Soybean germ oil inhibits oxidosqualene cyclase in 3T3 fibroblasts

Abstract

Soybean germ oil (SGO) could take an important place among nutraceuticals if the finding were confirmed that a daily intake of SGO helps to maintain a normal level of serum cholesterol. Adapting the rice milling technology to the soybean refining process, we achieved a rapid and efficient separation of soybean bran and cotyledon from the hypocotyle. Our soybean germ was no less than 95% hypocotyle. SGO obtained from it by typical hexane extraction was very rich in tocopherols (total content 4.35 g/kg) and phytosterols (β-sitosterol 57.4%, Δ-7-stigmastenol 20.2%, Δ-7-avenasterol 6.8%, stigmasterol 6.2%, campesterol 5.4%, Δ-7-campesterol 1.2%, Δ-5-avenasterol 0.95%, etc.; total sterols 44.3 g/kg). The most prominent fatty acids were linoleic (56.2%), linolenic (15.5%) and oleic acid (10.6%). Although isoflavones abound in soybean germ (17.7 g/kg), only traces of them passed into the hexane extract (7 mg/kg). In murine 3T3 fibroblasts, SGO was found to reduce the incorporation of [14C]acetate into sterols, by inhibiting oxidosqualene cyclase.