Stimulation of Fibroblast Proliferation Mediated by Calendula officinalis through PI3K Dependent Pathway and Identification of Bioactive Compounds Responsible for Wound Healing Potential

Calendula officinalis , a member of the Asteraceae family is a flowering plant and has been used for its wound healing activity since long time. We investigated the mode of action of Calendula officinalis ethanolic extract and its different fractions on human dermal fibroblast (HDF) viability initially for 24 h using MTT assay. Only the Calendula crude extract (CCE) and water fraction (CWF) stimulated HDF cell proliferation, increasing in a dose and time dependent manner when extended beyond 24 h upto 72 h. To study cell migration in vitro , scratch assay was performed with the optimum concentration of CCE and CWF on HDF cells. The migrations of the treated cells were faster at corresponding time points compared to control. The addition of PI3K inhibitors wortmannin and LY294002 prior to the addition of extract decreased both cell proliferation and cell migration suggesting its involvement in blocking the action of Calendula . An RT‐PCR analysis was carried out on HDF cells treated with CCE and CWF on a number of genes, among which an increased expression of CTGF has been observed. We further explored the active constituents present in Calendula extract by HPLC‐ESI MS, which revealed the presence of flavonol glycosides as the major compounds. For in vivo study, a circular excisional wound was created in mice and a faster healing was observed in the fractions compared to control. Altogether, our results showed that Calendula officinalis potentiated wound healing by stimulating proliferation and migration of fibroblast in a PI3K dependent pathway and the identified compounds are likely to be responsible for wound healing activity. Research Support : University Grants Commission, India