Induction of antioxidant defenses by diterpenic phenolics in human fibroblasts for nutritional applications toward anti-aging interventions

Abstract

Human lifespan is increasing in developed and developing countries, rising considerably the percentage of elderly people. Aging is characterized by the progressive accumulation of molecular damage, which leads to altered cellular functioning, reduced stress tolerance and susceptibility to diseases, such as cancer, neurodegenerative and cardiovascular diseases. Consumption of fruits, vegetables and herbs has been related with health promotion due to their content in bioactive phytochemicals. In a previous work, we have shown the ability of curcumin to induce antioxidant stress responses in human fibroblasts, protecting the cells to a further oxidant challenge, which suggests curcumin’s potential in anti-aging interventions [1]. In the present work, we propose to evaluate the ability of the phenolic diterpenes carnosic acid (CA) and carnosol (CS) to induce intracellular antioxidant defenses in normal human skin fibroblasts and relate that with anti-aging effects. The ability of these compounds to induce cellular antioxidant defenses was investigated by western blot and biochemical determinations. We observed that human fibroblasts are more susceptible to CS than CA. Carnosic acid was not toxic up to (the highest concentration tested), CS induced toxicity in human fibroblasts only at 40 μM. Both CA and CS at non-toxic concentrations induced significantly glutathione levels, an important intracellular antioxidant, in a concentration dependent manner. Both compounds were also able to induce cytoprotective enzymes such as HO-1, NQO1 and Hsp70, assessed by western blot. We also tested the capacity of these compounds to afford a cytoprotective action by pre-incubating cells with CA and CS before a further oxidant challenge with tert-butyl hydroperoxide (tert-BOOH). In conclusion, the induction of antioxidant defenses in human skin fibroblasts by CA and CS may be applied for nutritional applications toward cytoprotective and anti-aging interventions.

Acknowledgements: ACC is supported by BI1-PTDC/QUI-BIQ/101392/2008 grant. This work is supported by FCT research grant NaturAge – PTDC/QUI-BIQ/101392/2008, which is co-funded by the program COMPETE from QREN with co-participation from the European Community fund FEDER.

[1] Lima et al., Mol. Nutr. Food Res. 2011, 55: 430-42.