Metabolism, transformation and dynamic changes of alkaloids in silkworm during feeding mulberry leaves

Metabolism, transformation and dynamic changes of DNJ, 2-O-α-D-Gal-DNJ, fagomine, isofagomine and 4-O-β-d-Glc-fagomine from mulberry leaves in silkworms at different instars were observed. UPLC-Q/TOF-MS and UPLC-TQ/MS methods were adopted for qualitative and quantitative analysis respectively. Three species mulberry leaves were used to feed the silkworm as controls. By analyzing and comparing the content changes of DNJ, fagomine and their derivatives in silkworms and silkworm excrement at different instar, we revealed the dynamic changes, confirmed the enrichment effect of the polyhydroxy alkaloids by silkworm, and inferred the conversion process behind this effect. The experimental results indicated that DNJ and its derivatives turned into some intermediate substances in the metabolic process, and finally they converted back and the content increased. Fagomine and its derivatives interconverted into each other in the process, 4-O-β-d-Glc-fagomine transformed into fagomine, while fagomine transformed into isofagomine.