Exploration of the wound healing potential of Helichrysum graveolens (Bieb.) Sweet: Isolation of apigenin as an active component

In Turkish traditional medicine, the flowers of Helichrysum graveolens (Bieb.) Sweet (Asteraceae) have been used for the treatment of jaundice, for wound-healing and as a diuretic. In order to find scientific evidence for the traditional utilization of this plant in wound-healing, the effect of the plant extract was investigated by using in vivo and in vitro experimental models. Then through bioassay-guided fractionation procedures active wound-healing component(s) was isolated and its possible role in the wound-healing process was also determined. The linear incision and the circular excision wound models were applied in order to evaluate in vivo wound-healing potential of Helichrysum graveolens. Anti-inflammatory and antioxidant activities, which are known to involve in wound-healing process, were also assessed by the Whittle method and the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging assay, respectively. The total phenolic content of the crude extract and solvent fractions was estimated to find correlation between the phenolic content and the antioxidant activity. Combined application of the chromatographic separation techniques on sephadex and silica gel columns, and bioassay techniques have yielded the active wound-healing principle of Helichrysum graveolens. Moreover, in vitro inhibitory effect of active principle on hyaluronidase, collagenase and elastase enzymes were investigated to explore the activity pathways. The 85% methanol (MeOH) extract of Helichrysum graveolens flowers displayed significant wound-healing, anti-inflammatory and antioxidant activities. Then the crude extract was partitioned by successive solvent extractions, in increasing polarity, to give five solvent fractions. Among the solvent fractions, the ethyl acetate (EtOAc) fraction exerted the highest activity. The EtOAc fraction was further subjected to chromatographic separations to yield active constituent and its structure was elucidated to be apigenin by spectrometric methods. Further in vivo and in vitro assays revealed that apigenin was one of the components responsible for the wound-healing effect of the plant remedy and also found to possess significant anti-inflammatory, antioxidant, anti-hyaluronidase and anti-collagenase activities. Present study supported the traditional use of Helichrysum graveolens flowers for wound-healing and through bioassay-guided fractionation procedures from the crude extract apigenin was isolated as one of the active components. [D