Acidic heteroxylans from medicinal plants and their anti-ulcer activity Thales R. Cipriani a , Caroline G. Mellinger a , Lauro M. de Souza a , Cristiane H. Baggio b , Cristina S. Freitas b , Maria C.A. Marques b , Philip A.J. Gorin a , Guilherme L. Sassaki a , Marcello Iacomini a, * a Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, CP 19046, 81.531-980 Curitiba, PR, Brazil b Departamento de Farmacologia, Universidade Federal do Paraná, 81.531-980 Curitiba, PR, Brazil article info Article history: Received 19 December 2007 Received in revised form 21 February 2008 Accepted 25 February 2008 Available online 29 February 2008 Keywords: Maytenus ilicifolia Phyllanthus niruri Polysaccharide Acidic heteroxylan Anti-ulcer activity abstract Xylans are the main hemicelluloses found in higher plants, and are often present in phytotherapic med- icines. An acidic heteroxylan was obtained from Maytenus ilicifolia leaves by hot 10% aqueous KOH extrac- tion. This was subjected to freeze-thawing process, giving insoluble and soluble fractions and the latter treated with Fehling solution. Its insoluble fraction (MI-HX) was further examined. The acidic heteroxy- lan gave xylose, galactose, glucose, and 4-O-methylglucuronic acid in a 76:6:9:9 molar ratio and methyl- ation analyses and 13 C NMR spectroscopy showed its main chain consists of 4-O-linked b-D-Xylp units. This polysaccharide and another acidic heteroxylan from Phyllanthus niruri had anti-ulcer activity and were able to reduce gastric lesions induced by ethanol by 65% and 78%, with ED 50 = 40.0 and 20.4 mg/ kg, each respectively. These results suggest that this class of polysaccharide has a protective anti-ulcer effect, and that there is a relation between its chemical structure and biological function. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction The use of phytotherapeutic drugs in secondary or primary medical treatment is increasing worldwide. The efficacy of differ- ent classes of secondary metabolites, such as alkaloids, flavonoids, and polyphenols from higher plants has been widely demonstrated (Halberstein, 2005). Studies on the efficacy of primary metabolites, especially carbo- hydrates, have also been carried out, involving their chemical structure related to their biological and/or industrial importance (Bohn & BeMiller, 1995). Some researchers have attributed enhanced, synergic biological activity to crude or partially fractionated extracts, compared with their purified components. This is consistent with the interaction of different chemicals in a pill to interfere with the final result of a given treatment (Halberstein, 2005). Crude plant extracts or dried powdered plants used in phytomedical treatments are com- posed of more than the active metabolite primarily responsible for the biological response. Thus, based on the presence of xylans in some therapeutic pills, the following investigation has been carried out. Xylan-based polysaccharides are the main hemicelluloses found in higher plant cell-walls, and depending on the plant organ, may be present in up to 30% of its dry weight, significant in terms of pill production. They are present in all higher plants and have a great structural variability, although their main chain is commonly com- posed of b-(1 ? 4)-Xylp residues (Joseleau, Comtat, & Ruel, 1992). Studies have already showed biological properties of xylans, as immunological (Ebringerová, Hromadková, Alfodi, & Hribalová, 1998; Ebringerová, Hromadková, Malovíková, & Hribalová, 2002), anti-complementary (Samuelsen et al., 1999), and antitussive (Kardosová, Malovíková, Pätoprsty ´ , Nosál’ová, & Matáková, 2002). Two native Brazilian plant species were chosen for the present study, which are widely used in medicinal pills as well as in tea preparations. Maytenus ilicifolia is traditionally used and scientifi- cally proven to be efficient in treating and preventing stomach ul- cers (Cipriani et al., 2006; Souza-Formigoni et al., 1991). The chemical structure of its acidic heteroxylan is now determined. Conversely, the chemical structure of the acidic heteroxylan from Phyllanthus niruri is already known (Mellinger, Carbonero, Cipriani, Gorin, & Iacomini, 2005), although any biological activity for it has not been demonstrated. We now investigate the anti-ulcer activity of both acidic heteroxylans. 2. Experimental 2.1. Plant material Leaves of M. ilicifolia Mart. ex Reissek (Celastraceae) were col- lected in Curitiba (Southern Brazil) in July 2003, and identified by Dr. Olavo Guimarães, Department of Botany, Federal University of Paraná. A voucher specimen (No. 30842) is deposited at the Her- barium of Federal University of Paraná. 0144-8617/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbpol.2008.02.012 * Corresponding author. Tel.: +55 41 3361 1655; fax: +55 41 3266 2042. E-mail address: iacomini@ufpr.br (M. Iacomini). Carbohydrate Polymers 74 (2008) 274–278 Contents lists available at ScienceDirect Carbohydrate Polymers journal homepage: www.elsevier.com/locate/carbpol