Anthelmintic flavonoids and other compounds from Combretum glutinosum Perr. ex DC (Combretaceae) leaves.

A chemical study of the hydro-ethanol extract of the leaves of Combretum glutinosum resulted in the isolation of nine compounds, including 5-demethylsinensetin (1), umuhengerin (2), (20S,24R)-ocotillone (3), lupeol (4), ß-sitosterol (5), oleanolic acid (6), betulinic acid (7), corymbosin (8) and ß-sitosterol glucoside (9). Four compounds have been isolated for the first time from the genus Combretum [viz. (1), (2), (3) and (8)]. The crystal structures of flavonoid (2), C20H20O8, Z' = 2, and triterpene (3), C30H50O3, Z' = 1, have been determined for the first time; the latter confirmed the absolute configuration of native (20S,24R)-ocotillone previously derived from the crystal structures of related derivatives. The molecules of (3) are linked into supramolecular chains by intermolecular O-H...O hydrogen bonds. The crude extracts obtained by aqueous decoction and hydro-ethanolic maceration, as well as the nine isolated compounds, were tested for their anthelmintic activity on the larvae and adult worms of Haemonchus contortus, a hematophage that causes parasitic disorders in small ruminants. The evaluated anthelmintic activity showed that the extracts at different doses, as well as all the compounds tested at 150 µg ml-1, inhibited the migration of the larvae and the motility of the adult worms of the parasite compared with the phosphate buffer solution negative reference control. The best activity was obtained with flavonoids (1), (2) and (8) on both stages of the parasite. The flavones that showed good activity can be used for the further development of other derivatives, which could increase the anthelmintic efficacy.

Effect of salinity on cadmium tolerance, ionic homeostasis and oxidative stress responses in conocarpus exposed to cadmium stress: Implications for phytoremediation.

Contamination of soil with salinity and Cd negatively affects growth and productivity of plants. The proposed study has been planned to explore the effects of salinity on Cd uptake, tolerance and phytoremediation potential of conocarpus (Conocarpus erectus L.). One-month-old uniform plants of conocarpus were exposed to 0, 8.9, 44.5, 89 and 178 µM Cd alone or in combination with 0, 100 and 200 mM NaCl in Hoagland's nutrient solution. Results revealed that shoot and root biomasses, leaf water content and pigment content decreased more in response to combination of Cd and salinity compared to Cd alone. The Na+ and Cl- concentrations in shoot and root were not affected by Cd alone, but increased in Cd + salinity treatments. The K+ concentration decreased by Cd alone as well as Cd combination with salinity. Plant Cd uptake increased in the presence of salinity but its translocation from root to shoot remained unaffected. Exposure of plants to Cd alone and Cd + salinity caused oxidative stress via overproduction of H2O2 and inducing lipid peroxidation. The activities of antioxidant enzymes such as SOD, CAT, POD and APX increased to mitigate this oxidative stress. It is concluded that the tolerance of conocarpus against Cd stress is decreased in the presence of salinity due to increased uptake of toxic ions and intensification of oxidative stress. Moreover, the Cd uptake behavior of this tree indicates its suitability for phytostabilization of Cd contaminated saline and non-saline soils.

Characterization of Laguncularia racemosa transcriptome and molecular response to oil pollution.

Mangroves are ecosystems of economic and ecological importance. Laguncularia racemosa (Combretaceae), popularly known as white mangrove, is a species that greatly contributes to the community structure of neotropical and West African mangrove forests. Despite the significance of these ecosystems, they have been destroyed by oil spills that can cause yellowing of leaves, increased sensitivity to other stresses and death of trees. However, the molecular response of plants to oil stress is poorly known. In this work, Illumina reads were de novo assembled into 46,944 transcripts of L. racemosa roots and leaves, including putative isoform variants. In addition to improving the genomic information available for mangroves, the L. racemosa assembled transcriptome allowed us to identify reference genes to normalize quantitative real-time PCR (qPCR) expression data from oil-stressed mangrove plants, which were used in RNASeq validation. The analysis of expression changes induced by the oil exposure revealed 310 and 286 responsive transcripts of leaves and roots, respectively, mainly up-regulated. Enriched GO categories related to chloroplasts and photosynthesis were found among both leaf and root oil-responsive transcripts, while "response to heat" and "response to hypoxia" were exclusively enriched in leaves and roots, respectively. The comparison of L. racemosa 12-h-oil-stressed leaf expression profile to previous Arabidopsis heat-stress studies and co-expression evidence also pointed to similarities between the heat and oil responses, in which the HSP-coding genes seem to play a key role. A subset of the L. racemosa oil-responsive root genes exhibited similar up-regulation profiles to their Arabidopsis homologs involved in hypoxia responses, including the HRA1 and LBD41 TF-coding genes. Genes linked to the ethylene pathway such as those coding for ERF TFs were also modulated during the L. racemosa root response to oil stress. Taken together, these results show that oil contamination affects photosynthesis, protein metabolism, hypoxia response and the ethylene pathway in L. racemosa 12-h-oil-exposed leaves and roots.

Diagnosing the level of stress on a mangrove species (Laguncularia racemosa) contaminated with oil: A necessary step for monitoring mangrove ecosystems.

Monitoring the effects of pollution on mangrove vegetation is a challenge. A specific study using an oil spill simulation on mangrove species was conducted to address this challenge. We tested the effectiveness of the chlorophyll a fluorescence kinetics as a fast and robust method to diagnose the vitality of Laguncularia racemosa. We used L. racemosa plants contaminated with marine fuel oil in mangrove microcosm models. Several parameters of the JIP-test were capable of detecting the impairment of the photosynthetic function prior to the visual manifestation of symptoms in response to oil contamination. The results support the use of the chlorophyll fluorescence transient as a reliable, fast and easy to apply diagnostic method for evaluating oil-impacted mangroves. To the best of our knowledge, it is the first time that consistent data showing photosynthetic impairment in response to oil contamination is shown for a mangrove tree species.

Effect of pollution by particulate iron on the morphoanatomy, histochemistry, and bioaccumulation of three mangrove plant species in Brazil.

In Brazil, some mangrove areas are subjected to air pollution by particulate iron from mining activities. However, the effect of this pollutant on mangrove plants is not well known. This study aimed to comparatively analyze the morphoanatomy, histochemistry, and iron accumulation in leaves of Avicennia schaueriana, Laguncularia racemosa, and Rhizophora mangle. Samples were collected from five mangrove sites of Espírito Santo state, each of which is exposed to different levels of particulate iron pollution. The amount of particulate material settled on the leaf surface was greater in A. schaueriana and L. racemosa, which contain salt glands. High iron concentrations were found in leaves of this species, collected from mangrove areas with high particulate iron pollution, which suggests the foliar absorption of this element. None of the samples from any of the sites showed morphological or structural damage on the leaves. Scanning electron microscopy (SEM) coupled to X-ray diffraction rendered a good method for evaluating iron on leaves surfaces. A histochemical test using Prussian blue showed to be an appropriate method to detect iron in plant tissue, however, proved to be an unsuitable method for the assessment of the iron bioaccumulation in leaves of A. schaueriana and R. mangle. So far, this study demonstrates the need of evaluating the pathway used by plants exposed to contaminated particulate matter to uptake atmospheric pollutants.

Adaptive plasticity of Laguncularia racemosa in response to different environmental conditions: integrating chemical and biological data by chemometrics.

Mangroves are dynamic environments under constant influence of anthropic contaminants. The correlation between environmental contamination levels and possible changes in the morphology of plants, evaluated by multivariate statistics helps to highlight matching between these variables. This study aimed to evaluate the uptake and translocation of metals and metalloids in roots and leaves as well as the changes induced in both anatomy and histochemistry of roots of Laguncularia racemosa inhabiting two estuaries of Espírito Santo (Brazil) with different pollution degrees. The analysis of 14 elements in interstitial water, sediments and plants followed by multivariate statistics, allowed the differentiation of studied sites, showing good match between levels of elements in the environment with the corresponding in plants. L. racemosa showed variations in their root anatomy in different collection areas, with highest values of cortex/vascular cylinder ratio, periderm thickness and air gap area in Vitória Bay, the most polluted sampling area. These three parameters were also important to differentiate the mangrove areas by linear discriminant analysis. The development stage of aerenchyma in roots reflected the oxygen availability in the water, being found a negative correlation between these variables. The combined use of chemical and biological analyses responded quite well to different pollution scenarios, matching morphological responses to physical and chemical parameters, measured at different partitions within the estuary. Thus, L. racemosa can be confirmed as a reliable sentinel plant for biomonitoring of estuaries impacted by anthropic pollution.

Relationship of water transport to anatomical features in the mangrove Laguncularia racemosa grown under contrasting salinities.

The purpose of this study was to investigate the xylem anatomy and hydraulic characteristics of the mangrove Laguncularia racemosa grown under contrasting salinities. The study addressed the hypothesis that, at high salinity, water transport capacity may decrease in association with higher water use efficiency. Plants were grown in media to which 0, 15 and 30 NaCl was added. Vessel density and diameter were determined in transverse sections of stem and midrib leaves in terminal shoots, and hydraulic parameters were measured. In stems, the vessel density increased with salinity, while the anatomical diameter (d(a)) and hydraulic diameter (d(h)) declined; in leaves, these parameters remained unchanged with salinity. Huber value and hydraulic and specific conductivities decreased with salinity. Leaf blade resistance increased with salinity and represented the largest fraction of twig resistance. Xylem anatomy and leaf tissue of L. racemosa appeared to be modulated by salinity, which led to a coordinated decline in hydraulic properties as salinity increased. Therefore, these structural changes would reflect functional water use characteristics of leaves under salinity.