Received for review May 21, 2003. Revised manuscript received September 29, 2003. Accepted September 30, 2003. This work has been made possible by the financial support of Consejo Nacional de Ciencia y Tecnología (CONACyT) and Casa Cuervo S.A. de C.V. in Mexico.

Abstract:

Agave plants utilize crassulacean acid metabolism (CAM) for CO₂ fixation. Fructans are the principal photosynthetic products generated by agave plants. These carbohydrates are fructose-bound polymers frequently with a single glucose moiety. Agave tequilana Weber var. azul is an economically important CAM species not only because it is the sole plant allowed for tequila production but because it is a potential source of prebiotics. Because of the large amounts of carbohydrates in A. tequilana, in this study the molecular structures of its fructans were determined by fructan derivatization for linkage analysis coupled with gas chromatography-mass spectrometry (GC-MS), nuclear magnetic resonance (NMR), and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS). Fructans were extracted from 8-year-old A. tequilana plants. The linkage types present in fructans from A. tequilana were determined by permethylation followed by reductive cleavage, acetylation, and finally GC-MS analysis. Analysis of the degree of polymerization (DP) estimated by ¹H NMR integration and ¹³C NMR and confirmed by MALDI-TOF-MS showed a wide DP ranging from 3 to 29 units. All of the analyses performed demonstrated that fructans from A. tequilana consist of a complex mixture of fructooligosaccharides containing principally (2 1) linkages, but also (2 6) and branch moieties were observed. Finally, it can be stated that fructans from A. tequilana Weber var. azul are not an inulin type as previously thought.

Keywords: Agave tequilana; fructans; linkage; permethylated alditol acetates; degree of polymerization (DP); matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS)

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