OICC Press Trends in Phytochemical Research 2588-3631 5 2 2021 06 01 Preliminary phytochemical screening for antioxidant activity and content of phenols and flavonoids of 18 species of plants native to western Ecuador 93 104 EN Shirley Moncayo Laboratory of Biotechnology, Faculty of Natural Sciences, University of Guayaquil, Av. Juan Tanca Marengo, 090601, Guayaquil, Ecuador Xavier Cornejo Herbarium GUAY, Department of Botany, University of Guayaquil, Av. Juan Tanca Marengo, 090601, Guayaquil, Ecuador Jhon Castillo Laboratory of Biotechnology, Faculty of Natural Sciences, University of Guayaquil, Av. Juan Tanca Marengo, 090601, Guayaquil, Ecuador Viviana Valdez Laboratory of Biotechnology, Faculty of Natural Sciences, University of Guayaquil, Av. Juan Tanca Marengo, 090601, Guayaquil, Ecuador Journal Article 2021 06 01 The phytochemical screening, total phenolics and flavonoids content and antioxidant activity of plants native to western Ecuador were investigated to provide the basic information for further studies towards the discovery of new compounds. The species studied were Adenostemma platyphyllum Cass, Castilla elastica subsp . gummifera (Miq.) C.C. Berg., Cochlospermum vitifolium (Willd.) Spreng., Ectozoma pavonii Miers, Erythrochiton giganteus Kaastra & A.H. Gentry, Erythroxylum patens Ruiz ex O.E.Schulz, Ficus brevibracteata W.C. Burger, Ficus tonduzii Standl., Grias ecuadorica Cornejo & S.A. Mori, Handroanthus billbergii subsp . ampla (Bureau K. Schum.) S.O. Grose, Morisonia americana L., Operculina codonantha (Benth.) Hallier f., Passiflora macrophylla Spruce ex Mast., Podandrogyne jamesonii (Briq.) Cochrane, Pradosia montana T.D. Penn., Tecoma castaneifolia (D.Don) Melch, Urera baccifera (L.) Gaudich. ex Wedd., and Xanthosoma sagittifolium (L.) Schott.The highest percentage of inhibition of DPPH• was found in E. patens (92.41%). Most of the extracts evaluated exhibited antioxidant activity.