Eugenia luschnathiana (O.Berg) Klotzsch ex B.D.Jacks. (Myrtaceae) species, commonly known as pitomba-da-baía, occurs in Restinga region in the state of Ceara and has medicinal potential. The present study aimed to characterize the anatomy of E. luschnathiana leaves in the rainy and dry seasons, as well as in the sun and shade in the Restinga region of Ceara, aiming to generate useful information to understand the adaptive value of morphoanatomic responses to the natural conditions of occurrence of the species. Collections were performed at the State Botanical Park of Ceara, and leaves were completely expanded and fixed in FAA70, being replaced by 70% ethanol after 24 h. Samples were submitted to standard plant anatomy methodologies in order to qualitatively and quantitatively analyze the leaf blade and petiole structures. As a result, there were differences among sun and shade leaves, rain and dry. In relation to luminosity, most determinations were higher in sun leaves: trichome density and frequency; trichome scar frequency; stomatal frequency, stomatal index, length, width and area of stomata; thickness of leaf blade, mesophyll, cuticle, epidermis, palisade and spongy parenchyma; length and width of the central vein, area of the central vein vascular bundle, number of secretory cavities in the central vein; length and width of the petiole, area of the petiole vascular bundle; amount and area of secretory cavities in the petiole. In shade leaves, only the number of druses in the central vein and petiole were larger. Regarding seasonality, all determinations were higher in the rainy season, except for the length and width of the central vein; number of druses in the central vein and petiole; length of the petiole, area of the vascular bundle and secretory cavities of the petiole. Therefore, it could be concluded that E. luschnathiana has great acclimative capacity to conditions of intense luminosity and periods of water deficit.

RESUMO -O gênero Croton L., pertence à família Euphorbiaceae presente no bioma Caatinga do Nordeste brasileiro. O estudo objetivou avaliar a infl uência do ciclo circadiano e da sazonalidade no rendimento e na composição química dos óleos essenciais de Croton blanchetianus Baill., Croton nepetifolius Baill. e Croton zehntneri Pax & K. Hoff m. Para estudo do ciclo circadiano, as folhas foram coletadas no horário de 8, 12 e 20h e para a sazonalidade as coletas foram realizadas no horário de 8h. O ciclo circadiano e a sazonalidade infl uenciaram o rendimento apenas de C. zehntneri, indicando maior rendimento na colheita às 12 horas e na estação seca. A composição química das espécies estudadas foi infl uenciada pelo ciclo circadiano e a sazonalidade, constatando-se que determinados compostos só são produzidos em horários e estações específi cas. Portanto, os fatores ambientais estudados interferem no rendimento e composição química dos óleos essenciais das espécies de Croton spp. To study the circadian cycle, the leaves were collected at 8:00, 12:00 and 20:00 and for the seasonal collections they were carried out at 8h. The circadian cycle and seasonality only infl uenced the yield of C. zehntneri, indicating a greater yield in harvest at 12:00 and in the dry season. Chemical compositions of C. blanchetianus, C. nepetifolius and C. zehntneri oils were infl uenced by the circadian cycle and seasonality demonstrating that certain compounds are only produced at specifi c times and seasons. Therefore, the studied environmental factors aff ect the yield and chemical composition of essential oils of species of Croton. Palavras

The species Eugenia punicifolia (Kunth) DC. (myrtle) occurs in the coastal region of the state of Ceará and has ecological and medicinal importance. This study aimed to characterize the leaf anatomy of myrtle (E. punicifolia) in the rainy and dry seasons, as well as in the sun and shade in the restinga region of the state of Ceará and to contribute to the understanding of the morphoanatomic variations in response to the natural conditions of the occurrence of this species. For this, collections of fully expanded leaves were performed at the Botanical Park of Ceará and fixed in FAA70, being replaced by 70% ethanol after 24 hours. The usual anatomical procedures were then performed in order to qualitatively and quantitatively analyze the leaf blade, petiole and epidermis structures. As a result, it was found that myrtle has xeromorphic characteristics such as thick cuticle, hypoestomatic leaf and sclerenchyma fibers in the median vein vascular bundles. It was concluded that E. punicifolia has great plasticity to adjust well under the analyzed conditions.

Chemotherapy treatment of leishmaniasis is based on the use of pentavalent antimonials, but these drugs present low efficacy and high toxicity. In the search for new antileishmanial agents, essential oils (EOs) from four Croton species (C. argyrophylloides, C. jacobinensis, C. nepetifolius and C. sincorensis) were evaluated against Leishmania infantum chagasi, L. amazonensis and L. braziliensis. EOs were analyzed by gas chromatography combined with mass spectrometry. Spathulenol, β-caryophyllene, β-caryophyllene oxide, 1,8-cineole and methyl eugenol were the major constituents. The evaluation of antioxidant activity by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) method showed that all EOs have moderate antioxidant activity. All oils were similarly active against L. i. chagasi, and C. nepetifolius EO showed the best result against L. amazonensis, with median inhibitory concentrations (IC 50) of 9.87 μg mL-1 , similar to amphotericin B (IC 50 = 7.38 μg mL-1). The oils presented low cytotoxicity in macrophages. The in silico analysis revealed that spathulenol and 1,8-cineole were active against the enzyme Leishmania infantum trypanothione reductase (LiTR), showing excellent interaction energies, making them promising agents for leishmaniasis control.

Marmeleiros are popularly known for the medicinal properties ascribed to their essential oils. This research aimed to analyze the essential oil of leaves from three Croton species (Croton argyrophylloides, Croton jacobinensis, and Croton sincorensis), to verify whether the daily time and harvest season in the year may interfere with their essential oils performance and composition. From each species, 1,500g of green leaves were harvested in Viçosa do Ceará - CE, at 6am and 12pm, during both dry and rainy seasons. Essential oil extraction was conducted by the method of water vapor drag and chemical profile was analyzed by gas chromatography-mass spectrometry (GC/MS). The highest yield was obtained at 12pm in the dry season for C. argyrophylloides and C. jacobinensis, and at 6am in the rainy season for C. sincorensis. Bicyclogermacrene demonstrated higher relative abundance in C. argyrophylloides (28.09 to 30.59%), C. jacobinensis (25.2 to 30.14%), and C. sincorensis (23.86 and 21.71%), and the only exception was at 6am in C. sincorensis, where (E)-caryophyllene was the most abundant compound (25.34%). The yield and composition of the studied species were influenced by rainfall, temperature, and sunlight, presenting statistical significant differences between the different periods studied. The species produce constituents with specific biological properties; and therefore, they can be used as a natural source.

Colleters are secretory structures that play a role in protecting meristems from dehydration. Little attention has been given to the effect of seasonal variation on colleter exudates. Therefore, this study aimed to characterise the main chemical groups found in colleter exudates as well as to correlate the chemical nature of the secretion with seasonal variation. We used Myrcia splendens as a model to understand seasonal variation in colleter exudates. For that, meristems and shoot apices of M. splendens were collected and subjected to standard anatomical techniques. In M. splendens, colleters arise from protodermal cells and are similar to trichomes. Mature colleters are conic and composed of a short stalk and a long secretory head. Histochemical analyses found that colleter exudates differed according to the seasonality. Composition of the secretions was more diverse in the dry season than in the wet season. During the dry season, colleters secreted five different compounds (i.e. total polysaccharides, mucilage–pectins, total proteins, total lipids and phenolic compounds), whereas in the wet season, only three compounds were found (i.e. total proteins, total lipids and phenolic compounds). Our study extends what was known in earlier works, demonstrating changes in colleter exudates due to environmental seasonality.

Secretory cavities are structures that secrete compounds that protects plants against herbivory and pathogenic microorganisms. These cavities have been reported in many genera. However, there are few studies on secretory cavity ontogeny in the genus <i>Myrcia</i> (Myrtaceae) as well as the effects of luminosity and seasonality on such secretory cavities. Therefore, the objective of this is to provide new information regarding the ontogenesis, structure, histochemistry and effects of seasonality in <i>M. splendens</i>. We collected and analyzed leaves from ten M. splendens specimens exposed to sun and shade during both wet and dry seasons. Samples were subjected to standard anatomical techniques for light microscopy. <i>Myrcia splendens</i> has schizo-lysigenous ontogenesis with exudates composed of lipids, essential oils, oil-resins and alkaloids. The largest secretory cavities were found in leaves exposed to sun during the dry season. The presence of lipophilic compounds may be an important strategy to plant protection against herbivores. The seasonal variations observed in the leaf secretory cavities demonstrate the anatomical plasticity of such species to light and water availability. As total area of leaf cavities in <i>M. splendens</i> reflects the seasonal variation, this should be taken into account when aiming to produce crops meant to essential oils/alkaloids extractions.

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