Variability, toxicity, and antioxidant activity of Eupatorium cannabinum (hemp agrimony) essential oils

Eupatorium cannabinum L. (Asteraceae) is as a potential source of biologically active compounds. The plant is used in traditional medicine for the treatment of diarrhea and livers diseases.

The present study provides investigation on pharmacological properties (antioxidant and toxic activities) of essential oils of E. cannabinum, collected from 11 wild populations in Lithuania.

Twenty-two hemp agrimony essential oil samples were prepared by hydrodistillation according to the European Pharmacopoeia, and their chemical composition was determined by GC-FID and GC-MS. Compositional data were subjected to principal components analysis (PCA). Instead of conventional spectrophotometric methods, cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were applied to determine antioxidant activity of hemp agrimony essential oils. Meanwhile, toxicity of the oils was determined using brine shrimp (Artemia sp.) assay.

Chemical profiles of E. cannabinum oils were described according to the first predominant components: germacrene D (≤22.0%), neryl acetate (≤20.0%), spathulenol (≤27.2%), and α-terpinene (11.5%). For the first time, α-zingiberene (≤7.8%) was found to be among three major constituents (as the second one) for hemp agrimony oils. SWV measurements revealed that oxidation potentials of compounds present in the oils are lower (below 0.1 V) compared with that of well-known antioxidant quercetin (0.15 V). Toxicity tests evaluated that hemp agrimony oils containing predominant amounts of germacrene D and neryl acetate were notably toxic (LC50 value 16.3-22.0 μg/mL).

The study provided some new data concerning chemical composition and pharmaceutical properties of E. cannabinum essential oils.