José Antonio Ávila-Reyes

Flavonoid composition and antioxidant capacity of the edible flowers of Agave durangensis (Agavaceae)

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, EC50 = 0.074 µg/mL, and IC50 = 43.28 µg/mL, respectively). The flowers of A. durangensis represent an important source of antioxidant flavonols.

Foliar flavonoids distinguish Pinus leiophylla and Pinus chihuanuana (Coniferales: Pinaceae)

ABSTRACT The foliar flavonoid content of 142 individual pine trees (Pinus leiophylla, P. chihuahuana and P. lumholtzii) was analyzed by paper chromatography and ultraviolet spectroscopy with the aim of determining the ability of foliar profiles of flavonoids to distinguish closely related pine species and to determine if Pinus chihuahuana should be recognized as a distinct species or as a variety of P. leiophylla. The flavonoid composition of needles was evaluated within and among the taxa using Principal Coordinates Analysis (PCO). The results support the recognition of P. chihuahuana at the species level. Contrary to other reports, the results from this study suggest that needles of the three studied species contain a much greater number and diversity of flavonoids than previously reported for species of Pinus.

Foliar phenolic compounds of ten wild species of Verbenacea as antioxidants and specific chemomarkers

The family Verbenaceae hosts important species used in traditional medicine of many countries. The taxonomic controversies concerning the specific delimitation of several of its species make it difficult to guarantee the botanical origin of herbal preparations based on species of this family. To contribute to the development of both specific chemomarkers and a quality control tool to authenticate the botanical origin of herbal preparations of Verbenacea species, we determined the foliar HPLC-DAD phenolic profiles and the antioxidant properties of 10 wild species of this family occurring in Mexico. The contents of phenols and flavonoids varied significantly among species. Priva mexicana showed the highest levels of total phenolics (53.4 mg g-1 dry tissue) and Verbena carolina had the highest levels of flavonoids (17.89 mg g-1 dry tissue). Relevant antioxidant properties revealed by antiradical and reducing power were found for the analyzed species. These properties varied significantly in a species-dependent manner. The phenolic compounds accumulated were flavones and phenolic acids. Flavones were the only type of flavonoids found. The results of a cluster analysis showed that the compounds were accumulated in species-specific profiles. The phenolic profiles are proposed as valuable chemomarkers that can become a useful tool for the quality control concerning the botanical origin of herbal medicinal preparations based on the species analyzed. In addition, phenolic profiles could contribute importantly to solve the taxonomic controversies concerning species delimitation in the family Verbenaceae.

Phytochemical characterization and antioxidant properties of the wild edible acerola Malpighia umbellata Rose

ABSTRACT The objective of the current study was to determine the phenolic composition and carotenoid contents of leaves, bark, and fruits of Malpighia umbellata, assess the changes in the phenolic composition and contents of carotenoids and vitamin C of its fruits in different stages of maturity, and evaluate the antioxidant properties of its leaves, bark, and fruits. Leaves accumulated the highest levels of flavonoids (10.55 mg/g dry extract), tannins (21.16 mg/g dry extract), and carotenoids (424 63 µg/g dry tissue); whereas, the highest level of total phenolics was found in bark (47.12 mg/g dry extract). The vitamin C content decreased with the maturity of fruits. Twenty-two phenolics were characterized by high performance liquid chromatography with diode array detection (HPLC-DAD). Apigenin-7-O-glycosides, phenolic acids, and flavonols were predominant in leaves, bark, and fruits, respectively. Important chemical variations were found during fruit ripening. The 2,2-diphenyl-1-picrylhydrazyl (DPPH•) scavenging activity and 2,2ʹ-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) inhibition assays revealed important antioxidant properties for this acerola.

Genetic Variability in Natural Populations of Agave durangensis (Agavaceae) Revealed by Morphological and Molecular Traits

Abstract Agave durangensis is an endemic species that occurs in a reduced area in southern Durango and northern Zacatecas, Mexico. We analyzed the genetic variability of three populations of the species using two pairs of Inverse-Sequence-Tagged-Repeat primers and nine morphological characters to determine the species of the morphologically variable populations. The primers generated characteristic amplification profiles, which distinguished between populations of A. durangensis and revealed interspecific variability when compared with individuals of A. asperrima. Some incongruence between morphological and molecular variability was detected. High genetic variability was indicated by an elevated level of polymorphism (24.18–61.50%) among 91 genetic loci amplified and by the level of gene diversity (0.0807–0.2337) among populations. Genetic differentiation (0.0328–0.4857), gene flow (0.5294–14.7511), genetic distance (0.0200–0.3019), and genetic identity (0.7653–0.9802) among populations suggested that one of the three populations of A. durangensis is in a present advanced diversification process but may still maintain some level of gene flow with the other two populations. Urgent conservation efforts, including protection from harvest, should be addressed for maintaining the genetic variability of the natural populations of A. durangensis. Resumen Agave durangensis es una especie endémica que crece en un área reducida del sur de Durango y norte de Zacatecas, México. Analizamos la variabilidad genética de tres poblaciones de esa especie usando dos pares de iniciadores de los marcadores de Repetición de Secuencias Inversas Marcadas (ISTR por sus siglas en inglés) y nueve atributos morfológicos para determinar las especies de las poblaciones morfológicamente muy variables. Los iniciadores generaron perfiles de amplificación característicos, mostrando su capacidad para distinguir entre poblaciones de A. durangensis y para revelar variabilidad intereespecífica cuando los perfiles se compararon con los de A. asperrima. Incongruencia entre la variabilidad morfológica y la molecular fue detectada. Alta variabilidad genética fue encontrada, indicada por los elevados niveles de polimorfismo (24.18–61.50 %) entre 91 loci genéticos amplificados y por los valores de diversidad génica (0.0807–0.2337) entre poblaciones. Diferenciación genética interpoblacional (0.0328–0.4857), flujo genético (0.5294–14.7511), distancia genética (0.0200–0.3019) y la identidad genética (0.7653–0.9802) sugieren que una de las tres poblaciones de A. durangensis se encuentra en un proceso actual avanzado de diversificación, pero que aún existe flujo genético con las otras dos poblaciones. Esfuerzos urgentes de conservación incluyendo la protección de recolección se deberían de contemplar para mantener la variabilidad genética de las poblaciones naturales de A. durangensis.