Chemical characterization of the essential oil compositions from Iranian populations of Hypericum perforatum L.

Hypericum perforatum L. (St. Johns' wort) is the most commercially important species of the genus Hypericum and contains a wide range of components including naphthodianthrones, phloroglucinols, tannins, xanthones, phenolic acids and essential oil. In the present study, for the first time the variation of the essential oil compositions among 10 wild populations of H. perforatum growing in Iran was assessed. According to the GC-FID and GC-MS analyses, a total of forty-six components were identified in 10 H. perforatum populations with relatively high variation in their composition. Among chemicals, 2,6-dimethyl-heptane (6.25-36.07%), α-pinene (5.56-26.03%), δ-cadinene (0.0-22.58%) and γ-cadinene (0.0-16.9%) were found as the most abundant compounds in their essential oils. The higher amounts of this components were identified in the oil of Azadshahr, Kharw, Nor and Mashhad populations, respectively. Cluster analysis grouped the studied populations into four different chemotypes: chemotype I (δ-cadinene/α-humulene), chemotype II (α-pinene), chemotype III (γ-cadinene) and chemotype IV (2,6-dimethyl-heptane/α-pinene). In fact, local abiotic factors such as moisture, temperature, topography, edaphic and/or biotic selective factors (associated fauna and flora) act on loci of the terpene-biosynthesis pathways and contribute to the emergence of different chemical oil profiles. Intraspecific variation in the chemical profile of the Iranian populations provided possibility of selection of those with specific aromas or chemical profiles accompanied with biological document, being of interest at industrial level. Obtained results provided new insight for Iranian H. perforatum germplasm to be used in breeding programs and development of effective conservation strategies.