Sake lees extract obtained using a novel continuous phase-transition extraction method: evaluation of its bioactive composition, anti-aging efficacy and mechanism

For the high-value utilization of sake lees (SL), it is essential to explore its potential as a resource for anti-aging bioactives. However, the efficient extraction of SL, the compositional benefits provided, and the resulting anti-aging efficacy in vivo remain to be explored. Thus, a novel continuous phase-transition extraction (CPE) method, an amino acid analyzer, LC-MS, and GC-MS, as well as a classic anti-aging model of Caenorhabditis elegans (C. elegans) were adopted. The results showed that compared to ultrasound-assisted extraction, the total amino acid content of SL extract (SLE) obtained using 80% ethanol in CPE increased by 39.64%, with a notable enhancement in the in vitro scavenging ability of free radicals (p < 0.05). In SLE, the hydrophobic, acidic, and basic amino acids with antioxidant activity accounted for 77.11% of total amino acids. New potential anti-aging compounds were identified, including Lys-Gln, Leu-Arg-Lys, and sphinganine. In particular, 4 mg mL^-1 SLE not only promoted a 19.32% increase in the lifespan of C. elegans by enhancing oxidative stress and neuroprotective effects but also ameliorated age-related phenotypes like motoricity and age pigment. Further exploration revealed that the efficacy of SLE is mediated by SKN-1/Nrf2 and HSF-1 pathways, which can be confirmed by the upregulation of key genes, such as skn-1 and hsf-1, especially by inducing a 72.73% increase in nuclear transfer of the transcription factor SKN-1/Nrf2. Taken together, SLE obtained by CPE was abundant in bioactives and contains novel components, thus exerting prominent anti-aging effects in vivo. This study provides a new way to obtain anti-aging active substances efficiently, which is beneficial for application in the fields of health foods and cosmetics.