Curcumin Protects Skin against UVB-Induced Cytotoxicity via the Keap1-Nrf2 Pathway: The Use of a Microemulsion Delivery System

Figure 3

(a) ORAC value (equivalent trolox, mM) versus curcumin concentration for (■) curcumin-loaded microemulsion and (♦) curcumin dissolved in DMSO, (b) LDCL generated by “cocktail,” for curcumin-loaded microemulsion (b) and curcumin dissolved in DMSO (d) containing in increasing concentration (-) 27.1 mM curcumin, (♦) 20.4 mM curcumin, (▲) 13.9 mM curcumin, (×) 6.8 mM curcumin, and (■) microemulsion without curcumin (microemulsion and DMSO, respectively). Statistical analysis indicated significantly higher antioxidant activity indicated by a decrease in LDCL (). (c) Typical anodic peak as measured by cyclic voltammetry for (♦) curcumin dissolved in DMSO (1st oxidation potential, 407 mV) and (■) curcumin-loaded microemulsion (1st oxidation potential, 473 mV) in increasing curcumin concentrations. (e) Antioxidant activity of (♦) curcumin dissolved in DMSO and (■) curcumin-loaded microemulsion as measured by the DPPH assay and expressed in trolox equivalents.

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