Holothuria scabra extracts possess anti-oxidant activity and promote stress resistance and lifespan extension in Caenorhabditis elegans

Holothuria scabra is a sea cucumber that is mostly found in the Indo-Pacific region including Thailand. Extracts from many sea cucumbers possess pharmacological activities proposed to benefit human health. In this study, we investigated the anti-oxidant and anti-ageing activities of extracts from H. scabra by using Caenorhabditis elegans as a model organism. Parts of H. scabra were solvent-extracted and divided into nine fractions including whole body-hexane (WBHE), whole body-ethyl acetate (WBEA), whole body-butanol (WBBU), body wall-hexane (BWHE), body wall-ethyl acetate (BWEA), body wall-butanol (BWBU), viscera-hexane (VIHE), viscera-ethyl acetate (VIEA), and viscera-butanol (VIBU). All fractions of the extracts were tested for anti-oxidant activities by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays and for anti-ageing effects by lifespan assays using C. elegans as a model. The results showed anti-oxidant properties in all fractions with the highest activity shown by the DPPH assay in WBBU (EC₅₀ = 3.12 ± 0.09 mg/ml), and by the ABTS assay in WBHE (EC₅₀ = 0.31 ± 0.10 mg/ml). In lifespan assays the highest anti-ageing effect was detected in WBBU- and BWEA-treated C. elegans with increased mean lifespans of 8.12% and 4.77%, respectively. Furthermore, WBBU and BWEA-treated C. elegans exhibited significantly higher resistance against heat shock and paraquat-induced oxidative stresses than controls. By using LC-MS/MS, both extracts were characterized to contain triterpene glycosides as the main bioactive components. To explore mechanisms of H. scabra extracts on longevity and stress resistance, worms with genetic mutations in anti-ageing pathways were analyzed and showed that WBBU and BWEA did not prolong the lifespan of daf-16, age-1, sir-2.1, jnk-1, sek-1, and osr-1 mutants, suggesting that these genetic pathways are involved in mediating the anti-ageing effects of the H. scabra extracts. Moreover, WBBU and BWEA enhanced the nuclear translocation of the FoxO/DAF-16 transcription factor, and increased mRNA expression of this gene and its downstream targets sod-3, hsp12.3, and hsp16.2. In conclusion, this study strongly demonstrates anti-oxidant and anti-ageing properties of H. scabra extracts containing triterpene glycosides, which, in the C. elegans model, may be mediated via the insulin/IGF-1 signaling (IIS)-DAF-16 pathway.