Characterization, antimicrobial and antitumor activity of superoxide dismutase extracted from Egyptian honeybee venom (Apis mellifera lamarckii)

Antimicrobial proteins from oyster hemolymph improve the efficacy of conventional antibiotics

Discovering new antibiotics and increasing the efficacy of existing antibiotics are priorities to address antimicrobial resistance. Antimicrobial proteins and peptides (AMPPs) are considered among the most promising antibiotic alternatives and complementary therapies. Here, we build upon previous work investigating the antibacterial activity of a semi-purified hemolymph protein extract (HPE) of the Australian oyster Saccostrea glomerata. HPE showed antimicrobial-biofilm inhibitory activity toward laboratory and clinical strains of Streptococcus pneumoniae and Streptococcus pyogenes at 4.4 and 24.1 μg/mL total protein, respectively. In combination assays, the effectiveness of conventional antibiotics (ampicillin, gentamicin, trimethoprim and ciprofloxacin) was improved between 2 to 32-fold in the presence of HPE (1-12 μg/mL) against a range of clinically important bacteria including Streptococcus spp., Pseudomonas aeruginosa, Moraxella catarrhalis, Klebsiella pneumoniae and Staphylococcus aureus. Effective HPE concentrations are comparable to AMPPs currently approved for use or in clinical trials pipelines. Proteomics analysis of HPE identified a number of proteins including abundant known AMPPs. It was non-toxic to A549 human lung cells up to 205 μg/mL, demonstrating safety well above effective concentrations. Activity was retained with storage at -80°C and ambient laboratory temperature (~24°C), but declined after treatment at either 37°C or 60°C (1 h). This study is in agreement with growing evidence that AMPPs show specificity and a high capacity for synergism with antibiotics. The discovery of HPE provides great opportunities for both pharmaceutical and aquaculture industry development.

Structural, dielectric, and antimicrobial evaluation of PMMA/CeO2 for optoelectronic devices

In the current report, we have successfully synthesized nanocomposites of PMMA incorporating different doping of CeO2 through a chemical approach. XRD results reflects decent matching for CeO2 nanoparticles with 29 nm crystallite size. FTIR spectroscopy demonstrates the characteristic functional groups validating the successful formation of the composite. The optical study of PMMA and the nanocomposites has proven that the optical properties such as band gap, refractive index, optical permittivity, and loss tangent factor are affected by adding CeO2 to the PMMA matrix.The peak residing around 420 nm by UV measurements is allocated to occurring electrons photoexcitation from the valence to conduction band inherent in CeO2. The dielectric measurements were achieved using broadband dielectric spectroscopy upon a wide span of frequencies (10-1-107 Hz) and within temperatures from - 10 to 80 °C with a step of 10 °C. The permittivity decreases by adding CeO2 and the dielectric parameters are thermally enhanced, however, the temperature influence is based on CeO2 content, the higher the CeO2 amount, the higher the influence of temperature. The results of the nanocomposites revealed antibacterial activity counter to gram-positive bacteria strain (S. aureus, and B. subtilis), and gram-negative bacteria (E. coli, and K. pneumoniae), yeast (C. albicans, as well as fungi (A. niger). Inherently, the change in CeO2 concentration from 0.01 to 0.1 wt% delivers maximum influence against gram-negative bacteria. These PMMA CeO2-doped composites are beneficial for optoelectronic areas and devices.

Chemical Composition and Antimicrobial Properties of Honey Bee Venom

Due to its great medical and pharmaceutical importance, honey bee venom is considered to be well characterized both chemically and in terms of biomedical activity. However, this study shows that our knowledge of the composition and antimicrobial properties of Apis mellifera venom is incomplete. In this work, the composition of volatile and extractive components of dry and fresh bee venom (BV) was determined by GC-MS, as well as antimicrobial activity against seven types of pathogenic microorganisms. One-hundred and forty-nine organic C₁-C₁₉ compounds of different classes were found in the volatile secretions of the studied BV samples. One-hundred and fifty-two organic C₂-C₃₆ compounds were registered in ether extracts, and 201 compounds were identified in methanol extracts. More than half of these compounds are new to BV. In microbiological tests involving four species of pathogenic Gram-positive and two species of Gram-negative bacteria, as well as one species of pathogenic fungi, the values of the minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) were determined for samples of dry BV, as well as ether and methanol extracts from it. Gram-positive bacteria show the greatest sensitivity to the action of all tested drugs. The minimum MIC values for Gram-positive bacteria in the range of 0.12-7.63 ng mL^-1 were recorded for whole BV, while for the methanol extract they were 0.49-125 ng mL^-1. The ether extracts had a weaker effect on the tested bacteria (MIC values 31.25-500 ng mL^-1). Interestingly, Escherichia coli was more sensitive (MIC 7.63-500 ng mL^-1) to the action of bee venom compared to Pseudomonas aeruginosa (MIC ≥ 500 ng mL^-1). The results of the tests carried out indicate that the antimicrobial effect of BV is associated with the presence of not only peptides, such as melittin, but also low molecular weight metabolites.