Kruiden en ecologie

Invloed van omgeving op de kwaliteit van planten (inhoudsstoffen)

Molecules. 2009 Feb 11;14(2):682-725. doi: 10.3390/molecules14020682. Factors affecting polyphenol biosynthesis in wild and field grown St. John's Wort (Hypericum perforatum L. Hypericaceae/Guttiferae)Bruni R1, Sacchetti G.
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.

Planta Med. 2008 Mar;74(4):453-7. doi: 10.1055/s-2008-1034326. Altitudinal variation of secondary metabolite profiles in flowering heads of Matricaria chamomilla cv. BONA.
Ganzera M1, Guggenberger M, Stuppner H, Zidorn C.
The altitudinal variation of the contents of secondary metabolites in flowering heads of Matricaria chamomilla L. (Asteraceae) was assessed. Plants of M. chamomilla cultivar BONA were grown in nine experimental plots at altitudes between 590 and 2,230 m at Mount Patscherkofel near Innsbruck/Austria. The amounts of flavonoids and phenolic acids were quantified by HPLC/DAD. For both flavonoids and phenolic acids positive (r = 0.559 and 0.587) and statistically significant (both p < 0.001) correlations with the altitude of the growing site were observed. The results are compared to previous results on Arnica montana L. cv. ARBO. Moreover, various ecological factors, which change with the altitude of the growing site, are discussed as potential causes for the observed variation.

Oecologia. 2009 May;160(1):1-8. doi: 10.1007/s00442-009-1277-1. Epub 2009 Feb 5.Temperature is the key to altitudinal variation of phenolics in Arnica montana L. cv. ARBO.
Albert A1, Sareedenchai V, Heller W, Seidlitz HK, Zidorn C.
Plants in alpine habitats are exposed to many environmental stresses, in particular temperature and radiation extremes. Recent field experiments on Arnica montana L. cv. ARBO indicated pronounced altitudinal variation in plant phenolics. Ortho-diphenolics increased with altitude compared to other phenolic compounds, resulting in an increase in antioxidative capacity of the tissues involved. Factors causing these variations were investigated by climate chamber (CC) experiments focusing on temperature and ultraviolet (UV)-B radiation. Plants of A. montana L. cv. ARBO were grown in CCs under realistic climatic and radiation regimes. Key factors temperature and UV-B radiation were altered between different groups of plants. Subsequently, flowering heads were analyzed by HPLC for their contents of flavonoids and caffeic acid derivatives. Surprisingly, increased UV-B radiation did not trigger any change in phenolic metabolites in Arnica. In contrast, a pronounced increase in the ratio of B-ring ortho-diphenolic (quercetin) compared to B-ring monophenolic (kaempferol) flavonols resulted from a decrease in temperature by 5 degrees C in the applied climate regime. In conclusion, enhanced UV-B radiation is probably not the key factor triggering shifts in the phenolic composition in Arnica grown at higher altitudes but rather temperature, which decreases with altitude.