36 565
x-67 528, the standard curve equation of
β-sitosteryl ferulate was
y=35 601
x-32 177, and the correlation coefficients(
R2)of the standard curve regression equations of four main components were 0.999 5, 0.999 4, 0.999 0, and 0.998 6, respectively.The detection limit of cycloartenyl ferulate was 0.15 μg/mL.The detection limit of 24-methylenecycloartenyl ferulate was 0.15 μg/mL.The detection limit of campestanyl ferulate was 0.23 μg/mL.The detection limit of
β-sitosteryl ferulate was 0.17 μg/mL.The RSD of the retention time and peak area of the four main components were less than 5% in the instrument precision and sample repeatability experiments.The RSD of the retention time and peak area of the four main components were less than 5% in the sample stability experiments.The recovery rates of four main components and total amount of
γ-oryzanol were 83.25%-119.74% and 92.27%-110.87%, respectively.In the application of rice bran oil, the RSD of this recovery rate was less than 5%.This method could be applied to determine four main components of
γ-oryzanol in a simulation system with good repeatability, high sensitivity and accurate results.The preliminary research showed that its application in rice bran oil has similar effects to the simulation system.
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