Mean minimum inhibitory concentration (MIC (mg/mL)) in test samples against <i>Staphylococcus aureus</i> C-29.

<p>Mean minimum inhibitory concentration (MIC (mg/mL)) in test samples against <i>Staphylococcus aureus</i> C-29.</p

Growth effect of polyphenols on SEA-producing strain.

<p>(A) hydrolyzable tannins and (B) procyanidins. Values represent the mean ± SD for three independent experiments. The final concentration of polyphenol (mg/mL) is indicated between brackets.</p

Direct reactivity of polyphenols to SEA.

<p>(A) hydrolyzable tannins (0.25 mg/mL) and (B) procyanidins (0.25–0.50 mg/mL). Values represent the mean ± SD for three independent experiments. * represents <i>p</i> < 0.05 compared with the control. (); final concentration (mg/mL).</p

Affinity interaction of staphylococcal enterotoxin A (SEA) and hydrolyzable tannins.

<p>1; eugeniin, 2; castalagin, 3; punicalagin, 4; pedunculagin, 5; corilagin, 6; geraniin, 7; penta-galloyl-glucose, 8; sanguiin H-6, and 9; tannic acid. For the definition affinity interaction unit (AIU), see the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0157082#sec002" target="_blank">Materials and methods</a> section.</p

Western blot analysis of the influence of polyphenols on SEA production.

<p>(A) hydrolyzable tannins and (B) procyanidins. Values represent the mean ± SD for three independent experiments. * represents <i>p</i> < 0.05 compared to control, and ** represents <i>p</i> < 0.01 compared to control.</p

Inhibitory effect of polyphenols on the toxic activity of SEA against spleen cells.

<p>Values represent the mean ± SD for three independent experiments. * Represents <i>p</i> < 0.05 compared with the SEA (+) control. (); final concentration (μg/mL).</p

Identification of the phenolic compounds contributing to antibacterial activity in ethanol extracts of Brazilian red propolis

<div><p>The purpose of this study is to identify the quantity and antibacterial activity of the individual phenolic compounds in Brazilian red propolis. Quantitative analysis of the 12 phenolic compounds in Brazilian red propolis was carried out using reversed-phase high-performance liquid chromatography. The main phenolic compounds in Brazilian red propolis were found to be (3<i>S</i>)-vestitol (<b>1</b>), (3<i>S</i>)-neovestitol (<b>2</b>) and (6a<i>S</i>,11a<i>S</i>)-medicarpin (<b>4</b>) with quantities of 72.9, 66.9 and 30.8 mg g of ethanol extracts^− 1, respectively. Moreover, the antibacterial activities of each compound against <i>Staphylococcus aureus</i>, <i>Bacillus subtilis</i> and <i>Pseudomonas aeruginosa</i> were evaluated by measuring the minimum inhibitory concentrations. In particular, compound <b>4</b> exhibited the most potent antibacterial activity among all the assayed compounds against selected bacteria, indicating that <b>4</b> is the most active compound in Brazilian red propolis extracts. Thus, Brazilian red propolis may be used as food additives and pharmaceuticals to protect against bacteria.</p></div

Solophenols B–D and Solomonin: New Prenylated Polyphenols Isolated from Propolis Collected from The Solomon Islands and Their Antibacterial Activity.

Three new prenylated flavonoids, namely, solophenols B (<b>1</b>), C (<b>2</b>), and D (<b>3</b>), as well as a new prenylated stilbene, solomonin (<b>4</b>), were isolated from propolis collected from the Solomon Islands. In addition, 17 known compounds were identified. The structures of the new compounds were determined by a combination of methods, including mass spectrometry and NMR. These new compounds and several known compounds were tested for antibacterial activity against <i>Staphylococcus aureus</i>, <i>Bacillus subtilis</i>, and <i>Pseudomonas aeruginosa</i>. Most of them exhibited potent antibacterial activity. These findings may indicate that propolis from the Solomon Islands has potential applications as an ingredient in food additives or pharmaceuticals