Variability of the foliar phenol profiles of the Agave victoriae-reginae complex (Agavaceae)

The foliar phenol profiles of eight populations of the Agave victoriae-reginae complex were determined by high performance liquid chromatography with diode array detection in order to assess the variability of those compounds across the natural distribution of the complex, and to determine their taxonomical significance. With comparative aims Agave lechuguilla and A. striata were analyzed in the same manner. A total of 81 phenolic compounds were detected, comprising 18 phenolic acids, 51 flavonoids (26 flavonols, 19 dihydrovonoids, and six flavones), and 12 non identified phenols. Each population of the A. victoriaereginae complex showed a different foliar phenol composition, and A. pintilla, the most recently described species of the group, could be distinguished by four compounds not shared with any other analyzed population. Phenolic acids were detected in all taxa. However, a higher proportion of those compounds was found in the A. victoriae-reginae complex, while a predominance of flavonols (quercetin-3-O-glycosides) was found in A. striata, and a codominance of dihydroflavonoids and flavonols in A. lechuguilla, allowing to distinguish species-specific profiles. Differences in the contents of some phenolic compounds among those three species and within the A. victoriae-reginae complex were also found. Our results sustain the proposal of considering A. victoriaereginae as a species complex and the separation of A. pintilla as an independent species. The results also reveal the foliar phenol patterns as valuable chemical markers in Agave.