Aesculin offers increased resistance against oxidative stress and protective effects against Aß-induced neurotoxicity in Caenorhabditis elegans.

Aesculin, a coumarin compound, is one of the major active ingredients of traditional Chinese herbal medicine Qinpi (Cortex Fraxini), which has been reported to exhibit antioxidative, anti-inflammatory and neuroprotective properties against oxidative stress and cellular apoptosis. However, the regulatory mechanisms remain poorly characterized in vivo. This research was performed to explore the underlying molecular mechanisms behind aesculin response conferring oxidative stress resistance, and the protective effects on amyloid-ß (Aß)-mediated neurotoxicity in Caenorhabditis elegans. Study indicated that aesculin plays the protective roles for C. elegans against oxidative stress and Aß-mediated neurotoxicity and reduces the elevated ROS and MDA contents through enhancement of antioxidant defenses. The KEGG pathway analysis suggested that the differentially expressed genes are mainly involved in longevity regulating pathway, and the nuclear translocation of DAF-16 and the RNAi of daf-16 and hsf-1 indicated that DAF-16 and HSF-1 play critical roles in integrating upstream signals and inducing the expressions of stress resistance-related genes. Furthermore, the up-regulated expressions of their target genes such as sod-3 and hsp-16.2 were confirmed in transgenic GFP reporter strains CF1553 and CL2070, respectively. These results indicated that the regulators DAF-16 and HSF-1 elevate the stress resistance of C. elegans by modulating stress-responsive genes. Further experiments revealed that aesculin is capable of suppressing Aß-induced oxidative stress and apoptosis and improves chemosensory behavior dysfunction in Aß-transgenic nematodes. In summary, this study suggested that aesculin offers increased resistance against oxidative stress and protective effects against Aß-induced neurotoxicity through activation of stress regulators DAF-16 and HSF-1 in nematodes.

Neuroprotective Effects of Palmatine via the Enhancement of Antioxidant Defense and Small Heat Shock Protein Expression in Aß-Transgenic Caenorhabditis elegans.

Palmatine is a naturally occurring isoquinoline alkaloid that has been reported to display neuroprotective effects against amyloid-ß- (Aß-) induced neurotoxicity. However, the mechanisms underlying the neuroprotective activities of palmatine remain poorly characterized in vivo. We employed transgenic Caenorhabditis elegans models containing human Aß 1-42 to investigate the effects and possible mechanisms of palmatine-mediated neuroprotection. Treatment with palmatine significantly delayed the paralytic process and reduced the elevated reactive oxygen species levels in Aß-transgenic C. elegans. In addition, it increased oxidative stress resistance without affecting the lifespan of wild-type C. elegans. Pathway analysis suggested that the differentially expressed genes were related mainly to aging, detoxification, and lipid metabolism. Real-time PCR indicated that resistance-related genes such as sod-3 and shsp were significantly upregulated, while the lipid metabolism-related gene fat-5 was downregulated. Further studies demonstrated that the inhibitory effects of palmatine on Aß toxicity were attributable to the free radical-scavenging capacity and that the upregulated expression of resistance-related genes, especially shsp, whose expression was regulated by HSF-1, played crucial roles in protecting cells from Aß-induced toxicity. The research showed that there were significantly fewer Aß deposits in transgenic CL2006 nematodes treated with palmatine than in control nematodes. In addition, our study found that Aß-induced toxicity was accompanied by dysregulation of lipid metabolism, leading to excessive fat accumulation in Aß-transgenic CL4176 nematodes. The alleviation of lipid disorder by palmatine should be attributed not only to the reduction in fat synthesis but also to the inhibition of Aß aggregation and toxicity, which jointly maintained metabolic homeostasis. This study provides new insights into the in vivo neuroprotective effects of palmatine against Aß aggregation and toxicity and provides valuable targets for the prevention and treatment of AD.

Antioxidant Peptides from Sepia esculenta Hydrolyzate Attenuate Oxidative Stress and Fat Accumulation in Caenorhabditis elegans.

The hydrolysate of golden cuttlefish (Sepia esculenta) was prepared by using papain, and then, it was further separated by ultrafiltration, gel filtration chromatography, and reverse-phase high-performance liquid chromatography (RP-HPLC). The peptide components of the active fraction were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and then two novel peptides, SeP2 (DVEDLEAGLAK, 1159.27 Da) and SeP5 (EITSLAPSTM, 1049.22 Da), were obtained and displayed significant alleviation effects on oxidative stress in Caenorhabditis elegans. Studies indicated that S. esculenta antioxidant peptides (SePs) increase superoxide dismutase (SOD) activity but reduce reactive oxygen species (ROS) and malondialdehyde (MDA) levelsin oxidation-damaged nematodes. Using transgenic CF1553 nematodes, the sod-3p::GFP expression in the worms treated with SePs was significantly higher than that of the control nematodes. Real-time PCR also demonstrated that the expression of stress-related genes such as sod-3 is up-regulated by SePs. Furthermore, studies showed that SePs could obviously decrease fat accumulation as well as reduce the elevated ROS and MDA levels in high-fat nematodes. Taken together, these results indicated that SePs are capable of the activation of antioxidant defense and the inhibition of free radicals and lipid peroxidation, play important roles in attenuating oxidative stress and fat accumulation in C. elegans, and might have the potential to be used in nutraceutical and functional foods.