RESEARCH ARTICLE Anti-inflammatory effects of methyl ursolate obtained from a chemically derived crude extract of apple peels: potential use in rheumatoid arthritis Tatiana A. Pa ´dua • Bianca S. S. C. de Abreu • Thadeu E. M. M. Costa • Marcos J. Nakamura • Lı ´gia M. M. Valente • Maria das Grac ¸as Henriques • Antonio C. Siani • Elaine C. Rosas Received: 12 July 2013 / Accepted: 26 January 2014 Ó The Pharmaceutical Society of Korea 2014 Abstract Ursolic acid (UA), a pentacyclic triterpene acid found in apple peels (Malus domestica, Borkh, Rosaceae), has a large spectrum of pharmacological effects. However, the vegetal matrix usually produces highly viscous and poorly soluble extracts that hamper the isolation of this compound. To overcome this problem, the crude EtOH– AcOEt extract of commercial apple peels was exhaustively treated with diazomethane, after which methyl ursolate (MU) was purified by column chromatography and char- acterized spectrometrically. The anti-inflammatory effects of UA and MU (50 mg/kg) were analyzed by zymosan- induced paw edema, pleurisy and in an experimental arthritis model. After 4 h of treatment with UA and MU, paw edema was reduced by 46 and 44 %, respectively. Both UA and MU inhibited protein extravasation into the thoracic cavity; tibio-femoral edema by 40 and 48 %, respectively; and leukocyte influx into the synovial cavity after 6 h by 52 and 73 %, respectively. Additionally, both UA and MU decreased the levels of mediators related to synovial inflammation, such as KC/CXCL-1 levels by 95 and 90 %, TNF-a levels by 76 and 71 %, and IL-1b levels by 57 and 53 %, respectively. Both the compounds were equally effective when assayed in different inflammatory models, including experimental arthritis. Hence, MU may be considered to be a useful anti-inflammatory derivative to overcome the inherent poor solubility of UA for formu- lating pharmaceutical products. Keywords Ursolic acid Á Apple peels Á Zimosan-induced arthritis Introduction The triterpene ursolic (3b-hydroxy-olea-12-en-28-oic) acid (UA) has an important role as a chemical marker in some medicinal plants and phytopharmaceutical products (Takeoka et al. 2000; Baricevic et al. 2001). This com- pound presents antioxidative and hepatoprotective activi- ties, which have recently been comprehensively reviewed along with other closely related triterpene acids (Liu 2005). UA is also considered to be nutritionally important in the prevention of some chronic diseases, such as diabetes and cancer (He and Liu 2007; Lee et al. 2010). Furthermore, the immunomodulatory and anti-inflammatory actions of UA have been reported along with its ability to induce apoptosis on diverse cell lines (Ying et al. 1991; Mitaine- Offer et al. 2002; Ikeda et al. 2008; Sultana and Saify 2012). In experimental animal models, UA inhibits cell migration, vascular permeability, paw swelling, and the expression of pro-inflammatory cytokines, such as INF-c and TNF-a (Chattopadhyay et al. 2002; Ahmad et al. 2006). In addition, UA inhibits paw swelling, plasma PGE 2 levels, and radiological changes in the joints caused by complete Freund’s adjuvant-induced arthritis in rats (Kang et al. 2008). UA is widely distributed in the plant kingdom and is found in the apple (Malus domestica Borkh., Rosaceae) T. A. Pa ´dua Á B. S. S. C. de Abreu Á T. E. M. M. Costa Á M. J. Nakamura Á M. G. Henriques Á A. C. Siani (&) Á E. C. Rosas Department of Natural Products, Medicines and Drugs Technology Institute (Farmanguinhos), Oswaldo Cruz Foundation, Rua Sizenando Nabuco 100, Manguinhos, Rio de Janeiro, RJ 21041-250, Brazil e-mail: siani@far.fiocruz.br L. M. M. Valente Chemistry Institute, Federal University of Rio de Janeiro, Ilha do Funda ˜o, Rio de Janeiro, RJ, Brazil 123 Arch. Pharm. Res. DOI 10.1007/s12272-014-0345-1