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The extent of phenotypic variation of St. John's wort (Hypericum perforatum L.) plants transformed with wild agropine ATCC 15834 Agrobacterium rhizogenes plasmid was evaluated with respect to the number of rol genes integrations. The transfer of T(L)-DNA to plant explants during each transformation event was incomplete with different rolA, rolB, and rolC copy numbers. Along with typical features representing the hairy root syndrome, an altered size, number and density of dark and translucent glands, changes in ability to synthesize secondary metabolites, and reduced fertility were observed. The highest copy number of transferred rol genes resulted in weak expression of transgenic character and comparable quantitative parameters with the controls. Only 1 out of 11 transgenic clones was able to produce seed progeny and not more than 4 out of its 35 offsprings were positive for rolC gene integration. Sterility of the clones was due to retarded development of both gametophytes.

A study has been carried out on the chemical composition and in vivo anti-oedematogenic activity of several extracts from Hypericum grandifolium Choisy (Hypericaceae) collected in Tenerife (Canary Islands). The HPLC-MS analysis (HPLC-ESI/MS and HPLC-FT/MS) revealed the presence of hyperforin, flavonoids and probably benzophenone derivatives, while naphthodianthrones were absent. Pharmacological results revealed that the methanol extracts and the aqueous, butanol and chloroform fractions obtained therefrom possess anti-oedematogenic activity against TPA-induced ear oedema and carrageenan-induced paw oedema, the chloroform fraction being the most active. Subfractions derived from the chloroform fraction also showed anti-oedematogenic activity. From these results, it can be suggested that different constituents, such as the flavonoids and the benzophenone derivatives, could be responsible, at least in part, for the anti-oedematogenic effects observed for this species.

The phenolic constituents and antioxidant activity of ethanol and water extract of the flowers of Hypericum venustum, collected in Turkey, were investigated. The extracts possess strong reducing power, free radicals and hydrogen peroxide scavenging activity, as well as metal chelating ability.

Renewed interest in plant-derived drugs has led to an increased need for efficient extraction methods. Hypericum perforatum L. contains several groups of bioactive compounds with noteworthy pharmacological activities. Direct sonication of H. perforatum was investigated and compared with conventional maceration, indirect sonication, Soxhlet extraction, and accelerated solvent extraction (ASE). Highly selective liquid chromatography/tandem mass spectrometry analysis showed that the content of six investigated active compounds (hypericin, pseudohypericin, hyperoside, rutin, quercitrin, and hyperforin) in extracts obtained by direct sonication was significantly higher than in extracts obtained by the other methods. The active compound contents increased on increasing the ultrasonic power from 40 to 60 W when using direct sonication. Conventional maceration gave the lowest amount of analyzed active compounds. Soxhlet extraction gave better results than ASE or indirect sonication.