Objective: We investigated skin hydration and anti-ageing efficacies of Ectoine, a natural bacterial osmolyte, utilising human keratinocyte (HaCaT) and fibroblast (Hs68) cells under non- or UVB (30 mJ/cm2) exposure.
Methods: We incorporated various experimental techniques, including MTT assay (cell viability), small interfering RNA (siRNA) transfection, and immunoblotting analysis, to assess the molecular mechanisms of skin hydration and anti-ageing efficacies of Ectoine.
Results: The findings exhibited that Ectoine improved cell viability in the presence or absence of UVB exposure in HaCaT cells. Ectoine upregulated Src and HAS-2 expression in the presence or absence of UVB irradiation in HaCaT cells. Src knockdown reduced Ectoine-increased HAS-2 expression, implying that Ectoine provoked Src-mediated HAS-2 expression in the presence of or without UVB irradiation in HaCaT cells. Ectoine enhanced phosphorylated-ERK expression in a time- and dose-dependent manner in HaCaT cells. In addition, Ectoine increased phosphorylated-ERK expression in UVB-irradiated HaCaT cells. The ERK inhibitor (PD98059) remarkably decreased Ectoine-provoked HAS-2 expression, suggesting that Ectoine triggered ERK-mediated HAS-2 expression in HaCaT cells. Furthermore, Ectoine amplified JNK and AQP-3 levels in the presence or lack of UVB exposure in HaCaT cells. The JNK inhibitor (SP600125) significantly reduced Ectoine-triggered AQP-3 expression, suggesting that Ectoine provoked JNK-mediated AQP-3 expression in HaCaT cells. Ectoine increased collagen-I expression in the presence or lack of UVB irradiation in HaCaT cells. Notably, Ectoine enhanced collagen-I expression and inhibited MMP-1 expression in a dose-dependent manner in fibroblast (Hs68) cells.
Conclusion: We demonstrated that Ectoine exerts skin hydration effects without or with UVB exposure in human skin keratinocyte (HaCaT) cells and anti-ageing in fibroblast (Hs68) cells. Therefore, Ectoine could serve as a potential natural compound in cosmetic preparations for skin hydration and anti-ageing.