Journal of Agricultural Science; Vol. 9, No. 1; 2017 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education 204 Allelopathic Effects of Psychotria viridis Ruiz & Pavon on the Germination and Initial Growth of Lactuca sativa L. Amanda O. Andrade 1 , Maria A. P. da Silva 1 , Alison H. de Oliveira 1 , Marcos Aurelio F. dos Santos 1 , Lilian C. S. Vandesmet 1 , Maria E. M. Generino 1 , Helen K. R. C. Coelho 1 , Hemerson S. Landim 1 , Ana C. A. M. Mendonça 1 & Natália C. da Costa 1 1 Programa de Pós-graduação em Bioprospecção Molecular, Departamento de Ciências Biológicas, Universidade Regional do Cariri, Rua Cel. Antônio Luis, Crato, Ceará, Brazil Correspondence: Amanda O. Andrade, Programa de Pós-graduação em Bioprospecção Molecular, Departamento de Ciências Biológicas, Universidade Regional do Cariri, Rua Cel. Antônio Luis, 1161, 63100-000, Crato, Ceará, Brazil. E-mail: amanda_crato@hotmail.com Received: October 9, 2016 Accepted: November 10, 2016 Online Published: December 15, 2016 doi:10.5539/jas.v9n1p204 URL: http://dx.doi.org/10.5539/jas.v9n1p204 Abstract The effects of aqueous and ethanol extracts and leaf fractions of Psychotria viridis Ruiz & Pavon (chacrona) at different concentrations on the germination and initial growth of Lactuca sativa L. were tested, and the phenolic and flavonoid compounds of these extracts and fractions were assessed. The bioassays consisted of the following treatments: crude aqueous extract (CAE) at 25, 50, 75 and 100% concentration, crude ethanol extract (CEE) and ethyl acetate, dichloromethane and methanol fractions at 6.25, 12.5, 25, 50 and 100% concentration and a control group. All treatments consisted of five replicates. The CAE, CEE and the ethyl acetate fraction of P. viridis caused both positive and negative effects on the seeds and seedlings of L. sativa. By contrast, the dichloromethane and methanol fractions only caused negative effects on L. sativa. The following compounds were identified in the extracts and fractions: gallic acid, chlorogenic acid, caffeic acid, ellagic acid, catechin, orientin, vitexin, quercetin, apigenin, rutin and luteolin, and the presence of the alkaloid N,N-dimethyltryptamine (DMT) has also been reported in the literature. P. viridis had allelopathic effects in all types of plant extracts and fractions tested, and one of these compounds or their combined action may account for these effects. Keywords: allelochemicals, chacrona, extracts, fractions, High-Performance Liquid Chromatography (HPLC) 1. Introduction Psychotria viridis Ruiz & Pavon (Rubiaceae), commonly known chacruna or chacrona, occurs spontaneously in the Amazon forest (Taylor, 2014), Mexico, the Antilles, Bolivia, Argentina and southeastern Brazil, and it is also grown in several regions of the world for religious purposes (Taylor, 2007). Ayahuasca, an entheogenic beverage also known as daime, caapi, yajé, Hoasca or vegetal, commonly used in religious rituals, is produced from a mixture of P. viridis with Banisteriopsis caapi (Spruce ex Griseb.) C.V. Morton (Malpighiaceae) (Schultes & Hofmann, 1993; Pépin & Duffort, 2004). Certain plant species produce chemical substances that positively or negatively affect the germination and/or growth of other plants when released into the environment. This phenomenon is known as allelopathy, and its main function is to decrease or eliminate competition (Rice, 1984; Ferreira & Borghetti, 2004; Fujii & Hiradate, 2007). Bagchi, Jain, and Kumar (1997) considered allelochemicals as a resource for the development of natural herbicides to be used in organic farming to minimize the environmental impact caused by commercial herbicides or as plant growth stimulants given the variety of secondary metabolite activities, especially allelopathic activity. Accordingly, the present study aimed to evaluate the allelopathic effects of leaf extracts of P. viridis on the germination and growth of Lactuca sativa L. and to chemically identify the phenolic and flavonoid compounds present therein given the presence of the alkaloid N,N-dimethyltryptamine (DMT) in P. viridis leaves (Quinteiro, Teixeira, Moraes, & Silva, 2006) and the reports of alkaloids, flavonoids and phenolic compounds with allelopathic action, and because the occurrence of alkaloids has already been previously studied.