Influence of vitamins on polyphenolic content, morphological development, and stress response in shoot cultures of Hypericum spp

Abstract

Hypericin is a widely studied phytopharmaceutical produced by the more developed representatives of the Hypericum genus. We established that Gamborg’s (G5) vitamins significantly raised hypericins levels in H. rumeliacum and H. tetrapterum shoot cultures in comparison with the Murashige and Skoog’s (MS) vitamin supplementation. To elucidate this effect, we further examined the impact of the two vitamin formulations on the polyphenolic compounds, morphological development, hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels in the two species, as well as in hypericin non-producing H. calycinum. It was found that in all three species Gamborg vitamins decreased the polyphenolic compounds content, stimulated multiplication, decreased leaf compactness and increased dark glands density per square millimeter (for the two hypericin producing species) as compared to MS vitamins. In addition, the raised levels of hypericins in H. rumeliacum and H. tetrapterum, were also connected to increased content of H2O2 and MDA in vitro. Moreover, the values of these two parameters were considerably lower in hypericin non-producing H. calycinum, implying that oxidative stress either by increased metabolic activity, connected with higher hypericin production, or by a possible auto-toxic effect of the high amounts of pro-oxidant hypericin itself could be induced in Hypericum in vitro.