A Bioguided Approach for the Screening of Antibacterial Compounds Isolated From the Hydroalcoholic Extract of the Native Brazilian Bee's Propolis Using Mollicutes as a Model.

Nature is a vast source of medicinal substances, including propolis, which has been extensively investigated. Propolis is a resinous substance produced by bees from the exudates of plants that they collect and modify in their jaws; it is a rich and complex matrix with secondary metabolites of diverse botanical origins. The objective of this study was to apply an in vitro bioguided approach using as a model system the mollicutes with a sample of propolis from the Brazilian native bee Melipona quadrifasciata (mandaçaia) in order to identify potential new molecules with antimicrobial activity. A crude hydroalcoholic extract was obtained and submitted to liquid-liquid partitioning with solvents of different polarities, generating four different fractions: aqueous, dichloromethane, butanol, and ethyl acetate fractions. The antimollicute activity assays served as a basis for the bioguided fractionation. The dichloromethane fraction was the most promising, exhibiting a minimal inhibitory concentration (MIC) of 125 µg/mL against Mycoplasma pneumoniae. After purification by column liquid chromatography, a subfraction presenting MIC of 15.6 µg/mL against Mycoplasma genitalium was highlighted. The fractions were also tested against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Using gas chromatography coupled to a mass spectrometer (GC-MS), several volatile compounds were identified in the non-polar fractions of this propolis. However, the more purified molecules had no better antimollicute activity than their original subfraction. Apparently, the synergism among its compounds is largely responsible for the antibacterial activity of the propolis of this native Brazilian bee.

Mollicutes/HIV Coinfection and the Development of AIDS: Still Far from a Definitive Response.

Background. Mycoplasmas are known to cause various infections in humans, mainly in the respiratory and urogenital tracts. The different species are usually host-specific and cause diseases in well-defined sites. New species have been isolated, including those from HIV-infected persons. Summary. Its in vitro properties, combined with clinical findings, have led to the hypothesis that these microorganisms may act as cofactors of HIV in AIDS development. Even today this point of view is quite polemic among infectious disease specialists and many aspects remain to be clarified, in contrast to what happens, for instance, with HIV/Mycobacterium tuberculosis coinfection. Dozens of papers have been published covering aspects of Mollicutes/HIV coinfection, but they add little to no information about the putative contribution of Mollicutes to the evolution of AIDS. Very few researchers have devoted their efforts to trying to answer this question, which remains open. In this review, we discuss the evidences that may support this statement in the light of current knowledge in the field of mycoplasmology.

Evaluation of seasonal chemical composition, antibacterial, antioxidant and anticholinesterase activity of essential oil from Eugenia brasiliensis Lam.

This study describes the seasonal composition and the antibacterial, antioxidant and anticholinesterase activity of the essential oil from Eugenia brasiliensis leaves. Analysis by using GC allowed the identification of 40 compounds. It was observed that the monoterpenes varied more (42%) than the sesquiterpenes (14%), and that the monoterpene hydrocarbons suffered the greatest variation throughout the year (64%). Major compounds were spathulenol in the spring (16.02 ± 0.44%) and summer (18.17 ± 0.41%), τ-cadinol in the autumn (12.83 ± 0.03%) and α-pinene (15.94 ± 0.58%) in the winter. Essential oils were tested for their antibacterial activity, and the best result was obtained from the autumn oil, with MIC = 500 µg mL(- 1) against Staphylococcus saprophyticus and Pseudomonas aeruginosa. Antioxidant activity was evaluated using DPPH, lipid peroxidation and iron-reducing power assays, as well as the anticholinesterase activity. Both tests showed a weak performance of the essential oils.

Immune memory response induced in vitro by recombinant hepatitis B surface antigen challenge 13-18 years after primary vaccination.

The question of whether booster doses are required to maintain long-term protection against hepatitis B virus (HBV) after primary vaccination remains to be determined. Thus, the aim of this study was to evaluate the immune memory responses to hepatitis B surface antigen (HBsAg) challenge in vaccinated individuals through an in vitro-specific stimulation assay. Peripheral blood mononuclear cells (4 × 10(6) cells/ml) were stimulated with 50 ng/ml of recombinant HBsAg. In vitro anamnestic antibody responses, as shown by detection of high avidity antibody in culture supernatants, were found 13-18 years after primary vaccination and were not correlated with serum antibodies (r = -0.177; P = 0.377). In addition, the findings from this study indicate that immune memory against hepatitis B was well preserved in 40.0% and 60.0% of vaccinees with anti-HBs levels less than 10 IU/L or lacking serum antibodies altogether, respectively. In conclusion, the data suggest the presence of immunological memory in vaccinated individuals, including those who showed anti-HBs <10 IU/L or undetectable antibody.

In vitro lymphocyte stimulation by recombinant hepatitis B surface antigen: a tool to detect the persistence of cellular immunity after vaccination.

The study of the human immune response to hepatitis B virus (HBV) has been hampered by the lack of an adequate model to evaluate the hepatitis B surface antigen (HBsAg) specific cell response. Thus, this study was conducted to perform an in vitro analysis of the antigenic properties of recombinant HBsAg and demonstrate the influence of variables such as culture time, antigen concentration and cell density on lymphocyte proliferation. Peripheral blood mononuclear cells (PBMCs) were isolated from the venous blood of vaccinated individuals, and in vitro cellular immune responses were evaluated using an HBsAg-specific proliferation assay. Lymphoproliferative responses were detected in culture systems, despite the lack of serum antibodies. Optimal results were obtained when lymphocytes were stimulated at a seeding density of 4×10(6) cells/mL, with 50 ng/mL of recombinant HBsAg protein vaccine for 3 days. Data from the present study may contribute to the development of an adequate system to evaluate the cellular immune responses to HBsAg in vaccine recipients.

A new accurate, simple formula for LDL-cholesterol estimation based on directly measured blood lipids from a large cohort.

BACKGROUND: Low-density lipoprotein cholesterol (LDL-c) is the major measured parameter for cardiovascular risk assessment. The generally accepted formula (LDL-F) for estimating LDL-c developed by Friedewald and colleagues in 1972 using data from 448 individuals suffers from known inaccuracies at extremes of triglyceride (TG) and total cholesterol (TC) values. METHODS: We generated new formulas based on a large Brazilian database containing directly measured lipid values from 10,664 fasted individuals. This database LDL-c was measured by the LDL-C Select FS (DiaSys) system, a homogeneous method without centrifugation. The formulas were generated using linear and non-linear approaches, and the formula with the highest accuracy and simplicity for general clinical use was selected. RESULTS: The simple formula LDL-c = 3/4 (TC - HDL-c) provided an accurate estimate of LDL-c, a higher correlation with directly measured LDL (r = 0.93) compared with LDL-F (r = 0.87), and also a higher accuracy. CONCLUSIONS: The new formula outperformed several other LDL-c formulas over a wide range of TC, HDL-c and TG values. The validation and application of this formula in other populations is warranted.

Modulatory effect of mycophenolate mofetil on carrageenan-induced inflammation in the mouse air pouch model.

UNLABELLED: The treatment of some inflammatory diseases, such as rheumatoid arthritis, remains an important target for studies because some patients are refractory to conventional treatment. Mycophenolate mofetil (MMF), an immunosuppressive drug, has been shown to have a beneficial effect on the therapy of inflammatory and autoimmune diseases. In the present study, we aimed to analyse the anti-inflammatory effect of MMF administered by oral route in the mouse carrageenan-induced air pouch model. RESULTS: MMF significantly inhibited the influx of leukocytes, exudate concentrations (P<0.01), activities of myeloperoxidase (MPO) and adenosine deaminase (ADA), levels of nitrite/nitrate (NO(x)) and inducible nitric oxide synthase (iNOS) mRNA expression, as well as the levels of mRNA expression and proteins of tumor necrosis factor-alpha (TNF-α), Interleukin-beta (IL-1ß) and vascular endothelial growth factor-alpha (VEGF-α) (P<0.05). These results provide evidence that MMF has an important anti-inflammatory effect in reducing the influx of leukocytes and exudate concentrations. These inhibitory effects are correlated with the inhibition of specific pro-inflammatory enzymes (MPO, ADA and iNOS), and the levels of mRNA expression and proteins of TNF-α, IL-1ß and VEGF-α.