Journal of Ethnopharmacology 132 (2010) 461–465 Contents lists available at ScienceDirect Journal of Ethnopharmacology journal homepage: www.elsevier.com/locate/jethpharm Xanthine oxidase inhibitory properties of Czech medicinal plants Jaroslav Havlik a,∗ , Raquel Gonzalez de la Huebra a , Katerina Hejtmankova b , Javier Fernandez a , Jitka Simonova a , Martin Melich a,c , Vojtech Rada a a Department of Microbiology, Nutrition and Dietetics, Czech University of Life Sciences Prague, CZ-165 21 Prague 6, Czech Republic b Department of Chemistry, Czech University of Life Sciences Prague, CZ-165 21 Prague 6, Czech Republic c Department of Microbiology, Faculty of Biotechnology and Food Sciences, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, SK-949 76 Nitra, Slovakia article info Article history: Received 2 February 2010 Received in revised form 5 August 2010 Accepted 19 August 2010 Available online 26 August 2010 Keywords: Xanthine oxidase Gout Enzyme inhibition Populus nigra Betula pendula abstract Aim of the study: To investigate in vitro xanthine oxidase inhibitory properties of plants traditionally used in Czech Republic and Central-East Europe region for gout, arthritis or rheumatism treatment. Materials and methods: Methylene chloride–methanolic and two ethanolic extracts of 27 plant species were screened for in vitro xanthine oxidase inhibitory activity using a spectrophotometric method. Results: Around 50% of the species exhibited some degree of xanthine oxidase inhibitory properties at 200 g/mL, showing a moderate correlation (r = 0.59) with total phenol content. The most active were methylene chloride–methanolic extracts of Populus nigra and Betula pendula, with IC 50 of 8.3 and 25.9 g/mL, respectively, followed by 80% ethanolic extract of Caryophyllus aromaticus and Hypericum perforatum, both under 50 g/mL. Conclusions: Populus nigra and Betula pendula were identified as species with the highest xanthine oxidase inhibitory potential in our study. This correlates with the ethnobotanical data on their use in Central European folklore and provides the basis for further investigation on these plants. © 2010 Elsevier Ireland Ltd. All rights reserved. 1. Introduction In vitro screening studies for pharmacological activity may lead to identification of new medicines, foods or dietary recommen- dations for the treatment or prevention of various ailments. In Eastern Europe, traditional medicine is amalgamated with modern medicine, and the number of prescriptions containing medicinal plants was more than 60% at the end of 20th century (Husain, 1991). In Czech Republic and Central-East Europe, strong herbal and folk traditions persisted throughout history, and liberalisation of health care systems has led to a surge of interest in complemen- tary therapies (Fisher and Ward, 1994). Decoctions, ointments and herbal steam bath from medicinal plants are often a first choice for many illnesses, and local knowledge of specific medicinal herbs is high. In Europe, several medicinal plants are traditionally used to treat gout and rheumatic diseases. Gout is one of the most com- mon metabolic disorders affecting humans. It occurs in 1–2% of the population, and its recurrence and severity is reportedly increas- ing over the last decades (Lee et al., 2006). The disease is caused by marked hyperuricemia, leading to the deposition of monosodium urate crystals in joints or kidneys, resulting in gouty arthritis or ∗ Corresponding author. Tel.: +420 224382679; fax: +420 224382760. E-mail address: havlik@af.czu.cz (J. Havlik). uric acid nephrolithiasis (Kramer and Curhan, 2002). In humans, serum urate is the end product of purine metabolism mediated by xanthine oxidase, an enzyme catalyzing the hydroxylation of hypoxanthine to xanthine and of xanthine to urate. Thus, this enzyme is a possible target for urate-lowering drugs such as allo- purinol, a drug used predominately in hypouricemic therapy for more than 45 years. Although generally recognized as safe, there are several contraindications in approximately 2% of people, which is a striking fact, leading researchers to search for novel XO inhibitors, among natural products. Another potential benefit of XO inhibitors is a possible antioxidant action, as the XO generates hydrogen per- oxide and might be therefore an initiator of tissue damage in a range of pathological states (Lespade and Bercion, 2010). Until now, phenolics and in particular flavonoids were found as a large chemical class with XO inhibitory properties, and their role has been thoroughly evaluated (Nagao et al., 1999; Van Hoorn et al., 2002; Lespade and Bercion, 2010). Moreover, several systemic in vitro screening studies on XO inhibitory properties of foods (Dew et al., 2005) or medicinal plants used in traditional medicines around the globe were published (Owen and Johns, 1999; Kong et al., 2000; Sweeney et al., 2001; Nguyen et al., 2004; Umamaheswari et al., 2007). Although in Europe a strong ethnopharmacological knowledge of plants used against rheumatic disorders exists and is recorded in old herbals, this knowledge has not been researched to the same extent such as that of TCM or Ayurveda, and only few of 0378-8741/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.jep.2010.08.044