The antioxidant properties and the flavonoid composition of extracts of different hydrophobicity prepared from the entire edible flowers of Agave durangensis were evaluated. Separately, total extracts of tepals and anthers-pollen were analyzed in the same manner. The high performance liquid chromatography with photodiode array detection (HPLC-DAD) analysis revealed a total of eight flavonols (five quercetin glycosides and three kaempferol glycosides), varying in number and concentration in the different extracts. The total extracts of the entire flowers showed the highest flavonoid content (1210.4 µg/g dry extract) and the most complex flavonoid profile (eight compounds). All the extracts showed important antioxidant activity, which was not evidently associated with their flavonoid content. The total extracts of tepals showed the highest antioxidant properties (total antioxidant capacity, free radical scavenging activity, and iron reducing capacity: 30.2 mg ascorbic acid equivalents, EC 50 = 0.074 µg/mL, and IC 50 = 43.28 µg/mL, respectively). The flowers of A. durangensis represent an important source of antioxidant flavonols.Keywords: Agave durangensis; edible flowers; flavonoid profiles; antioxidant capacity; flavonol glycosides Se evaluaron las propiedades antioxidantes y composición fenólica de extractos de diferente hidrofobicidad de flores comestibles enteras de Agave durangensis. Separadamente, se analizaron extractos crudos de tépalos y anteras-polen. El análisis de HPLC-DAD reveló en total ocho flavonoles (cinco glicósidos de quercetina y tres glicósidos de canferol), que variaron en número y concentración en los extractos. Los extractos totales de las flores enteras tuvieron el contenido más alto de flavonoides (1210,4 µg/g extracto seco) y el perfil de flavonoides más complejo (ocho compuestos). Todos los extractos mostraron importante actividad antioxidante, no claramente asociada al contenido de flavonoides. Los extractos crudos de tépalos mostraron las propiedades antioxidantes más altas (capacidad antioxidante total, capacidad bloqueadora de radicales libres, y capacidad reductora de fierro: 30,2 mg de equivalentes de ácido ascórbico, EC 50 = 0,074 µg/mL, e IC 50 = 43,28 µg/mL, respectivamente). Las flores de A. durangensis representan una fuente importante de flavonoles antioxidantes.

The antioxidant properties and the foliar phenol composition of 25 Mexican varieties of Phaseolus vulgaris L. (common bean) were evaluated. Phaseolus coccineus was analysed with comparative aims. The high performance liquid chromatography with photodiode array detection analysis revealed 27 phenolics in the leaves of P. vulgaris (13 quercetin-3-O-glycosides, 8 kaempferol-3-O-glycosides, 2 myricetin glycosides and 4 phenolic acids) and 5 in P. coccineus (2 kaempferol-3-O-glycoside, 2 apigenin-7-O-glycoside and 1 luteolin-7-O-glycoside). All extracts showed high levels of phenols and flavonoids (0.964-5.601 mg g⁻¹ dry tissue, and 0.287-1.418 mg g⁻¹ dry tissue, respectively) and relevant antioxidant properties, suggesting that the leaves of the varieties of P. vulgaris are a significant source of natural antioxidants. The foliar phenol profiles were species-specific and, besides, the qualitative variation allowed discriminating among varieties of P. vulgaris. These profiles can represent an important varietal authenticity proof.

Abstract:The foliar phenol profi les 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 signifi cance. 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 fl avonoids (26 fl avonols, 19 dihydrovonoids, and six fl avones), and 12 non identifi ed 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 fl avonols (quercetin-3-O-glycosides) was found in A. striata, and a codominance of dihydrofl avonoids and fl avonols in A. lechuguilla, allowing to distinguish species-specifi c profi les. 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. Key words: Agave lechuguilla, Agave striata, Agave victoriae-reginae, chemical variability, phenol profi les.Resumen: Se determinaron los perfi les fenólicos foliares de ocho poblaciones del complejo Agave victoriae-reginae por medio de cromatografía líquida de alta resolución con detector de arreglo de diodos para evaluar la variabilidad de esos compuestos a través de la distribución natural del complejo, y para determinar su valor taxonómico. Con fi nes comparativos Agave lechuguilla y Agave striata se analizaron de la misma manera. Se encontró un total de 81 compuestos fenólicos, que incluyeron 18 ácidos fenólicos, 51 fl avonoides (26 fl avonoles, 19 dihidrofl avonoides y seis fl avonas), además de 12 compuestos fenólicos no identifi cados. Cada población del complejo A. victoriae-reginae presentó una composición fenólica foliar diferente, y A. pintilla, la especie más recientemente descrita del grupo, se pudo distinguir por cuatro compuestos no compartidos con ninguna otra población analizada. En todos los taxa se detectaron ácidos fenólicos; sin embargo, una predominancia de estos compuestos se encontró en el complejo A. victoriae-reginae, mientras que en A. striata se encontró predominancia de fl avonoles (derivados de quercetina), y en A. lechuguilla una codominancia de dihidrofl avonoides y fl avonoles, lo que permitió discernir perfi les especie-específi cos. Diferencias en los contenidos de algunos compuestos fenólicos entre estas tres especies ...

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Carex section Schiedeanae (subg. Euthyceras) has long been thought to comprise at most five species of Mexican sedges. Our morphological studies in the field and herbarium, however, supported by more recent DNA sequencing work, demonstrate that the section is, in fact, three times as species-rich, making it one of the largest sections in Mexico. Its 15 species range from Chihuahua to Tamaulipas south to Veracruz and Oaxaca; a single species, Carex muriculata, extends into the United States. The section has unusual inflorescences with simple (except in Carex complexa), uniformly androgynous, sessile spikes, utriculiform cladoprophylls, and perigynia with a unique combination of pubescence types composed of papillae; unicellular, simple hairs; and (in many species) multicellular tubercles. We recognize five previously described species (C. muriculata, Carex perstricta, Carex schiedeana, Carex stellata, and Carex vizarronensis) and describe 10 additional species (Carex angustilepis, Carex cabralii, Carex complexa, Carex dentata, Carex gypsophila, Carex mesophila, Carex paneroi, Carex planilamina, Carex revoluta, and Carex tehuacana). We have expanded the morphological features used in the section to include particularly anther, staminate scale, and style features, and more detailed micromorphology of the perigynia, especially indumentum. In total, 13 of the 15 species recognized herein, with a total of 32 individuals, were examined for ETS and ITS for phylogenetic reconstruction. Phylogenetically, the xeric species (plus C. paneroi) form a grade leading to a clade of the more mesophytic species adapted to forest understories, plus the unique cliff dwelling C. complexa.