Identification of Anthocyanins and Phenolic Acid in the Flowers of Three Lungwort (Pulmonaria) Cultivars and Their Comparisons during Flower Developmental Stage

Abstract

Three anthocyanins, delphinidin 3-O-glucoside, petunidin 3,5-di-O-glucoside, and petunidin 3-O-glucoside, and rosmarinic acid were isolated and identified from the flowers of three lungwort (Pulmonaria) cultivars. Composition of these compounds were quantitatively compared during two developmental stages, i.e. violet color in early flowering stage and blue color in later flowering stage. In addition, pH values of petal juices and flower color value were measured in both stages. Qualitative differences among three cultivars were observed in anthocyanins. However, qualitative and quantitative changes during development was not observed. Increase of rosmarinic acid was observed in one cultivar during development of the flowers. Notable alkalization was not revealed in vacuoles. These results mean that the flower bluing in these lungwort cultivars is not mediated by intramolecular copigmentation and alkalization of vacuole. Furthermore, we performed in vitro examination using the isolated anthocyanin, delphinidin 3-O-glucoside or petunidin 3-O-glucoside, and rosmarinic acid. As the results, it was shown that the absorption curves of the mixture solutions and intact petal did not match. Thus, it was suggested that the petal bluing after flowering may be due to intermolecular interaction which was influenced by metal ions.