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ABSTRACT
The leaf oil from Baccharis punctulata D.C. specimens from Argentina, analyzed by GC and GC/MS during a one-year phenological cycle, showed important changes. In spring and summer, during the stem and floral bud development, the percentages of amorpha-4,7(11)-diene, amorpha-4-en-7-ol, amorpha-4,7-diene-11-ol and amorpha-4,7(11)-dien-8-one increased, while the percentage of verboccidentafuran decreased (c.a. 50% to 10%). The percentage of the guaiane alismol, which was negligible in other months, also increased (19.1–24.8 %). Alismol structure was spectroscopically established. Interesting, when buds opened, alismol percentage fell, so pre- and full-flowering oil composition resulted very different. Germacra-1(10),5-dien-4α-ol (16.7–23.0 %), verboccidentafuran (16.1–18.4%) and elemane-type sesquiterpenes were main components at flowering. Germacra-1(10),5-dien-4α-ol may have the adequate configuration and conformation to be biosynthetically related to alismol. Finally, germacra-1(10),5-dien-4α-ol and elemene derivative percentages decreased. Verboccidentafuran (27.6–52.4%) was the main compound in winter. These cyclic changes appear to be associated with the phenological stages of the plant during the year.
Acknowledgements
I would like to thank Dr. Daniel Giuliano for his help by identifying the plant materials and to Dr. Lucas Fabián for the Nuclear Magnetic Resonance spectra. I also thank the Basic Science Department of the National University of Luján for financially supporting this investigation.
Disclosure statement
No potential conflict of interest was reported by the author.
Data availability statement
The data that support the findings of this study are available from the corresponding author, [M.D.G.], upon request.