Comparative study on major chemical constituents in volatile oil of true cinnamon (<i>Cinnamomum verum</i> Presl. syn. <i>C. zeylanicum</i> Blum.) and five wild cinnamon species grown in Sri Lanka

Abstract

The genus Cinnamomum has 250 species distributed from South, East and South East Asia to Australia. There are eight species of cinnamon grown in Sri Lanka, of which, Cinnamomum verum Pres1 (syn. C. zeylanicum Blume) which is widely cultivated in the country. In addition, seven other species of wild cinnamon are also grown which are endemic to Sri Lanka which are considered wild cinnamon. In this study, six Cinnamomum species were selected namely Cinnamomum verum, Cinnamomum dubium Nees (Sinhala: Sewel Kurundu or Wal Kurundu), Cinnamomum citriodorum (Sinhala: Pangiri Kurundu), Cinnamomum rivulorum Kostermans, Cinnamomum sinharajense Kostermans, Cinnamomum capparu-corende (Sinhala: Kapuru Kurundu). Much work has been carried out with Cinnamomum verum, however, work on wild cinnamon varieties is scanty. In this backdrop, this study was carried out to identify and quantify the major chemical constituents of volatile oils obtained from bark and leaves of wild and true cinnamon species cultivated or grown in Sri Lanka. It was revealed that leaf oil of Cinnamomum verum contains significantly (p<0.05) higher percentage of volatile oil (3.23%). The highest bark oil content (3.53%) was observed in Cinnamomum sinharajense, the lowest leaf oil (0.41%) and stem bark oil (0.51%) contents were observed in the Cinnamomum rivulorum. Fifteen major volatile chemical constituents were identified by Liquid Gas Chromatographic analysis in the essential oils obtained from bark and leaf of different cinnamon species. The highest cinnamaldehyde content (67.57%) was observed in Cinnamomum verum. Cinnamomum sinharajense contained comparatively higher amount of cinnamaldehyde (57.46%) than the other wild cinnamon species. The highest euginol content (87.53%) was observed in Cinnamomum sinharajense leaf. When compared with the chemical composition of Cinnamomum dubium leaf oil, geraniol was the most abundant (24.05%) among the volatile chemical constituents. β-Caryophyllene (41.31%) was identified in Cinnamomum dubium stem bark oil. The highest Euginol (22.29%) content was present in essential oil obtained from Cinnamomum rivulorum stem bark which was not observed in other cinnamon species.