Pentaclethra Macroloba Research Articles

New Information of the Anatomy and Phytochemical Screening of Pentaclethra macroloba (Willd.) Kuntze (Caesalpinioideae-Leguminosae) Seeds

Pentaclethra macroloba (Willd.), whose common name is “pracaxi,” is naturally found in the Amazon region. The present study is aimed at analyzing the anatomy, seed histochemistry, and chemical composition in fatty acid profile of P. macroloba seed oils. Seeds were collected in the cities of Belém, Marituba, and São Domingos do Capim-PA. For the study in light microscopy, scanning electron microscopy, and histochemistry, seeds were sectioned in cross and longitudinal sections of the embryonic axis and fixed in formaldehyde, acetic acid, and 50% ethyl alcohol; neutral-buffered formalin; and formaldehyde and ferrous sulfate and stored in 70% ethyl alcohol. For the anatomical study, the seeds were subjected to the usual techniques of plant anatomy. Histochemical tests were performed on plant material, freehand sectioned, and embedded in histological paraffin with DMSO. The fatty acid profile was determined for gas chromatography (GC-FID). Integument is divided into three strata, monoseriate exotesta, mesotesta formed by several layers of parenchyma cells, and monoseriate endotesta, formed by compressed cells. Cotyledons are composed of thin-walled parenchyma cells with several secretory cavities and secretory idioblasts. The main metabolic classes are lipids, phenolic compounds, carbohydrates, proteins, and alkaloids. The main fatty acids found in P. macroloba oil are oleic, behenic, lignoceric, and linoleic. P. macroloba seeds have important anatomical characteristics for their circumscription in Leguminosae and also in Caesalpinioideae, and their oil is rich in fatty acids essential to the human diet, providing many benefits to the human health, such as fatty acids belonging to the omega family (linoleic, oleic).

Population dynamics of Pentaclethra macroloba, a hyperdominant tree in the Amazon River estuary

Pentaclethra macroloba is a hyperdominant tree of the Amazon estuary and highly exploited in the region, because the oil of its seeds has medicinal properties. Little is known about the influence of the flood polymodal cycle on the population dynamics of trees in the Amazon estuary. We evaluated the influence of tree diversity, climate, soil properties and flood level on the population dynamics of P. macroloba. During five years of monitoring (from 2011 to 2015), population density and mortality, recruitment and growth rates data were obtained of three populations of P. macroloba (Mazagão Velho, Maracá and Ajuruxi areas). Four transects were used in each area and 20 permanent plots were installed in each transect to study the population dynamics. Linear models were used to evaluate the relationship between biotic/abiotic factors and population density of P. macroloba. The population density of the three populations analyzed showed a significant decrease between the period from 2011 to 2015 (F = 381.3; p < 0.001). The Maracá area had a higher mortality rate (4.50% year−1) compared to Mazagão Velho (3.24% year−1) and Ajuruxi (1.96% year−1). The recruitment rate in Ajuruxi and Mazagão Velho were 1.05% year−1 and 0.32% year−1, respectively, and in Maracá there were no recruits. Annual growth rate of the Maraca area was higher (0.93 cm−1 year−1) compared to Ajuruxi (0.75 cm−1 year−1) and Mazagão Velho (0.65 cm−1 year−1) populations. The flood level had a negative and significant correlation with the population density of P. macroloba in the Maracá (F = 39.7; p < 0.01), Ajuruxi (F = 9.9; p < 0.05) and Mazagão Velho (F = 19.6; p < 0.05) areas. Only the Ajuruxi area had a positive and significant correlation with arboreal richness (β = 0.14; p < 0.05). The flood gradient is an environmental driver that regulates the population growth of P. macroloba. The hyperdominant characteristic of this species is the result of its adaptability and interactions between soil fertility and tree diversity.

Poly (ε-caprolactone)-Based Scaffolds with Multizonal Architecture: Synthesis, Characterization, and In Vitro Tests.

Tissue engineering is vital in treating injuries and restoring damaged tissues, aiming to accelerate regeneration and optimize the complex healing process. In this study, multizonal scaffolds, designed to mimic tissues with bilayer architecture, were prepared using the rotary jet spinning technique (RJS scaffolds). Polycaprolactone and different concentrations of alginate hydrogel (2, 4, and 6% m/v) were used. The materials were swollen in pracaxi vegetable oil (PO) (Pentaclethra macroloba) and evaluated in terms of surface morphology, wettability, functional groups, thermal behavior, crystallinity, and cytotoxicity. X-ray diffraction (XRD) showed the disappearance of the diffraction peak 2θ = 31.5° for samples from the polycaprolactone/pracaxi/alginate (PCLOA) group, suggesting a reduction of crystallinity according to the presence of PO and semi-crystalline structure. Wettability gradients (0 to 80.91°) were observed according to the deposition layer and hydrogel content. Pore diameters varied between 9.27 μm and 37.57 μm. Molecular interactions with the constituents of the formulation were observed via infrared spectra with Fourier transform (FTIR), and their influence was detected in the reduction of the maximum degradation temperature within the groups of scaffolds (polycaprolactone/alginate (PCLA) and PCLOA) about the control. In vitro tests indicated reduced cell viability in the presence of alginate hydrogel and PO, respectively.

A Comprehensive Study on the Chemical Characterization and Neuroprotective Evaluation of Pracaxi Nuts Extracts Obtained by a Sustainable Approach.

The Amazonian Pentaclethra macroloba (Willd.) Kuntze nuts contain a lipidic fraction with health-promoting effects, but little is known about the bioactivity of other constituents. In this study, the lipidic fraction obtained using supercritical fluid extraction (SFE) with CO2 was chemically characterized by using lipidomics techniques. The SFE-CO2 residue, named as pracaxi cake, was re-extracted by pressurized liquid extraction following a biorefinery approach. Using a response surface methodology and based on the extraction yield and different in vitro assays, two optimum conditions were obtained: 80% and 12.5% of ethanol at 180 °C. Under these conditions, extraction yield and different in vitro measurements related to neuroprotection were assessed. Chemical characterization of these extracts suggested the presence of triterpenoid saponins and spermidine phenolamides, which were not previously reported in pracaxi nuts. These results suggest that pracaxi oil extraction by-products are a valuable source of bioactive compounds with neuroprotective potential.

Let it Grow (Back): A Call for the Conservation of Secondary Forests as Medicinal Plant Habitat

Costa Rica is widely regarded as a global leader in conservation practices. In the Maquenque National Wildlife Refuge (MNWLR), within Costa Rica’s Northern Zone, a strong commitment to conservation has led to protecting highly biodiverse mature forests. However, a significant opportunity to strengthen conservation in this region is being overlooked at a great cost to the local community and environment: the protection of regenerating secondary forests. Secondary forests account for over 50% of global tropical forests and serve vital ecological and cultural functions. Within the MNWLR, many species in the secondary forests provide medicinal value to the rural communities where western medical care is difficult to access. Recent research, however, has shown that secondary forests in Costa Rica are re-cleared within 20 years, before they have accumulated the previously lost biomass and biodiversity. In this paper, we call for conservation and management strategies to incorporate community held knowledge about culturally significant species, and for there to be economic incentives for keeping secondary forests intact and for determining which forests are designated as Protected Areas. We discuss previous research with two trees that are common in secondary forests in the MNWLR (Vismia macrophylla and Pentaclethra macroloba), recognizing that these are some of the many species that have great potential to both the ecological and social communities. While our focus area is in the Northern Zone of Costa Rica, the integration of community use and local knowledge into conservation should be a global priority.

Characterization and subchronic oral toxicity of Pentaclethra macroloba (pracaxi) oil in Rattus norvegicus (lin. Wistar)

The trend of replacing antimicrobials as growth promoters in animal nutrition is growing. Functional oils emerge as an alternative because of their richness in bioactive compounds and bioavailability. The present study aims to evaluate the fatty acid profile, antioxidant capacity, composition of phenolic compounds, and toxic capacity in Wistar rats of pracaxi oil (Pentaclethra macroloba). DDPH (2,2-diphenyl-1-picrylhydrazyl), FRAP (Ferric Reducing Antioxidant Power), and ABTS (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) were performed to assess antioxidant capacity. The composition of phenolic compounds was determined by specific reagents. For the evaluation of subchronic oral toxicity, 40 Wistar albino rats (20 males and 20 females) were randomized into 10 groups with different levels of pracaxi oil administered orally. The doses administered were 0, 300, 600, 1200 and 2400 mg/kg (Group 1 to 5 females and Group 6 to 10 males). The animals were submitted to evaluations described in the OECD manual (Guide 407). The analytical results showed that pracaxi oil has different fatty acids in its chemical composition: oleic, linoleic, arachidic, and behenic acids, which account for more than 90% of its composition. In a smaller percentage, lauric acid (0.17%), myristic (0.09%), palmitic (1.49%), stearic (3.45%), and linolenic acid (1.39%) were also found. According to the results of the antioxidant tests, pracaxi oil has a high antioxidant capacity and is a product with a high presence of phenolic compounds. Regarding the toxicity assessment, there were no alterations in the clinical signs and weight of organs. However, in histology, there were mild alterations of a possible toxic process with the increase in the oil dose. This research is extremely valuable since pracaxi oil is a product with little information about its potential use in animal nutrition.

Pentaclethra macroloba: A Review of the Biological, Pharmacological, Phytochemical, Cosmetic, Nutritional and Biofuel Potential of this Amazonian Plant.

Pracaxi (Penthaclethra macroloba (Willd.) Kuntze) is an Amazonian plant, traditionally used by the native population to treat health disorders such as inflammation, erysipelas, wound healing, muscle pain, ear pain, diarrhea, snake and insect bites as well as for cancer treatment. Other common uses include using the oil for frying, skin and hair beautification, and as an alternative source of energy. This review is focused on highlighting its taxonomy, occurrence and botanical origins, popular uses, pharmacology and biological activities, cytotoxicity, biofuel activity and phytochemistry in order to explore future therapeutic use and other applications. Pracaxi contains triterpene saponins, sterols, tannins, oleanolic acid, unsaturated fatty acids and long-chain fatty acids, with a high behenic acid value, which may serve for incorporation into drug delivery systems as well for the development of new drugs. These components are correlated with its anti-inflammatory, antimicrobial, healing, anti-hemolytic, anti-hemorrhagic, antiophidic, and larvicidal activities against Aedes aegypti and Helicorverpa zea, which ratify the popular/traditional uses. The species is nitrogen fixing; it is easy to propagate in floodplains and the terra firma, and it can be used for the reforestation of degraded areas. Additionally, the oil extracted from the seeds can leverage the bioeconomy of the region based on sustainable exploration.

Antimicrobial effect of Pentaclethra Macroloba plant extract against Enterococcus Faecalis.

This study evaluated the antimicrobial efficacy of a new intracanal drug based on Pentaclethra macroloba extract, a plant of Amazonian origin, against Enterococcus faecalis using macrodilution test and intratubular evaluation with Confocal Laser Scanning Microscopy (CLSM). The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the pure extract of Pentaclethra macroloba andits association with calcium hydroxide and ultracall were determined. Then, thirty-three dentin cylinders were prepared and inoculated with E. faecalis, to evaluate the antimicrobial effect of the medications on the dentinal tubules with CLSM. The data was analyzed using the Kruskal-Wallis and Dunn tests. The extract in association with calcium hydroxide showed a lower CBM, and in the intratubular test all tested medications were effective against E. faecalis (P >0.05). The new intracanal drug based on P. macroloba extract has an antimicrobial effect against E. faecalis and further studies are needed for its clinical use.

Preparation and characterization of patauá and pracaxi Brazilian vegetable oil emulsions

In this work, the stability of oil-in-water emulsions (O/W) of patauá (Oenocarpus bataua) and pracaxi (Pentaclethra macroloba) oils, both from Amazon rainforest, was investigated. Low-energy emulsification methods were used, such as Emulsion Inversion Point (EIP) and Phase Inversion Temperature (PIT), both based on the minimal interfacial surface, combined with optimized Hydrophilic-Lipophilic Balance (HLB). Phase inversion was determined by electrical conductivity measurements. The surfactants used were Span® 80, Tween® 20, Tween® 60, and Tween® 80. Surfactant mixtures of Span® 80 + Tween® 80 were the best samples prepared. The composition of the most stable samples was 80.00 wt% aqueous phase, 15.00 wt% nonionic surfactants, and 5.00 wt% oil phase (patauá or pracaxi oil). The samples with the best kinetic results were those prepared with the required HLB and PIT values of 12.86 and 84.05 °C, for patauá oil, and of 9.61 and 79.50 °C for pracaxi oil. The kinetic stability of the oil emulsions was characterized by creaming index (CI), by evolution over time of the droplet size, viscosity, and electric conductivity. The results showed that: (1) the droplet size distribution influenced electric conductivity; (2) the relative amount of surfactants Tween® and Span® used is more important to determine the physicochemical and interfacial properties of the emulsion than the oil identity itself; (3) it is crucial to pay attention to the influence of air bubbles—involuntarily inserted into the mixture during the emulsification process—in the physicochemical properties of the system. These conclusions can be extended to other oil-in-water emulsions.

Pracaxi oil affects xenobiotic metabolisms, cellular proliferation, and oxidative stress without cytotogenotoxic effects in HepG2/C3A cells

Pentaclethra macroloba (Willd.) Kuntze seeds oil has been used as a topical healing agent, applied mainly to parturients and snake bites. The objective was to investigate the effects of pracaxi oil (POP) on HepG2/C3A cells under cytogenotoxicity, cell cycle and apoptosis influence, and expression of metabolism and other related cell types proliferation genes. Cytotoxicity was analyzed by MTT test and apoptosis and cell cycle interferences by flow cytometry. To identify genotoxicity were used comet and micronucleus tests. RT-qPCR investigated gene expression. PO chemical characterization has shown two significant triterpenes, identified as oleanolic acid and hederagenin. The results showed that the PO did not reduce cell viability at concentrations ranging from 31 to 500 μg/ml. Comet and micronucleus assays revealed the absence of genotoxic effects, and flow cytometry showed no cell cycle or apoptosis disturbance. RT-qPCR indicated that PO up-regulated genes related to metabolism (CYP3A4, CYP1A2, CYP1A1), cell proliferation (mTOR), and oxidative stress (GPX1). The data indicate that PO has no cytogenotoxic effects and suggest that it activated the PI3/AKT/mTOR cascade of cell growth and proliferation. Inside the cells, the PO activated xenobiotic metabolizing genes, responsible for reactive oxygen species (ROS) generation, can neutralize ROS with increased GPX1 gene expression without genetic damage, interruption of the cell cycle, or induction of apoptosis.

EFFECTS OF CANOPY OPENNESS ON SEEDLING SURVIVAL AND GROWTH AFTER SELECTIVE LOGGING IN A MONODOMINANT LOWLAND SWAMP FOREST IN COSTA RICA

The mechanism proposed to explain tree monodominance in tropical forests is that the dominant species forms a dense canopy and produces shade-tolerant seedlings, which together favor selfreplacement. Under this hypothesis, seedlings of monodominant species should have limited ability to respond to drastic increases in understory light, like those resulting from logging. Therefore, monodominant species should lose their seedling dominance after logging-induced canopy opening. To test this hypothesis, the current study measured seedling survival and growth of the monodominant species, Prioria copaifera, and its main competitor, Pentaclethra macroloba, in two forest stands that differ in logging history and in an unlogged stand in southeastern Costa Rica. Although, growth rates and survival of previously established seedlings were similar for both species across the three stands, seedling survival and growth decreased as light increased, with the effect being more pronounced for Prioria than for Pentaclethra. The study also investigated the ability of Prioria to respond to changing light environments by transplanting seedlings into logging-induced canopy gaps. Contrary to prediction, Prioria seedlings survived and grew better in gap centers than in gap edges or under a closed canopy. This result contrasts with established seedlings that cannot acclimate to changes in light conditions. Therefore, we conclude that continued Prioria dominance in selectively logged forests depends more on seedling production after canopy disturbance than on the established seedling present before disturbances.

Demographic and growth patterns of Pentaclethra macroloba (Willd.) Kuntze, a hyperdominant tree in the Amazon River estuary

AbstractLittle is known about the life history and environmental factors that regulate the growth rate of hyperdominant trees in flooded Amazonian forests. Pentaclethra macroloba is a hyperdominant tree, and it is widely explored in the Amazon, because its seed oil is a powerful herbal medicine. We evaluated the demographic structure and growth patterns of P. macroloba and tested the effect of the Amazon River flood pulse on its growth. We modeled the growth and determined the age of P. macroloba by analyzing the growth rings of 30 monitored trees in relation to hydroclimatic variables. We also inventoried 240 juvenile and 2072 adult trees arranged in a clustered pattern. The diametric distribution pattern of the juvenile and adult trees was exponential and log‐normal, respectively. The trees were found to be up to 102 years old, and 47% of them grew freely toward the canopy. Peak growth in height and diameter occurred at 24 (61.7 cm year‐1) and 46 (9.38 mm year‐1) years, respectively. Pentaclethra macroloba showed cambial dormancy during the seasonal peak of rainfall (R2 = 0.41; t = −2.62; p < 0.01) and flooding of the Amazon River (R2 = 0.47; t = −3.01; p < 0.01). Increases in rainfall and flood level of the river in the rainy season control the growth rate of P. macroloba, making it a seasonal process. The demographic and growth patterns of P. macroloba respond to the environmental heterogeneity of the estuarine floodplain forest and also reflect its life history over time.

Three‐Partner Symbiosis among Legumes, Mycorrhizae, and N‐Fixing Bacteria Changes with Light and Soil Nitrogen Conditions

Photo 1. A canopy gap at La Selva Biological Station in Costa Rica, created from treefalls during a storm. Seedlings planted under gap conditions were located here, and seedlings planted under understory conditions were in adjacent intact forest. Photo credit: Orlando Vargas Ramirez. Photo 2. Half of the seedlings planted in the gap were kept under a shade cloth to mimic understory light conditions (depicted in panel A). This experimental design allowed us to explore the effects of light alone on the tripartite symbiosis, as it is only one of many factors that vary between gaps and intact forest. Panel B is a top-down view of one of the experimental plots. There are two seedlings of each of the three legume species used in the experiment: (from top to bottom) Stryphnodendron microstachyum, Zygia longifolia, and Pentaclethra macroloba. Photo credit: Lindsay McCulloch. Photo 3. One mm of a root colonized by arbuscular mycorrhizal fungi, stained, and observed under 200× magnification. 100 such images were observed for each seedling to estimate the percentage of each seedling’s root system that was colonized by arbuscular mycorrhizal fungi. This metric was a proxy for carbon investment in arbuscular mycorrhizal fungi by the seedling. Photo credit: Nikayla Ficano. These photographs illustrate the article “Tripartite legume–rhizobia–mycorrhizae relationship is influenced by light and soil nitrogen in Neotropical canopy gaps” by Nikayla Ficano, Stephen Porder, and Lindsay A. McCulloch published in Ecology. https://doi.org/10.1002/ecy.3489.

Light fuels while nitrogen suppresses symbiotic nitrogen fixation hotspots in neotropical canopy gap seedlings.

Mature neotropical lowland forests have relatively lower symbiotic nitrogen fixation (SNF) rates compared with secondary forests. Canopy gap formation may create transient SNF hotspots in mature forests that increase overall SNF rates in these ecosystems, as canopy gaps are pervasive across the landscape and increasing in frequency. However, what environmental conditions are driving SNF upregulation in canopy gaps is unknown. In a field experiment to test these potential environmental controls on SNF, we grew 540 neotropical nitrogen-fixing legume seedlings (Pentaclethra macroloba, Zygia longifolia, and Stryphnodendron microstachyum) under manipulated light and soil nitrogen availability in canopy gaps and intact forests at La Selva Biological Station, Costa Rica. Seedling biomass, nodule biomass, and SNF (g N seedling-1 h-1 ) were 4-, 17- and 42-fold higher, respectively, in canopy gaps than in the intact forest. Nitrogen additions decreased SNF, but light had a stronger positive effect. Upregulation of SNF in canopy gaps was driven by increased plant growth and not a disproportionate increased SNF allocation. These data provide evidence that canopy gap SNF hotspots are driven, in part, by light availability, demonstrating a potential driver of SNF spatial heterogeneity. This further suggests that canopy gap dynamics are important for understanding the biogeochemistry of neotropical forests.

Light, nitrogen supply, and neighboring plants dictate costs and benefits of nitrogen fixation for seedlings of a tropical nitrogen-fixing tree.

The ability to fix nitrogen may confer a competitive advantage or disadvantage to symbiotic nitrogen-fixing plants depending on the availability of soil nitrogen and energy to fuel fixation. Understanding these costs and benefits of nitrogen fixation is critical to predicting ecosystem dynamics and nutrient cycling. We grew inoculated (with symbiotic bacteria) and uninoculated seedlings of Pentaclethra macroloba (a nitrogen-fixing tree species) both in isolation and with Virola koschnyi (a nonfixing species) under gradients of light and soil nitrogen to assess how the ability to fix nitrogen and fixation activity affect growth, biomass allocation, and responses to neighboring plants. Inoculation itself did not provide a growth advantage to nitrogen fixers, regardless of nitrogen limitation status. Higher nitrogen fixation rates increased biomass growth similarly for nitrogen-limited and nitrogen-saturated fixers. Nodule production was offset by reduced fine-root biomass for inoculated nitrogen fixers, resulting in no change in total belowground allocation associated with nitrogen fixation. Under nitrogen-limited conditions, inoculated nitrogen fixers partially downregulated fixation in the presence of a nonfixing neighbor. These results suggest that nitrogen fixation can provide a growth advantage, even under nitrogen-saturated conditions, and that nitrogen fixers may reduce fixation rates to minimize facilitation of neighbors.

Phenological behavior and floral visitors of Pentaclethra macroloba, a hyperdominant tree in the Brazilian Amazon River estuary

Phenological behavior and floral visitors of Pentaclethra macroloba, a hyperdominant tree in the Brazilian Amazon River estuary

Morphology, germination, and geographic distribution of Pentaclethra macroloba (Fabaceae): a hyperdominant Amazonian tree

Introduction: Pentaclethra macroloba is a hyperdominant tree in the Amazon estuary of great socioeconomic importance for the region because the oil from its seeds is a powerful herbal medicine. Objective: We aimed to characterize the morphological structure, the morphological adaptations in response to the daily flooding of the Amazon estuary and the biogeographic area of P. macroloba. Methods: Detailed description of the external morphology, from germination to the adult tree, was obtained from individuals located in floodplain forest, Northeast Amazonia. The occupation area and the geographical extension of P. macroloba were determined from point of geographical coordinates of botanical samples deposited in the digital collections of Mobot and SpeciesLink. Results: Adult individuals have adapted structures in response to daily flooding, such as: adventitious roots to increase respiratory efficiency and lenticels in the trunk, serving as a connection point for oxygen transport between the root and the aerial part. Dried fruit favours the activation of the explosive dehiscence mechanism, allowing the seed to be expelled long distance. Deltoid shape of the seed allows water fluctuation and more efficient dispersal. Seedling is phanerocotylar hypogeal and with one pair of reserve cotyledons that provide the seedling an extra source of energy to escape the flood. Germination rate was 78 % and the speed was 0.2 seeds.day-1. Circular buffer method revealed the presence of 123 subpopulations of P. macroloba distributed in a radius of 5 699 943 km² across the Neotropical region. Conclusions: Much of the morphological structures of P. macroloba are adaptive and evolutionary responses to the periodically flooded environment of the Amazon estuary, showing that these environments select the trees, best adapted, to inhabit the flood. P. macroloba has a wide geographical area denotes the plasticity of adapting to different environments, which may justify its monodominance in some regions.

Influence of Two Important Leguminous Trees on Their Soil Microbiomes and Nitrogen Cycle Activities in a Primary and Recovering Secondary Forest in the Northern Zone of Costa Rica

Inga edulis and Pentaclethra macroloba are dominant N-fixing forest trees in Costa Rica, likely important for recovery of soil N and C after deforestation, yet little is known of their soil microbiomes nor how land use impacts them. Soils from both trees in a primary and secondary forest were assessed for N-cycle metrics and DNA sequence-based composition of total bacterial, potential N-fixing bacterial, and potential ammonium oxidizing bacterial genera. The compositions of the functional groups of bacteria, but not their total relative abundance of DNA, were different across the soils. The P. macroloba soils had greater NO3− levels and richness of both functional groups, while I. edulis soils had greater NH4+ levels, consistent with its NH4+ preference for root nodule development. The bacterial communities were different by habitat, as secondary forest I. edulis microbiomes were less rich, more dominant, possibly more affected by the disturbance, or reached equilibrium status quicker than the richer, less dominant P. macroloba microbiomes, which may be developing slower along with secondary forest succession, or were less affected by the disturbance. Functional redundancy and switching of 10 N-cycle bacterial genera was evident between the primary and secondary forest soils, likely to maintain stable levels of N-cycle activity following disturbance. In summary, the two tree soil microbiomes are different, land use differentially affects them, and, thus, both tree species should be used during forest regeneration strategies in this region.

Differences in the soil microbiomes of Pentaclethra macroloba across tree size and in contrasting land use histories

Legacy attributes from land-use history have lingering effects on soil and its below-ground components undergoing succession that has important consequences for regenerating tropical secondary forests. Yet, even landscapes of similar origins with analogous land-use histories have exhibited differing routes of forest recovery with different outcomes. There is increasing evidence that tree species-generated soil microbial heterogeneity is an important factor in facilitating regeneration, particularly nitrogen (N)-fixing tree species. However, it is unclear how land-use history influences the soil microbiome of important N-fixing plants developing under these conditions; at different life stages of N-fixing plant development; and how this compares to a primary forest. We examined differences in composition of the soil bacterial and fungal communities and their determinants (i.e. soil environmental factors) associated with large-, medium-, and small-sized Pentaclethra macroloba trees in a primary forest and in a 23-year-old secondary forest with contrasting land-use histories. We show that as Pentaclethra increases in size (and/or age), the soil microbiome associated with Pentaclethra also changes, and that these soil microbiomes can become similar even when developed in soils of contrasting land-use histories. We found that soil NH4+ and NO3− explained 61% of the variation in the soil bacterial community composition of small trees between the primary and secondary forest. This highlights the importance of inorganic N during tree soil microbiome development in contrasting land-use history of soils. Our findings suggest that legacy effects on may be mediated through size (and/or age) of Pentaclethra and its associated soil microbiome.

Composition, thermal behavior and antioxidant activity of pracaxi (Pentaclethra macroloba) seed oil obtained by supercritical CO2

Abstract The Amazonian tree Pentaclethra macroloba (pracaxi) has pod-shaped fruits with flattened seeds mostly composed of lipids, carbohydrates, and proteins, besides secondary compounds, which provide potential use by many industries. This study evaluated the supercritical carbon dioxide (SC-CO2) extraction of pracaxi seed oil (PSO) at different conditions of pressure (200–300 bar) and temperature (40–60 °C). The PSO was assessed for its fatty acids and triacylglycerols (TAG) compositions, total phenolic content and antioxidant activity, as well as the oxidative stability and thermal behavior. SC-CO2 extractions provided oil yields (Ye) from 12 to 42 g/100 g, which represented up to 79% of the Ye obtained with hexane (Soxhlet). The pressure was the only significant variable (p