Improvement in the turnover rate of the stratum corneum in false aged model rats by the administration of geniposidic acid in Eucommia ulmoides Oliver Leaf.

We earlier reported that collagen synthesis in false aged model rats was stimulated by the administration of a methanol extract from the leaves of Eucommia ulmoides OLIVER. When the methanol extract was fractionated to n-hexane, ethyl acetate, acetone and methanol fractions by silica gel chromatography, we discovered that geniposidic acid and aucubin, contained in the acetone fraction, were the active ingredients. In the current study, we set out to examine if active compounds found in the Eucommia ulmoides OLIVER leaf (EUOL) improved the low turnover rate in the stratum corneum of false aged model rats. The turnover rate in the stratum corneum in rats was measured as 50% dansyl chloride clearance day. In the first experiment, administration of a 2.4% water soluble methanol extract (WSME) of EUOL, along with an 11% protein diet, led to a 20% higher turnover rate in the stratum corneum (p<0.05, Mann-Whitney) than the control value. The WSME mainly contained iridoid mono-glycosides such as geniposidic acid. In the second experiment, treatment with geniposidic acid similarly caused a higher turnover rate in the stratum corneum, increasing turnover by 23% (p<0.05, Mann-Whitney) compared to the control value. In this paper we reveal that the WSME contains compounds effective against aging, and one of them is geniposidic acid.