Multi-Level Evaluation of Antioxidant Activity, Aging-Related Physiological Functions, and Longevity Effects of Nelumbo nucifera Gaertn. Embryo Extract, Pleuropterus multiflorus (Thunb.) Turcz. ex Nakai Stilbene Glycoside, and Pterostilbene

Despite known antioxidant activity, the effects of plant-derived compounds on aging-related physiological functions and mechanisms remain unclear, which necessitates investigation at cellular and organismal levels. To examine whether these compounds can mitigate age-related physiological decline, Nelumbo nucifera Gaertn. (sacred lotus) embryo extract–water-soluble fraction (NEW), stilbene glycoside from Pleuropterus multiflorus (Thunb.) Turcz. ex Nakai (PM-SG), and pterostilbene were investigated through chemical profiling, antioxidant activity, HepG2 liver cells, and Caenorhabditis elegans longevity assays, while principal component analysis (PCA) elaborated on the results. Quantitative LC-MS revealed that NEW extract was rich in alkaloids (neferine and liensinine), while PM-SG mainly contained 2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside. PM-SG showed the strongest radical-scavenging activity (DPPH, TEAC, and ORAC), followed by pterostilbene. However, pterostilbene exhibited the strongest cellular antioxidant activity among the three test materials (NEW, PM-SG, and pterostilbene), an effect attributed to its superior cellular uptake, although it was less potent than the reference standards EGCG and quercetin. All samples extended the lifespan of C. elegans dose-dependently, with the strongest effect from pterostilbene (40–50%), then PM-SG (25–35%) and NEW (18–22%). Pterostilbene and PM-SG improved health measures, including enhanced resistance to heat and oxidative stress, and maintained feeding function. Discrepancies between in vitro antioxidant rankings and observed cellular effects indicate that radical-scavenging activity alone cannot fully predict in vivo anti-aging efficacy, which depends on cellular uptake, activation of endogenous defense mechanisms, and modulation of longevity pathways. Further clinical studies are needed to determine the potential relevance of these findings to human health.