Nepetalactone content in shoot cultures of three endemic Nepeta species and the evaluation of their antimicrobial activity.

Rapid micropropagation of Nepeta rtanjensis, N. sibirica and N. nervosa was performed. Qualitative and quantitative nepetalactone content in methanol extracts of in vitro grown plants was analysed by reverse-phase HPLC coupled with UV and MS detection. Only trans,cis-nepetalactone was detected in shoots of N. rtanjensis, while cis,trans-nepetalactone stereoisomer was present in N. sibirica. No nepetalactone was observed in shoots of N. nervosa. The antimicrobial activity of methanol extracts, against eight bacterial and eight fungal species, was evaluated. All the tested extracts showed significant antibacterial and strong antifungal activity. However, N. rtanjensis extract exhibited the best antimicrobial potential.

Spontaneous plant regeneration and production of secondary metabolites from hairy root cultures of Centaurium erythraea Rafn.

We have established an efficient protocol for plant regeneration and production of secondary metabolites in hairy root culture of Centaurium erythraea Rafn. Because the hairy roots and regenerated plants produce bitter secoiridoid glucosides and xanthones similar to the plants in nature, the use of in vitro cultures as an alternative source of their production is feasible. This chapter describes a protocol for the induction of adventitious shoots and transgenic plants from hairy root cultures of C. erythraea and their phytochemical analysis.

Antimicrobial activity of Bryum argenteum.

The antimicrobial activity of Bryum argenteum ethanol extracts was evaluated by microdilution method against four bacterial (Escherichia coli, Bacillus subtilis, Micrococcus luteus and Staphilococcus aureus) and four fungal species (Aspergillus niger, Penicillium ochrochloron, Candida albicans and Trichophyton mentagrophyes). All the investigated ethanol extracts have been proved to be active against all bacteria and fungi tested.

Gibberellic acid nitrite stimulates germination of two species of light-requiring seeds via the nitric oxide pathway.

We used two species of light-requiring seeds, Paulownia tomentosa, which have absolute light requirement (no germination in darkness), and Stellaria media seeds, which germinate in darkness to a certain extent because of presence of preformed active phytochrome, to obtain results strongly suggesting that gibberellic acid nitrite stimulates seed germination via its capability as a functional NO donor. Exogenous application of gibberellic acid nitrite stimulates gibberellin-insensitive Stellaria media seed germination in darkness as do a wide variety of NO donors. Pure gibberellic acid could replace the light requirement of P. tomentosa seeds, thus enabling them to germinate in darkness. Gibberellic acid nitrite did not have this effect. A stimulative effect from gibberellic acid nitrite could be detected only after exposure of these seeds to short, 10 min, pulse of red light. Taken together, these results suggest that gibberellic activity of gibberellic acid nitrite is lost after nitrosation but, regarding to the presence of -O-NO moiety in the molecule, gibberellic acid nitrite shares stimulative properties in seed germination with other compounds with NO-releasing properties.

Xanthones and secoiridoids from hairy root cultures of Centaurium erythraea and C. pulchellum.

Shoots of Centaurium erythraea and C. pulchellum were inoculated with suspension of Agrobacterium rhizogenes cells, strain A4M70GUS. Five clones of C. erythraea hairy roots (A-E) and three clones of C. pulchellum hairy roots (F-H) were selected according to morphological differences. Spontaneous bud initiation occurred in clones C, D, G and H. Hairy roots retained the capacity for xanthone biosynthesis, with some variation being observed between individual clones. The concentration of xanthones in hairy roots was higher than that in naturally occurring plants. In transgenic plants both, secoiridoid and xanthone compounds were detected.