Glucosyltyrosine in Silkworm Haemolymph as a Transient Metabolite of Insects

Trehalose, the major haemolymph sugar in the silkworm, is partly regulated in concentration by diapause hormone. During the course of our re-investigation on the developmental changes of sugars in polyvoltine silkworm pupae, a new sugar (Sugar-A) was found out at the late stage of pupal-adult development. The amount of Sugar-A was five times as much as that of trehalose at its maximum, but it disappeared almost completely with emergence. The structure of Sugar-A was determined as β-glucosyl-O-tyrosine by 270 MHz PMR, FDMS and chemical methods. The physiological function of glucosyltyrosine is also discussed.