Molecular phylogenetics and character evolution of the “sacaca” clade: Novel relationships of Croton section Cleodora (Euphorbiaceae)

Exploring four South African Croton species for potential anti-inflammatory properties: in vitro activity and toxicity risk assessment

ETHNOPHARMACOLOGICAL RELEVANCE

The African Continent harbours approximately 26 Croton species. Many Croton species are used in traditional medicine in southern Africa to treat a variety of ailments including malaria, tuberculosis, microbial infection and inflammation. Considering the high diversity of the genus Croton, the ethnopharmacological information available on southern African species is rather limited. Furthermore, the potential for novel anti-inflammatory drug scaffolds has not previously been investigated.

AIM OF THE STUDY

The aim of the study was to evaluate the potential of four South African Croton species extracts (Croton gratissimus, Croton pseudopulchellus, Croton sylvaticus, and Croton steenkampianus) for anti-inflammatory activity targeting the TLR4 signalling pathway and to assess the potential risk for hepatotoxicity and genotoxicity using an in vitro cellomics approach.

MATERIAL AND METHODS

Leaf extracts of C. gratissimus, C. pseudopulchellus, C. sylvaticus and C. steenkampianus were prepared using methanol and chloroform (1:1, v/v). The anti-inflammatory activity was determined using LPS induced nitric oxide production in RAW 264.7 macrophages, while the hepatotoxicity and genotoxicity was evaluated using multi-parameter end point analysis in C3A and Vero cells, respectively. Mitochondrial membrane potential, mitochondrial mass, oxidative stress, lysosomal content and lipid accumulation were used as markers to assess the risk for hepatotoxicity.

RESULTS

All four species attenuated nitric oxide production with negligible cytotoxicity. However, C. gratissimus yielded the most favorable profile. Cell density was significantly reduced in both C3A and Vero cells with the C. gratissimus extract providing a suitable toxicity profile amenable to further high content analysis. While there was no meaningful effect on mitochondrial dynamics, a strong dose dependent increase in lipid content, paralleled by an expansion of the lysosomal compartment, identifies a potential risk for steatosis. Risk for genotoxicity was investigated using the micronucleus assay which revealed a dose dependent increase in micronuclei formation. Changes in nuclear morphology and cell ploidy further strengthens the associated risk for genotoxicity and suggests the extract from C. gratissimus may function as an aneugen. Collectively, the data demonstrates that although the selected species possess anti-inflammatory components, the risk for possible hepatotoxic and genotoxic side effects may negate their prospect towards further drug development.

Diversity of Croton (Euphorbiaceae) in the Itatiaia National Park, Brazil

Abstract In this work, we provide a taxonomic treatment of Croton species from Itatiaia National Park - INP. The taxonomic study was based on herbarium collections, besides fieldwork to understand the morphological variability of the species. We have recorded seven species of Croton at the INP: C. alchorneicarpus, C. campanulatus, C. dichrous, C. floribundus, C. lundianus, C. organensis and C. vulnerarius, of which two are endemic of the Montane Ombrophilous Forests of Serra da Mantiqueira - C. alchorneicarpus and C. campanulatus.

Phylogeny and biogeography of Astraea with new insights into the evolutionary history of Crotoneae (Euphorbiaceae)

We investigated species relationships in Astraea, a primarily Neotropical genus of tribe Crotoneae centered in Brazil, using data from the nuclear ribosomal ITS, and the plastid trnL-trnF and psbA-trnH spacers. With all species of Astraea sampled, along with representatives from across Crotoneae, the evolutionary history of Astraea was interpreted in a broader framework, as well as divergence time estimates and reconstructions of ancestral areas and morphological character states for Crotoneae. Our results show that Astraea is monophyletic, consisting of three main clades, and that most of its diversification took place from the Oligocene to the Pliocene, coincident with the formation of the South American "dry diagonal". As for Crotoneae, our data show incongruent phylogenetic positions between the nuclear and chloroplast data for most of its genera, and that the ancestor of the tribe was probably arborescent and might have occupied the Amazon Basin, most likely in moist forest, from which it spread throughout South America in the early Eocene. Ancestral state reconstruction recovered deeply lobed leaves and staminate petals bearing moniliform trichomes as putative synapomorphies for Astraea, whereas the absence or strong reduction of pistillate petals is widespread in Crotoneae and may be a synapomorphy for the tribe.

Free radicals and ultrafine particulate emissions from the co-pyrolysis of Croton megalocarpus biodiesel and fossil diesel

BACKGROUND

The atmosphere has become a major transport corridor for free radicals and particulate matter from combustion events. The motivation behind this study was to determine the nature of particulate emissions and surface bound radicals formed during the thermal degradation of diesel blends in order to assess the health and environmental hazards of binary transport fuels.

METHODOLOGY

Accordingly, this contribution explored the interactions that occur when Croton megalocarpus biodiesel and fossil diesel in the ratio of 1:1 by weight were co-pyrolyzed in a quartz reactor at a residence time of 0.5 s under an inert flow of nitrogen at 600 °C. The surface morphology of the thermal char formed were imaged using a Feld emission gun scanning electron microscope (FEG SEM) while Electron paramagnetic resonance spectrometer (EPR) was used to explore the presence of free radicals on the surface of thermal char. Molecular functional groups adsorbed on the surface of thermal char were explored using Fourier transform infrared spectroscopy (FTIR).

RESULTS

FTIR spectrum showed that the major functional groups on the surface of the char were basically aromatic and some methylene groups. The particulate emissions detected in this work were ultrafine (~ 32 nm). The particulates are consistent with the SEM images observed in this study. Electron paramagnetic resonance results gave a g-value of 2.0027 characteristic of carbon-based radicals of aromatic nature. Spectral peak-to-peak width (∆Hp-p) obtained was narrow (4.42 G).

CONCLUSIONS

The free radicals identified as carbon-based are medically notorious and may be transported by various sizes of particulate matter on to the surface of the human lung which may trigger cancer and pulmonary diseases. The nanoparticulates determined in this work can precipitate severe biological health problems among humans and other natural ecosystems.

Phytochemical analysis and anti-inflammatory evaluation of compounds from an aqueous extract of Croton cajucara Benth

Croton cajucara Benth. is a medicinal plant popularly used in the Brazilian Amazonia, where it is known as sacaca, being consumed as tea, decoction or infusion of the leaves and stem bark. From a decoction of the leaves, a comprehensive phytochemical analysis was developed by liquid chromatography-mass spectrometry. Many compounds were identified for the first time in C. cajucara, such as O-glycosides of kaempferol and quercetin, flavonoid-C-glycosides, tannins and cinnamic acid derivatives. These compounds were fractionated by polarity and assayed for their anti-inflammatory activity, using a model of mice edema, induced by an intraplantar injection of carrageenan. All fractions exhibited anti-inflammatory properties.

Force of habit: shrubs, trees and contingent evolution of wood anatomical diversity using Croton (Euphorbiaceae) as a model system

Background and Aims

Wood is a major innovation of land plants, and is usually a central component of the body plan for two major plant habits: shrubs and trees. Wood anatomical syndromes vary between shrubs and trees, but no prior work has explicitly evaluated the contingent evolution of wood anatomical diversity in the context of these plant habits.

Methods

Phylogenetic comparative methods were used to test for contingent evolution of habit, habitat and wood anatomy in the mega-diverse genus Croton (Euphorbiaceae), across the largest and most complete molecular phylogeny of the genus to date.

Key Results

Plant habit and habitat are highly correlated, but most wood anatomical features correlate more strongly with habit. The ancestral Croton was reconstructed as a tree, the wood of which is inferred to have absent or indistinct growth rings, confluent-like axial parenchyma, procumbent ray cells and disjunctive ray parenchyma cell walls. The taxa sampled showed multiple independent origins of the shrub habit in Croton , and this habit shift is contingent on several wood anatomical features (e.g. similar vessel-ray pits, thick fibre walls, perforated ray cells). The only wood anatomical trait correlated with habitat and not habit was the presence of helical thickenings in the vessel elements of mesic Croton .

Conclusions

Plant functional traits, individually or in suites, are responses to multiple and often confounding contexts in evolution. By establishing an explicit contingent evolutionary framework, the interplay between habit, habitat and wood anatomical diversity was dissected in the genus Croton . Both habit and habitat influence the evolution of wood anatomical characters, and conversely, the wood anatomy of lineages can affect shifts in plant habit and habitat. This study hypothesizes novel putatively functional trait associations in woody plant structure that could be further tested in a variety of other taxa.

An overview of recent taxonomic studies on Euphorbiaceae s.l. in Brazil

The Euphorbiaceae sensu lato are distributed mainly in the tropics, in various types of vegetation and habitats, being one of the largest, most complex and diverse families of angiosperms. It has recently been divided into four families, according to classification systems based on molecular phylogeny: Euphorbiaceae sensu stricto, Phyllanthaceae, Putranjivaceae, and Picrodendraceae. There is a proposition to establish Peraceae still under discussion. There were also changes in the taxonomic position of genera widely distributed in the Brazilian territory, such as Amanoa, Drypetes, Pera, Phyllanthus, Podocalyx, Pogonophora, and Richeria, among others. In addition, new species have been proposed and the limits of taxa distribution are expanding in Brazil. Thus, the authors provide an overview of recent studies and advances in the taxonomy of Euphorbiaceae s.l. in the Northern, Northeastern, Southeastern and Southern regions of Brazil, concentrating on review works and regional floras, as well as the changes that resulted in setting a new taxonomic family.