Factors Affecting Polyphenol Biosynthesis in Wild and Field Grown St. John’s Wort (Hypericum perforatum L. Hypericaceae/Guttiferae)

Abstract

The increasing diffusion of herbal products is posing new questions: why are products so often different in their composition and efficacy? Which approach is more suitable to increase the biochemical productivity of medicinal plants with large-scale, low-cost solutions? Can the phytochemical profile of a medicinal plant be modulated in order to increase the accumulation of its most valuable constituents? Will polyphenol-rich medicinal crops ever be traded as commodities? Providing a proactive answer to such questions is an extremely hard task, due to the large number of variables involved: intraspecific chemodiversity, plant breeding, ontogenetic stage, post-harvest handling, biotic and abiotic factors, to name but a few. An ideal path in this direction should include the definition of optimum pre-harvesting and post-harvesting conditions and the availability of specific Good Agricultural Practices centered on secondary metabolism enhancement. The first steps to be taken are undoubtedly the evaluation and the organization of scattered data regarding the diverse factors involved in the optimization of medicinal plant cultivation, in order to provide an interdisciplinary overview of main possibilities, weaknesses and drawbacks. This review is intended to be a synopsis of the knowledge on this regard focused on Hypericum perforatum L. (Hypericaceae/Guttiferae) secondary metabolites of phenolic origin, with the aim to provide a reference and suggest an evolution towards the maximization of St. John's Wort bioactive constituents. Factors considered emerged not only from in-field agronomic results, but also from physiological, genetical, biotic, abiotic and phytochemical data that could be scaled up to the application level. To increase quality for final beneficiaries, growers’ profits and ultimately transform phenolic-rich medicinal crops into commodities, the emerging trend suggests an integrated and synergic approach. Agronomy and genetics will need to develop their breeding strategies taking account of the suggestions of phytochemistry, biochemistry, pharmacognosy and pharmacology, without losing sight of the economic balance of the production.

Arbuscular mycorrhizal fungi altered the hypericin, pseudohypericin, and hyperforin content in flowers of Hypericum perforatum grown under contrasting P availability in a highly organic substrate

“…Please note that P fertilization × AMF interaction for root biomass was not significant (Table 1) increased hyperforin content. Such a difference can depend on the different features of the growth substrate used in both experiments, as also suggested by Bruni and Sacchetti (2009). Hyperforin biosynthesis in H. perforatum starts from amino acid precursors and proceeds with prenylation (Karppinen et al 2007).…”

Effects of plant growth regulators and elicitors on production of secondary metabolites in shoot cultures of Hypericum hirsutum and Hypericum maculatum

“…It has generally been accepted that these biologically active substances are synthesized, or accumulate in, different types of secretory structures including the dark glands, translucent glands, and secretory canals located in different organs of the plants (leaf, stem and flower tissues) (Soelberg et al 2007;Zobayed et al 2006;Kirakosyan et al 2008). A recent review by Bruni and Sacchetti (2009) shed light on the morphological and chemical variations among different Hypericum species and varieties. Only a small part of the genus has been studied, and the chemical content of approximately threequarters of Hypericum species has not been surveyed (Karioti and Bilia 2010).…”

RFLP analysis of cpDNA in the genus Hypericum

“…This important medicinal plant contains pharmacologically active compounds, such as naphthodianthrones, hypericin and pseudohypericin, phloroglucinols, hyperforin and adhyperforin, as well as characteristic xanthones, flavonoids, biflavonoids, tannins and phenolic acids (Barnes et al 2001;Greeson et al 2001). As important compounds occur in a few sections of the genus (Bruni & Sacchetti 2009), a considerable number of its species are likely to have useful pharmaceutical properties, which emphasizes the importance of this genus.…”