Tabebuia Species Research Articles

Seasonal metabolic variation in the essential oil composition of various Tabebuia species and evaluation of their anti-inflammatory activity in vitro and in silico.

The seasonal variation in essential oil from four Tabebuia species, T. impetiginosa, T. rosea, T. argentea, and T. guayacan, was explored using gas chromatography-mass spectrometry analysis. A total of 90 components were tentatively identified. Among the four Tabebuia species, the most predominant components in spring were phytol (67.5%), limonene (50.1%), (Z,Z,Z)-7,10,13-hexadecatrienal (67.5%), and 1-octen-3-ol (80.4%), respectively. Chemometric discrimination of the four Tabebuia species was performed employing principal component analysis, which classified the samples into three main clusters while the rest of the samples were scattered in the whole plot. The season of collection impact on essential oils composition and yield was illustrated. 5-Lipooxygenase inhibitory effect of spring season essential oils was assessed, showing that all essential oils exhibited certain inhibition, where T. rosea showed the most potent effect, exhibiting an IC50 value of 1.8 μg/mL, compared to the standard zileuton (0.68 μg/mL). Moreover, an in silico molecular docking study was performed for the predominant metabolites against the 5-LOX active pocket. Among all the docked compounds, eicosane showed the best fitting score, then norphytane, with ∆G of -38.39 and -29.77 kcal/mol, respectively. Thus, Tabebuia species could offer a natural and relatively safe anti-inflammatory candidate that requires further clinical trials to be supported.

Identification of Commercial Cultivars in the Tabebuia Alliance Using Genotyping-by-Sequencing

The Tabebuia alliance is widely planted in tropical and subtropical countries. However, the lack of accurate taxonomic information for many commercial cultivars leads to commercial disputes. We sought to clarify the background of commercial cultivars in China and to provide a robust basis for patent protection. We collected 82 Tabebuia cultivars and 12 reference individuals, then developed large-scale single nucleotide polymorphism (SNP) markers using genotyping-by-sequencing. We obtained 73,219 SNPs from the test samples, which represented a substantial increase compared with previous studies of Tabebuia species. Based on these SNPs and a clustering analysis, we detected six species among the samples, as well as an uncertain population which may be a hybrid between Handroanthus impetiginosus (Mart. ex DC) Mattos and H. heptaphyllus (Vell.) Mattos. An analysis of genetic diversity to assess germplasm resources indicated that excessive heterozygosity of these cultivars in China, which may explain the genetic basis of “novel-preferred” selection in ornamental plants or a narrow genetic background. After rigorous selection, we identified numerous high-quality molecular markers for cultivar identification, then constructed a concise fingerprint with 54 SNPs. Our work clarifies the background information of commercial cultivars of Tabebuia in China and provides information for cultivar identification. It will serve as an important technical resource for genetic studies, and it will help to protect patents that involve Tabebuia species.

Characterization of Promising Cytotoxic Metabolites from Tabebuia guayacan Hemsl.: Computational Prediction and In Vitro Testing.

Genus Tabebuia is famous for its traditional uses and valuable phytoconstituents. Our previous investigation of Tabebuia species noted the promising anticancer activity of T. guayacan Hemsl. leaves extract, however, the mechanism underlying the observed anticancer activity is still unexplored. The current research was designed to explore the phytochemical content as well as to address the phytoconstituent(s) responsible for the recorded anticancer activity. Accordingly, sixteen compounds were isolated, and their structures were elucidated using different spectroscopic techniques. The drug-likeness of the isolated compounds, as well as their binding affinity with four anticancer drug target receptors: CDK-2/6, topoisomerase-1, and VEGFR-2, were evaluated. Additionally, the most promising compounds were in vitro evaluated for inhibitory activities against CDK-2/6 and VEGFR-2 enzymes using kinase assays method. Corosolic acid (3) and luteolin-7-O-β-glucoside (16) were the most active inhibitors against CDK-2 (−13.44 kcal/mol) and topoisomerase 1 (−13.83 kcal/mol), respectively. Meanwhile, quercetin 3-O-β-xyloside (10) scored the highest binding free energies against both CDK-6 (−16.23 kcal/mol) as well as against VEGFR-2 protein targets (−10.39 kcal/mol). Molecular dynamic simulation indicated that quercetin 3-O-β-xyloside (10) exhibited the least fluctuations and deviations from the starting binding pose with RMSD (2.6 Å). Interestingly, in vitro testing results confirmed the potent activity of 10 (IC50 = 0.154 µg/mL) compared to IC50 = 0.159 µg/mL of the reference drug ribociclib. These findings suggest the three noted compounds (3, 10, and 16) for further in vivo anticancer studies.

DNA fingerprinting of five Tabebuia species with reference to their anti-trypanosomal activity

DNA fingerprinting of five Tabebuia species with reference to their anti-trypanosomal activity

New derivatives of the iridoid specioside from fungal biotransformation.

Iridoids are widely found from species of Bignoniaceae family and exhibit several biological activities, such as anti-inflammatory, antimicrobial, antioxidant, and antitumor. Specioside is an iridoid found from Tabebuia species, mainly in Tabebuia aurea. Thus, here fungus-mediated biotransformation of the iridoid specioside was investigated by seven fungi. The fungus-mediated biotransformation reactions resulted in a total of nineteen different analogs by fungus Aspergillus niger, Aspergillus flavus, Aspergillus japonicus, Aspergillus terreus, Aspergillus niveus, Penicillium crustosum, and Thermoascus aurantiacus. Non-glycosylated specioside was the main metabolite observed. The other analogs were yielded from ester hydrolysis, hydroxylation, methylation, and hydrogenation reactions. The non-glycosylated specioside and coumaric acid were yielded by all fungi-mediated biotransformation. Thus, fungus applied in this study showed the ability to perform hydroxylation and glycosidic, as well as ester hydrolysis reactions from glycosylated iridoid. KEY POINTS: • The biotransformation of specioside by seven fungi yielded nineteen analogs. • The non-glycosylated specioside was the main analog obtained. • Ester hydrolysis, hydroxylation, methylation, and hydrogenation reactions were observe.

Metabolic profiling of cytotoxic metabolites from five Tabebuia species supported by molecular correlation analysis

Tabebuia is the largest genus among the family Bignoniaceae. Tabebuia species are known for their high ornamental and curative value. Here, the cytotoxic potential of extracts from the leaves and stems of five Tabebuia species was analyzed. The highest activity was observed for T. rosea (Bertol.) DC. stem extract against HepG2 cell line (IC50 4.7 µg/mL), T. pallida L. stem extract against MCF-7 cell line (IC50 6.3 µg/mL), and T. pulcherrima stem extract against CACO2 cell line (IC50 2.6 µg/mL). Metabolic profiling of the ten extracts using liquid chromatography–high-resolution mass spectrometry for dereplication purposes led to annotation of forty compounds belonging to different chemical classes. Among the annotated compounds, irridoids represent the major class. Principle component analysis (PCA) was applied to test the similarity and variability among the tested species and the score plot showed similar chemical profiling between the leaves and stems of both T. pulcherrima and T. pallida L. and unique chemical profiling among T. rosea (Bertol.) DC., T. argentea Britton, and T. guayacan (Seem.) Hemsl. leaf extracts and the stem extract of T. rosea (Bertol.) DC. Additionally, a molecular correlation analysis was used to annotate the bioactive cytotoxic metabolites in the extracts and correlate between their chemical and biological profiles.

Characterization of the first chloroplast genome of Tabebuia (Bignoniaceae)

The chloroplast genome of Tabebuia nodosa is described and characterized here. This species is endemic to the Chaco and the first species of Tabebuia to have its organelle genome sequenced, providing a genomic resource for phylogenetic inferences. The plastome of T. nodosa is 158,454 bp in length, with a large single-copy of 85,406 bp, a small single-copy of 12,785 bp, and inverted repeats of 30,116 bp each. It contains 131 genes, with 86 protein-coding genes, 37 tRNA, and 8 rRNA. Overall, the GC content is 38.2%. The T. nodosa plastome resembles the structural organization of plastomes commonly found in flowering plants, including those of other genera of Bignoniaceae. A phylogenetic analysis combining a subset of Bignoniaceae plastomes confirms the placement of T. nodosa within the Tabebuia alliance with maximum support.

Fingerprinting of cerrado species based on cork lipophilic constituents

Cerrado is a savanna ecosystem of central and southeastern Brazil. Many woody species of cerrado have thick layers of cork. The present work aimed to characterize, by GC/MS analysis, the constituents of n-hexane extracts from the cork of common species from cerrado. Cork samples from 31 individuals, corresponding to 14 species and six families, were analyzed. Similarities and differences were noticed between cork and cuticular waxes regarding profiles of lipophilic constituents. The distribution of cork constituents was analyzed using the UPGMA clustering method and DICE coefficient. All clusters in the dendrogram obtained comprise individuals from a same species, suggesting that the distribution of lipophilic cork constituents is useful for species characterization and possibly also for species identification, resembling results commonly obtained with molecular markers. Seven samples of Bignoniaceae, corresponding to two genera and seven species, emerged in a common cluster, in an arrangement in accordance with the recent segregation of Tabebuia species to a new genus Handroanthus. The markers analyzed were not efficient regarding characterization of other families.

Green synthesis of silver nanoparticles using leaf extract from Tabebuia roseoalba and T. pentaphylla

Metal nanoparticles are nanostructures that can be applied to biotechnology because they present different biological activities. Among them, the silver nanoparticles (AgNPs) are known to present antimicrobial activity allowing their application in several areas such as medicine and industry. The biological synthesis of AgNPs is ecologically correct and advantageous techniques. The objective of this work was to evaluate the synthesis of AgNps through the green synthesis using extracts of leaves of Tabebuia roseoalba and T. pentaphylla grown in vivo and in vitro. The nanoparticle synthesis solution was colorimetrically evaluated, and the nanoparticles were physically characterized. The results obtained demonstrate that both extracts of both Tabebuia species tested are able to synthesize AgNPs, however only when cultured under in vivo conditions. These data suggest that photosynthesis under natural conditions promotes the production of metabolites that are essential to green synthesis.

Taxonomy, phylogeny, and divergence time estimation for Apiosphaeria guaranitica, a Neotropical parasite on bignoniaceous hosts

ABSTRACTApiosphaeria guaranitica, the causal agent of brown crust disease of several bignoniaceous hosts, among them Handroanthus and Tabebuia species, has been traditionally placed in Phyllachoraceae, based exclusively on morphological studies, without supporting molecular evidence. Here, we provide molecular data for the link between sexual and asexual states of the fungus and elucidate the phylogeny of A. guaranitica. The multilocus phylogenetic analyses employed sequences from the 18S subunit (18S), 28S subunit (28S), and nuclear internal transcribed spacers (ITS1-5.8S-ITS2 = ITS) of the nuc rDNA, second-largest subunit of RNA polymerase II (RPB2), and translation elongation factor 1-α (TEF1) genetic loci. Estimates of the divergence time of this lineage were supported by fossil calibration (FC) and secondary calibration (SC) strategies. Our results indicate a natural placement of Apiosphaeria within Diaporthaceae (Diaporthales), where it represents an ancient lineage of the crown group of Diaporthaceae, diverging during the late Paleocene at 61.15 (FC) and 60.63 (SC) million years ago. This divergence time estimate within Diaporthales is based on Spataporthe taylori, a diaporthaceous fossil.

Use of counter-current chromatography as a selective extractor for the diterpenequinone 7α-hydroxyroyleanone from Tetradenia riparia

A solvent system was developed for selective isolation by high-speed counter-current chromatography (HSCCC) of the benzoquinone 7α-hydroxyroileanone, 1, a bioactive diterpene from a dichloromethane extract of Tetradenia riparia leaves. Several solvent systems were initially studied, including hexane-ethyl acetate-methanol-water in several ratios, hexane-acetone-methanol-water, hexane-ethanol-water and hexane-acetonitrile-methanol, which gave recovery rates for the target compound between 13.4 and 35.9%. The new solvent system hexane-5% aqueous Na2CO3 (1:1) was developed based on the chemical ionization reaction of the benzoquinone hydroxyl group in the basic pH of the carbonate solution, prompted by the extraction procedure used for the extraction of lapachol (a natural naphtoquinone) from a Tabebuia species wood. By using the HSCCC chromatograph as a liquid–liquid extractor with the above mentioned solvent system the recovery rate of 1 increased to 81.8%, affording the quinone with 97% purity.

Redox Center Modification of Lapachones towards the Synthesis of Nitrogen Heterocycles as Selective Fluorescent Mitochondrial Imaging Probes

We describe herein a synthetic strategy for the synthesis of new fluorescent imidazole and phenazine derivatives synthesized from lapachol, a naturally occurring naphthoquinone isolated from Tabebuia species (ipê tree). The photophysical properties and computational details of these compounds have been studied, aiming at gaining a complete understanding of the potential of these derivatives as probes capable of staining mitochondria selectively. Cell imaging experiments proved the capacity of the imidazole derivatives as selective fluorescent mitochondrial imaging probes. These heterocycles present the same staining patterns as MitoTracker Red, corroborating the potential of these compounds as new mitochondria markers permeable to the cell membrane.

Effects of the Aqueous Extract from Tabebuia roseoalba and Phenolic Acids on Hyperuricemia and Inflammation.

Tabebuia species (Bignoniaceae) have long been used in folk medicine as anti-inflammatory, antirheumatic, antimicrobial, and antitumor. The aim of this study was to investigate if aqueous extract from the leaves (AEL) of Tabebuia roseoalba (Ridl.) Sandwith, Bignoniaceae, and its constituents could be useful to decrease serum uric acid levels and restrain the gout inflammatory process. HPLC analysis identified caffeic acid and chlorogenic acid in AEL. Antihyperuricemic effects and inhibition of liver XOD (xanthine oxidoreductase) by AEL and identified compounds were evaluated in hyperuricemic mice. Anti-inflammatory activity was evaluated on MSU (monosodium urate) crystal-induced paw edema. In addition, AEL antioxidant activity in vitro was evaluated. AEL, caffeic, and chlorogenic acids were able to reduce serum uric acid levels in hyperuricemic mice probably through inhibition of liver xanthine oxidase activity and significantly decreased the paw edema induced by MSU crystals. AEL showed significant antioxidant activity in all evaluated assays. The results show that the AEL of Tabebuia roseoalba can be a promising agent for treatment for gout and inflammatory diseases. We suggest that caffeic and chlorogenic acids may be responsible for the activities demonstrated by the species.

Tabebuia roseoalba: In Vivo Hypouricemic and Anti-inflammatory Effects of Its Ethanolic Extract and Constituents.

Tabebuia species have several uses in folk medicine, including their use to treat inflammation and rheumatism. The aim of this study was to investigate whether the ethanolic extract of leaves from Tabebuia roseoalba and isolated compounds could be useful to decrease serum uric acid levels and restrain the gout inflammatory process. The compounds α-amyrin, β-amyrin, sitosterol, and stigmasterol were isolated from the ethanolic extract. Rutin and caffeic acid were identified in the ethanolic extract by HPLC analysis. The anti-hyperuricemic effect, liver xanthine oxidoreductase inhibition, and anti-inflammatory activity of the ethanolic extract and isolated compounds were evaluated on hyperuricemic mice and on paw edema induced by monosodium urate crystals in mice. The ethanolic extract of leaves from T. roseoalba, β-amyrin, and stigmasterol were able to reduce serum uric acid levels in hyperuricemic mice through inhibition of liver xanthine oxidase activity and significantly decreased the paw edema induced by monosodium urate crystals. The antioxidant activity of the ethanolic extract and its ability to inhibit xanthine oxidase were also evaluated in vitro. The ethanolic extract of leaves from T. roseoalba showed significant antioxidant activity in the three evaluated assays. Results were analyzed using GraphPad Prism 5.01. One-way ANOVA followed by Student's Newman-Keul's test was used to determine the significant differences between groups. The results show that the ethanolic extract of leaves from T. roseoalba, β-amyrin, and stigmasterol can be promising agents for the treatment for gouty arthritis, hyperuricemia, and inflammation. Stigmasterol, β-amyrin, and rutin contribute to the observed effects of the ethanolic extract of leaves from T. roseoalba.

Fluorescent oxazoles from quinones for bioimaging applications

This work describes a synthetic strategy for the syntheses of four new fluorescent excited state intramolecular proton transfer (ESIPT) prone oxazole derivatives synthesized from lapachol, a naturally occurring naphthoquinone isolated from the Tabebuia species (ipe tree).

Separation of New Naphthoxazole Derivatives of Lapachol by High-Speed Counter-Current Chromatography

This work describes the use of high-speed counter-current chromatography as an efficient and economic method in the separation and purification of new naphthoxazolic heterocyclic derivatives from lapachol (1), a naturally occurring naphtoquinone from different species of Tabebuia. A series of naphthoxazoles was obtained by nucleophilic condensation of lapachol (1) with aromatic aldehydes in ammonium medium. Each reaction led to the formation of two main products, derivatives from β-xyloidone, and the naphthoxazoles with the isoprenyl side chain of lapachol (1). Reaction products were purified by counter-current chromatography, using hexane–acetonitrile–methanol (2:2:1, v/v/v) as a non-aqueous solvent system.

Morphological phylogenetics of Bignoniaceae Juss.

The most recent classification of Bignoniaceae recognized seven tribes, Phylogenetic and monographic studies focusing on clades within Bignoniaceae had revised tribal and generic boundaries and species numbers for several groups, the portions of the family that remain most poorly known are the African and Asian groups. The goal of the present study is to identify the primary lineages of Bignoniaceae in Egypt based on macromorphological traits. A total of 25 species of Bignoniaceae in Egypt was included in this study (Table 1), along with Barleria cristata as outgroup. Parsimony analyses were conducted using the program NONA 1.6, preparation of data set matrices and phylogenetic tree editing were achieved in WinClada Software. The obtained cladogram showed that within the studied taxa of Bignoniaceae there was support for eight lineages. The present study revealed that the two studied species of Tabebuia showed a strong support for monophyly as well as Tecoma and Kigelia. It was revealed that Bignonia, Markhamia and Parmentiera are not monophyletic genera.

Restoring abandoned pasture land with native tree species in Costa Rica: Effects of exotic grass competition and light

Understanding the early establishment requirements and performance of tropical tree seedlings is essential to ensuring the success of restoration plantings. This study was designed to characterize growth and light requirements of six common neotropical tree species Pseudosamanea guachapele (Fabaceae), Tabebuia impetiginosa (Bignoniaceae), Ceiba pentandra (Bombacaceae), Pachira quinata (Bombacaceae), Dalbergia retusa (Fabaceae), and Tabebuia rosea (Bignoniaceae) in an abandoned pasture under contrasting light environments and grass competition. Field studies were conducted in the pastures of the Santa Ana Conservation Center in Costa Rica. Two differing grass competition sites were selected, one dominated by a tall grass, Hyparrhenia rufa and another dominated by a short grass, Cynodon mlenfluensis. Three light treatments were created (2, 37 and 100% light) using either neutral shade cloth (2 and 37%) or no shade cloth (100%). Growth characteristics and biomass partitioning of the seedlings were measured. Species differed in their relative growth rates (RGRs). The light × species interaction was significant at both sites. While all species had similar performance under 100% light on both short grass and tall grass sites, species growth differences were evident under 37 and 2% light levels. For example, at the short grass site, T. rosea had higher RGR than D. retusa and P. quinata under 2% light whereas both Tabebuia species performed better than other species at the tall grass site. The general trend was to increase root mass ratio and decrease leaf mass ratio with increasing levels of light. As an initial step for restoring abandoned pasture lands we recommend using all these species in direct and moderate light conditions. Incorporating all species will create a more heterogeneous environment. Choosing light demanding species that can tolerate grass competition may help ensure success in the early stage of restoration.

Anatomia foliar com implicações taxonômicas em espécies de ipês

Tendo em vista a dificuldade de identificação dos ipês brasileiros em estado vegetativo, este trabalho objetivou levantar caracteres que possibilitassem reconhecê-los pela anatomia foliar (lâmina foliar e pecíolo). Folhas de seis espécies de Handroanthus (ipês amarelos: H. chrysotrichus, H. ochraceus e H. serratifolius; ipê branco: H. roseo-albus; ipês roxos: H. heptaphyllus e H. impetiginosus) e de uma espécie de Tabebuia (ipês amarelo: T. aurea) foram preparadas para observação em microscopias de luz (exame histológico) e eletrônica de varredura (exame de superfície). Caracteres provenientes da anatomia foliar possibilitaram a diagnose dos ipês, sendo mais relevantes na lâmina foliar, o número de camadas da epiderme, a posição dos estômatos em relação às demais células epidérmicas, a presença de domácias, a presença de espessamento de parede das células parenquimáticas na margem, o tipo de mesofilo e a presença de parênquima paravenal; no pecíolo, destacaram-se seu formato, a forma das células epidérmicas e a presença de fibras na região interna do floema.

Ontogenia da semente de Tabebuia ochracea (Cham.) Standl. (Bignoniaceae)

The present work describes seed ontogeny in T. ochracea through histological analysis with special reference to the endospermogenesis. The ovule is anatropous, unitegmic and tenuinucelate; hypostase, nutrient passage route and endothelium are present. The endosperm is cellular with posterior development of Catalpa type. The chalazal haustorium of endosperm is primary, bicellular and it is totally degenerated during seed maturity; on the contrary the micropylar one is secondary, multicellular, differentiates latter, and remains active until the seed maturity.A latter differentiated endosperm was observed forming, together with the endothelium, a membranaceous envelope of the embryos. The endospermogenesis are in accord with previous results from other species of Tabebuia. Furthermore, the micropylar haustorium diferentiation and the membranaceous envelope origin were elucidated, the latter probably is the same in other species that present this structure.