The natural phytochemical trans-communic acid inhibits cellular senescence and pigmentation through FoxO3a activation

Ageing is characterized by the accumulation of chronic and irreversible oxidative damage, chronic inflammation and organ dysfunction. To attenuate these ageing-related changes, various natural phytochemicals are often applied. Trans-communic acid (TCA), an active component of brown pine leaf extract, has antimicrobial and cancer chemopreventive activity and inhibits ultraviolet B (UVB)-induced MMP-1 expression. To determine whether the phytochemical TCA could affect the lifespan of an ageing model, Caenorhabditis elegans prevent ageing-related phenotypes of the skin. Caenorhabditis elegans (C. elegans) wild-type N2 and mutant strains were used in this study to explore the lifespan extension effect of TCA and its mechanism. We estimated lipofuscin accumulation and melanin levels, which are closely associated with skin senescence. Moreover, we explored the mechanism of action associated with ageing attenuation. We performed oxidative stress resistance and thermotolerance assays in C. elegans and surface plasmon resonance analysis of TCA binding with the forkhead box-O3a (FoxO3a) protein. TCA, which is the active component in Korean red pine (Pinus densiflora), attenuated ageing-related changes in skin cells. TCA lowered lipofuscin accumulation in fibroblasts and decreased melanin levels in melanocytes. These protective effects were mediated by activation of the representative longevity gene FoxO3a, which was induced by direct binding with TCA. Interestingly, TCA extended the lifespan of C. elegans, although it did not affect stress resistance, oxidative stress or thermotolerance. These results strongly suggest that TCA prevents the senescent phenotype of model organisms and exhibits beneficial effects on ageing-related skin phenotypes through direct FoxO3a activation.