Productos naturales y derivados semisintéticos de Ageratina jah-nii y Ageratina pichinchensisNatural products and semisynthetic derivatives obtained from Ageratina jahnii and Ageratina pichinchenis (Asteraceae) species

Abstract

El estudio de la composición química de los extractos alcohólicos secos de las partes aéreas de las especies Ageratina jahnii (B. L. Rob) R. M. King & H. Rob. y Ageratina pichinchensis (Kunth) R. M. King & H. Rob., mediante el uso de la cro-matografía en columna, en capa fina y en capa preparativa, así como, de las técnicas espectroscópicas de infrarrojo, ultravioleta, resonancia magnética nuclear (uni y bidimensional) y espectrometría de masas, permitió el aislamiento e identificación de seis productos naturales. De A jahnii se aislaron cinco compuestos: dos diterpenos denominados ácido ent-kaur-16-en-19-oico y ent-kaur-16-en-3a-ol; tres flavonoides identificados como 5-hidroxi-7,4'-dimetoxiflavona, 5,7-dihidroxi-4'-metoxiflavona y 5,4'-dihidroxi-7-metoxiflavona. Además, de A. pichinchensis se aisló el 6-acetil-7-hidroxi-2,2-dimetil-8-metoxi-2H-1-cromeno. Adicionalmente, a partir del ent-kaur-16-en-19-oico; 5-hidroxi-7,4'-dimetoxiflavona y 6-acetil-7-hidroxi-2,2-dimetil-8-metoxi-2H-1-cromeno, se prepararon cuatro derivados químicos: ent-kaur-16-en-19-oato de metilo; 5-acetoxi-7,4´-dimetoxiflavona; 6-acetil-7-acetoxi-2,2-dimetil-8-metoxi-2H-1-cromeno y 6-acetil-7-hidroxi-2,2-dimetil-8-metoxi-3-yodo-2H-1-cromeno; éste último reportado por primera vez según la base de datos Science Finder.The phytochemical study of dried alcoholic extracts from aerial parts of Ageratina jahnii (B. L. Rob) R. M. King & H. Rob. and Ageratina pichinchensis (Kunth) R. M. King & H. Rob., based on column chromatography, thin layer chromatography and preparative separations, as well as by characterization using infrared, ultraviolet, nuclear magnetic resonance (one and two dimensional) and mass spectrometry leaded the isolation and identification of six natural products. From A. jahnii, five compounds were isolated: two diterpenes known as ent-kaur-16-en-19-oic acid and ent-kaur-16-en-3a-ol; three flavonoids identified as 5-hydroxy-7,4'-dimethoxyflavone, 5,7-dihydroxy-4'-methoxyflavone and 5,4'-dihydroxy-7-methoxyflavone. Furthermore, from A. pichinchensis, 6-acetyl-7-hydroxy-2,2-dimethyl-8-methoxy-2H-1-chromene was cha-racterized. In addition, from the following natural compounds ent-kaur-16-en-19-oic acid, 5-hydroxy-7,4'-dimethoxyflavone and 6-acetyl-7-hydroxy-2,2-dimethyl-8-methoxy-2H-1-chromene; four chemical derivatives were ob-tained: methyl ent-kaur-16-en-19-oate, 5-acetoxy-7,4´-dimethoxyflavone, 7-acetoxy-6-acetyl-2,2-dimethyl-8-methoxy-2H-1-chromene and 6-acetyl-7-hydroxy-3-iodine-2,2-dimethyl-8-methoxy-2H-1-chromene. According to Science Finder data base, the last compound was prepared for first time in this investigation