| Royal jelly (RJ) was secreted by hypopharyngeal and mandibular glands of nurse honeybees (Apis mellifera) as the primary food for the honeybee larvae during the first3days of life and the unique food for the honeybee queen for its lifetime, respectively. The chemical composition of RJ was very complicated, while proteins had been confirmed to play a very critical role in RJ. Proteins, which made up about fifty percent of RJ dry matter, were divided into two parts, water-soluble and water-insoluble. Water-soluble proteins, consisted of82%to90%of total larval jelly proteins, were also named major royal jelly proteins (MRJPs).Firstly, considering the protein stability and production cost, the effects of the ratio of solvent to material, pH value, extraction time and ionic strength on MRJPs extraction were conducted and optimized by orthogonal test. Results showed that the optimum technology conditions of MRJPs extraction were:the ratio of solvent to material8:1(V/W), pH8, extraction for8h and ionic strength0.5. Under the optimized conditions, the maximum MRJPs extraction rate reached81.14%. Meanwhile, the10-HDA and total sugar of the centrifugation were reused. The recycling rate of10-HDA and total sugar of the centrifugation were2.91%and1.26%, respectively. The protein extractions were analyzed with SDS-PAGE. The molecular mass of proteins ranged from42.1kDa to97.4kDa in profile, and all the protein bands were obvious, especially the band of57kDa, which suggested that MRJPs were successfully extracted.Next, the base diet (negative control), and diets added1.25%casein (positive control),1.25%,2.50%and5.00%MRJPs were prepared and fed Canton-S Drosophila, respectively. Compared with the negative control and positive control groups, the mean lifespan of flies fed5.00%MRJPs was extended by11.93%and7.78%in male flies, respectively (p<0.05), and the mean lifespan of flies fed2.50%MRJPs was extended by8.98%and7.40%, respectively (p<0.05). These results demonstrated that MRJPs possessed anti-aging effects of both genders in Drosophila. The feeding assay and fecundity assay showed that MRJPs could also significantly improve the diet weight ingested by per fly and the egg amount per female fly (p<0.05), which suggested that the MRJPs had not side effects affecting the both factors related to anti-aging. Furthermore, it was found that MRJPs could significantly increase SOD(Cu, Zn) activity (p<0.05), and decrease MDA level (p<0.05) of both genders in Drosophila at7day and21day old, which exhibited that MRJPs had a strong antioxidative activity in vivo.Finally, with rp49gene as the house keeping gene, the expression levels of SOD(Cu, Zn), S6K, MAPK and Egfr were detected, respectively. The results showed that MRJPs could delay the down-regulation of the four genes related with aging in Drosophila.This research firstly confirmed that MRJPs possessed the anti-aging effects in Drosophila, and proposed the relative biochemical and molecular mechanism of the proteins, which had provided an important basis for the development of the functional food with royal jelly. |
