α- and β-Santalols Delay Aging in Caenorhabditis elegans via Preventing Oxidative Stress and Protein Aggregation

Perillaldehyde alleviates polyQ-induced neurodegeneration through the induction of autophagy and mitochondrial UPR in Caenorhabditis elegans

Huntington's disease (HD) is a fatal neurodegenerative disease associated with autophagy disorder and mitochondrial dysfunction. Here, we identified therapeutic potential of perillaldehyde (PAE), a monoterpene compound obtained from Perilla frutescens (L.) Britt., in the Caenorhabditis elegans (C. elegans) model of HD, which included lifespan extension, healthspan improvement, decrease in polyglutamine (polyQ) aggregation, and preservation of mitochondrial network. Further analyses indicated that PAE was able to induce autophagy and mitochondrial unfolded protein reaction (UPRmt) activation and positively regulated expression of associated genes. In lgg-1 RNAi C. elegans or C. elegans with UPRmt-related genes knockdown, the effects of PAE treatment on polyQ aggregation or rescue polyQ-induced toxicity were attenuated, suggesting that its neuroprotective activity depended on autophagy and UPRmt. Moreover, we found that pharmacological and genetic activation of UPRmt generally protected C. elegans from polyQ-induced cytotoxicity. Finally, PAE promoted serotonin synthesis by upregulating expression of TPH-1, and serotonin synthesis and neurosecretion were required for PAE-mediated UPRmt activation and its neuroprotective activity. In conclusion, PAE is a potential therapy for polyQ-related diseases including HD, which is dependent on autophagy and cell-non-autonomous UPRmt activation.

Diosgenin intervention: targeting lipophagy to counter high glucose diet-induced lipid accumulation and lifespan reduction

Diosgenin (DG), a well-known steroidal sapogenin, is abundantly found in the plants of the Dioscoreaceae family and exhibits diverse pharmacological properties. In our previous study, we demonstrated that DG supplementation protected Caenorhabditis elegans from high glucose-induced lipid deposition, oxidative damage, and lifespan reduction. Nevertheless, the precise biological mechanisms underlying the beneficial effects of DG have not yet been described. In this context, the present study aims to elucidate how DG reduces molecular and cellular declines induced by high glucose, using the powerful genetics of the C. elegans model. Treatment with DG significantly (p < 0.01) prevented fat accumulation and extended lifespan under high-glucose conditions without affecting physiological functions. DG-induced lifespan extension was found to rely on longevity genes daf-2, daf-16, skn-1, glp-1, eat-2, let-363, and pha-4. Specifically, DG regulates lipophagy, the autophagy-mediated degradation of lipid droplets, in C. elegans, thereby inhibiting fat accumulation. Furthermore, DG treatment did not alter the triglyceride levels in the fat-6 and fat-7 single mutants and fat-6;fat-7 double mutants, indicating the significant role of stearoyl-CoA desaturase genes in mediating the reduction of fat deposition by DG. Our results provide new insight into the fat-reducing mechanisms of DG, which might develop into a multitarget drug for preventing obesity and associated health complications; however, preclinical studies are required to investigate the effect of DG on higher models.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-04017-3.

Geroprotective Effect of Levilactobacillus brevis and Weizmannia coagulans in Caenorhabditis elegans

The prophylactic use of lactic acid bacteria (LAB) to maintain human health is one of the most important research areas in recent times. LAB supplementation confers a wide range of health benefits to the host, but few studies have focused on their possible role in delaying the aging process. This study explored the health and life-promoting properties of two LAB, Levilactobacillus brevis and Weizmannia coagulans, using the Caenorhabditis elegans model. We found that L. brevis and W. coagulans enhanced the intestinal integrity and intestinal barrier functions without affecting the overall physiological functions of C. elegans. Wild-type worms preconditioned with LAB strains increased their survival under oxidative and thermal stress conditions by reducing intracellular reactive oxygen levels. Live L. brevis and W. coagulans significantly extended the lifespan of C. elegans under standard laboratory conditions independently of dietary restrictions. Genetic and reporter gene expression analysis revealed that L. brevis and W. coagulans extend lifespan via insulin/insulin-like growth factor-1 signaling and the p38 MAPK signaling axis. Furthermore, sirtuin, JNK MAPK, and mitochondrial respiratory complexes were found to be partially involved in W. coagulans-mediated lifespan extension and stress resilience. Preconditioning with LAB ameliorated age-related functional decline in C. elegans and reduced ectopic fat deposition in an NHR-49-dependent manner. Together, our findings indicated that L. brevis and W. coagulans are worth exploring further as "gerobiotic" candidates to delay aging and improve the healthspan of the host.

Model nematodes as a practical innovation to promote high throughput screening of natural products for anthelmintics discovery in South Asia: Current challenges, proposed practical and conceptual solutions

With the increasing prevalence of anthelmintic resistance in animals recorded globally, and the threat of resistance in human helminths, the need for novel anthelmintic drugs is greater than ever. Most research aimed at discovering novel anthelmintic leads relies on high throughput screening (HTS) of large libraries of synthetic small molecules in industrial and academic settings in developed countries, even though it is the tropical countries that are most plagued by helminth infections. Tropical countries, however, have the advantage of possessing a rich flora that may yield natural products (NP) with promising anthelmintic activity. Focusing on South Asia, which produces one of the world's highest research outputs in NP and NP-based anthelmintic discovery, we find that limited basic research and funding, a lack of awareness of the utility of model organisms, poor industry-academia partnerships and lack of technological innovations greatly limit anthelmintics research in the region. Here we propose that utilizing model organisms including the free-living nematode Caenorhabditis elegans, that can potentially allow rapid target identification of novel anthelmintics, and Oscheius tipulae, a closely related, free-living nematode which is found abundantly in soil in hotter temperatures, could be a much-needed innovation that can enable cost-effective and efficient HTS of NPs for discovering compounds with anthelmintic/antiparasitic potential in South Asia and other tropical regions that historically have devoted limited funding for such research. Additionally, increased collaborations at the national, regional and international level between parasitologists and pharmacologists/ethnobotanists, setting up government-industry-academia partnerships to fund academic research, creating a centralized, regional collection of plant extracts or purified NPs as a dereplication strategy and HTS library, and holding regional C. elegans/O. tipulae-based anthelmintics workshops and conferences to share knowledge and resources regarding model organisms may collectively promote and foster a NP-based anthelmintics landscape in South Asia and beyond.

Fermented cereal-origin gerobiotic cocktails promote healthy longevity in Caenorhabditis elegans

There is growing interest in dietary interventions, particularly gerobiotics, that directly target aging. Several single-strain gerobiotics have proven to be beneficial in alleviating aging and age-related functional declines across species, but multistrain/multispecies gerobiotics have been proven even more advantageous due to the potential synergy and additive effects among individual isolates. However, there is very limited research on how multistrain/multispecies gerobiotic combinations or cocktails extend healthy longevity. This study comprehensively analyzed probiotic bacteria from traditionally fermented Barnyard millet and compared their efficacy in promoting healthy longevity under various combinations using Caenorhabditis elegans. We have shown that dramatic lifespan extension can be achieved by combining gerobiotics, and the effect was found to be strictly strain-specific. Among the 120 combinations tested, we identified two synergistic gerobiotic combinations, cocktail 55 (combination of B. licheniformis PS70, L. delbrueckii subsp. bulgaricus PS77, and L. amylovorus PS60) and cocktail 112 (combination of L. delbrueckii subsp. bulgaricus PS77, L. lactis PS10, and P. pentosaceus PS91), extending the mean lifespan of C. elegans by up to 46.2% and 53.1%, respectively. Our mechanistic study showed that the life-promoting effect of cocktail 55 relied on the p38 MAPK-SKN-1 pathway, while cocktail 112 acted on multiple signaling pathways, including IIS, β-catenin, and TGF-β pathways, to achieve its impact on the host. Moreover, feeding gerobiotic cocktails improved several healthspan markers reported to decline with age. These observations showed that the gerobiotic cocktails target different subsets of the gene regulatory network controlling the aging process in C. elegans, thereby extending healthy longevity.

Anti-Aging Activity and Modes of Action of Compounds from Natural Food Sources

Aging is a natural and inescapable phenomenon characterized by a progressive deterioration of physiological functions, leading to increased vulnerability to chronic diseases and death. With economic and medical development, the elderly population is gradually increasing, which poses a great burden to society, the economy and the medical field. Thus, healthy aging has now become a common aspiration among people over the world. Accumulating evidence indicates that substances that can mediate the deteriorated physiological processes are highly likely to have the potential to prolong lifespan and improve aging-associated diseases. Foods from natural sources are full of bioactive compounds, such as polysaccharides, polyphenols, carotenoids, sterols, terpenoids and vitamins. These bioactive compounds and their derivatives have been shown to be able to delay aging and/or improve aging-associated diseases, thereby prolonging lifespan, via regulation of various physiological processes. Here, we summarize the current understanding of the anti-aging activities of the compounds, polysaccharides, polyphenols, carotenoids, sterols, terpenoids and vitamins from natural food sources, and their modes of action in delaying aging and improving aging-associated diseases. This will certainly provide a reference for further research on the anti-aging effects of bioactive compounds from natural food sources.

Latilactobacillus curvatus FFZZH5L isolated from pickled cowpea enhanced antioxidant activity in Caenorhabditis elegans by upregulating the level of glutathione S-transferase

Latilactobacillus curvatus is a potential probiotic that possesses beneficial health properties and fermentation traits; however, the extent of understanding of the antioxidant activities of L. curvatus is limited. This study investigates the antioxidant activities of a new L. curvatus FFZZH5L strain. The strain exhibits broad tolerance to acids, bases and salts and demonstrated good adaption to the gastrointestinal environment, with a survival rate of 45% after 24 h of treatment in artificial gastrointestinal juice. Moreover, L. curvatus FFZZH5L exhibits inhibitory effects on Staphylococcus aureus, with a self-aggregation rate of 34.8% and a co-aggregation rate of 82.2%. In vitro, the DPPH radical scavenging ability and GSH-px enzyme activity of L. curvatus FFZZH5L reach 64.27% and 15.95 U mL-1, respectively. Treatment of C. elegans with L. curvatus FFZZH5L in vivo significantly extended the organism's lifespan. Furthermore, the activity of SOD, GSH-px and T-AOC was increased by 33.6%, 43.4% and 58.3%, respectively. Feeding C. elegans with L. curvatus FFZZH5L decreased the MDA, lipofuscin and ROS levels by 9%-36.4%. L. curvatus FFZZH5L effectively protected C. elegans against juglone-induced oxidative stress damage and led to a significant increase in the organism's survival under heat stress. The RT-qPCR analysis suggests that feeding C. elegans with L. curvatus FFZZH5L upregulates the expression levels of antioxidant-related genes including glutathione S-transferase 4 (gst-4), gst-1, gst-10, sod-3, sod-5, and sod-10 in C. elegans. Our investigation confirms the probiotic and antioxidant properties of L. curvatus, indicating its potential application in functional foods and the pharmaceutical industry.

Antibacterial peptides from Monochamus alternatus induced oxidative stress and reproductive defects in pine wood nematode through the ERK/MAPK signaling pathway

Pine wilt disease is a devastating disease of pine caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus. Long-term use of chemical nematicides leads to the development of resistance in nematodes and harms the environment. Evaluations for green environmental protection agents, identified the antibacterial peptide, MaltDef1, from Monochamus alternatus which had nematicidal effect. We studied its nematicidal activity and action against PWN. In this study, the antibacterial peptide S-defensin was synthesized from M. alternatus. The results showed that S-defensin caused mortality to the PWN, causing shrinkage, pore, cell membrane dissolution and muscle atrophy. In addition, PWN reproduction was also affected by S-defensin; it decreased in a concentration dependent manner with increasing treatment concentration. By contrast, reactive oxygen species (ROS) in vivo increased in a concentration-dependent manner. We applied transcriptome to analyze the changes in gene expressions in S-defensin treated PWN, and found that the most significantly enriched pathway was the ERK/MAPK signaling pathway. RNAi was used to validate the functions of four differential genes (Let-23, Let-60, Mek-2 and Lin-1) in this pathway. The results showed that knockdown of these genes significantly decreased the survival rate and reproductive yield of, and also increased ROS in PWN. The antibacterial peptide S-defensin had a significant inhibitory effect on the survival and reproduction of PWN, shown by cell membrane damage and intracellular biological oxidative stress via regulating the ERK/MAPK signaling pathway. This indicates that S-defensin has a target in B. xylophilus, against which new green target pesticides can be developed.

Green synthesis of zinc oxide nanoparticles using Cananga odorata essential oil and its antibacterial efficacy in vitro and in vivo

Zinc oxide (ZnO) nanostructure exhibits antimicrobial properties, which have prompted more research on their bactericidal effect against foodborne pathogens. The present work focused on the green synthesis of ZnO nanoparticles (ZnO NPs) using Cananga odorata essential oil. The synthesized ZnO NPs were characterized by XRD, UV-Vis spectroscopy, zeta potential, SEM, and FT-IR analysis. The bactericidal activity of biosynthesized ZnO NPs was tested against Pseudomonas aeruginosa and Staphylococcus aureus. The in vitro results indicate that ZnO NPs have excellent antibacterial activity and that the bactericidal and bacteriostatic mechanisms are based on ROS production and depend on its penetration and interaction with bacterial cells. Moreover, ZnO NPs were found to be non-toxic to Caenorhabditis elegans, an in vivo animal model, up to 1 g/L and exert antibacterial activity by reducing the growth and colonization of pathogens. By reducing pathogen virulence, ZnO NPs significantly improved worms' physiological functions such as pharyngeal pumping, body length, reproduction, and movement. The competitive effect of ZnO NPs against pathogenic bacteria increased the gut-barrier integrity of C. elegans. The most interesting observation was noted that ZnO treatment increased the mean survival rate of P. aeruginosa and S. aureus infected C. elegans by 56.6 % and 62.4 %, respectively. As an outcome, our study proved that green synthesized ZnO NPs exhibit remarkable biological properties and can be used as an efficient bactericidal agent against foodborne pathogens.

Suppression of Selective Voltage-Gated Calcium Channels Alleviates Neuronal Degeneration and Dysfunction through Glutathione S-Transferase-Mediated Oxidative Stress Resistance in a Caenorhabditis elegans Model of Alzheimer's Disease

Calcium homeostasis plays a vital role in protecting against Alzheimer's disease (AD). In this study, amyloid-β (Aβ)-induced C. elegans models of AD were used to elucidate the mechanisms underlying calcium homeostasis in AD. Calcium acetate increased the intracellular calcium content, exacerbated Aβ _1-42 aggregation, which is closely associated with oxidative stress, aggravated neuronal degeneration and dysfunction, and shortened the lifespan of the C. elegans models. Ethylene glycol tetraacetic acid (EGTA) and nimodipine were used to decrease the intracellular calcium content. Both EGTA and nimodipine showed remarkable inhibitory effects on Aβ _1-42 aggregations by increasing oxidative stress resistance. Moreover, both compounds significantly delayed the onset of Aβ-induced paralysis, rescued memory deficits, ameliorated behavioral dysfunction, decreased the vulnerability of two major (GABAergic and dopaminergic) neurons and synapses, and extended the lifespan of the C. elegans AD models. Furthermore, RNA sequencing of nimodipine-treated worms revealed numerous downstream differentially expressed genes related to calcium signaling. Nimodipine-induced inhibition of selective voltage-gated calcium channels was shown to activate other calcium channels of the plasma membrane (clhm-1) and endoplasmic reticulum (unc-68), in addition to sodium-calcium exchanger channels (ncx-1). These channels collaborated to activate downstream events to resist oxidative stress through glutathione S-transferase activity mediated by HPGD and skn-1, as verified by RNA interference. These results may be applied for the treatment of Alzheimer's disease.

Santalol Isomers Inhibit Transthyretin Amyloidogenesis and Associated Pathologies in Caenorhabditis elegans

Transthyretin (TTR) is a homotetrameric protein found in human serum and is implicated in fatal inherited amyloidoses. Destabilization of native TTR confirmation resulting from mutation, environmental changes, and aging causes polymerization and amyloid fibril formation. Although several small molecules have been reported to stabilize the native state and inhibit TTR aggregation, prolonged use can cause serious side effects. Therefore, pharmacologically enhancing the degradation of TTR aggregates and kinetically stabilizing the native tetrameric structure with bioactive molecule(s) could be a viable therapeutic strategy to hinder the advancement of TTR amyloidoses. In this context, here we demonstrated α- and β-santalol, natural sesquiterpenes from sandalwood, as a potent TTR aggregation inhibitor and native state stabilizer using combined in vitro, in silico, and in vivo experiments. We found that α- and β-santalol synergize to reduce wild-type (WT) and Val30Met (V30M) mutant TTR aggregates in novel C. elegans strains expressing TTR fragments fused with a green fluorescent protein in body wall muscle cells. α- and β-Santalol extend the lifespan and healthspan of C. elegans strains carrying TTR_WT::EGFP and TTR_V30M::EGFP transgene by activating the SKN-1/Nrf2, autophagy, and proteasome. Moreover, α- and β-santalol directly interacted with TTR and reduced the flexibility of the thyroxine-binding cavity and homotetramer interface, which in turn increases stability and prevents the dissociation of the TTR tetramer. These data indicate that α- and β-santalol are the strong natural therapeutic intervention against TTR-associated amyloid diseases.

Oxidative Stress Protection by Canary Seed (Phalaris canariensis L.) Peptides in Caco-2 Cells and Caenorhabditis elegans

During oxidative stress, degenerative diseases such as atherosclerosis, Alzheimer’s, and certain cancers are likely to develop. Recent research on canary seed (Phalaris canariensis) peptides has demonstrated the high in vitro antioxidant potential. Thus, this study aimed to assess the cellular and in vivo antioxidant capacity of a low-molecular-weight (<3 kDa) canary seed peptide fraction (CSPF) using Caco-2 cells and the Caenorhabditis elegans model. The results show that the CSPF had no cytotoxicity effect on Caco-2 cells at any tested concentration (0.3−2.5 mg/mL). Additionally, the cellular antioxidant activity (CAA) of the CSPF was concentration-dependent, and the highest activity achieved was 80% by the CSPF at 2.5 mg/mL. Similarly, incubation with the CSPF significantly mitigated the acute and chronic oxidative damage, extending the lifespan of the nematodes by 88 and 61%, respectively. Furthermore, it was demonstrated that the CSPF reduced the accumulation of reactive oxygen species (ROS) to safe levels after sub-lethal doses of pro-oxidant paraquat. Quantitative real-time PCR revealed that the CSPF increased the expression of oxidative-stress-response-related gene GST-4. Overall, these results show that the CSPFs relied on GST-4 upregulation and scavenging of free radicals to confer oxidative stress protection and suggest that a CSPF can be used as a natural antioxidant in foods for health applications.

Para-Hydroxybenzyl Alcohol Delays the Progression of Neurodegenerative Diseases in Models of Caenorhabditis elegans through Activating Multiple Cellular Protective Pathways

The traditional Chinese medicine Gastrodia elata (commonly called “Tianma” in Chinese) has been widely used in the treatment of rheumatism, epilepsy, paralysis, headache, and dizziness. Phenolic compounds, such as gastrodin, para-hydroxybenzyl alcohol (HBA), p-hydroxybenzaldehyde, and vanillin are the main bioactive components isolated from Gastrodia elata. These compounds not only are structurally related but also share similar pharmacological activities, such as antioxidative and anti-inflammatory activities, and effects on the treatment of aging-related diseases. Here, we investigated the effect of para-hydroxybenzyl alcohol (HBA) on neurodegenerative diseases and aging in models of Caenorhabditis elegans (C. elegans). Our results showed that HBA effectively delayed the progression of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease in models of C. elegans. In addition, HBA could increase the average lifespan of N2 worms by more than 25% and significantly improve the age-related physiological functions of worms. Moreover, HBA improved the survival rate of worms under stresses of oxidation, heat, and pathogenic bacteria. Further mechanistic investigation revealed that HBA could activate FOXO/DAF-16 and SKN-1 to regulate antioxidative and xenobiotic metabolism pathway. HBA could also activate HSF-1 to regulate proteostasis maintenance pathway, mitochondrial unfolded stress response, endoplasmic stress response and autophagy pathways. The above results suggest that HBA activated multiple cellular protective pathways to increase stress resistance and protect against aging and aging-related diseases. Overall, our study indicates that HBA is a potential candidate for future development of antiaging pharmaceutical application.

Oxidative distress in aging and age-related diseases: Spatiotemporal dysregulation of protein oxidation and degradation

The concept of oxidative distress had arisen from the assessment of cellular response to high concentrations of reactive species that result from an imbalance between oxidants and antioxidants and cause biomolecular damage. The intracellular distribution and flux of reactive species dramatically change in time and space contributing to the remodeling of the redox landscape and sensitivity of protein residues to oxidants. Here, we hypothesize that compromised spatiotemporal control of generation, conversions, and removal of reactive species underlies protein damage and dysfunction of protein degradation machineries. This leads to the accumulation of oxidatively damaged proteins resulted in an age-dependent decline in the organismal adaptability to oxidative stress. We highlight recent data obtained with the use of various cell cultures, animal models, and patients on irreversible and non-repairable oxidation of key redox-sensitive residues. Multiple reaction products include peptidyl hydroperoxides, alcohols, carbonyls, and carbamoyl moieties as well as Tyr-Tyr, Trp-Tyr, Trp-Trp, Tyr-Cys, His-Lys, His-Arg, and Tyr-Lys cross-links. These lead to protein fragmentation, misfolding, covalent cross-linking, oligomerization, aggregation, and ultimately, causing impaired protein function and turnover. 20S proteasome and autophagy-lysosome pathways are two major types of machinery for the degradation and elimination of oxidatively damaged proteins. Spatiotemporal dysregulation of these pathways under oxidative distress conditions is implicated in aging and age-related disorders such as neurodegenerative and cardiovascular diseases and diabetes. Future investigations in this field allow the discovery of new drugs to target components of dysregulated cell signaling and protein degradation machinery to combat aging and age-related chronic diseases.

p21-Activated kinase 1 (PAK1) in aging and longevity: An overview

The p21-activated kinases (PAKs) belong to serine/threonine kinases family, regulated by ∼21 kDa small signaling G proteins RAC1 and CDC42. The mammalian PAK family comprises six members (PAK1-6) that are classified into two groups (I and II) based on their domain architecture and regulatory mechanisms. PAKs are implicated in a wide range of cellular functions. PAK1 has recently attracted increasing attention owing to its involvement in oncogenesis, tumor progression, and metastasis as well as several life-limiting diseases and pathological conditions. In Caenorhabditis elegans, PAK1 functions limit the lifespan under basal conditions by inhibiting forkhead transcription factor DAF-16. Interestingly, PAK depletion extended longevity and attenuated the onset of age-related phenotypes in a premature-aging mouse model and delayed senescence in mammalian fibroblasts. These observations implicate PAKs as not only oncogenic but also aging kinases. Therefore, PAK-targeting genetic and/or pharmacological interventions, particularly PAK1-targeting, could be a viable strategy for developing cancer therapies with relatively no side effects and promoting healthy longevity. This review describes PAK family proteins, their biological functions, and their role in regulating aging and longevity using C. elegans. Moreover, we discuss the effect of small-molecule PAK1 inhibitors on the lifespan and healthspan of C. elegans.