title: Influence of cryopreservation on the antioxidative activity ofin vitrocultivatedHypericumspecies.
abstract: Antioxidative activity of twoin vitrocultivatedHypericumspecies -H. rumeliacumBoiss. andH. tetrapterumFr. - was estimated after cryopreservation. Both species were successfully regenerated after a cryopreservation procedure performed by the vitrification method.H. tetrapterumdid not manifest any significant oxidative stress-induced changes caused by low-temperature treatment. Conversely, a decrease in green pigments' content ofH. rumeliacumwas measured, particularly pronounced in chlorophyllb, which was accompanied by an increase of carotenoids in the regenerated plants. A strong increase of malone dialdehyde and H2O2levels inH. rumeliacumtissues was detected. Superoxide dismutase activity was enhanced by 170%, as well as the catalase activity, which was 220% above the control. The same trend was observed inH. tetrapterum, although less pronounced - 143% increase of superoxide dismutase and 112% of catalase. Cryopreservation did not influence the phenol content in the examined plants, but it led to an increase of flavonoid content, especially inH. tetrapterum, by 237%. Total antioxidant activity in regeneratedH. tetrapterumvaried around the control level, but it was increased inH. rumeliacum. The free proline content inH. tetrapterumremained almost unaffected after freezing, as opposed toH. rumeliacum, where a strong increase of proline content (208% above the control) occurred. An electrolyte leakage from the cells ofH. rumeliacumregenerated after cryopreservation was also registered, albeit not significant.
authors.affiliation: Faculty of Biology, Sofia University 'St. Kliment Ohridski' , Sofia , Bulgaria.
authors.forename: Elena
authors.initials: E
authors.lastname: Georgieva
authors.affiliation: Faculty of Biology, Sofia University 'St. Kliment Ohridski' , Sofia , Bulgaria.
authors.forename: Detelina
authors.initials: D
authors.lastname: Petrova
authors.affiliation: Faculty of Biology, Sofia University 'St. Kliment Ohridski' , Sofia , Bulgaria.
authors.forename: Zhenya
authors.initials: Z
authors.lastname: Yordanova
authors.affiliation: Faculty of Biology, Sofia University 'St. Kliment Ohridski' , Sofia , Bulgaria.
authors.forename: Veneta
authors.initials: V
authors.lastname: Kapchina-Toteva
authors.affiliation: Faculty of Science, Institute of Biology and Ecology, Pavol Jozef Šafárik University of Košice , Košice , Slovak Republic.
authors.forename: Eva
authors.initials: E
authors.lastname: Cellarova
authors.affiliation: Faculty of Biology, Sofia University 'St. Kliment Ohridski' , Sofia , Bulgaria.
authors.forename: Ganka
authors.initials: G
authors.lastname: Chaneva
keywords: Hypericum rumeliacum; Hypericum tetrapterum; cryopreservation; flavonoids; phenols