Potential Beneficial Effects of Digitaria ciliaris Flower Absolute on the Wound Healing-Linked Activities of Fibroblasts and Keratinocytes

Digitaria ciliaris is widely reported to be a problematic weed in agricultural areas and is mainly used as an indicator plant for the development of herbicides. However, its bioactivities on skin regeneration and wound healing have not been investigated. In the present study, we investigated the effects of D. ciliaris flower absolute on skin wound healing and skin regeneration-related events, that is, proliferation, migration, and collagen biosynthesis, in human fibroblasts and keratinocytes. For this study, we extracted absolute from the D. ciliaris flower by solvent extraction and identified the composition of D. ciliaris flower absolute using GC/MS analysis. We also tested the effect of D. ciliaris flower absolute in CCD986sk fibroblasts and/or HaCaT keratinocytes using the WST assay and 5-bromo-2 '-deoxyuridine incorporation assay, Boyden chamber assay, ELISA, sprouting assay, and immunoblotting. GC/MS analysis of D. ciliaris flower absolute revealed that it contained 15 compounds. The absolute increased the proliferations of keratinocytes and fibroblasts and the migration of fibroblasts but did not affect cell viabilities. In addition, it enhanced the syntheses of type I and IV collagen in fibroblasts, but not in keratinocytes. The sprouting assay showed increased sprout outgrowth of fibroblasts. In addition, D. ciliaris flower absolute induced the phosphorylation of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase in fibroblasts. These results indicate that D. ciliaris flower absolute may promote skin wound healing/regeneration by inducing the proliferation, migration, and collagen synthesis of fibroblasts, as well as the proliferation of keratinocytes. Therefore, D. ciliaris flower absolute may be a potential natural source for cosmetic or pharmaceutical agents that promote skin wound healing/regeneration.