Herein we report the extraction of labdane-type diterpenoids from the needles of the common juniper (Juniperus communis ssp. communis var. communis L.), and identification of them as the major class of compounds in this species. Furthermore, and to the best of our knowledge we provide the first-ever report some of these compounds (nor-16-imbricatolic, nor-16-acetylimbricatolic and acetylimbricatolic acids) as natural compounds. Imbricataloic and imbricatolic acids were the most abundant compounds, accounting for 65% of the total extract. We also found long-chain secondary alcohols (n-alkan-10-ols) and secondary/secondary alkanediols (4,10-, 5,10-, 6,10-, 7,10-), which we report here for the first time ever in the genus Juniperus. In total, we identified 127 compounds: of these, 48 (nonacosan-10-ols, -tocopherols and lignans) are described here for the first time in Juniperus and 54 (including alkanols, phytol, sterols and flavonoids), for the first time in common juniper.
Highlights 127 phytochemical constituents of the needles of Juniperus communis were investigated with imbricatolic and imbricatalic acid as the most abundants 3 Labdane-type diterpenoids are new natural products 17 compounds have no precedent in Juniperus genus and 32 are described for the first time from Juniperus communis Keywords: Juniperus communis; Common juniper; Diterpenoids; Labdane-type; Alkanediols; Imbricatolic acid; Gas chromatography-Mass spectrometry (GC/MS); Trimethylsilyl (TMS) ether derivatives.
IntroductionThe genus Juniperus (Cupressaceae) comprises 68 species and 36 varieties growing principally in the northern hemisphere . The chemical composition of the genus Juniperus has been extensively reviewed by Seca & Silva (2006). Table 1 summarizes the phytochemical characteristics of the principal compounds from the genus Juniperus, excluding terpenes, secondary alcohols and secondary diols, which we discuss separately in a latter section.The species Juniperus communis L. comprises four subspecies, including the common juniper (J. communis ssp. communis), a coniferous evergreen shrub that has a broad geographic range throughout the holarctic region. In fact, it exhibits the largest range of any woody plant, spanning the cool, temperate, part of the Northern Hemisphere: from mountains in the southern arctic, to roughly 30ºN latitude in North America, Europe and Asia. It tolerates a variety of climatic and edaphic conditions. The surface layer of plant leaves typically contains many classes of compounds, including alkanes, primary alcohols, acids, aldehydes, terpenes and phenols. However, there are very few reports on the overall composition of common-juniper needles. Thus, in the study reported here, we sought to analyze the soluble fraction of common-juniper needles.We analyzed the total extract of common-juniper needles and identified each wax-class of compounds, discovering many acyclic and cyclic compounds from three major groups: terpenoids (e.g. sesquiterpenes and diterpenes); phenols (including phenolic acids,...