Lipid Oxidation Inhibitory Effects and Phenolic Composition of Aqueous Extracts from Medicinal Plants of Colombian Amazonia

Diverse plants of ethnobotanic interest in Amazonia are commonly used in traditional medicine. We determined the antioxidant potential against lipid peroxidation, the antimicrobial activity, and the polyphenol composition of several Amazonian plants (Brownea rosademonte, Piper glandulosissimum, Piper krukoffii, Piper putumayoense, Solanum grandiflorum, and Vismia baccifera). Extracts from the plant leaf, bark, and stem were prepared as aqueous infusions, as used in folk medicine, and added to rat liver microsomes exposed to iron. The polyphenolic composition was detected by reverse-phase HPLC coupled to diode-array detector and MS/MS analysis. The antimicrobial activity was tested by the spot-on-a-lawn method against several indicator microorganisms. All the extracts inhibited lipid oxidation, except the P. glandulosissimum stem. The plant extracts exhibiting high antioxidant potential (V. baccifera and B. rosademonte) contained high levels of flavanols (particularly, catechin and epicatechin). By contrast, S. grandiflorum leaf, which exhibited very low antioxidant activity, was rich in hydroxycinnamic acids. None of the extracts showed antimicrobial activity. This study demonstrates for the first time the presence of bioactive polyphenolic compounds in several Amazonian plants, and highlights the importance of flavanols as major phenolic contributors to antioxidant activity.We would like to thank MsC. Marco A. Correa-Munera, University of Amazonia (Florencia, Colombia) and Ricardo Callejas-Posada, from the Biology Institute of the University of Antioquia (Colombia) for the identification and classification of the plants. This work was supported by research grants from the Basque Country Government (Department Education, Universities and Research, reference IT514-10 and reference IT413-10, and DCIT, reference SA-2010/00125), University of the Basque Country UPV/EHU (CLUMBER UFI11/20) and Research Institute of Free Radicals and Metabolism (ERRASMIK/IRALMET, grant to L.J.L.). Maria Viloria-Bernal thanks University of the Basque Country UPV/EHU. Technical and human support provided by SGIKer (UPV/EHU, MICINN, GV/EJ, ESF) is gratefully acknowledged