Plant-Derived Molecules alpha-Boswellic Acid Acetate, Praeruptorin-A, and Salvianolic Acid-B Have Age-Related Differential Effects in Young and Senescent Human Fibroblasts In Vitro

Testing and screening of plant-derived molecules on normal human cells in vitro is a widely used approach for discovering their eventual health beneficial effects for human ageing and longevity. As little is known about age-associated differential effects of such molecules, here we report that young (90% replicative lifespan completed) human skin fibroblasts exposed for 1-15 days to a wide range of concentrations (0.1-100 mu M) of the three selected phytochemicals, namely alpha-boswellic acid acetate (ABC), praeruptorin-A (PTA), and salvianolic acid-B (SAB) had age-related differential effects. The parameters studied were the metabolic activity (MTT assay), cellular morphological phenotype, one-step growth characteristics, expression of genes involved in the cell cycle regulation and cytokine network genes, protein levels of p53, cytosolic superoxide dismutase (SOD1) and microtubule-associated protein 1A/1B-light chain 3 (LC3), and the extent of protein carbonylation and protein aggregation as a sign of oxidative stress. All three compounds showed biphasic hormetic dose response by stimulating cell growth, survival and metabolic activity at low doses (up to 1 mu M), while showing inhibitory effects at high doses (>10 mu M). Furthermore, the response of early passage young cells was different from that of the late passage near-senescent cells, especially with respect to the expression of cell cycle-related and inflammation-related genes. Such studies have importance with respect to the use of low doses of such molecules as health-promoting and/or ageing-interventions through the phenomenon of hormesis.