α-tocopherol, γ-tocopherol, α-tocotrienol and γ-tocotrienol
were purchased from Sigma-Aldrich Co. Pure γ-oryzanol was kindly
provided by Dr. Z. Xu and Dr. J. S. Godber (Department of Food
Science, LSU Agricultural Center, Baton Rouge, LA, USA). All solvents
used were analytical or HPLC grade.