Inhibitory effect of the extract of rhizome of Curcuma longa L in gelatinase activity and its effect on human skin.

Exposure to UV radiation to human skin up-regulates the synthesis of matrix metalloproteinase (MMP) family. Gelatinases are member of MMPs which have been suggested to play an important role in photoaging such as wrinkle formation. To inhibit gelatinase activity is regarded to be very important to keep healthy skin and to protect wrinkle formation. On the other hand, anti-photoaging agents are expected to be derived from natural resources, especially plants. Plant extracts having gelatinase-inhibitory effect that might be used as safe anti-photoaging ingredient were widely screened. An extract of rhizomes of Curcuma longa L. showed inhibitory effect of gelatinase activity. Curcuminoids and slight amount of compound, 6,11-dihydroxy-3-(4-hydroxy-3-mthoxyphenethyl)-7-[(E)-4-(4-hydroxy-3-methoxyphenyl)-2-oxo-3-butenyl]-10-methoxy-2-oxabicyclo[6.3.1.]dodeca-1(11),8(12),9-trien-5-yl (E)-3-(4-hydroxy-3-methoxyphenyl)-2-propenoate (curcuminoid D) were isolated as the gelatinase-inhibitory components from methanol extract of rhizomes. The structure of curcuminoid D was determined by means of spectral data including H- and C-NMR, and IR. Curcumin exerted the enhancing effect on deposition of basement membrane component at dermal-epidermal junction in skin equivalent model. Topical application of cream containing turmeric extract significantly improved facial skin elasticity and decreased the number of gelatinase-positive stratum corneum clusters in human facial skins. These results indicated that turmeric is an effective ingredient to improve skin condition and to prevent skin from photoaging by suppressing activation of gelatinase chronically caused by UV.