Azulenes in cells of allelopathic plants species in arid biocenosis

Using spectral methods, we studied the condition of leaves with blue or silver colour from 14-allelopathic medicinal species of arid zone of Kalmykia near Caspian Sea coast. The presence of blue azulene pigments on the surface and inside the cells was evaluated. Using microspectro-photometry techniques, the dynamics of the number of azulenes on the surface of intact cells according to their absorption spectra (maxima in the region of 570-630 nm) was seen, confirmed by spectral analysis of ethanol and acetone extracts of these pigments during short 10-min extraction of intact leaves. Prolonged extraction for 24 h also indicated the presence of azulenes inside the cells. The large amount of these pigments was found in all extraction samples, characteristic of the highest ultraviolet insolation and salt-enriched inhabitations. Azulenes were observed in 10-day old seedlings of some plants studied, mainly on the leaf surface. Testing of synthetic azulene and purified azulene fractions from several plants on unicellular cells of diatoms Ulnaria ulna, pollen of Hibiscus sp. or Equisetum arvense vegetative microspores decreased their vitality and germination. Among the possible mechanisms of azulene’s action in biocenosis, it was considered redox reactions with cellular components or external allelochemicals and synthesis of new compounds based on the link with 7-chain ring or 5-chain ring in the molecule. It was assumed that this was due to the antioxidant protection of azulenes from the damaging effects of the formed reactive oxygen species in the arid zone.