INDUCTION OF VASCULARIZATION BY AN AQUEOUS EXTRACT OF THE FLOWERS OF CALENDULA-OFFICINALIS L THE EUROPEAN MARIGOLD

Calendula officinalis L. (calendula) is a plant whose recorded history is indicative of intrinsic wound healing capabilities. The wound heal ing process involves several distinct phases in which the formation of new blood vessels plays an essential role. This report describes the angiogenic activity of a freeze-dried aqueous extract of the flowers o f Calendula officinalis L. (the European marigold) utilizing the chick chorioallantoic membrane (CAM) assay. The CAM assay is a standard and well established method for assessing the angiogenic activity in impu re and pure preparations and is suitable for studies requiring examina tion of large numbers of sample test materials. The angiogenic activit y of calendula was measured by examination of CAMs using stereomicrosc opy. Further histological investigation and quantification of neovascu larization was performed utilizing microvascular counts. The histologi cal sections of CAMs were also examined for the presence of hyaluronan (HA), a tissue glycosaminoglycan associated with neovascularization, by hyaluronidase digestion and staining of tissue sections by alcian b lue. All calendula treated CAMs were positive for HA; no HA could be d emonstrated in control CAMs. The numbers of microvessels in calendula- treated CAMs were statistically significantly higher than in the contr ol CAMs (p < 0.0001). Thin layer chromatography indicated that the cal endula extract contained water-soluble compounds such as flavonoids, b ut the exact nature of the active angiogenic component(s) has not yet been identified.