No abstract

Sanguisorba officinalis L. (family Rosaceae, subfamily Rosoideae) is a plant found throughout Southern Europe, Northern Africa, and Eastern Asia. This study demonstrated the antibacterial activity of a purified polyphenolic extract (PPE) from S. officinalis L. against Bacillus subtilis using growth inhibitory and apoptosis assays, and investigated the antibacterial mechanism responsible for changes in cell membrane properties. Fourier transform infrared spectroscopy suggested that PPE altered the cell wall and membrane properties of B. subtilis. Further determination of cell membrane integrity and permeability revealed that B. subtilis membrane integrity was more severely damaged by PPE at the minimum inhibitory concentration (MIC) than at the minimum bactericidal concentrati on (MBC). Instead, PPE at the MBC reduced cell membrane fluidity by significantly decreasing the proportion of anteiso‐ and iso‐branched phospholipid fatty acids (PLFAs) from 64.17 ± 0.28% and 27.23 ± 0.03% in the control to 5.57 ± 1.06% and 6.00 ± 1.40%, respectively (P < 0.001). Scanning electron microscopy revealed different effects of PPE on cell morphology, demonstrating that, at the MIC and MBC, PPE exerted antibacterial activity by disrupting the cell membrane and reducing cell membrane fluidity, respectively. Consequently, this study elucidated changes in the bacterial membrane due to exposure to PPE and its potential use as an antimicrobial agent.Practical ApplicationThe abuse of synthetic chemical preservatives raises food safety concerns; however, plant‐derived polyphenolic compounds may be a safe and effective alternative. This study demonstrated the strong antibacterial activity of a purified polyphenolic extract (PPE) of Sanguisorba officinalis L. and revealed its antibacterial mechanism against Bacillus subtilis, suggesting that it may provide a useful antimicrobial agent in food industry applications.

Background. Xanthine oxidase (XO) enzyme inhibitors are used to treat hyperuricemia. Certain natural substances have been reported to be strong inhibitors of xanthine oxidase. The purpose of this study was to evaluate the antioxidant activity and XO inhibition effect of ethanolic extract from mulberry leaves. Material and methods. The chemical composition of Mulberry leaf ethanolic extract (MLEE) was identified by the LC-MS/MS method. Antioxidant activity was measured by three different assays (i.e. superoxide, hydrogen peroxide, and hydroxyl radicals assays). The inhibitory effect on XO and its inhibitory mechanism were investigated through the testing of inhibition kinetics and inhibition rate. Results. MLEE showed significant antioxidant activity in the superoxide, hydrogen peroxide, and hydroxyl radicals assays (IC 50 of 0.33 ±0.006 mg/mL, 45 ±0.8 μg/mL, and 2.54 ±0.05 mg/mL for each assay respectively). The effects of XO inhibitory activity showed that MLEE was a reversible and competitive inhibitor with IC 50 values of 1104.76 ±7.1 μg/mL. Eleven compounds, including six flavonoids and five phenolic acids, were identified. Conclusion. MLEE has been shown to exhibit antioxidant activity and XO inhibitory effect, which provides a new insight into the properties of mulberry leaves and their potential future applications as a natural antigout drug.