Sesquiterpene Lactones, Acyl Phenyl Propanoids and Other Constituents from Schkuhria pinnata var. wislizeni. Antioxidant Evaluation*
Alejandra León, Blanca M. Reyes, María Isabel Chávez, Rubén A. Toscano, and Guillermo Delgado*
Instituto de Química de la Universidad Nacional Autónoma de México. Circuito Exterior, Ciudad Universitaria. Coyoacán 04510. México, D. F. *Responsible author: delgado@unam.mx
Received August 5, 2009
Accepted September 25, 2009
Abstract
Chemical investigation of aerial parts of Schkuhria pinnata var wislizeni (Asteraceae) allowed the characterization of the sesquiterpene lactones 1, 2 and 5, the flavonoids 3 and 4, and the acyl phenyl propanoids 10 and 11. Structure 2, named dischkuhriolin, was confirmed as a Diels Alder adduct of 1 as dienophile and a guaianolide as diene. Spectroscopic analysis of 5 and its diacetyl derivative allowed the structural correction of compounds previously reported from Schkuhria. 2, 10 and 11 are new natural compounds. Biological assays indicated that the mixture 10 + 11 showed antioxidant activity expressed as inhibition of AAPH–induced damage in rat pancreatic homogenate.
Key words: Asteraceae, Schkuhria pinnata var. wislizeni, 11,13–dehydroeriolin, dischkuhriolin, 14–O–schkuhridin B, flavonoids, acyl phenyl propanes, antioxidant activity.
Resumen
La investigación química de las partes aéreas de Schkuhria pinnata var wislizeni (Asteraceae) permitió la caracterización de las lactonas sesquiterpénicas 1, 2 y 5, los favonoides 3 y 4, y los acil fenil propanoides 10 y 11. La estructura 2, nombrada como dieschkuhriolina, fue confirmada como un aducto de Diels Alder de 1 como dienófilo y una guayanólida como dieno. El análisis epectroscópico de 5 permitió la corrección estructural de compuestos reportados previamente de Schkuhria. 2, 10 y 11 son nuevos compuestos naturales. Los ensayos biológicos indicaron que la mezcla 10 + 11 mostró actividad antioxidante expresada como inhibición del daño inducido por HAAP en homogenado pancreático de rata.
Palabras clave: Asteraceae, Schkuhria pinnata var. wislizeni, 11,13–dehidroeriolina, dieschkuhriolina, 14–O–skuhridina B, flavonoides, acil fenil propanos, actividad antioxidante.
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This work was supported by Universidad Nacional Autónoma de México and Consejo Nacional de Ciencia y Tecnología (Scholarships to A.L. and B.M.R.). The assistance of Ma. Teresa Ramírez Apan, Rocío Patiño, Beatriz Quiroz, José M. Narváez–Mastache, Antonio Nieto, Héctor Ríos, Luis Velasco, Javier Pérez Flores and José Luis Villaseñor is gratefully acknowledged.
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*Dedicated to the memory of Prof. Ernest L. Eliel.
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