Multiple biological defects caused by calycosin-7-O -β-d -glucoside in the nematode Caenorhabditis elegans are associated with the activation of oxidative damage

N-3 polyunsaturated fatty acids attenuate amyloid-beta-induced toxicity in AD transgenic Caenorhabditis elegans via promotion of proteasomal activity and activation of PPAR-gamma

Alzheimer's disease (AD) is a common neurodegenerative disease that causes progressive cognitive decline. A major pathological characteristic of AD brain is the presence of senile plaques composed of β-amyloid (Aβ), the accumulation of which induces toxic cascades leading to synaptic dysfunction, neuronal apoptosis, and eventually cognitive decline. Dietary n-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are beneficial for patients with early-stage AD; however, the mechanisms are not completely understood. In this study, we investigated the effects of n-3 PUFAs on Aβ-induced toxicity in a transgenic AD Caenorhabditis elegans (C. elegans) model. The results showed that EPA and DHA significantly inhibited Aβ-induced paralytic phenotype and decreased the production of reactive oxygen species while reducing the levels of Aβ in the AD worms. Further studies revealed that EPA and DHA might reduce the accumulation of Aβ by restoring the activity of proteasome. Moreover, treating worms with peroxisome proliferator-activated receptor (PPAR)-γ inhibitor GW9662 prevented the inhibitory effects of n-3 PUFAs on Aβ-induced paralytic phenotype and diminished the elevation of proteasomal activity by n-3 PUFAs, suggesting that PPARγ-mediated signals play important role in the protective effects of n-3 PUFAs against Aβ-induced toxicity.

Comparative oxidative damages induced by silver nanoparticles with different sizes and coatings in Caenorhabditis elegans

Silver nanoparticles (AgNPs) are widely used in many commercial and medical products. Serious concerns are paid on their adverse potentials to the environment and human health. In this study, toxic effects and oxidative stress induced by AgNPs with different sizes and coatings (20 nm AgNPs, 20 nm polyvinylpyrrolidone (PVP) -AgNPs and 50 nm AgNPs) in Caenorhabditis elegans (C. elegans) were investigated. The toxic effects including the shortened lifespan and decreased frequency of head thrashes and body bends of C. elegans were induced in a dose-dependent manner by AgNPs. The reactive oxygen species (ROS) production and the oxidative stress-related indicators including malondialdehyde (MDA) and glutathione (GSH) in nematodes were changed after exposure to three kinds of AgNPs. These effects were the most obvious in a 20 nm PVP-AgNPs exposure group. AgNPs could also induce the expression of genes related to oxidative stress in nematodes. In addition, the up-regulation of mtl-1 and mtl-2 in nematodes might reduce the oxidative damage caused by AgNPs, by using transgenic strains CF2222 and CL2120 nematodes. Metallothionein (MT), an antioxidant, could relieve the oxidative damage caused by AgNPs. These results suggested that 20 nm PVP-AgNPs with a smaller particle size and better dispersion have stronger toxic effects and the oxidative damage to nematodes. Mtl-1 and mtl-2 might be involved in alleviating the oxidative damage caused by AgNPs. Our findings provide clues for the safety evaluation and mechanism information of metal nanoparticles.

Planococcus maritimu ML1206 Strain Enhances Stress Resistance and Extends the Lifespan in Caenorhabditis elegans via FOXO/DAF-16

The antioxidant effect of probiotics has been widely recognized across the world, which is of great significance in food, medicine, and aquaculture. There are abundant marine microbial resources in the ocean, which provide a new space for humans to explore new probiotics. Previously, we reported on the anti-infective effects of Planococcus maritimu ML1206, a potential marine probiotic. The antioxidant activity of ML1206 in C. elegans was studied in this paper. The study showed that ML1206 could improve the ability of nematodes to resist oxidative stress and effectively prolong their lifespan. The results confirmed that ML1206 could significantly increase the activities of CAT and GSH-PX, and reduce the accumulation of reactive oxygen species (ROS) in nematodes under oxidative stress conditions. In addition, ML1206 promoted DAF-16 transfer to the nucleus and upregulated the expression of sod-3, hsp-16.2, and ctl-2, which are downstream antioxidant-related genes of DAF-16. Furthermore, the expression of the SOD-3::GFP and HSP-16.2::GFP was significantly higher in the transgenic strains fed with ML1206 than that in the control group fed with OP50, with or without stress. In summary, these findings suggest that ML1206 is a novel marine probiotic with an antioxidant function that stimulates nematodes to improve their defense abilities against oxidative stress and prolong the lifespan by regulating the translocation of FOXO/DAF-16. Therefore, ML1206 may be explored as a potential dietary supplement in aquaculture and for anti-aging and antioxidant purposes.

Carotenoids from mamey (Pouteria sapota) and carrot (Daucus carota) increase the oxidative stress resistance of Caenorhabditis elegans

Carotenoids are natural pigments and antioxidants found in fruits and vegetables such as carrot, tomato, orange, mango, yellow corn, pumpkin, and mamey. In this study, we evaluated the antioxidant potential of mamey (Pouteria sapota) carotenoids and compared them to carrot (Daucus carota) carotenoids. The carotenoids were extracted from mamey and carrot, and their antioxidant capacity were determined via in vitro (ABTS method) and in vivo assays (resistance against oxidative stress in Caenorhabditis elegans). The carotenoid contents in mamey and carrot were 4.42 ± 0.12 and 5.47 ± 0.04 mg β-carotene/100 g, respectively. Despite the differences between the carotenoid contents in both products (p < 0.05), the in vitro antioxidant capacity results showed no significant differences between the extracts (p > 0.05). The mamey and carrot carotenoid extracts decreased the oxidative damage in C. elegans by 20–30% and 30–40%, respectively. Both extracts increased the resistance and enhanced the survival of the nematodes, and showed better effects than pure β-carotene, probably owing to the complex mixture in the carotenoid extracts. These results suggest that mamey is a good alternative source of carotenoids and that it protects against oxidative stress in C. elegans. The protective effect of mamey carotenoids was similar to the effect of carrot carotenoids.

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Mamey carotenoids displayed similar antioxidant activity to carrot carotenoids.

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Mamey and carrot carotenoids increased the oxidative stress resistance of C. elegans.

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Continuous exposure to carotenoids enhanced the resistance of the progeny.

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Natural mixture of carotenoids had better antioxidant effects than pure β-carotene.

Astragaloside IV Extends Lifespan of Caenorhabditis elegans by Improving Age-Related Functional Declines and Triggering Antioxidant Responses

Astragaloside IV (AS-IV) is a representative component of astragaloside saponins in dried roots of Astragali Radix. Astragaloside possesses a broad spectrum of pharmacological activities, including antibacterial, anti-fibrosis, antioxidant, anti-inflammatory, and neuroprotective effects. However, the role of AS-IV in antiaging remains unclear. In this article, we studied the function of AS-IV in antiaging by using the Caenorhabditis elegans (C. elegans) model. We showed that AS-IV can prolong the lifespan of C. elegans in a natural aging model, a paraquat injury model, and a heat stress model and improve the movement capacity of nematodes. ¹H-NMR data indicate an improvement of glutamate content and a decrease in glucose in the AS-IV treatment group compared with the control. Further investigation revealed that AS-IV can induce the mRNA expression of superoxide dismutase (SOD) and catalase (CAT) genes and increase the activities of SOD and CAT in the nematode. Interestingly, AS-IV could not extend the lifespan of sod-1, sod-2, sod-3, sod-4, sod-5, ctl-1, ctl-2, ctl-3, and daf-16 mutants. These data indicate that AS-IV prevents aging via mainly improving age-related functional declines, the antioxidant capacity of nematodes and partially modulating the insulin/insulin growth factor 1 signaling pathway activity. Our results provide new insights into how AS-IV prevents and treats aging.

Secoisolariciresinol Diglucoside Delays the Progression of Aging-Related Diseases and Extends the Lifespan of Caenorhabditis elegans via DAF-16 and HSF-1

Secoisolariciresinol diglucoside (SDG) is a phytoestrogen and rich in food flaxseed, sunflower seeds, and sesame seeds. Among the beneficial pharmacological activities of SDG on health, many are age related, such as anticancer, antidiabetes, antioxidant, and neuroprotective effects. Thus, we investigated if SDG had an effect on antiaging in Caenorhabditis elegans (C. elegans). Our results showed that SDG could extend the lifespan of C. elegans by up to 22.0%, delay age-related decline of body movement, reduce the lethality of heat and oxidative stress, alleviate dopamine neurodegeneration induced by 6-hydroxydopamine (6-OHDA), and decrease the toxicity of Aβ protein in C. elegans. SDG could increase the expression of the downstream genes of DAF-16, DAF-12, NHR-80, and HSF-1 at mRNA level. SDG could not extend the lifespan of mutants from genes daf-16, hsf-1, nhr-80, daf-12, glp-1, eat-2, and aak-2. The above results suggested that SDG might enhance the stress resistance, delay the progression of aging-related diseases, and extend the lifespan of C. elegans via DAF-16 and HSF-1.

Tectochrysin increases stress resistance and extends the lifespan of Caenorhabditis elegans via FOXO/DAF-16

Aging is related to the lowered overall functioning and increased risk for various age-related diseases in humans. Tectochrysin is a flavonoid compound and rich in a traditional Chinese Medicine Alpinia oxyphylla Miq., which has antioxidant, anti-inflammatory, anti-cancer, anti-bacterial, anti-diarrhea, hepatoprotective, and neuro-protective effects. Therefore, we tested if tectochrysin had an effect on aging in Caenorhabditis elegans (C. elegans). Our results showed that tectochrysin could extend the lifespan of C. elegans by up to 21.0%, delay the age-related decline of body movement, improve high temperature-stress resistance and anti-infection capacity, and protected worms against Aβ1-42-induced toxicity. Tectochrysin could not extend the lifespan of the mutants from genes daf-2, daf-16, eat-2, aak-2, skn-1, and hsf-1. Tectochrysin could increase the expression of DAF-16 regulated genes. The extension of lifespan by tectochrysin requires FOXO/DAF-16 and HSF-1. Overall, our findings suggest that tectochrysin may have a potential effect on extending lifespan and age-related diseases.

Biocatalytic Synthesis of Calycosin-7-O-β-D-Glucoside with Uridine Diphosphate–Glucose Regeneration System

Calycosin-7-O-β-D-glucoside (Cy7G) is one of the principal components of Radix astragali. This isoflavonoid glucoside is regarded as an indicator to assess the quality of R. astragali and exhibits diverse pharmacological activities. In this study, uridine diphosphate-dependent glucosyltransferase (UGT) UGT88E18 was isolated from Glycine max and expressed in Escherichia coli. Recombinant UGT88E18 could selectively and effectively glucosylate the C7 hydroxyl group of calycosin to synthesize Cy7G. A one-pot reaction by coupling UGT88E18 to sucrose synthase (SuSy) from G. max was developed. The UGT88E18–SuSy cascade reaction could recycle the costly uridine diphosphate glucose (UDPG) from cheap sucrose and catalytic amounts of uridine diphosphate (UDP). The important factors for UGT88E18–SuSy cascade reaction, including UGT88E18/SuSy ratios, different temperatures, and pH values, different concentrations of dimethyl sulfoxide (DMSO), UDP, sucrose, and calycosin, were optimized. We produced 10.5 g L−1 Cy7G in the optimal reaction conditions by the stepwise addition of calycosin. The molar conversion of calycosin was 97.5%, with a space–time yield of 747 mg L−1 h−1 and a UDPG recycle of 78 times. The present study provides a new avenue for the efficient and cost-effective semisynthesis of Cy7G and other valuable isoflavonoid glucosides by UGT–SuSy cascade reaction.

Didymin improves UV irradiation resistance in C. elegans

Didymin, a type of flavono-o-glycoside compound naturally present in citrus fruits, has been reported to be an effective anticancer agent. However, its effects on stress resistance are unclear. In this study, we treated Caenorhabditis elegans with didymin at several concentrations. We found that didymin reduced the effects of UV stressor on nematodes by decreasing reactive oxygen species levels and increasing superoxide dismutase (SOD) activity. Furthermore, we found that specific didymin-treated mutant nematodes daf-16(mu86) & daf-2(e1370), daf-16(mu86), akt-1(ok525), akt-2(ok393), and age-1(hx546) were susceptible to UV irradiation, whereas daf-2(e1371) was resistant to UV irradiation. In addition, we found that didymin not only promoted DAF-16 to transfer from cytoplasm to nucleus, but also increased both protein and mRNA expression levels of SOD-3 and HSP-16.2 after UV irradiation. Our results show that didymin affects UV irradiation resistance and it may act on daf-2 to regulate downstream genes through the insulin/IGF-1-like signaling pathway.