Viola calcarata L. and Viola dubyana Burnat ex Gremli hydrolates: DI-SPME-GC-MS analysis and biological activity evaluation

The hydrolates obtained from the aerial parts
of two indigenous Viola L. species (V. calcarata L. and V.
dubyana Burnat ex Gremli) growing in the Italian Alps
were studied for the first time. The direct immersion
solid-phase microextraction (DI-SMPE) sampling and
the GC–MS analysis revealed the presence of methyl
salicylate as the main compound in both samples along
with a different set of terpenes for each hydrolate and
some other minor compounds. The most interesting
results were achieved by evaluating their phytotoxic
potential against two target species (Sinapis alba L. and
Lolium multiflorum Lam.) through treatments without
direct contact with the seeds. In general, the hydrolates
showed species and dose-dependent effects. They
were more active on growth (maximum reduction =
-86.8% due to V. dubyana hydrolate on S. alba) than on
germination (maximum inhibition = -45.9% due to V.
calcarata hydrolate on S. alba). No sign