Determinaion of 1-deoxynojirimicin (DNJ) in mulberry leaves (Morus app. L.), silkworms and silk by HPLC-TQ-MS

Introduction DNJ is a constituent of mulberry leaves and when consumed as part of the diet it showed beneficial properties on health: suppression of high blood glucose levels, antibacterial and antiviral activities [1,2]. In this work DNJ content in different matrices was investigated, the importance lies in the potential uses of these products as food and feed, nutraceutical and medical device. Methods Twenty-nine samples of mulberry leaves from an experimental field (CREA-Padova), silk worms larvae and silk cocoons were analyzed by HILIC technique. EtOH:H2O 50% solution and water 60° were employed for leaves extraction. Grinded cocoons and freeze-dried larvae were extracted with EtOH:H2O 50% (at 60°C for cocoons). The detection was performed by using ESI in positive ion MRM mode. Results The optimized mass conditions allowed the identification of three usable transitions (one for the quantification of DNJ 164.1146.1, others as qualifier ions 164.1128.1, 164.1110.1). DNJ was detected in all the considered matrices and determined by using its calibration curve (r2=0.9865). In the case of leaves, water infusion resulted less efficient with respect to EtOH:H2O extraction. The mean concentration value in leaves obtained with infusion is 0.073±0.004 mg/g while 2.56±0.3 mg/g for extracts. The mean concentration recovered in larvae is 0.034±0.001 mg/g whereas substantially lower amounts were obtained for silk (3.12*10-5 mg/g). Conclusions In this work an efficient HPLC-TQ-MS method was applied to the determination of DNJ in leaves, larvae and silk. The study showed that Morus nigra L. presents the highest content among the tested species and that DNJ is detectable also in larvae and silk. These results could be useful in the further development of herbal supplements and for the potential use of larvae as medicated feed or functional food.