Marcetia Taxifolia Research Articles

Antiviral activity of myricetin glycosylated compounds isolated from Marcetia taxifolia against chikungunya virus.

The chikungunya virus (CHIKV) has produced epidemic outbreaks of significant public health impact. The clinical symptoms of this disease are fever, polyarthralgia, and skin rash, generally self-limiting, although patients may develop a chronic disabling condition or suffer lethal complications. Unfortunately, there is no specific treatment or vaccine available. Thus, the search for effective therapies to control CHIKV infection is an urgent need. This study evaluated the antiviral activity of flavonoids isolated from Marcetia taxifolia by in vitro and in silico analysis. Cytotoxicity of compounds was determined by MTT assay and viral load was assessed in cell substrates supernatants by plaque-forming and RT-qPCR assays. Selected molecules were analyzed by molecular docking assays. Myricetin 3-rhamnoside (MR) and myricetin 3-(6-rhamnosylgalactoside) (MRG) were tested for antiviral assays and analyzed by the TCID50 method and RT-qPCR. MR exhibited dose-dependent antiviral activity, reducing viral titer at concentrations of 150-18.8 μg/mL by at least 1-log. Similarly, MRG showed a significant decrease in viral titer at concentrations of 37.5, 9.4, and 2.3 μg/mL. RT-qPCR analysis also displayed a substantial reduction of CHIKV RNA for both flavonoids. Furthermore, molecular docking of the selected flavonoids proposed the nsP3 macrodomain as a possible target of action. Our study reveals that MR and MRG could be considered promising anti-CHIKV therapeutic agents. Molecular modeling studies showed MR and MRG ligands with a high affinity for the N-terminal region of the nsP3 macrodomain, postulating them as a potential target of action for the CHIKV control.

Inverse Molecular Docking Study of NS3-Helicase and NS5-RNA Polymerase of Zika Virus as Possible Therapeutic Targets of Ligands Derived from Marcetia taxifolia and Its Implications to Dengue Virus.

Dengue and Zika are two mosquito-borne diseases of great impact on public health around the world in tropical and subtropical countries. DENV and ZIKV belong to the Flaviviridae family and the Flavivirus genus. Currently, there are no effective therapeutic agents to treat or prevent these pathologies. The main objective of this work was to evaluate potential inhibitors from active compounds obtained from Marcetia taxifolia by performing inverse molecular docking on ZIKV-NS3-helicase and ZIKV-NS5-RNA polymerase as targets. This computational strategy is based on renormalizing the binding scores of the compounds to these two proteins, allowing a direct comparison of the results across the proteins. The crystallographic structures of the ZIKV-NS3-helicase and ZIKV-NS5-RNA-polymerase proteins share a great similarity with DENV homologous proteins. The P-loop active site of the crystallographic structure of ZIKV-NS3-helicase presents a high percentage of homology with the four dengue serotypes. It was found that most ligands of the active compounds (5,3’-dihydroxy-3,6,7,8,4′-pentamethoxyflavone (5DP); 5-hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone (5HH); myricetin-3-O-rhamnoside (M3OR)) from Marcetia taxifolia had a better affinity for ZIKV-NS3-helicase than for ZIKV-NS5-RNA polymerase, as indicated by the negative multiple active site correction (MASC) score, except for M3RG that showed a higher affinity for ZIKV-NS5-RNA polymerase. On the other hand, the AutoDock Vina scores showed that M3OR had the highest score value (−9.60 kcal/mol) and the highest normalized score (1.13) against ZIKV-NS3-helicase. These results in silico demonstrated that the nonstructural proteins NS3-helicase and NS5-RNA polymerase, which share similar molecular structures between the selected viruses, could become therapeutic targets for some bioactive compounds derived from Marcetia taxifolia.

Early Acacia invasion in a sandy ecosystem enables shading mediated by soil, leaf nitrogen and facilitation

Australian species of the genus Acacia are amongst the most invasive trees. As nitrogen fixers, they are able to invade oligotrophic ecosystems and alter ecosystem functioning to their benefit. We aimed to answer three questions: How does early Acacia invasion influence nitrogen and light in a sandy savanna? How does early Acacia invasion impact biodiversity? Does early invasion alter ecosystem functioning towards the dominance of Acacia? We analyzed (using generalized linear mixed models and richness estimators) paired plots focused on plants of Acacia mangium (Fabaceae) and plants of Marcetia taxifolia (Melastomataceae) by taking hemispherical photos and sampling plants, leaves and soil for measurements of light, richness, leaf nitrogen, leaf δ15N, soil nitrogen and soil coarse sand. The results suggest that early Acacia invasion alters the control of soil and of leaf nitrogen and increases shading, enabling a much wider range of light variation. The δ15N results suggest that the nitrogen taken up by Acacia is transferred to neighboring plants and influences the light environment, suggesting facilitation. The enrichment of plant species observed during early Acacia invasion is consistent with the wider range of light variation, but the forecasted leaf nitrogen conditions during the established phase of Acacia invasion might cause loss of light-demanding species because of increased shading. If early Acacia invasion turns into an established phase with highly increased shading, Acacia seedlings might be favored and ecosystem functioning might change towards its dominance.

Methoxyflavones from Marcetia taxifolia as HIV-1 Reverse Transcriptase Inhibitors

Methoxyflavones are flavonoid widely distributed in plants and has been reported as potent antitumor agents and some of them have shown activity against HIV-1. In this work, two methoxyflavones isolated from Marcetia taxifolia were evaluated in vitro and in silico as HIV-1 inhibitors. Pentamethoxyflavone (5,3’-dihydroxy-3,6,7,8,4’-pentamethoxyflavone) (PMF) and Hexamethoxyflavone (5-Hydroxy-3,6,7,8,3’,4’-hexamethoxyflavone) (HMF) showed activity against HIV-1. The EC50 for HMF was 0.05 μM and 0.04 μM for PMF. The methoxyflavones also inhibited HIV-1 reverse transcriptase (RT), with an IC50 of 4.1 μM for HMF and 0.4 μM for PMF. PMF exhibited an IC50 lower than nevirapine (1.4 μM). These results are in agreement with the in silico prediction for the interaction of these flavonoids with RT. Furthermore, the effect of some methoxyflavones with different patterns of methoxylation was evaluated on RT activity in a virtual screening; found that the inhibitory activity was inversely proportional to the degree of methoxylation.

The role of the glycosyl moiety of myricetin derivatives in anti-HIV-1 activity in vitro

BackgroundPlant extracts are sources of valuable compounds with biological activity, especially for the anti-proliferative activity against pathogens or tumor cells. Myricetin is a flavonoid found in several plants that has been described as an inhibitor of Human immunodeficiency virus type 1 (HIV-1) through its action against the HIV reverse transcriptase, but myricetin derivatives have not been fully studied. The aim of this study was to evaluate the anti-HIV-1 activity of glycosylated metabolites obtained from Marcetia taxifolia and derived from myricetin: myricetin rhamnoside and myricetin 3-(6-rhamnosylgalactoside).MethodsCompounds were obtained from organic extracts by maceration of aerial parts of M. taxifolia. All biological assays were performed in the MT4 cell line. Antiviral activity was measured as inhibition of p24 and reverse transcriptase with a fluorescent assay.ResultsBoth flavonoids have antiviral activity in vitro, with an EC50 of 120 µM for myricetin 3-rhamnoside (MR) and 45 µM for myricetin 3-(6-rhamnosylgalactoside) (MRG), both significantly lower than the EC50 of myricetin (230 µM). Although both compounds inhibited the reverse transcriptase activity, with an IC50 of 10.6 µM for MR and 13.8 µM for MRG, myricetin was the most potent, with an IC50 of 7.6 µM, and an inhibition greater than 80%. Molecular docking approach showed correlation between the free energy of binding with the assays of enzyme inhibition.ConclusionsThe results suggest that glycosylated moiety might enhance the anti-HIV-1 activity of myricetin, probably by favoring the internalization of the flavonoid into the cell. The inhibition of the HIV-1 reverse transcriptase is likely responsible for the antiviral activity.

In vitro photoprotective effects of Marcetia taxifolia ethanolic extract and its potential for sunscreen formulations

The species Marcetia taxifolia (A.St.-Hil.) DC., Melastomataceae, which is endemic of the rupestrian fields of northeastern Brazil, contains a significant amount of flavonoids. In this work, the potential of the ethanolic extract of M. taxifolia as the active principle in a sunscreen photoprotection (UV-A and UV-B) formulation was investigated. The Liquid Chromatography High Performance-Diode Array Detector quantification (quercetin), total flavonoid content, antioxidant activity through 2.2-diphenyl-1- picrylhydrazil method, photoprotective activity against UV-B and UV-A radiation in vitro (spectrophotometric method) and potential for eye irritation using the methodology of the hen egg test-chorioallantoic membrane were performed in the extract. After that, the formulations were prepared using different concentrations of active ethanolic extract (5, 10, 20 and 30%) and the evaluation of the sun protection factor was carried out using the same methodology used for the crude extract. The crude extract showed UV-A photoprotection and low eye irritation in the hen egg test-chorioallantoic membrane test. All formulations containing M. taxifolia extract had ≥ 6 sun protection factor. Its shows the possibility to use this extracts as a sunscreen in pharmaceutical preparations.

Multivesicular bodies differentiate exclusively in nutritive fast-dividing cells in Marcetia taxifolia galls.

Marcetia taxifolia (A. St.-Hil.) DC. hosts two gall morphotypes, a pistil-shaped gall induced by a Cecidomyiidae (Diptera) and a fusiform stem gall induced by a Lepidoptera. The cytological study of these galls aimed to answer how the difference in nutritive tissues of Diptera and Lepidoptera galls could be explained on cytological basis. The nutritive tissues of lepidopteran galls have a fast-dividing cell zone, the storage nutritive tissue, which replaces the cells of the typical nutritive tissue, where the larvae feed. The differentiation of multivesicular bodies in the plasma membrane occurred exclusively in these fast-dividing cells of the lepidopteran galls, evidencing the meristematic condition of such tissue. The accumulation of reactive oxygen species (ROS) analyzed in situ in the nutritive cells is not sufficient to induce programmed cell death (PCD), as the cells of M. taxifolia have plastoglobules and accumulate polyphenols and terpenoids, which are diagnostic defenses against oxidative stress. The two taxa of galling insects have different nutritional requirements, thus inducing specific cytoplasm-enriched cells on their nutritive tissues.

Floral-like destiny induced by a galling Cecidomyiidae on the axillary buds of Marcetia taxifolia (Melastomataceae)

The galls induced by Cecidomyiidae, Diptera, are very diverse, with conspicuous evidence of tissue manipulation by the galling herbivores. Bud galls, as those induced by an unidentified Cecidomyiidae species on Marcetia taxifolia, Melastomataceae, can be considered as one of the most complex type of prosoplasma galls. The gall-inducer manipulate the axillary meristem of the plant in a way that gall morphogenesis may present both vegetative and reproductive features of the host plant. Herein, we analyzed traces of determinate and indeterminate growth in the bud gall of M. taxifolia, looking for parallels between the features of the leaves and flowers, natural fates of the meristematic cells. The bud galls are induced by the cecidomyiid fly, and are formed by the connation of eight leaf primordia, a common process in ovary morphogenesis. The bud gall corresponds to a pistil-shaped gall morphotype, with anatomical features similar to those of an hypanthium and sepals. The gall mimics an ovary, which has protective barriers at the apex, and a nutritive tissue (with storage of lipids and proteins) or a placenta, respectively, at the basal portion. The redifferentiation of the promeristem into a nutritive tissue at the base of the gall confers a determinate destiny to the axillary bud. Comparatively, the gradients of cell expansion and of accumulation of primary metabolites also indicate that the gall and the ovary are convergent structures. Some constraints of the host plant cells, such as the absence of lignification, and the accumulation of polyphenols, lipids and terpenoids, are not altered and may confer chemical protection for plant tissues and the larva against oxidative stress.

Developmental stem anatomy and tissue redifferentiation induced by a galling Lepidoptera on Marcetia taxifolia (Melastomataceae)

The developmental anatomy of the stems of Marcetia taxifolia (A. St.-Hil.) DC. fits the patterns described for other Melastomataceae. The galling effect of the Lepidoptera caused discrete structural alterations and conspicuous histochemical profiles. Epidermis and cortical parenchyma were hyperplasic with hypertrophied cells. The vascular system showed smaller changes. Tracheal elements did not change in width, refuting the constriction hypothesis, i.e., no improvement in water supply occurs in this gall system. Fiber lignification increased, providing additional support for the gall structure. A true nutritive tissue was redifferentiated from pith cells and accumulated two groups of metabolites. The first, consisting of starch, reducing sugars, and polyphenols, was detected in the outer cell layers, and the second, consisting of lipids and terpenoids, was detected in the inner ones. Histochemical analysis revealed that the distribution of these compounds formed gradients, with the first group being more concentrated outwards, and the second being more concentrated inwards. These gradients differ from those described for other insect galls and seem to be specific for lepidopteran galls. This is the first description of such a gradient in Lepidoptera-induced galls and shows that the current view that these galls are simple and nonnutritive should be changed.

Alocação preferencial de recursos e morfologia de órgãos subterrâneos em plantas resistentes ao fogo em vegetação campestre

The underground systems are important for survival of plants and their morphological characteristics have special meaning in environments under disorder. The present study evaluated the existence of preferential allocation of resources in the underground parts of plants resistant to fire and discuss implications of resource allocation and morphology in spatial and temporal dynamics of grassland communities susceptible to fire. The study was restricted to six species of grassland, three monocots (Hypolytrum pulchrum, Echinolaena inflexa and Andropogum sp.) and three eudicots (Euphorbia sarcodes, Eryngium paraguariense and Marcetia taxifolia). The morphological characterizations were performed in about five individuals of each species from anatomical cuts, photos, measurements with digital calipers, tape measures and quantification of biomass share of overhead and underground. The plants showed different spatial arrangements that allow the coexistence in space through a set of skills associated with morphofunctional features integrated aerial and underground parts. Most species showed underground system integrated into networks with preferential allocation of resources to aerial parts, except for E. sarcodes. The morphology is a crucial factor in the competitive responses. The buds developed mainly on rhizomes of plants abundant in these open areas are evidence of the importance of these structures in the dynamics of grassland communities.

Morfologia e anatomia foliar de três morfotipos de Marcetia taxifolia (A. St.-Hil.) DC. (Melastomataceae) na Serra do Cipó, MG

Some morphotypes of Marcetia taxifolia have many polymorphic features in campos rupestres of Serra do Cipo, MG. This study aimed to characterize and compare the morphology and anatomy of three morphotypes of M. taxifolia in their natural habitat and in cultivating conditions. The natural selected morphotypes were denominated White and Crystal Pink, according to the color of the flowers and to the soil type where each morphotype was found. For leaf anatomical studies, permanent and semi-permanent prepations with transverse sections were done. At green house conditions, thirty seeds of each morphotype were planted on their own soil and on the soil of the other two morphotypes. The most significant differences among the morphological parameters evaluated were plant height, number of stems, and leaf area. White and Crystal Pink natural morphotypes plants had the higher and the lower values of height and leaf area, respectively. The Crystal Pink plants presented more branches than the other two morphotypes. Marcetia taxifolia great phenotypic plasticity is mainly evidenced by the morphological variation observed in the three morphotypes, in field and cultivating conditions. Species plasticity is poorly reflected in anatomical level, therefore anatomical features were insufficient to distinguish M. taxifolia morphotypes. Environmental factors, such as soil fertility, especially iron and aluminum concentrations, and water abundance may be the major factors that influence the divergences found in this study.

Influência da luz e da temperatura na germinação de sementes de Marcetia taxifolia (A. St.-Hil.) DC. (Melastomataceae)

Marcetia taxifolia (A. St.-Hil.) DC. (Melastomataceae) é um arbusto amplamente distribuído nos campos rupestres da Serra do Cipó, Brasil. É uma espécie com potencial na recuperação de áreas degradadas e este estudo apresenta os primeiros dados sobre o efeito da luz e da temperatura na germinação de suas sementes. Sementes foram coletadas em maio/2001 e foram submetidas a testes de germinação nas temperaturas constantes de 15, 20, 25, 30 e 35ºC sob fotoperíodo de 12 horas e em ausência de luz durante 30 dias. Foram encontradas diferenças significativas entre a percentagem de germinação e tempo médio de sementes submetidas ao tratamento claro e escuro a 15, 20, 25 e 30ºC (p < 0,05; todos). Sob a temperatura de 35ºC, a germinação foi completamente inibida. As maiores percentagens de germinação foram obtidas a 15 e 20ºC, as quais foram superiores a 25 e 30ºC (ANOVA = 13,65; p < 0,001). Os dados contribuem para estudos posteriores que visem a propagação da espécie com fins de reabilitação ambiental.

Three New Brazilian Species in the Genus Marcetia (Melastomataceae, Melastomeae)

Three new species of Marcetia are described and illustrated. Marcetia semiriana occurs only in Serra do Cip6, Minas Gerais. Marcetia shepherdii, collected in Marai1, at sea level, and M. lychnophoroides, from Chapada Diamantina, are both endemic to Bahia. The new species Marcetia shepherdii and M. lychnophoroides, together with M. luetzelburgii Markgraf, constitute a group of closely related species. They share in common subcoriaceous, fleshy, imbricate to subimbricate, revolute leaves. Marcetia shepherdii is distinguished by its rigid, erect branchlets, yellowish green leaves that are glabrous on the adaxial surface, unappendaged and broadly dilated connectives, linear-oblong thecae with a ventrally inclined pore, and a unique 2locular ovary. Marcetia lychnophoroides has velutinous to sublanate branchlets, cinereous-green leaves that are densely puberulous-sericeous on the abaxial surface, unprolonged and inconspicuously bilobulate connectives, and a 3or 4-locular ovary. Marcetia semiriana is very similar to M. taxifolia (A. Saint-Hilaire) DC., differing in the prostrate branches, long pedunculate flowers, and straight anthers. Marcetia is a neotropical genus of 27 species largely endemic to Brazil. Except for the widespread Marcetia taxifolia, which has a bicentric distribution in eastern Brazil and northwestern South America (Colombia, Venezuela, and Guyana), all other species of Marcetia have restricted distributions. Marcetia species are usually shrubs or subshrubs that occur in campo rupestre in the Serra do Espinhago, Minas Gerais, in the mountains of Goi s, and especially in the Chapada Diamantina, Bahia. Campo rupestre is an exclusively Brazilian complex mosaic of vegetation types characterized by extensive outcrops of highly acidic rocks, nutrient-poor soils, and local variations in topography, slope, aspect, and moisture regime. A few Marcetia species occur in both montane and littoral areas, such as M. ericoides (Sprengel) 0. Berg ex Cogniaux and M. canescens Naudin. Marcetia shepherdii is the only species in the genus that is endemic to coastal Bahia, where it occurs in the sandy vegetational formation commonly referred to as restinga. The genus Marcetia can be distinguished within the tribe Melastomeae mainly by the combination of tetramerous flowers and simple anthers that lack basally prolonged connectives (except in M. shepherdii) and, in some species, may have short ventral tuberculate appendages. Three of the species studied in my taxonomic revision of Marcetia (Martins, 1989) are new. They are described and illustrated here. Marcetia shepherdii A. B. Martins, sp. nov. TYPE: Brazil. Bahia: Maraui, 4 km de Mara6, 12 Mar. 1977 (fl, fr), G. J. Shepherd, L. S. Kinoshita, J. B. Andrade & N. Taroda 4550 (holotype, UEC). Figure 1. Haec species Marcetiae luetzelburgii affinis, sed ab ea foliis arcte adpressis sessilibus revolutis dense imbricatis internodia brevia occultantibus, ramis basin versus denudatis, conspicue annulis foliorum delapsorum praeditis, lamina foliari supra glabra in sicco flavovirescenti, staminum filamentis ter longioribus, antheris apice rotundato ventraliter minute dehiscenti atque ovario biloculari differt. Erect subshrub ca. 60 cm, compactly branched; branchlets rigid, subterete to inconspicuously quadrangular, moderately puberulous or nearly glabrous, at the base defoliating with age and with conspicuous leaf scars. Leaves opposite, sessile, appressed, densely imbricate and concealing the short internodes; blade lanceolate-ovate, 2.5-3 x 1 mm, fleshy-coriaceous, basally cordate, apically recurved and mucronulate, margins revolute, glabrous on the adaxial surface, glandular-pubescent abaxially, obscurely 1-nerved. Flowers 4-merous, subsessile, solitary in upper leaf axils resembling a terminal foliaceous spiciform inflorescence, becomNOVON 10: 224-229. 2000. This content downloaded from 157.55.39.45 on Fri, 02 Sep 2016 06:22:09 UTC All use subject to http://about.jstor.org/terms Volume 10, Number 3 2000 Luckow & Du Puy Gagnebina bakoliae from Madagascar 225