Anti-inflammatory effects of different preparations of cat's claw

South America has two predominant species of Cat's Claw (Uña de Gato), Uncaria tomentosa and U. guianensis, which are both used in traditional medicine to treat inflammation. In this study, two commercial preparations of U. tomentosa and a hydroethanolic preparation of U. guianensis were evaluated and compared in various assays, including their effect on the production of the inflammatory mediators, tumour necrosis factor (TNF-α), Interleukin-6 (IL-6) and nitric oxide (NO) by LPS-activated RAW 264.3 macrophages, serum levels of the same mediators in mice 1h after challenge with LPS (lipopolysaccharide) and cellular levels of NF-KB, an important nuclear factor involved in the inflammatory response. All the extracts, as well as several of the fractions obtained by reverse phase HPLC, showed an inhibitory effect on NO production, particularly a U. guianensis subfraction (UgAIV) in vitro (85% at 30µg/ml) and one commercial U. tomentosa fraction B in vivo (73% at 5mg/Kg). The UgAIV subfraction also showed the greatest inhibitory effect on the TNF-α and IL-6 responses both in vitro and in vivo, as well as inhibiting NF-κB activation. Further subfractionation and biological evaluation of UgAIV are currently being carried out to determine the compound(s) responsible for these activities.