Abstract:In the history of human medicine, antibiotics represent epochal examples of medical progress. However, with an approaching antibiotic crisis due to the emergence and extensive spread of antimicrobial resistance among bacterial agents, as well as to increasing number of patients with chronic and recalcitrant bacterial biofilm-associated infections, the naturally occurring molecules may become new sources of antibacterial and antibiofilm drugs for clinical usage. Polyphenols represent a class of plant natural products which are important in plant defense against microbial pathogens. The main focus of the review is on the antibiofilm activities of phenolic compounds against bacteria which play an essential role in medical device biofilm-associated infections. The other, not negligible part of the review is devoted to polyphenols' activity against bacterial agents that cause dental caries and periodontal disease.

It is supposed that plant functional foods, rich in phytochemicals, may potentially have preventive effects in carcinogenesis. In this study, the anticancer effects of cloves in the in vivo and in vitro mammary carcinoma model were assessed. Dried flower buds of cloves (CLOs) were used at two concentrations of 0.1% and 1% through diet during 13 weeks after the application of chemocarcinogen. After autopsy, histopathological and immunohistochemical analyses of rat mammary carcinomas were performed. Moreover, in vitro evaluation using MCF‐7 cells was carried out. Dietary administered CLO caused the dose‐dependent decrease in tumour frequency by 47.5% and 58.5% when compared to control. Analysis of carcinoma cells in animals showed bcl‐2, Ki67, VEGFA, CD24 and CD44 expression decrease and Bax, caspase‐3 and ALDH1 expression increase after high‐dose CLO administration. MDA levels were substantially decreased in rat carcinomas in both CLO groups. The evaluation of histone modifications revealed increase in lysine trimethylations and acetylations (H4K20me3, H4K16ac) in carcinomas after CLO administration. TIMP3 promoter methylation levels of CpG3, CpG4, CpG5 islands were altered in treated cancer cells. An increase in total RASSF1A promoter methylation (three CpG sites) in CLO 1 group was found. In vitro studies showed antiproliferative and pro‐apoptotic effects of CLO extract in MCF‐7 cells (analyses of cytotoxicity, Brdu, cell cycle, annexin V/PI, caspase‐7, Bcl‐2 and mitochondrial membrane potential). This study showed a significant anticancer effect of clove buds in the mammary carcinoma model in vivo and in vitro.

Our results demonstrate, for the first time, a distinct tumour-suppressive effect of oregano in the breast cancer model.

Rosmarinic acid protected aortic endothelial function and ultrastructure against diabetes-induced damage. Both antioxidant and anti-inflammatory effects of rosmarinic acid seemed to participate in the mechanism of this protection.

The subject of study was the evaluation of antibacterial activities of rosmarinic acid (RA) on clinical Staphylococcus aureus strains obtained from catheterrelated infections. Minimal inhibitory (MIC) and minimal bactericidal concentrations (MBC) of RA were tested by broth microdilution assay. Biofilmeradication activity was detected on 24-hour biofilm in microtiter plates using a regrowth technique; activity on biofilm formation was measured by a microtiter plate method after RA application to bacterial samples after 0, 1, 3 and 6 hours of biofilm development. RA had antimicrobial activity on all tested strains in concentrations from 625 to 1250 μg.mL-1 (MICs equal to MBCs). No biofilm-eradication activity on 24-hour biofilm was observed in the tested range of concentrations (from 156 to 5000 μg.mL-1). Subinhibitory RA concentrations suppressed the biofilm production, when applied at early stages of its development. Concentrations lower than subinhibitory stimulated the biofilm mass production in a concentration-and time-dependent manner. Considering our results, RA could be a candidate for a topical antimicrobial agent with killing activity on planktonic forms of bacteria and suppressing activity in the early stages of biofilm development, but probably not for the therapy of catheter-related infections as a sole agent.

A taxonomic study into the anatomical, morphological and phytochemical differentiation of the genus Mentha L (Lamiaceae) in Bosnia & Hercegovina and Slovakia is presented. Following a population-based approach and using hierarchical cluster analyses the following basic species and hybrids corresponding to exclusive branches, i.e. groups, in the constructed hierarchies were recognized: Mentha aquatica, M. spicata, M. arvensis, M. longifolia, M. rotundifolia, M. × piperita, M. × villosa, M. × verticillata, M. × gentillis, M. × gracilis and M. pulegium. These groups were independently found by separate analyses of the sampled anatomical and morphological variation. In contrast, these anatomically and morphologically defined species exhibited a high level of phytochemical polymorphism which was largely inconsistent with the hierarchical classification. Among the analysed characters, the inflorescence type, dentation of the leaf margin, hair density, the type of capitate glandular hairs, and the main containing compound in essential oil proved most useful for the discrimination of taxa. However, most of the observed traits were not exclusive to a particular species and only the combined consideration of traits revealed coherent taxonomic groups. Basic species and hybrids are described in detail based on the anatomical, morphological and phytochemical characters used for their definition. The performed cluster analysis finally supported hypotheses on the parentage of some of the studied hybrids.

In the present study, we investigated the potential protective effect of selected natural substances in a rat model of heart and mesenteric ischemia-reperfusion (I/R). Experiments were performed on isolated Langendorff-perfused rat hearts, subjected to 30-min global ischemia, followed by 30-min reperfusion. Arbutin, curcumin, rosmarinic acid and extract of Mentha x villosa were applied in the concentration of 1 × 10⁻⁵ mol/l 10 min before the onset of ischemia and during reperfusion, through the perfusion medium. Mesenteric ischemia was induced by clamping the superior mesenteric artery (SMA) for 60 min, subsequent reperfusion lasted 30 min. Production of reactive oxygen species (ROS) by SMA ex vivo was determined by luminol-enhanced chemiluminiscence (CL). The effect of the substances was tested after their incubation with tissue. Curcumin and extract of Mentha x villosa were found to be the most effective in reducing reperfusion-induced dysrhythmias--ventricular tachycardia and fibrillation. This effect was accompanied by bradycardic effect. The mesenteric I/R induced an increase in CL in vascular tissue which was dampened by substances tested. All substances tested were found to have antioxidant properties, as demonstrated by a reduction in ROS production in mesenteric vessels. This effect was confirmed in curcumin and extract of Mentha x villosa which reduced reperfusion dyshythmias.

Diabetes mellitus (DM) is frequently diagnosed at a time when patients already suffer from several cardiovascular complications. Our previously published data (Molecules 201520 (11): 20538-50) on the anti-oxidative properties of Agrimonia eupatoria L. (AE) and Cynara cardunculus L. (CC) prompted us to extend the available evidence on their possible protective activities on selected DM-related parameters in a streptozotocin-induced DM rat model and in a series of in vitro experiments. Male rats were divided into four groups: control group, untreated diabetic group, AE and CC treated diabetic groups. During a five-week period, changes in blood glucose and body weight were monitored. Then, rats were sacrificed and subjected to the assessment of changes in the reactivity of aortas and measurement of butyrylcholinesterase activity. To complete the panel of experiments, α-glucosidase activity was assessed in vitro. Our results demonstrate that both tested extracts exert similar anti-diabetic activities. However, better anti-oxidant activity of the A. eupatoria extract indicates its higher clinical potential in the prevention and/or adjuvant therapy of developing cardiovascular complications related to DM and diseases associated with oxidative stress.