No abstract

Hedyotis diffusa Willd (Rubiaceae) is a widely used and resourceful traditional Chinese medicine that exerts protection against aging and age‐related diseases. However, the underlying mechanisms of the protective effects remain largely unclear. Alzheimer's disease (AD) is an age‐related neurodegenerative disease, of which β‐amyloid (Aβ)‐induced toxicity has been suggested as a main cause. Herein, we use the transgenic Caenorhabditis elegans CL4176, CL2006, and CL2355 strains, which express human Aβ1‐42 peptide, to investigate the effects and the possible mechanisms of n‐butanol extract of H.diffusa (HDB)‐mediated protection against Aβ toxicity in vivo. During the experiments, a method of quality control for HDB was established by HPLC. Additionally, we examined the effects of HBD on gene expression changes with qRT‐PCR, aggregation of Aβ plagues with thioflavin‐S staining, and protein detection with GFP labeling. HDB improved lifespan, locomotion, and stress resistance. Further study showed that HDB decreased paralysis, the accumulation of ROS, and AChE activity. Moreover, HDB suppressed neuronal Aβ‐expression‐induced defects in chemotaxis behavior and increased SOD activity. HDB also downregulated the Aβ mRNA level and decreased the number of Aβ deposits. Furthermore, HDB increased the expression levels of sod‐3, daf‐16, hsf‐1, and hsp‐16.2 gene and upregulated hsp‐16.2::GFP and gst‐4::GFP expression. Taken together, these results suggest that HDB may protect against Aβ‐induced toxicity in C. elegans via the insulin/insulin‐like growth factor‐1 (IGF‐1) signaling pathway.

Hedyotis diffusa Willd. (H. diffusa), a kind of traditional Chinese medicine, has been evaluated to potential display antioxidant and anti‐aging effects in vitro experiments. In this work, we investigated the effects on lifespan and stress resistance of the butanol extract from H. diffusa (NHD) in vivo using a Caenorhabditis elegans (C. elegans) model. The phytochemicals of NHD were identified by UPLC‐ESI‐qTOF‐MS/MS method. NHD‐treated wild‐type N2 worms showed an increase in survival time under both normal and stress conditions. Meanwhile, NHD promoted the healthspan of nematodes by stimulating growth and development, reducing the deposition of age pigment, increasing the activities of superoxide dismutase (SOD) and glutathione peroxidase dismutase (GSH‐Px), and decreasing the level of ROS without impairing fertility. Moreover, the upregulating of the expression of daf‐16, gst‐4, sod‐3, hsp12.6 genes and the downregulating of the expression of daf‐2 were involved in the NHD‐mediated lifespan extension. Finally, the increasing of the expression of GST‐4::GFP in CL2166 transgenic nematodes and the life‐span‐extending activity of NHD was completely abolished in daf‐2 and daf‐16 mutants further revealed that the potential roles for these genes in NHD‐induced longevity in C. elegans. Collectively, our findings suggest that NHD may have an active effect in healthy aging and age‐related diseases.