Accumulation of 1-deoxynojirimycin in silkworm, Bombyx mori L

Abstract

1-deoxynojirimycin (1-DNJ) contents in the silkworm, Bombyx mori, at different developmental stages and tissues were investigated by using reverse-phase high-performance liquid chromatography. The 1-DNJ contents of silkworm larvae change significantly with their developmental stages. The male larvae showed higher accumulation efficiency of 1-DNJ than the females and also a significant variation was observed among the silkworm strains. The present results show that tissue distribution of 1-DNJ was significantly higher in blood, digestive juice, and alimentary canal, but no 1-DNJ was observed in the silkgland. Moreover, 1-DNJ was not found in silkworms fed with artificial diet that does not contain mulberry leaf powder. This proves that silkworms obtain 1-DNJ from mulberry leaves; they could not synthesize 1-DNJ by themselves. The accumulation and excretion of 1-DNJ change periodically during the larval stage. There was no 1-DNJ in the newly-hatched larvae and 1-DNJ was mainly accumulated during the early and middle stages of every instar, while excreted at later stages of larval development. Further, it is possible to extract 1-DNJ from the larval feces and it is optimal to develop the 1-DNJ related products for diabetic auxiliary therapy.

Fig. 1

High-performance liquid chromatograms of DNJ analysis (a) Chromatogram of separation of DNJ standard solution; (b) Chromatogram of separation of mulberry powder solution; (c) Chromatogram of separation of silkworm powder solution. 1-GLY-FMOC: 1-glycine-fluorenyl-methyl chl-oroformate

Fig. 1

High-performance liquid chromatograms of DNJ analysis (a) Chromatogram of separation of DNJ standard solution; (b) Chromatogram of separation of mulberry powder solution; (c) Chromatogram of separation of silkworm powder solution. 1-GLY-FMOC: 1-glycine-fluorenyl-methyl chl-oroformate

Fig. 1

High-performance liquid chromatograms of DNJ analysis (a) Chromatogram of separation of DNJ standard solution; (b) Chromatogram of separation of mulberry powder solution; (c) Chromatogram of separation of silkworm powder solution. 1-GLY-FMOC: 1-glycine-fluorenyl-methyl chl-oroformate

Fig. 2

DNJ contents among silkworm varieties Silkworm varieties: 1, Jingsong; 2, Chunlei×Zhenzhu; 3, Luqi; 4, Haoyue; 5, 9202×Luqi; 6, 9202; 7, Luhuang; 8, Jingsong×Haoyue; 9, 973×974. DNJ was measured using the larvae of the 3rd day in the 5th instar. Each value is the mean±SE of replications

Fig. 3

DNJ distribution in larval organs and tissues DNJ was measured using the larvae of the 3rd day in the 5th instar. Larval organs or tissues: 1, blood; 2, intestinal juice; 3, alimentary canal; 4, Malpighian tubule; 5, midgut peritrophic membrane; 6, cuticles; 7, body wall; 8, fat body; 9, trachea; 10, silk gland

Fig. 4

DNJ contents in mulberry leaves during growing stages Mulberry variety: Nongsang 14. Growing days refer the day order since the sprouting

Fig. 5

DNJ change in the larval body and feces during the growing stages Stage of development: 1, newly-hatched larva; 2, 3rd day of 1st instar; 3, molting stage of 1st instar; 4, larva in the middle of 2nd instar; 5, molting larva of 2nd instar; 6, larva in the middle of 3rd instar; 7, molting larva of 3rd instar; 8, larva in the middle of 4th instar; 9, molting larva of 4th instar; 10, 1st day of 5th instar; 11, 2nd day of 5th instar; 12, 3rd day of 5th instar; 13, 4th day of 5th instar; 14, 5th day of 5th instar; 15, 6th day of 5th instar; 16, 7th day of 5th instar; 17, mature larvae