A novel peptide derived from residue exhibits anti-aging activity in the insulin/IGF-1 signaling pathway.

To explore the value of () residue remaining after astaxanthin extraction and being discarded uneconomically, in our previous study, we discovered a novel peptide (HPp) as a potential bioactive component. However, the possible anti-aging activity was not illuminated. In this study, the capacity of extending the lifespan and the mechanism based on () were determined. The results showed that 100 μM HPp not only enhanced the lifespan of in normal environments by 20.96% but also strengthened the lifespan in oxidative and thermal conditions effectively. Moreover, HPp succeeded in lessening the decline in physiological functions of aging worms. In terms of antioxidant efficacy, SOD and CAT enzyme activity were promoted, but the level of MDA was diminished significantly after HPp treatment. Subsequent analysis directly reflected the relationship between higher stress resistance and up-regulation of and , and between greater antioxidant ability and up-regulation of and . Further studies illustrated that HPp up-graded the mRNA transcription of the genes associated with the insulin/insulin-like growth factor signaling (IIS) pathway and some co-factors, including , , , and . Particularly, the activation of the IIS pathway required the regulation of subcellular localization of DAF-16/FOXO. Taken together, HPp could promote longevity with improved stress resistance and antioxidant properties through the IIS pathway. These data suggested that HPp might serve as a good source of anti-aging actives, and in particular, laid a foundation for the high value-added application of marine microalgae.