Déborah Yara Alves Cursino dos Santos

Foliar epicuticular wax of Arrabidaea brachypoda: flavonoids and antifungal activity

The epicuticular wax of the leaves of Arrabidaea brachypoda was analyzed for its flavonoid content and four compounds (1–4) were isolated. They are known flavonoids and showed antifungal activity against Cladosporium sphaerospermum. They were identified by mass spectrometry, proton nuclear magnetic resonance spectroscopy and nuclear Overhauser effect spectroscopy (NOESY) as 3′,4′-dihydroxy-5,6,7-trimethoxyflavone (1), cirsiliol (2), cirsimaritin (3) and hispidulin (4). Two major chemical features resulting from this work are the first report of 1 as a natural product and the first finding of cirsiliol in Bignoniaceae.

Foliar flavonoids of nine species of Bauhinia

Foliar flavonoids of nine species of Bauhinia were isolated and identified. All the compounds correspond to glycosides derived from kaempferol, quercetin, isorhamnetin and myricetin. Derivatives of the latter aglyconhe seem to be rare in Bauhinia. Derivatives of isorhamnetin are commonly found in species of subgenus Bauhinia and were not detected in the two species of subgenus Phanera. Flavonoid patterns of species of the former subgenus are in general more complex than those of the latter.

Five vicariant genera from Gondwana: the Velloziaceae as shown by molecules and morphology [corrected].

BACKGROUND AND AIMS The amount of data collected previously for Velloziaceae neither clarified relationships within the family nor helped determine an appropriate classification, which has led to huge discordance among treatment by different authors. To achieve an acceptable phylogenetic result and understand the evolution and roles of characters in supporting groups, a total evidence analysis was developed which included approx. 20 % of the species and all recognized genera and sections of Velloziaceae, plus outgroups representatives of related families within Pandanales. METHODS Analyses were undertaken with 48 species of Velloziaceae, representing all ten genera, with DNA sequences from the atpB-rbcL spacer, trnL-trnF spacer, trnL intron, trnH-psbA spacer, ITS ribosomal DNA spacers and morphology. KEY RESULTS Four groups consistently emerge from the analyses. Persistent leaves, two phloem strands, stem cortex divided in three regions and violet tepals support Acanthochlamys as sister to Velloziaceae s.s., which are supported mainly by leaves with marginal bundles, transfusion tracheids and inflorescence without axis. Within Velloziaceae s.s., an African Xerophyta + Talbotia clade is uniquely supported by basal loculicidal capsules; an American clade, Barbacenia s.l. + Barbaceniopsis + Nanuza + Vellozia, is supported by only homoplastic characters. Barbacenia s.l. (= Aylthonia + Barbacenia + Burlemarxia + Pleurostima) is supported by a double sheath in leaf vascular bundles and a corona; Barbaceniopsis + Nanuza + Vellozia is not supported by an unambiguous character, but Barbaceniopsis is supported by five characters, including diclinous flowers, Nanuza + Vellozia is supported mainly by horizontal stigma lobes and stem inner cortex cells with secondary walls, and Vellozia alone is supported mainly by pollen in tetrads. CONCLUSIONS The results imply recognition of five genera (Acanthochlamys (Xerophyta (Barbacenia (Barbaceniopsis, Vellozia)))), solving the long-standing controversies among recent classifications of the family. They also suggest a Gondwanan origin for Velloziaceae, with a vicariant pattern of distribution.

Flavonoids of species of Cuphea (Lythraceae) from Brazil

Abstract From 16 species of Cuphea collected in “campos rupestres”, an altitudinal ecosystem found in Southeast and Central Brazil, 35 flavonoids have been identified. Most compounds are 3-O-glycosides of flavonols, but flavones were also found. Cuphea is akin to Diplusodon (another lythraceous genus) due to a frequent occurrence of derivatives of myricetin and the presence (though not frequent) of glycosides containing glucuronic acid. The mentioned genera may be distinguished from one another by the following characters, found in samples of Cuphea: presence of derivatives of rhamnetin and isorhamnetin; a rare occurrence of derivatives of kaempferol and flavones; a relatively frequent occurrence of glycosides of galactose; an apparent absence of glucuronic acid in glycosides of myricetin. Among the sections of Cuphea, Trispermum stands out, thanks to an absence of kaempferol and methylated flavonols (rhamnetin and isorhamnetin). The occurrence of flavone glycosides in members of subsection Hilariella (section Euandra) distinguishes them from species of Oidemation. The general flavonoid pattern of Cuphea seems to support proposals of seggregation of the genus as a well differentiated taxon among the Lythraceae.

Guava flavonoids and the effects of industrial air pollutants

Abstract Saplings of Psidium guajava (guava, Myrtaceae), a tropical tree species, were exposed to industrial air pollutants at Cubatâo, the largest industrial complex of Latin America, along two periods, each one comprising one-year: period I, July/2000 – June/2001; period II, December/2000 – November/2001. Saplings were exposed in two experimental sites: Piloes River Valley (PV), reference site, with low contamination by air pollutants; and Mogi River Valley (MV), a site severely affected by pollutants from chemical, fertilizer, ceramic, iron and steel industries. At both sites, the main flavonoids found were guaijaverin, quercitrin and two quercetin diglycosides. No interactions among factors were found as well as no significant differences were found among periods and among sites. However, total foliar flavonoid amounts showed the tendency of decrease after 12 months of experimentation. Cubatao industrial air pollution, with high concentrations of NO2, SO2 and particulate matter, plus climatic conditions of the initial months of exposure seem that does not influence flavonoid composition and quantities.

Comparison of radial growth rate of the mutualistic fungus of Atta sexdens rubropilosa forel in two culture media.

In vitro culture of the mutualistic fungus of leaf-cutting ants is troublesome due to its low growth rate, which leads to storage problems and contaminants accumulation. This paper aims at comparing the radial growth rate of the mutualistic fungus of Atta sexdens rubropilosa Forel in two different culture media (Pagnocca B and MEA LP). Although total MEA LP radial growth was greater all along the bioassay, no significant difference was detected between growth efficiencies of the two media. Previous evidences of low growth rate for this fungus were confirmed. Since these data cannot point greater efficiency of one culture medium over the other, MEA LP medium is indicated for in vitro studies with this mutualistic fungus due its simpler composition and translucent color, making the analysis easier.

Chemical composition and efficacy of dichloromethane extract of Croton sphaerogynus Baill. (Euphorbiaceae) against the cattle tick Rhipicephalus microplus (Acari: Ixodidae).

The cattle tick Rhipicephalus microplus is widely distributed in tropical and subtropical regions, causing high economic impact on cattle production. The control of tick infestations is regarded worldwide as critical and has been based on the use of organophosphates, synthetic pyretroids, amitraz and recently ivermectin and fipronil. The present study reports the analysis by gas chromatography/mass spectrometry of the constituents of leaf extracts of Croton sphaerogynus and results of acaricidal activity against the cattle tick R. microplus. The larval package test using the serial dilutions 0.625%, 1.25%, 2.5%, 5.0%, 10.0% and 20.0% (v/v) gave mortality rates 2.25%, 8.26%, 8.81%, 24.80%, 83.66% and 99.32%, respectively. Relevant constituents identified were abietanes, podocarpenes and clerodane type furano diterpenes. The present work may represent a possibility of attainment of natural substances useful for the control of R. microplus.

Influence of caffeine on the survival of leaf-cutting ants Atta sexdens rubropilosa and in vitro growth of their mutualistic fungus.

BACKGROUND Leaf-cutting ants collect plant fresh material for the cultivation of their mutualistic fungus. Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae) cause great economic losses through their foraging activity, mainly in agriculture. The main control method is the application of granulated toxic baits incorporated with an active ingredient (AI). The present goal is to evaluate the effect of caffeine on in vitro growth of the mutualistic fungus and on the survival of the leaf-cutting ants, aiming to verify the potential toxicity of this secondary metabolite over these organisms. RESULTS Three distinct patterns of fungal growth correlated with caffeine concentration were observed: (1) no effect (0.01% caffeine); (2) intermediate growth reduction (0.05% caffeine); (3) drastic growth reduction (0.10 and 0.50% caffeine). The highest caffeine concentration causes fungus death in the first week. As for insect survival, caffeine does not seem to exert any effect. The treatments with diet containing caffeine showed similar values of M50, irrespective of caffeine concentration. CONCLUSION As caffeine was shown to reduce growth of the mutualistic fungus of Atta sexdens rubropilosa, but with no conclusive effect on insect survival, a hypothetical explanation for the selection of different Coffea species by this leaf-cutting ant species might be associated with caffeine toxicity to the fungus.

Mycosporine-like amino acids from Gracilariopsis tenuifrons (Gracilariales, Rhodophyta) and its variation under high light

Mycosporine-like amino acids (MAAs) have been identified as photoprotective agents for photosynthetic organisms, mainly against ultraviolet radiation. However, the role of these compounds associated with high intensity of photosynthetically active radiation (PAR) is not completely understood. In the present study, the MAA profile of laboratory-cultivated Gracilariopsis tenuifrons was investigated at three PAR levels. Ethanolic extract afforded a mixture of five components. Four of them were identified as asterina-330, palythinol, palythene, and usujirene. This is the first report of usujirene for Gracilariaceae. Despite the fact that the PAR increase did not alter the qualitative composition of MAAs, a clear correlation between palythinol amount and irradiance during the 7-day experiment was detected. This increase of palythinol correlated to high PAR supports the hypothesis of photoprotection related to these compounds.

Comparative study of reserve lipid accumulation during somatic and zygotic Acca sellowiana (O. Berg.) Burret embryogenesis

Somatic embryogenesis is an in vitro morphogenetic route in which isolated cells or a small group of somatic cells give rise to bipolar structures resembling zygotic embryos. Lipids, carbohydrates, and proteins are major compounds in plant and animal metabolism. Comparative analysis along different developmental stages of Acca sellowiana (Myrtaceae) zygotic and somatic embryos, revealed a progressive increase in levels of total lipids. A high degree of similarity could be found in the total lipids composition between A. sellowiana somatic and zygotic embryos. High lipid levels were found in zygotic embryos in the torpedo and cotyledonary stages, and these levels increased according to the progression in the developmental stages. Somatic embryos obtained through direct embryogenesis route showed higher levels of lipids than in indirect somatic embryogenesis. The compounds most frequently were linoleic acid (C18:2), palmitic (C16:0) and oleic (C18:1). These results indicate a high similarity degree of accumulation of total lipids, regardless of zygotic or somatic embryogenesis.