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Exosomes are a type of extracellular vesicle whose study has grown exponentially in recent years. This led to the understanding that these structures, far from being inert waste by-products of cellular functioning, are active players in intercellular communication mechanisms, including in the interactions between cancer cells and the immune system. The deep comprehension of the crosstalk between tumors and the immune systems of their hosts has gained more and more importance, as immunotherapeutic techniques have emerged as viable options for several types of cancer. In this review, we present a comprehensive, updated, and elucidative review of the current knowledge on the functions played by the exosomes in this crosstalk. The roles of these vesicles in tumor antigen presentation, immune activation, and immunosuppression are approached as the relevant interactions between exosomes and the complement system. The last section of this review is reserved for the exploration of the results from the first phase I to II clinical trials of exosomes-based cell-free cancer vaccines.

The objective of this study was to identify the possible involvement of the GABAergic system in the anesthetic effect of Lippia alba essential oil (EO). We propose a new animal model using silver catfish (Rhamdia quelen) exposed to an anesthetic bath to study the mechanism of action of EO. To observe the induction and potentiation of the anesthetic effect of EO, juvenile silver catfish (9.30 ± 1.85 g; 10.15 ± 0.95 cm; N = 6) were exposed to various concentrations of L. alba EO in the presence or absence of diazepam [an agonist of high-affinity binding sites for benzodiazepinic (BDZ) sites coupled to the GABAA receptor complex]. In another experiment, fish (N = 6) were initially anesthetized with the EO and then transferred to an anesthetic-free aquarium containing flumazenil (a selective antagonist of binding sites for BDZ coupled to the GABAA receptor complex) or water to assess recovery time from the anesthesia. In this case, flumazenil was used to observe the involvement of the GABA-BDZ receptor in the EO mechanism of action. The results showed that diazepam potentiates the anesthetic effect of EO at all concentrations tested. Fish exposed to diazepam and EO showed faster recovery from anesthesia when flumazenil was added to the recovery bath (12.0 ± 0.3 and 7.2 ± 0.7, respectively) than those exposed to water (9.2 ± 0.2 and 3.5 ± 0.3, respectively). In conclusion, the results demonstrated the involvement of the GABAergic system in the anesthetic effect of L. alba EO on silver catfish.

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Recebido em 26/2/08; aceito em 22/10/08; publicado na web em 6/3/09 SEASONAL VARIABILITY AND TERPENOID BIOSYNTHESIS OF THE ESSENTIAL OIL OF Lippia alba (Mill.) N. E. BROWN (VERBENACEAE). The essential oil of the leaves of Lippia alba chemotype linalool-1,8-cineol was extracted by hidrodistillation at different seasons and analyzed by GC/MS. Qualitative and quantitative variations in regard to the period of harvesting have been performed and the results were correlated with meteorological data. The essential oil yield varied from 0.33 to 0.67%. The chemical diversity of the constituents increased throughout the year, being 1,8-cineol and linalool the major components. Possible biosynthetic routes of mono and sesquiterpenoids present in the essential oil are discussed.Keywords: Lippia alba; terpenoids; seasonal variability. introdUÇÃoLippia alba (Mill.) N. E. Brown (Verbenaceae) é uma planta medicinal nativa da América do Sul, conhecida popularmente como falsa-melissa.1 Infusões, banhos e xaropes, preparados com suas folhas ou raízes, são utilizados na medicina popular para o tratamento de distúrbios estomacais, afecções das vias respiratórias, no combate à hipertensão e como sedativo. 2Entre os metabólitos secundários descritos para L. alba encontram-se flavonóides, taninos, iridóides, saponinas triterpênicas, resinas, mucilagens e óleo essencial. 3Variações qualitativas e quantitativas dos principais componentes do óleo essencial desta espécie têm levado a sua separação em quimiotipos ou raças químicas: citral, 4,5 carvona, 4 linalol -1, 8-cineol, 6 entre outros. Adicionalmente, a influência de fatores abióticos como luz, temperatura, água, solo e altitude sobre a biossíntese de certos constituintes vegetais, especialmente os terpenóides, foi comprovada em diferentes espécies vegetais. 7 A variabilidade na composição do óleo essencial das folhas de L. alba foi demonstrada anteriormente em função das diferentes regiões do ramo vegetal, 5 das épocas e horários de coleta, 5,6,8 bem como da metodologia empregada na sua extração. 9No entanto, até o momento, não há trabalhos publicados interligando, por meio de dados meteorológicos, as variações observadas aos fatores abióticos. O presente trabalho teve como objetivo avaliar a variação do teor e da composição química do óleo essencial das folhas de L. alba, provenientes de cultivo e coletadas nas diferentes estações do ano, relacionando as variações observadas com dados meteorológicos de temperatura, insolação, umidade relativa e chuva acumulada. As possíveis rotas biossintéticas para os mono e sesquiterpenóides presentes no óleo essencial também são discutidas.

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Abstract:Plants from the genus Pterocaulon are popularly used as antifungal and wound-healing agents. Such activities have been related to coumarins, which are abundant in those plants. Coumarins are soluble in organic solvents, such as hexane and dichloromethane, and some of them are also soluble in hot water. Considering that infusion and decoctions of these plants are used in traditional medicine, the aim of this study was to identify and quantify the coumarins in the aqueous extract of Pterocaulon balansae. The aqueous extract was obtained by dynamic maceration and the compounds were characterized by UPLC-UV-MS analysis. A new coumarin and 5-methoxy-6,7-methylenedioxycoumarin, used for validation of the analytical HPLC method were obtained by partition of the aqueous extract with n-hexane. The HPLC method validated was linear, specific, and precise. Seven coumarins were characterized in the aqueous extract in a range of 0.584-54 mg/g of dry plant material. The main compound, 5,6-dimethoxy-7-(3′-methyl-2′,3′-dihydroxybutyloxy)coumarin, is described for the first time in P. balansae together with a new compound, 5,6-dimethoxy-7-(2′,3′-epoxy-3′-methylbutyloxy)coumarin.