A Lecithin-Based Delivery Form of Quercetin Promotes Stress Resistance and Longevity in Caenorhabditis elegans

Background/Objectives: The flavonoid quercetin (Q) has recently been suggested as a natural anti-aging and senolytic agent. However, its low stability and poor oral bioavailability may limit its efficacy. To address this, we investigated whether a lecithin-based formulation of Q, Quercefit™ (QF), enhances stress resistance and delays aging in vivo. Methods: The nematode Caenorhabditis elegans was used as an animal model to evaluate the effects of QF under physiological and stress conditions. Unformulated Q was administered as a control. Worm survival, healthspan, resistance to thermal and oxidative stress, and expression of stress- and longevity-related genes were assessed. All the experiments were conducted at least in triplicate, each including a minimum of 15 worms. The data were analyzed using Student's t-test, one-way or two-way ANOVA, and Bonferroni's post hoc test. Results: One hundred micromolar Q administered in QF was more effective than equimolar unformulated Q in increasing the worms' ability to resist acute thermal stress at 35 °C (tested on 75 worms/group) and oxidative stress caused by 0.5 mM hydrogen peroxide (tested on 75 worms/group). In this last case, the protective effect of QF was similar to that of N-acetylcysteine and ascorbic acid. Under experimental conditions mimicking the long-term consequences of thermal stress, QF, like Q, increased the worms' lifespan and healthspan by approximately 50%, counteracting the age-related decline associated with stress (120 worms/group). These benefits are supported by QF's capacity to act as a reactive oxygen species scavenger; suppress heat-shock element gene transcription activated by thermal stress, such as hsp-16.2 and hsp-70, and stimulate the sod-3 and gst-4 genes that are involved in antioxidant and detoxification responses. Conclusions: These findings suggest that Q, when administered in the QF formulation, can act at the transcriptional level to protect against aging induced by stressful conditions.