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>