Abstract
Alpha-ketoglutarate is a key intermediate in the Krebs cycle, and a rate-limiting cofactor of prolyl-4-hydroxylase. It also has a potent effect on increasing the proline pool during collagen production, but the details underlying the boosting effect on collagen production by α-ketoglutarate remain as yet unreported. To investigate the effects of α-ketoglutarate on procollagen production and wrinkle formation, we conducted experiments in cultured human dermal fibroblasts and UVB-irradiated hairless mice. Based on ELISA measurements, α-ketoglutarate (10 μM) stimulated procollagen production in fibroblasts by 25.6±4.6% compared to vehicle (dH2O)-treated control cells. Also, we demonstrated that α-ketoglutarate increased activities of prolidase, which is known to play an important role in collagen metabolism, in fibroblasts and N-benzyloxycarbonyl-L-proline (Cbz-Pro), prolidase inhibitor, inhibited procollagen synthesis by α-ketoglutarate in fibroblasts. To determine the effect of topically applied α-ketoglutarate on wrinkle formation, α-ketoglutarate (1%) and vehicle (70% propylene glycol, 30% ethanol) were applied on the dorsal skin of UVB-induced hairless mice for twelve weeks. We found that α-ketoglutarate decreased wrinkle formation upon long-term topical application. These results suggest that α-ketoglutarate diminishes UVB-induced wrinkle formation by increasing collagen production, through a pathway that involves prolidase activation. Therefore, application of α-ketoglutarate may represent an effective anti-wrinkle agent for the cosmetic field.
