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This study was carried out during January 2020–December 2020 in a semi-desert ecosystem in southern Sonora, Mexico, to determine the annual and daily variations in water potential and the normalized difference vegetation index (NDVI) of Bursera fagaroides Engl., Monogr. Phan., Parkinsonia aculeata L., Sp. Pl.; Prosopis laevigata (Humb. & Bonpl. ex Willd.), and Atriplex canescens (Pursh) Nutt. Soil electrical conductivity, cation content, and physical characteristics were determined at two depths, and water potential (ψ) was measured in roots, stems, and leaves. The daily leaf ψ was measured every 15 days each month to determine the duration of stress (hours) and the stress intensity (SI). The electrical conductivity determinations classified the soil in the experimental area as strongly saline. A significant difference was noted in electrical conductivity between soil depths. The four studied species showed significant gradients of ψ in their organs. In this soil, all four species remained in a stressed condition for approximately 11 h per day. The mean SI was 27%, and B. fagaroides Engl., Monogr. Phan. showed the lowest value. The four species showed increased NDVI values during the rainy months, with P. laevigata (Humb. & Bonpl. ex Willd.) and Parkinsonia aculeata L., Sp. Pl. showing the highest values. The capacity for ψ decrease under saline conditions identified A. canescens (Pursh) Nutt., B. fagaroides Engl., Monogr. Phan. and P. aculeata L., Sp. Pl. as practical and feasible alternatives for establishment in saline soils in southern Sonora for purposes of soil recovery and reforestation.

Podophyllotoxins are natural lignans with known cytotoxic activity on several cell lines. The structural basis for their actions is mainly by the aryltetralin-lignan skeleton. Authors have proposed a cytotoxic mechanism of podophyllotoxins through the topoisomerase-II inhibition activity, however, several studies have also suggested that podophyllotoxins can inhibit the microtubules polymerization. In this work, the two possible mechanisms of action of two previously isolated compounds from the stem bark of Bursera fagaroides var. fagaroides: acetylpodophyllotoxin (1) and 5’-desmethoxydeoxypodophyllotoxin (2), was analyzed. An in vitro anti-tubulin epifluorescence on the MCF10A cell line and enzymatic topoisomerase II assays were performed. The binding affinities of compounds 1 and 2 in the colchicine binding site of tubulin by using rigid- and semiflexible-residues were calculated and compared using in silico docking methods. The two lignans were active by the in vitro anti-tubulin assay but could not inhibit TOP2 activity. In the in silico analysis, the binding modes of compounds into both rigid- and semiflexible-residues of tubulin were predicted, and only for the semiflexible docking method, a linear correlation between the dissociation constant and IC50 previously reported was found. Our results suggest that a simple semiflexible-residues modification in docking methods could provide an in vitro correlation when analyzing very structurally similar compounds.

Se evalúa la acumulación de biomasa en estacas de cuatro especies de Bursera durante cuatro estaciones del año, en cinco sustratos bajo condiciones de invernadero. Se establecieron bajo un diseño experimental completamente aleatorizado con arreglo factorial para aplicarles muestreo destructivo al final de cada estación del año (2013) y calcular biomasa estructural. El factor especie y estación de crecimiento mostraron efectos en la acumulación de biomasa. Bursera fagaroides acumuló mayor biomasa en raíz, ramas y hojas (2.85, 1.67 y 3.76 g/planta respectivamente); junto con B. glabrifolia presentó mayor área foliar (386.34 y 205.65 cm2/planta respectivamente), buena relación biomasa aérea/biomasa subterránea y porcentajes de supervivencia altos (78 y 58% respectivamente).

Trees generate resources for other guilds (e.g., lianas), including the production of supporting branches for the establishment of epiphytes. In a tropical dry forest of central Mexico, we studied whether branch mortality is associated with phorophyte quality. For a one-year period, we monitored the survival of branches with and without vascular epiphytes in tree species with high epiphyte loads (Bursera copallifera (Sessé & Moc. Ex DC.) Bullock, Bursera glabrifolia (Kunth.) Engl.) and low (Bursera fagaroides (Kunth) Engl., Conzattia multiflora (B.L. Rob.) Standl., Ipomoea pauciflora M.Martens & Galeotti, Sapium macrocarpum Müll.Arg.). The lowest (C. multiflora) and highest (I. pauciflora) branch mortalities occurred in phorophytes with low epiphyte loads, whereas branch mortality in S. macrocarpum was 60% and in all Bursera species was

Antecedentes. Las condiciones ambientales en los bordes de los fragmentos de vegetación afectan las características del ciclo de vida de la biota nativa (efecto de borde). Evaluamos el efecto de borde en dos especies de Bursera , las cuales son representativas de la comunidad madura del bosque tropical caducifolio (BTC) en México. Hipótesis. Esperábamos una estructura poblacional que reflejara la afectación de la reproducción supervivencia y crecimiento en los bordes de los fragmentos de BTC. Especies en estudio. Bursera fagaroides, B. palmeri . Sitio de estudio y fechas. Querétaro (Qro.), Apaseo el Grande (Gto.), México. Trabajo de campo: mayo-septiembre 2012. Métodos. Dentro de cada uno de los nueve fragmentos de BTC, trazamos parcelas en dos condiciones ambientales contrastantes (de borde e interior), entre las que se comparó la densidad, estructura de la población y el éxito reproductivo de las dos especies de Bursera, así como estimadores de la radiación solar y la compactación del suelo. Resultados. La radiación solar y la compactación del suelo no fueron diferentes entre las condiciones ambientales. En ambas especies la densidad de individuos fue mayor en el borde, donde los individuos con tamaños medianos y grandes fueron predominantes. El potencial reproductivo de los individuos, así como la viabilidad y la germinación de sus semillas, fueron similares entre los ambientes de borde e interior. Conclusiones. La densidad y la estructura poblacional mostraron una variación congruente con mayores tasas de reclutamiento, crecimiento y supervivencia en el ambiente de borde, las cuales podrían haberse presentado en las condiciones iniciales de mayor incidencia de la radiación en los bordes. La similitud que se observa actualmente en la radiación solar entre el borde y el interior de los fragmentos, pudo ser el resultado de la recuperación rápida del dosel bajo condiciones de una incidencia de la luz más alta en los bordes.

Se describen atributos de especies arbustivas y arbóreas, componentes del bosque tropical caducifolio dentro del Municipio de Querétaro, Querétaro. Se utilizó un muestreo aleatorio de 36 sitios de vegetación natural con criterios de exclusión. Para cada sitio se delimitó un cuadrante de 25 m × 25 m. Dentro del cuadrante se identificaron y evaluaron el total de especies arbóreas y arbustivas mayores a 150 cm de altura, excluyendo especies de cactáceas y suculentas. Se evaluaron atributos de los árboles como: diámetro basal, diámetro a la altura del pecho, altura total del árbol, altura de la copa, diámetro de copa y se estimó la capacidad de captura de carbono por especie considerando las variables climáticas del sitio donde crecen. Se observaron 22 especies de arbustos y árboles dentro las que destacan por su abundancia: Acacia schaffneri, Bursera fagaroides, Forestiera phillyreoides, Karwinskia humboldtiana, Dodonaea viscosa e Ipomea murucoides, mientras las que presentan mayor potencial de almacenar carbono son: Prosopis laevigata y Leucaena leucocephala; en contraparte, las menos abundantes fueron: Randia thurberi y Erytrina coralloides. Estos resultados son indispensables para el desarrollo y diseño de propuestas de conservación y reforestación del bosque tropical caducifolio.

Three new aryldihydronaphthalene-type lignans, namely, 7′,8′-dehydropodophyllotoxin (1); 7′,8′-dehydro acetylpodophyllotoxin (2); and 7′,8′-dehydro trans-p-cumaroylpodophyllotoxin (3), were isolated from the stem bark of Bursera fagaroides var. fagaroides (Burseraceae), together with six known lignans, podophyllotoxin (4), acetylpodophyllotoxin (5), 5′-desmethoxy-β-peltatin A methylether (6), acetylpicropodophyllotoxin (7), burseranin (8), and hinokinin (9). The coumarin scopoletin (10) was also isolated from this bark. The chemical structure of all these compounds was determined by spectroscopic analyses including 2D NMR. We demonstrated that compounds 1–3 show different degrees of cytotoxic activity against human nasopharyngeal (KB), colon (HF-6), breast (MCF-7) and prostate (PC-3) cancer cell lines, with IC50 values ranging from 1.49 to 1.0 × 10−5 μM. In vivo studies of the effect of these natural lignans on the cell cycle, cell migration and microtubule cytoskeleton of developing zebrafish embryos, demonstrated their antimitotic molecular activity by disturbing tubulin. This is the first report on the occurrence of aryldihydronaphthalene lignans in the genus Bursera of the Burseraceae family, as well as on the determination of their cytotoxic activity and mechanism of action.

By using a zebrafish embryo model to guide the chromatographic fractionation of antimitotic secondary metabolites, seven podophyllotoxin-type lignans were isolated from a hydroalcoholic extract obtained from the steam bark of Bursera fagaroides. The compounds were identified as podophyllotoxin (1), &beta, peltatin-A-methylether (2), 5&prime, desmethoxy-&beta, peltatin-A-methylether (3), desmethoxy-yatein (4), desoxypodophyllotoxin (5), burseranin (6), and acetyl podophyllotoxin (7). The biological effects on mitosis, cell migration, and microtubule cytoskeleton remodeling of lignans 1&ndash, 7 were further evaluated in zebrafish embryos by whole-mount immunolocalization of the mitotic marker phospho-histone H3 and by a tubulin antibody. We found that lignans 1, 2, 4, and 7 induced mitotic arrest, delayed cell migration, and disrupted the microtubule cytoskeleton in zebrafish embryos. Furthermore, microtubule cytoskeleton destabilization was observed also in PC3 cells, except for 7. Therefore, these results demonstrate that the cytotoxic activity of 1, 2, and 4 is mediated by their microtubule-destabilizing activity. In general, the in vivo and in vitro models here used displayed equivalent mitotic effects, which allows us to conclude that the zebrafish model can be a fast and cheap in vivo model that can be used to identify antimitotic natural products through bioassay-guided fractionation.

Shrub species were selected for potential use in restoration projects in the semiarid shrublands of Central Mexico. Ecological characteristics of the species were considered, including tolerance to climate change. Inventories of shrubs were carried out in 17 semiarid shrubland fragments of xeric shrubland. The 46 species recorded were ordered using a principal component analysis, considering ecological characteristics such as frequency, land cover, sociability and interaction with mycorrhizal fungi. From these, the 10 species that presented the highest values of the desired characteristics were selected. The response of these species to climate change was evaluated using current potential distribution models and by applying climate change scenario A2, using MaxEnt. The species that presented suitable ecological qualities for restoration and maintained or increased their distribution under the climate change scenario were Acacia schaffneri, Ageratina espinosarum, Bursera fagaroides, Dalea bicolor, Eysenhardtia polystachya and Karwinskia humboldtiana. These species are therefore recommended for use in medium and long-term ecological restoration projects in the semi-arid region in Central Mexico.

Giardiasis, a diarrheal disease, is highly prevalent in developing countries. Several drugs are available for the treatment of this parasitosis; unfortunately, all of them have variable efficacies and adverse effects. Bursera fagaroides has been known for its anti-inflammatory and antidiarrheal properties in Mexican traditional medicine. We investigated the in vitro anti-giardial activities of four podophyllotoxin-type lignans from Bursera fagaroides var. fagaroides, namely, 5′-desmethoxy-β-peltatin-A-methylether (5-DES), acetylpodophyllotoxin (APOD), burseranin (BUR), and podophyllotoxin (POD). All lignans affected the Giardia adhesion and electron microscopy images revealed morphological alterations in the caudal region, ventral disk, membrane, and flagella, to different extents. Only 5-DES, APOD, and POD caused growth inhibition. Using the Caco-2 human cell line as a model of the intestinal epithelium, we demonstrated that APOD displayed direct antigiardial killing activity and low toxicity on Caco-2 cells. This finding makes it an attractive potential starting point for new antigiardial drugs.

The hydroalcoholic extract of the steam bark of B. fagaroides var. fagaroides displayed potent cytotoxic activity against four cancer cell lines, namely KB (ED50 = 9.6 × 10(-2) μg/mL), PC-3 (ED50 = 2.5 × 10(-1) μg/mL), MCF-7 (ED50 = 6.6 μg/mL), and HF-6 (ED50 = 7.1 × 10(-3) μg/mL). This extract also showed anti-tumour activity when assayed on mice inoculated with L5178Y lymphoma cells. Bioactivity-directed isolation of this extract, afforded seven podophyllotoxin-type lignans identified as podophyllotoxin (1), β-peltatin-A-methylether (2), 5'-desmethoxy-β-peltatin-A-methylether (3), desmethoxy-yatein (4), desoxypodophyllotoxin (5), burseranin (6), and acetyl podophyllotoxin (7) by 1D and 2DNMR and FAB-MS analyses, and comparison with reported values. All the isolated compounds showed potent cytotoxic activity in the cell lines tested, especially compound 3, which exhibited greater activity than camptothecin and podophyllotoxin against PC-3 (ED50= 1.0 × 10(-5) μg/mL), and KB (ED50 = 1.0 × 10(-5) μg/mL). This is the first report of the isolation of podophyllotoxin and its acetate in a Bursera species.

It has been hypothesized that environmental variability can influence the sex ratio of a plant population, and it has been observed that in stressful environments, male plants are more abundant than females. However, it is unknown whether this is due to differential mortality rates between males and females. In this study, we analyzed sex ratio, mortality, and size distribution in a population of the neotropical tree/bush Bursera fagaroides in two different environments (east- and west-oriented slopes) over a 10-year period. We determined that the sex ratio favored males in the more stressful environment (east-facing slope) and that females were significantly larger in the less stressful environment (west-facing slope). Despite a significant difference in size between sexes by slope aspect, the difference in sex ratio cannot be explained by slope or by mortality during the 10 years of observation.

A BSTRACT We studied the seed dispersal process of a population of Bursera fagaroides (Burseraceae) on the coast of the Gulf of Mexico by considering 1) all phases of the dispersal process (i.e., fruit removal, effect of seed passage through digestive tract, seed deposition, removal of seeds from the ground, germination, growth and survival of seedlings and adults, and seed set); 2) plant and animal components and their interaction; and 3) spatial variation in these components using different subpopulations. Hill aspect and surrounding microenvironment or habitat affected individuals of B. fagaroides, and this effect depended on life stage (seed, seedling, or adult). Seed germination was greater in moderately-shaded areas (below the perennial plant species Coccoloba barbadensis) than in relatively open sites (below B. fagaroides or on bare sand); seedlings grew less on sites in bright sunlight; adult individuals were not detected in highly-shaded places; and females inhabiting open sites (grassland) had more removed seeds than those of shaded areas (shrubland and dry forest). Vireo griseus and Dumetella carolinensis, the only species consuming fruits of B. fagaroides during our study, differed in their effect on seeds: seeds ingested by V. griseus did not germinate, whereas 17% of seeds ingested by D. carolinensis germinated. Additionally, even though both bird species preferred the tropical dry forest, their foraging behavior differed. Vireo griseus was mostly found at mid-canopy height in tree-dominated sites, and D. carolinensis used the understory of shrubby areas; B. fagaroides does not inhabit tree-dominated sites. Our results indicated that there was no ‘‘best’’ place for a seed to land. What is suitable for a seed might not be optimal for a fruiting plant. Thus, patterns of seed dispersal are almost certainly altered by processes that happen long after seed deposition.

In the coastal zone of central Veracruz, Mexico, we recorded the abundance of orchid plants growing on termite carton trails or directly on the peeling bark of Bursera fagaroides. Although only 19 percent of the surveyed trees contained termite carton trails, trees with termites hosted 92 percent of all orchid individuals. A disproportionate number of orchid seedlings occurred on termite cartons given the relative availability of carton and bark substrate. Our results show for the first time that orchids can establish on termite trails, and we discuss the potential for termite facilitation of orchid populations.

Scaling is relevant for the analysis of plant-frugivore interaction, since the ecological and evolutionary outcomes of seed dispersal depend on the spatial and temporal scale at which frugivory patterns emerge. We analyse the relationship between fruit abundance and frugivore activity at local and landscape spatial scales in two different systems composed, respectively, by the bird-dispersed woody plants Juniperus communis and Bursera fagaroides, and their frugivore assemblages. We use a hierarchical approach of nested patchiness of fruit-resource, where patches are defined by individual plants within site, at the local scale, and by sites within region, at the landscape scale. The structure of patches is also described in terms of contrast (differences in fruit availability among patches) and aggregation (spatial distribution of patches). For J. communis, frugivore activity was positively related to fruit availability at the landscape scale, this pattern seldom emerging at the local scale; conversely, B. fagaroides showed a general trend of positive local pattern that disappeared at the landscape scale. These particular trends might be partially explained by differences in contrast and aggregation. The strong contrast among plants within site together with a high aggregation among sites would promote the B. fagaroides pattern to be only local, whereas in J. communis, low aggregation among sites within region would favour a sharp landscape-scale pattern. Both systems showed discordant patterns of fruitresource tracking among consecutive spatial scales, but the sense of discordance differed among systems. These results, and the available multi-scale frugivory data, suggest that discordance among successive scales allows to link directly frugivory patterns to resource-tracking mechanisms acting at particular scales, resulting, thus, more informative than concordance observational data, in which landscape patterns might result from accumulated effect of local mechanisms. In this context, we propose new methodological approaches for a better understanding of the hierarchical behavioural mechanisms underpinning the multi-scale resource tracking by frugivores.

In order to evaluate the 'fruit crop size' hypothesis, we analyzed the effect of fruit availability on the number of visits by birds and on the proportion of removed fruits, and on how much of the variation in the proportion of removed fruits could be explained by spatio-temporal variability. Fieldwork was done on the coast of the state of Veracruz, Mexico, using the small tree Bursera fagaroides (Burseraceae) and its frugivorous feeding assemblage, on four hills during four years. The number of fruits produced, the number of visits by birds, and the proportion of removed fruits varied between years with more than half an order of magnitude. The number of available fruits was associated to both the number of visits by birds and the proportion of fruits removed from each plant individual, and supports the fruit crop size hypothesis. However, the hypothesis varies in strength depending on total fruit production by the population per year and per hill. The spatio-temporal variation of the system was the effect of variation in the intensity of fructification betweep years and hills; the inclusion of spatio-temporal variability helped to explain most of the variation found in our results. The latter approach may explain the explain the conflicting results found by other authors in studies done in only one year or at one site, where variation is greatly reduced. Considering the number of published reports, a meta-analysis seems to be in order to determine the existence of a general effect between fruit production, the number of visits by birds and the proportion of fruits removed. If this is possible, we hypothesize that the association between fruit production and the number of visits by birds should be of low intensity.

Despite prevention and treatment options, breast cancer (BC) has become one of the most important issues in the present day. Therefore, the need for more specific and efficient compounds remains paramount. We evaluated four previously isolated aryltetralin lignans: 5′-demethoxy-β-peltatin-A-methylether (1), acetylpodophyllotoxin (2), 5′-demethoxydeoxypodophyllotoxin (3), and 7′,8′-dehydroacetylpodophyllotoxin (4) for cytotoxicity, clonogenicity, and selectivity against three BC cell lines: MCF-7, MDA-MB-231, and BT-549, as well as the non-tumorigenic mammary epithelial cell line MCF-10A. Cytotoxicity was evaluated after 72 h of treatment, and clonogenicity was determined at 72 h post-treatment; experiments were performed using the sulforhodamine B staining assay. Selective-index (SI) was calculated by comparing pure compound IC50 values in MCF-10A cell line against the IC50 of the same compound in cancer cell lines. Structural similarities among lignans and controls (podophyllotoxin and etoposide) were analyzed using the Tanimoto coefficient (Tc). Lignans were cytotoxic against all tested cell lines (0.011–7.22 µM) and clonogenicity testing showed a dose-dependent cytocidality for all lignans (≥0.08 µg/mL); compounds 2 and 3 were more potent (14.1 and 7.6 respectively) than etoposide in BT-549 cell line, while compound 2 displayed selectivity (SI = 28.17) in BT-549 cell line. Tc values of lignans suggested a greater similarity with podophyllotoxin structure.

Se presenta el estudio de los árboles y arbustos de la familia Burseraceae que se localizan en el estado de Aguascalientes, México. Se incluye una clave para la identificación de las especies, descripciones con datos de nombre común, altitud, abundancia, localidad en la cual fueron encontradas, mapas de distribución e ilustraciones. Se reconoce la presencia de seis especies de Bursera: B. bipinnata, B. fagaroides, B. multijuga, B. palmeri, B. penicillata y B. roseana, la mayoría localizadas en el municipio de Calvillo, en selva baja caducifolia y matorral subtropical a 1650-2500 m. B. fagaroides es la de más amplia distribución y abundancia en el estado.