Efficacy of Daphne oleoides subsp. kurdica used for wound healing: identification of active compounds through bioassay guided isolation technique

Abstract

Ethnopharmacological relevance: In Turkish traditional medicine, the aerial parts of Daphne oleoides Schreber subsp. kurdica (DOK) have been used to treat malaria, rheumatism and for wound healing. The aim was to evaluate the ethnopharmacological usage of the plant using in vivo and in vitro pharmacological experimental models, and to perform bioassay-guided fractionation of the 85% methanolic extract of DOK for the isolation and identification of active wound-healing component(s) and to elucidate possible mechanism of the wound-healing activity.

Materials and methods: In vivo wound-healing activity was evaluated by the linear incision and the circular excision wound models. Anti-inflammatory and antioxidant activities, which are known to support the wound healing process, were also assessed by the Whittle method and the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging assays, respectively. The total phenolic content of the extract and subextracts was estimated to establish any correlation between the phenolic content and the antioxidant activity. The methanolic extract of DOK was subjected to various chromatographic separation techniques leading to the isolation and identification of the active component(s). Furthermore, in vitro hyaluronidase, collagenase and elastase enzymes inhibitory activity assays were conducted on the active components to explore the activity pathways of the remedy.

Results: After confirmation of the wound-healing activity, the methanolic extract was subjected to successive solvent partitioning using solvents of increasing polarity creating five subextracts. Each subextract was tested on the same biological activity model and the ethyl acetate (EtOAc) subextract had the highest activity. The EtOAc subextract was subjected to further chromatographic separation for the isolation of components 1, 2 and 3. The structures of these compounds were elucidated as daphnetin (1), demethyldaphnoretin 7-O-glucoside (2) and luteolin-7-O-glucoside (3). Further in vivo testing revealed that luteolin-7-O-glucoside was responsible for the wound-healing activity of the aerial parts. It was also found to exert significant anti-inflammatory, antioxidant, anti-hyaluronidase and anti-collagenase activities.

Conclusion: The present study explored the wound-healing potential of Daphne oleoides subsp. kurdica. Through bioassay-guided fractionation and isolation techniques, luteolin-7-O-glucoside was determined as the main active component of the aerial parts. This compound exerts its activity through inhibition of hyaluronidase and collagenase enzymes activity as well as interfering with the inflammatory stage.