Induction of hypericins in Hypericum perforatum in response to chromium Bruno Tirillini a, ⁎ , Antonio Ricci a , Giorgio Pintore b , Mario Chessa b , Simona Sighinolfi c a Institute of Botany, University of Urbino, Via Bramante, 28, 61029 Urbino, Italy b Dipartimento Farmaco Chimico Tossicologico, University of Sassari, Via Muroni 23/A, 07100 Sassari, Italy c Department of Chemistry, University of Modena and Reggio Emilia, via G. Campi 183, 41100 Modena, Italy Received 7 March 2005; accepted 10 January 2006 Available online 6 March 2006 Abstract Seedlings of Hypericum perforatum were grown with 0.01 and 0.1 mM of chromium added to the nutrient media. A treatment with 0.01 mM Cr(VI) for seven days resulted in an increased production of protopseudohypericin (+ 135%), hypericin (+ 38%) and pseudohypericin (+5%). Treatment with 0.1 mM Cr(VI) for two days also caused an increase of protopseudohypericin (+167%), hypericin (25%) and pseudohypericin (+ 5%). The greatest effect of chromium treatment was observed at a concentration of 0.1 mM for seven days: protopseudohypericin increased + 404% and pseudohypericin to + 379%. Hypericin was not affected by this treatment. © 2006 Elsevier B.V. All rights reserved. Keywords: Hypericum perforatum; St. John's wort; Chromium; Hypericin; Pseudohypericin; Protopseudohypericin 1. Introduction Hypericum perforatum L. (St. John's wort) is a perennial flowering plant of the Hypericaceae. This plant is used in traditional folk medicine to treat various ailments [1]. Currently, St John's wort is widely used as an herbal remedy to treat mild to moderate depression [2]. Extracts of H. perforatum are known to contain compounds from six major natural product groups: naphthodianthrones, acylphloroglucinols, flavonol glycosides, biflavones, proanthocyanidins and phenylpropanes [3]. Hypericins, which include five known compounds, hypericin, pseudohypericin, protohypericin, protopseudohy- pericin, and cyclopseudohypericin, are considered to be the principal agents in the range of biological activities reported for H. perforatum [4–9]. Chromium is a major heavy metal pollutant in waterways; it is released mainly from leather tanning, textile, carpet and electroplating industries. Chromium usually occurs in two forms: Cr(III) and Cr(VI), and both forms are taken up by plants [10]. Chromium interferes with several metabolic processes and is toxic to the plants causing reduced root growth and phytomass, chlorosis, photosynthetic impairment, stunting and finally death [11– 17]. It is still ambiguous whether chromium has any role in plant metabolism. Chromium has both inhibitory Fitoterapia 77 (2006) 164 – 170 www.elsevier.com/locate/fitote ⁎ Corresponding author. Tel.: +39 722 303771; fax: +39 722 303777. E-mail address: tirillini@uniurb.it (B. Tirillini). 0367-326X/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.fitote.2006.01.011