A low-cost yeast-based biofuel cell: an educational green approach

<p>This paper describes the construction and characterization of a biofuel cell with low-cost materials. The system uses the baker’s yeast (<i>Saccharomyces cerevisiae</i>) as the microorganism responsible for the generation of voltage, whose interaction with the electrode is mediated by methylene blue. Simple experiments are proposed to evaluate the effects of different substrates, inhibitors and cell viability, improving both the knowledge of the system as well as metabolic pathway concepts to the student. The proposed device was able to generate a power density of 41 ± 0.3 mW m⁻², similar to those obtained with yeast-based biofuel cells. The low cost and easily acquisition of materials described allow the introduction of biofuel cell theme in different teaching levels, from high school to the college level.</p

The effect of seasons on Brazilian red propolis and its botanical source: chemical composition and antibacterial activity

<p>The aim of this study was to evaluate the effect of seasons on the chemical composition and antibacterial activity of Brazilian red propolis (BRP) and its plant source. BRP was collected from Maceio, Alagoas state, north-east of Brazil, during one year. Chemical composition was determined by physicochemical analyses and HPLC while antimicrobial activity was assessed against <i>Streptococcus mutans</i>, <i>Streptococcus sobrinus</i>, <i>Staphylococcus aureus</i> and <i>Actinomyces naeslundii</i> by determining the minimal inhibitory and bactericidal concentrations (MIC and MBC, respectively). The comparative chemical profiles varied quantitatively according to the collection period. Formononetin was the most abundant compound in both propolis and resin, while isoliquiritigenin, (3S)-neovestitol, (3S)-vestitol are suggested to be responsible for antimicrobial activity of Brazilian red propolis. MIC varied from 15.6 to 125 μg/mL, whereas MBC varied from 31.2 to 500 μg/mL. Therefore, season in which propolis and its botanical source are collected indeed influences their chemical compositions, resulting in variations in their antibacterial activity.</p

Activity of seven variants of organic propolis in the activation of NF-κB on macrophages.

<p>The groups were: control (vehicle) and organic propolis (OP1–OP7) at the concentrations of 0.1, 1, and 10 μg/mL. Data were expressed as mean ± SD using ANOVA followed by the Tukey’s test. The results were considered statistically significant when <i>p</i> < 0.05. #<i>p < 0</i>.<i>05 compared to the control group</i> (C); <i>*p < 0</i>.<i>05 compared</i> to LPS (–).</p

Total phenolic content, flavonoid content, and scavenging activity of seven variants of Brazilian organic propolis (OP1–OP7).

<p>Total phenolic content, flavonoid content, and scavenging activity of seven variants of Brazilian organic propolis (OP1–OP7).</p

Inhibition of <i>Streptococcus mutans</i> biofilm formation by seven variants of organic propolis (OP1–OP7).

<p>Statistical analysis performed using ANOVA followed by Kruskal-Wallis test. Means followed by different letters differ statistically at the same concentrations of different variants of OP (<i>p</i> ≤ 0.05).</p

HPLC chromatograms of seven variants of organic propolis (OP1–OP7) detected at 260 nm (positive peaks) and 734 nm (negative peaks).

<p>Peak numbers refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0165588#pone.0165588.t001" target="_blank">Table 1</a>.</p

Characterization of individual peaks with antioxidant activity of seven variants of Brazilian organic propolis (OP1–OP7).

<p>Characterization of individual peaks with antioxidant activity of seven variants of Brazilian organic propolis (OP1–OP7).</p

Citotoxicity effect of seven different organic propolis on macrophages.

<p>The groups were: control (vehicle) and organic propolis (OP1–OP7) at the concentrations 0.1, 1, 10, and 100 μg/mL. Data were expressed as means ± SD using ANOVA followed by the Tukey’s test. The results were considered statistically significant when <i>p</i> < 0.05. *<i>p</i> < 0.05 compared to the control group (C).</p

Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of ethanolic extracts of propolis (EEP), obtained from seven variants of Brazilian organic propolis (OP1–OP7), against <i>Streptococcus mutans</i>, <i>Streptococcus oralis</i>, <i>Streptococcus sobrinus</i>, <i>Staphylococcus aureus</i>, <i>Pseudomonas aeruginosa</i>, and <i>Escherichia coli</i>.

<p>Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of ethanolic extracts of propolis (EEP), obtained from seven variants of Brazilian organic propolis (OP1–OP7), against <i>Streptococcus mutans</i>, <i>Streptococcus oralis</i>, <i>Streptococcus sobrinus</i>, <i>Staphylococcus aureus</i>, <i>Pseudomonas aeruginosa</i>, and <i>Escherichia coli</i>.</p

Food-grade delivery systems of Brazilian propolis from Apis mellifera: From chemical composition to bioactivities in vivo

Brazilian propolis from Apis mellifera is widely studied worldwide due to its unique chemical composition and biological properties, such as antioxidant, antimicrobial, and anti-inflammatory. However, although many countries produce honey, another bee product, the consumption of propolis as a functional ingredient is linked to hydroethanolic extract. Hence, other food uses of propolis still have to be incorporated into food systems. Assuming that propolis is a rich source of flavonoids and is regarded as a food-grade ingredient for food and pharmaceutical applications, this review provides a theoretical and practical basis for optimising the bioactive properties of Brazilian propolis, encompassing the extraction processes and incorporating its bioactive compounds in the delivery systems for food applications. Overall, pharmacotechnical resources can optimise the extraction and enhance the chemical stability of phenolic compounds to ensure the bioactivity of food formulations.</p