The antioxidant capacity related to the phenolic composition of monospecific honeybee-collected pollen extract from the mesquite tree (Prosopis juliflora) from Durango, Mexico, was evaluated in an in vitro-biological system (as inhibitor of lipid peroxidation on mouse hepatic microsomal preparations) and in an in vivo system (on homogenized liver of bromobenzene-intoxicated mice) by quantification of thiobarbituric acid-reactive substances (TBARS). The comparison of results obtained from these two different systems was also made. The results obtained suggest that pollen of P. juliflora is an important source of flavonoids, which can be considered as natural antioxidants. Mesquite pollen extracts showed antioxidant activity related to the flavonol concentration in both the in vitro-biological system and the in vivo system with a lower activity in the latter of these systems. Under in vivo conditions and in those in which a state of oxidation in not induced, a high concentration of flavonols in the extract of mesquite pollen can have a pro-oxidant effect. r

BackgroundFruits of wild species of the genus Physalis are consumed as food and calyces and leaves are used in traditional medicine. The phenolic composition of the species of this genus have been scarcely studied. To contribute to a better knowledge for the use of all the potential of these wild species of plants, leaves, fruits, and calyces of five wild species of the genus were analyzed for their phenolic composition and antioxidant properties.ResultsImportant tissue- and species-dependent variations were found. Calyces of Physalis subulata showed the highest contents of phenolics (176.58 mg of gallic acid equivalents/g dry tissue), flavonoids (39.63 mg/g dry tissue), and phenolic acids (50.57 mg of quercitrin equivalents/g dry tissue), and its leaves displayed the highest total antioxidant capacity (3.59 mg of ascorbic acid equivalents/mL) and one of the highest reduction powers (0.54 µg of ascorbic acid equivalents/mL). A high performance liquid chromatography with photodiode array detection analysis revealed a total of 28 phenolic compounds in foliar tissues (mainly kaempferol-3-O-glycosides), 16 in fruits (mainly phenolic acids), and 16 in calyces (mainly kaempferol-3-O-glycosides); the profiles of these compounds in the three types of tissue were species-specific.ConclusionsThe studied species of Physalis are important sources of phenolics with relevant antioxidant activity. The current results indicate that phenolic profiles are valuable specific chemical markers and can be relevant as food tracing and authenticity indicators for plant-based preparations involving species of Physalis.

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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.

In this work, a new, easy and rapid method of analyzing phenolic compounds in pollen extract, based on capillary electrophoresis coupled with electrospray ionization time-of-flight-mass spectrometry (CE-ESI-TOF-MS), has been developed. A systematic investigation of separation parameters has been performed with respect to resolution, sensitivity, analysis time and peak shape. The electrophoretic parameters and electrospray conditions must be optimized to obtain reproducible analyses. Using this method, several important phenolic compounds such as acetin-glucoside, 7-O-methylherbacetin-3-sophoroside, galloyl-glucose, quercetin-3-sophoroside, apigenin-6,8-di-C-glycoside, quercetin-3-rutinoside, genistein-7-O-beta-D: -glucoside, luteolin-7-O-glucoside, apigenin-7-O-glucoside and 2',4',6'-trihydroxy-3'-formyldihydrochalcone have been determined directly from pollen extract. The efficiency, the rapidity, the small amounts of sample required, and the high resolution of CE coupled with the sensitivity, the selectivity, the accurate masses and the true isotopic patterns obtained using TOF-MS point to the potential of this approach for identifying the phenolic compounds present in pollen.