ABSTRACT
Dietary Fat Sources. Soybean oil was obtained from Wako Pure Chemical, Osaka, Japan. Raw materials for preparation of triacylglycerol (TAG) containing a particular CLN isomer were pomegranate (Punica granatum) seed oil for c9,t11,c13-CLN, bitter gourd (Momordica charantia) seed oil for c9,t11,t13-CLN, catalpa (Catalpa ovata) seed oil for t9,t11,c13-CLN, and pot marigold (Calendula officinalis) seed oil for t8,t10,c12-CLN. The seeds were ground to a powder with an electric mill, and extracted with n-hexane 3 times at room temperature. After standing with occasional shaking for ~6 h, n-hexane was evaporated below 30°C in a rotary evaporator and vacuum pump. CLA oil was kindly donated by Kaneka, Takasago, Japan. CLN-or CLA-containing oils were passed through a column packed with a 1:1 n-hexane slurry mixture (w/w) of activated carbon and Celite 545 to remove tocopherols and pigments. Recovered lipids were refined on a silicic acid column (Silicagel 60, Merck, Darmstadt, Germany) eluting with n-hexane and a mixture of diethyl ether/n-hexane solution (5:95, 10:90, and 20:80, vol/vol). The TAG fraction that eluted with diethyl ether/nhexane (10:90) was used for the present study as pomegranate oil (PGO), bitter gourd oil (BGO), catalpa oil (CTO), pot marigold oil (PMO), and CLA oil (CLA). Each fraction gave only a single spot corresponding to TAG on the thinlayer chromatogram with normal phase silica plates (Merck) developed with diethyl ether/n-hexane/acetic acid (40:60:1, by vol). The peroxide value of each dietary oil (soybean oil and soybean oil + CLA or CLN containing TAG) was <1.0 as determined by the AOCS official method (21).
