No abstract

O fungo Aspergillus flavus isolado como endofítico da planta Paspalum maritimum Trin. foi avaliado quanto ao seu potencial de aplicação em reações de biotransformações. Os compostos chalcona (1), 3,4,5-trimetoxichalcona (2) e 2,3,4,4'-tetrametoxichalcona (3) foram biotransformados, respectivamente, na diidrochalcona (4), 3,4,5-trimetoxidiidrochalcona (5) e 2,3,4,4'-tetrametoxidiidrochalcona (6). As estruturas destes compostos foram determinadas por análises de RMN uni e bidimensionais e por espectrometria de massas. As diidrochalconas 5 e 6 são substâncias inéditas. The fungus Aspergillus flavus isolated as endophytic of the plant Paspalum maritimumTrin. was evaluated for its potential application in biotransformation reactions. The compounds chalcone (1), 3,4,5-trimethoxychalcone (2) and 2,3,4,4'-tetramethoxychalcone (3) were biotransformed, respectively, in dihydrochalcone (4), 3,4,5-trimethoxydihydrochalcone (5) and 2,3,4,4'-tetramethoxydihydrochalcone (6). The structures were elucidated by spectroscopic methods including 1D and 2D NMR techniques, and MS analysis. The dihydrochalcones 5 and 6 are new compounds.

The natural compound ravenelin was isolated from the biomass extracts of Exserohilum rostratum fungus, and its antimicrobial, antiplasmodial, and trypanocidal activities were evaluated. Ravenelin was isolated by column chromatography and HPLC and identified by NMR and MS. The susceptibility of Gram-positive and Gram-negative bacteria strains to ravenelin was determined by microbroth dilution assay. Cytotoxicity was evaluated in hepatocarcinoma cells (HepG2) and BALB/c peritoneal macrophages by using MTT. SYBR Green I-based assay was used in the asexual stages of Plasmodium falciparum. Trypanocidal activity was tested against the epimastigote and intracellular amastigote forms of Trypanosoma cruzi. Ravenelin was active against Gram-positive bacteria strains, with emphasis on Bacillus subtilis (MIC value of 7.5 µM). Ravenelin’s antiparasitic activities were assessed against both the epimastigote (IC50 value of 5 ± 1 µM) and the intracellular amastigote forms of T. cruzi (IC50 value of 9 ± 2 µM), as well as against P. falciparum (IC50 value of 3.4 ± 0.4 µM). Ravenelin showed low cytotoxic effects on both HepG2 (CC50 > 50 µM) and peritoneal macrophage (CC50 = 185 ± 1 µM) cells with attractive selectivity for the parasites (SI values > 15). These findings indicate that ravenelin is a natural compound with both antibacterial and antiparasitic activities, and considerable selectivity indexes. Therefore, ravenelin is an attractive candidate for hit-to-lead development.

RESUMO -Vários metabólitos produzidos por plantas apresentam atividade herbicida. Essa característica tem levado à possibilidade de utilizar essas substâncias como herbicidas mais integrados às atuais exigências da sociedade. Entretanto, a obtenção dessas moléculas apresenta várias limitações, sendo, dessa forma, a síntese uma alternativa. Este trabalho teve por objetivo determina r as variações na atividade alelopática da cha lcona, 2,4 ' -dimetoxichalcona, em função dos precursores, ortoanisaldeído e 4-metoxiacetofenon a, e de alterações nestes. Os bioensaios foram monitorados em condições controladas de 25°C e fotoperíodo de 12 horas. Como plantas-teste foram utilizadas as plantas daninhas malícia (Mimosa pudica) e mata-pasto (Senna obtusifolia). A atividade alelopática foi analisada em concentrações fixas de 100, 200 e 300 mg L -1 . A chalcona foi obtida via reação de condensação entre a 4-metoxiacetofenona e o ortoanisaldeído. Os resultados indicaram que a atividade alelopática está relacionada, em princípio, ao precursor A, 4-metoxiacetofenona. Mudanças nos precursores indicaram a possibilidade de aumentar a atividade alelopática, em especial no precursor A. Ausência do grupo CH 3 O propiciou redução na atividade alelopática, indicando ser importante para a atividade. A presença de dois grupamentos OCH 3 no precursor da porção B da chalcona aumentou para 62% a atividade do aldeído. Esses resultados indicam que alterações de substâncias com atividades alelopáticas são uma possível via para enfrentar os problemas atrelados aos processos de isolamento e identificação de moléculas químicas com atividade alelopática, em espécies de plantas.Palavras-chave: alelopatia, aleloquímico, germinação, síntese de chalcona. ABSTRACT -Several secondary metabolites produced by plants can be used as herbicides.These products are expected to offer fewer risks to the environment and to meet social demands. However, the availability of compounds is very limited, so synthesis is an alternative. The objective of this work was to evaluate the allelopathic activity of synthetic chalcone, 2,4'-dimethoxychalcone, its precursors, 4-methoxyacetophenone (A) and ortho-anisaldehyde (B)

The purpose of this study is to evaluate the toxicity of synthetic chalcones 1 and 2 in uninfected hamsters and anti-Leishmania activity of synthetic chalcones 1 and 2 in hamsters infected with Leishmania (Viannia) braziliensis. For the toxicity test, uninfected animals were treated with chalcones 1 and 2, and clinical and biochemical parameters and histological aspects of the liver and kidneys were assessed. Chalcones 1 and 2 were then intraperitoneally or topically administered (10 mg/kg body weight) three times per week in animals infected with promastigotes of L. (V.) braziliensis. We monitored the thickness of the infected footpads, determined parasitic load, performed histological analysis, and detected apoptosis in situ. The results were analyzed using Student's t test and Mann-Whitney test at a significance level of 5%. Neither of the chalcones showed toxicity. Chalcone 2 administered intraperitoneally significantly reduced the thickness of the infected footpad compared with the beginning of treatment. The parasite load of the lymph node and spleen was reduced in the groups treated with chalcones 1 (topical) and 2 (intraperitoneal). Chalcone 2 (topical) reduced parasite burden only in the lymph node. The histological analysis revealed reconstitution of the tissue and reductions of inflammation and apoptosis in the infected footpad in these groups. The synthetic chalcones 1 (topical) and 2 (intraperitoneal and topical) at a dose of 10 mg/kg showed anti-Leishmania activity in vivo, no renal or hepatic toxicity, and a reduction of apoptosis of the cells in the lesions. These chalcones may have substantial potential for the treatment of cutaneous leishmaniasis.