Effects of Calendula officinalis on Human Gingival Fibroblasts

Introduction: Calendula officinalis is commonly called the marigold. It is a staple topical remedy in homeopathic medicine. It has anti-oxidants and anti-inflammatory properties. Quercetin, one of the active components in Calendula, has been shown to inhibit matrix metalloproteinase (MMP) activity and decrease their gene expression. Objective:  To examine the effects of Calendula on human gingival fibroblast (HGF) mediated collagen degradation and MMP activity. Methods: Lactate dehydrogenate (LDH) assays were performed to determine the non-toxic concentrations of Calendula, doxycycline and quercetin that could be used to treat the HGFs. Cell-mediated collagen degradation assays were then performed to examine the effects that Calendula, doxycycline and quercetin have on inhibiting cell-mediated collagen degradation in vitro. Gelatin zymography was performed to examine the effects that Calendula, doxycycline and quercetin have directly on MMP-2 activity. The concentration of quercetin in Calendula was determined and correlated with the activity of pure quercetin. The experiments were repeated 3 times and ANOVA (Analysis of Variance) was used for statistical analysis. Results: Calendula at 2-3% completely inhibited the MMP-2 activity in the zymograms. Doxycycline inhibited HGF-mediated collagen degradation at 0.005, 0.01, 0.02 and 0.05% and MMP-2 activity completely at 0.05%. Quercetin inhibited HGF-mediated collagen degradation at 0.005, 0.01 and 0.02% and MMP-2 activity in a dose-dependent manner. Calendula inhibited HGF-mediated collagen degradation and MMP-2 activity more than the same correlated concentration of pure Quercetin. Conclusion: The mother tincture Calendula can inhibit HGF-mediated collagen degradation and MMP-2 activity more than the corresponding concentration of Quercetin. This may be attributed to other components in Calendula in addition to Quercetin.