Abstract
Viola calcarata L. and Viola dubyana Burnat ex Gremli belong to the V. calcarata complex in Viola section Melanium (Violaceae family). For the first time, the essential oils (EOS) obtained by hydrodistillation from dried flowers, were analyzed by GC/MS and SPME-GC/MS to describe their volatile chemical profile. Differences in the qualitative and quantitative composition between the two violets have been found. A total of 43 compounds were identified among which methyl salicylate was the most abundant (from 45.5 to 68.0%) both in the vapor and liquid phase. The performed bioactivity tests pointed out the greater effect of V. dubyana EO compared to that obtained from V. calcarata. Nevertheless, both EOs proved to be good scavengers, especially toward the ABTS⋅+ radical. They also showed a dose-dependent phytotoxic action against Sinapis alba and Lolium multiflorum. Their seed germination was inhibited up to 100% and 25%, respectively, in response to the highest used dose (100 μL) of each EO. Furthermore, a significant decrease in root and shoot length was observed. The resulting seedling vigor index was reduced by 15–100% and 8–82% for S. alba and by 11–91% and 4–91% for L. multiflorum by V. dubyana and V. calcarata EOS, respectively.
Highlights
Essential oils (EOs) are a more or less complex mixture of natural organic substances of the secondary metabolism of plants where they play different roles as elements of interaction with the environment
The inhibition percentage was calculated and the results reported as μM eq Trolox mL−1 EO
In the two violet EOs, we have found two other bioactive compounds such as 2(4H)benzofuranone,5,6,7,7a-tetrahydro-4,4,7a-trimethyl and hexahydrofarnesyl acetone with relative high percentages
Summary
Essential oils (EOs) are a more or less complex mixture of natural organic substances of the secondary metabolism of plants where they play different roles as elements of interaction with the environment. EOs are able to defend plants from pests and predators or to attract pollinators and disseminators [1]. The bioactivity of EOs was widely demonstrated. Among others, they have shown remarkable antimicrobial, anti-inflammatory, antioxidant, cytotoxic, and anticancer effects both in in vitro and in vivo models [3,4,5,6]. Some EOs with allelopathic potential have been identified [7,8,9]
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