Volatile organic compounds from pachyrhizus ferrugineus and pachyrhizus erosus (Fabaceae) leaves

In Mexico, Pachyrhizus erosus (Fabaceae) commonly called "jicama", is widely known for its edible tubers. It is cultivated since the pre-Columbian period, and the powdered seeds have been used for the treatment of mange, lice, and fleas, due to their content of rotenone, a well-known insecticidal compound. On the other hand, P. ferrugineus, a wild species can only be found in the Tropical Forests, and has no commercial value. It is known that plants release volatile organic compounds (VOCs) showing qualitative and quantitative differences if are wild or cultivated. VOCs are also involved as repelling or attracting chemical signals to insect herbivores, and their natural enemies. Until now, the VOCs of the leaves of P. erosus and P. ferrugineus have not been investigated. In the present contribution the VOCs of both species were characterized by headspace solid-phase (HS-SPME) extraction and gas chromatography-mass spectrometry (GC-MS-TOF). In P. erosus 21 VOCs were found, being the most abundant: cyclohexanone (32.8 percent), 3-hexen-1-ol (Z) (32.7 percent), 3-hexenal (Z) (10.5 percent). The majoritarian compounds were C6 or C5 derivatives In P. ferrugineus, the most abundant VOCs were: 5-hexene-1-ol acetate (51.5 percent), undecanal (22.4 percent), 2-hepten-1-al (14.5 percent). The majoritarian compounds were C6, C7 or C11 derivatives. En Mexico, Pachyrhizus erosus (Fabaceae) es llamada comunmente "jicama" y es conocida por sus tuberculos comestibles. Se ha cultivado desde el periodo pre-Colombino y las semillas se han utilizado para el tratamiento topico de la sarna, piojos, pulgas; las semillas contienen rotenona, un compuesto insecticida. Por otra parte, P. ferrugineus solo esta presente en estado silvestre en los bosques tropicales y carece de valor comercial. Se sabe que las plantas liberan compuestos organicos volatiles (COV) y muestran diferencias cualitativas y cuantitativas dependiendo, si son silvestres o cultivadas. Los COV tambien son senales quimicas atrayentes o repelentes de los insectos herbivoros y a sus enemigos naturales. Hasta ahora, los COV en las hojas de P. erosus y P. ferrugineus no han sido investigados. En el presente trabajo, los COV se identificaron mediante la microextraccion (HS-SPME) en fase solida, e identificados por cromatografia de gases acoplada a espectrometria de masas (GC-MS-TOF). En P. erosus se encontraron 21 COV, siendo los mas abundantes: ciclohexanona (32.8 por ciento), 3-hexen-1-ol (Z) (32.7 por ciento) y 3-hexenal (Z) (10.5 por ciento). Los compuestos mayoritarios son C6 y C5. En P. ferrugineus los mas abundantes fueron: 5-hexen-1-ol acetato (51.5 por ciento), undecanal (22.4 por ciento) y 2-hepten-1-al (14.5 por ciento). Los compuestos mayoritarios son C6, C7 o C11.