Accumulation of Dietary Conjugated Linoleic Acid (CLA) in Silkworm, Bombyx mori

Conjugated linoleic acid (CLA) exhibits potent anti-carcinogenic and other biological activities in several animal models. We report here that dietary CLA, chemically synthesized from corn oil, accumulates in silkworm, Bombyx mori, which is used as a therapeutic agent for diabetes in Korea and Japan. Mulberry leaves treated with 0.1 or 10% CLA in ethanol were supplied to silkworms from the end of the 3rd instar to the 3rd day of the 5th instar. Fresh mulberry leaves or leaves treated with 10% corn oil in ethanol were fed as a check treatment. The amount of total lipids in the larval body ranged from 17.4 to 19.1 ㎎/g of body tissue, which was not significantly affected by the source of the diets. No CLA was found in the control silkworms. But the level of CLA significantly increased to 83.5 ㎎/g of fat, when fed with mulberry leaves treated with 10% CLA. Only trace amounts of CLA were detected in the larvae reared with check leaves and 0.1% CLA-treated leaves. Mulberry leaves treated with corn oil or CLA were not palatable to the larvae, resulting in a reduction of larval weight. These results suggest that silkworms containing CLA in body lipids could be produced by dietary CLA.