Antimicrobial Activity of Propolis from the Brazilian Stingless Bees Melipona quadrifasciata anthidioides and Scaptotrigona depilis (Hymenoptera, Apidae, Meliponini).

Melipona quadrifasciata anthidioides and Scaptotrigona depilis are species of stingless bees capable of producing propolis, which has considerable bioprospecting potential. In this context, the objective of this study was to determine the chemical compositions and evaluate the antimicrobial activity of propolis produced by M. q. anthidioides and S. depilis. The ethanolic extracts of propolis of M. q. anthidioides (EEP-M) and S. depilis (EEP-S) were prepared, and their chemical constituents were characterized by HPLC-ESI-MS. The antimicrobial activity was evaluated against bacteria and fungi, isolated from reference strains and hospital origin resistant to the action of antibiotics. From EEP-M, phenolic compounds were annotated, including gallic acid, ellagic acid, and flavonoids, as well as diterpenes and triterpenes. EEP-S showed mainly triterpene in its chemical composition. Both extracts inhibited the growth of medically relevant bacteria and fungi, including hospital-acquired and antimicrobial-resistant. In general, EEP-S showed better antimicrobial activity compared to EEP-M. The MIC of EEP-S against vancomycin-resistant Enterococcus faecalis was 3.50 mg/mL, while the MIC of EEP-M was 5.33 ± 0.16 mg/mL. In conclusion, this study shows that propolis produced by M. q. anthidioides and S. depilis has the potential to be used for the prevention or treatment of microbial infections.

Acute Toxic and Genotoxic Effects of Aluminum and Manganese Using In Vitro Models.

The objective of this study was to use the same concentrations of aluminum (Al) and manganese (Mn) detected previously in groundwater above those permitted by Brazilian law and assess their cytotoxic and genotoxic effects in hamster ovary cell lines and their mutagenic effects through the Salmonella microsome assay. Chinese hamster ovary (CHO) and CHO-XRS5 cells were treated with different concentrations of Al and Mn (0.2 to 2.0 mg/L and 0.1 to 3.0 mg/L, respectively). The Ames test was used to analyze the concentrations of Al and Mn ranging from 0.025 to 1.0 mg/L and 0.0125 to 1.5 mg/L, respectively. Both metals showed cytotoxic effects on both cell lines and two bacterial strains (TA98 and TA100). The genotoxic effects of the highest concentrations of Al and Mn in cell lines showed nuclear buds, micronuclei, and DNA damage; however, none of the concentrations showed a positive mutagenic response in the Ames test. This is one of the few studies to demonstrate the cytotoxic effects of Al and Mn through the Ames test. In addition, the metals caused genomic instability in cell lines. Therefore, this study may help hasten the review of established regulatory standards for human consumption of groundwater.

Adepamycin: design, synthesis and biological properties of a new peptide with antimicrobial properties.

Antimicrobial peptides (AMP) are molecules with a broad spectrum of activities that have been identified in most living organisms. In addition, synthetic AMPs designed from natural polypeptides have been largely investigated. Here, we designed a novel AMP using the amino acid sequence of a plant trypsin inhibitor from Adenanthera pavonina seeds (ApTI) as a template. The 176 amino acid residues ApTI sequence was cleaved in silico using the Collection of Antimicrobial Peptides (CAMPR3), through the sliding-window method. Further improvements in AMP structure were carried out, resulting in adepamycin, an AMP designed from ApTI. Adepamycin showed antimicrobial activity from 0.9 to 3.6 µM against Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus strains. Moreover, this peptide also displayed activity against Candida albicans and Candida tropicalis. No toxic effects were observed on healthy human cells. Studies on the mechanism of action of adepamycin were carried out using an E. coli and C. tropicalis. Adepamycin triggers membrane disturbances, leading to intracellular nucleic acids release in E. coli. For C. tropicalis, an initial interference with the plasma membrane integrity is followed by the formation of intracellular reactive oxygen species (ROS), leading to apoptosis. Structurally, adepamycin was submitted to circular dichroism spectroscopy, molecular modeling and molecular dynamics simulations, revealing an environment-dependent α-helical structure in the presence of 2,2,2- trifluoroethanol (TFE) and in contact with mimetic vesicles/membranes. Therefore, adepamycin represents a novel lytic AMP with dual antibacterial and antifungal properties.

Interação entre o receptor AT1 da angiotensina II e o mas protoc-oncogene / Interation between the protooncogene mas product and the angiotensin II AT1 receptor

1. Em vista de evidências de que o mas proto-oncogene pode modular as respostas do receptor AT1 à angiotensina II (AngII), o objetivo deste trabalho foi avaliar, por meio de técnicas de biologia molecular e ensaios farmacológicos, a possível interação entre os receptores AT1 e o mas. Para isso foram construídos mutantes do AT1 com alterações de resíduos com possível participação num hipotético heterodímero: (a) os resíduos Cys18 e Lys20 do domínio N-terminal, sugeridos como estabilizadores de um sítio regulador na região extracelular do receptor AT1 (Santos e cols, 2004) são portanto possíveis mediadores do processo de dimerização. (b) a Lys102, cuja substituição por alanina promoveu a formação de um dímero funcional com o mutante K199A (Monnot e cols. 1996). 2. O receptor AT1 selvagem e os seus mutantes K102A, C18F/K20A, bem como o mas proto-oncogene, foram expressos e co-expressos de forma correta como planejado para o desenvolvimento deste trabalho. 3. Mutações simultâneas (C18F/K20A), mas não isoladas, dos resíduos Cys18 e Lys20 comprometem a ligação do receptor AT1 à AngII. 4. Células CHO expressando o receptor mas ou os mutantes C18F/K20A (da região N-terminal) e K102A (da terceira hélice transmembranar) do receptor AT1, não apresentam ligação e resposta funcional significativa quando estimuladas com AngII. 5. A co-expressão dos receptores AT1 selvagem+mas em boa afinidade pelo agonista AngII porém em deficiência na ativação funcional, em comparação com AT1 selvagem. 6. Células CHO co-expressando receptores K102A+mas não apresentaram ligação nem ativação funcional quando estimuladas pela AngII. 7. A co-expressão dos receptores C18F/K20A+mas promove ligação e ativação funcional próximas às observadas para o receptor AT1 selvagem em resposta ao agonista AngII. 8. A região N-terminal do receptor AT1 de AngII é um importante ponto de interação com o agonista e com outros receptores, possivelmente através da formação de heterodímeros