No abstract

Atta mexicana is a polyphagous insect that can exploit a wide range of plant species to cultivate its main food source, the symbiotic fungus Leucoagaricus gongylophorus. In the present study, we evaluated the foraging rate of Atta mexicana workers among leaves of three favored and three rejected plant species under laboratory conditions. In addition, we conducted a phytochemical characterization of leaves of these six plant species. Ants preferred leaf-discs of Rosa x alba, Trema micrantha and Styrax glabrescens, but rejected those of Coffea arabica, Citrus reticulata and Psidium guajava.In a second behavioral experiment using plant extracts, the results suggest that in the case of C. reticulata, rejection was not due chemical composition, but may have been due to different foliar attributes that could modulate the ant's foraging preferences in this species.Alkaloids, phenols, flavonoids, and tannins were present at different concentrations in all six plant species. Furthermore, C. arabica leaves presented significantly higher concentrations of alkaloids and this species, together with P. guajava, exhibited the highest concentration of phenols. Rejected plant species showed high concentrations of chlorogenic acid, (-)-epicatechin, quercetin-3, 4-di-O-glucoside (in C. arabica); shikimic acid, ellagic acid and (-)-epicatechin (in P. guajava), and scopoletin (in C. reticulata). Some of the 2 identified compounds have been shown to possess antifungal effects and/or to dissuade leaf-cutter ants from defoliation. We discuss the likely implications on foraging on such plant species by A. mexicana, and on the growth of its symbiotic fungus.

Spinosad is a naturally derived insecticide that has shown potential as a mosquito larvicide. To determine the activity of spinosad against blackflies, late-instar larvae from a community comprising Simulium triittatum (63.6%) and seven other species, including three known vectors of onchocerciasis in Mexico (S. metallicum, S. ochraceum, and S. callidum), were subjected to concentration-mortality laboratory bioassays following World Health Organization guidelines. Cephalic capsule measurements confirmed the relatively homogeneous distribution of experimental larvae. The 50% lethal concentration of spinosad was estimated at 1.48 ppm spinosad (95% confidence interval: 1.07-2.33) for a 10-min exposure period, whereas larvae treated with 0.05 ppm of the organophosphate temephos experienced 61% mortality. Immature aquatic insects were identified to genus and tested for their susceptibility to spinosad in the laboratory. After exposure to 12 ppm spinosad for 10 min, ephemeropterans, odonates, trichopterans, and hemipterans did not experience significantly increased mortality over that of untreated controls, whereas a significant increase in mortality was observed in spinosad-treated Plecoptera (P < 0.001). Tilapia and trout fry exposed to 12 ppm spinosad for 10 min did not experience increased mortality at 24-h postexposure over that of the controls. We conclude that spinosad is less toxic than temephos to these blackfly species, but is likely to have a low impact on nontarget members of the aquatic community.

Juniperus plant species are rich sources of bioactive secondary metabolites and are traditionally used for the treatment of several illnesses, including those related to hyperglycemia and diabetes. The major bioactive compounds identified in certain species of this genus are terpenes and phenolics. Juniperus deppeana Steud. is mainly used as a wood resource and its chemical composition has been partially established. Our goal was to perform a comprehensive profiling of a methanolic extract of leaves of J. deppeana, and to determine its potential as a source of α-amylase and α-glucosidase inhibitors. Terpene and phenolic compounds were putatively identified based on their accurate mass spectrometric data. Regarding terpenes, we found mainly diterpenes, specifically dehydroabietic acid-like, hinokiol-like, agathic acid-like and dihydroxyabietatrienoic acid-like compounds. Isopimaric acid was also identified and its identity was confirmed by coelution with an authentic standard via comparing retention time, mass spectrum, and collisional cross section (CCS) values. For phenolic compounds, we identified mainly compounds with a chemical structure similar to the biflavonoids amentoflavone and bilobetin. Besides, the methanolic extract of J. deppeana leaves show inhibition of α-amylase (IC50= 85.11 ± 11.91 µg mL-1) and α-glucosidase (IC50= 32.50 ± 3.40 µg mL-1) enzymes, demonstrating a potential alternative for the search of antidiabetic natural products.

Antecedentes y Objetivos: Las hojas de Bursera simaruba se utilizan tradicionalmente para tratar diversas enfermedades. Sin embargo, existen pocos reportes sobre la descripción de los fitoquímicos potencialmente responsables de tales actividades biológicas. Por lo tanto, este estudio tuvo como objetivo describir el potencial antifúngico, antibacteriano y antidiabético mediante experimentos in vitro, así como contribuir al conocimiento de la composición química de las hojas de B. simaruba. Métodos: Se analizó la actividad antibacteriana, antifúngica y antidiabética de un extracto metanólico (MeOH-Ex) de hojas de B. simaruba, y se detectaron diferentes grupos de metabolitos secundarios mediante ensayos cualitativos. Además, el análisis fitoquímico de MeOH-Ex se determinó con cromatografía líquida de ultra alta resolución acoplada a espectrometría de masas de alta resolución (UHPLC-ESI+-MS-QTOF), y las identificaciones putativas se realizaron utilizando bases de datos espectrales públicas. Resultados clave: El MeOH-Ex de las hojas de B. simaruba contiene cualitativamente alcaloides, terpenos y esteroides, saponinas, taninos, cumarinas y compuestos fenólicos, tales como ácido cafeico, ácido clorogénico, apigenina, kaempferol, florizina, quercitrina, quercetina-glucósido y apigenina-glucósido. Además, se identificaron tentativamente los lignanos burseran y yatein. El MeOH-Ex exhibió una baja actividad antifúngica contra Fusarium solani (16.3% de inhibición del crecimiento micelial) y un alto efecto antidiabético por inhibición in vitro de las enzimas α-amilasa (87.7%) y α-glucosidasa (75.9%). Finalmente, el estándar de ácido clorogénico mostró una inhibición significativa de las enzimas α-amilasa (49.5%) y α-glucosidasa (85.1%). Conclusiones: El MeOH-Ex de las hojas de B. simaruba representa una fuente de metabolitos secundarios con potencial actividad antidiabética. Los compuestos fenólicos tentativamente identificados podrían desempeñar un papel importante en la prevención de trastornos por hiperglucemia posprandial al inhibir las enzimas α-amilasa y α-glucosidasa. Destaca la presencia de ácido clorogénico como uno de los principales compuestos bioactivos potenciales en las hojas de B. simaruba.