Abstract. Phenothiazines have been used in many areasPhenothiazines are unanimously one of the most versatile compounds from the view of biological activity. Since their discovery, new exploitable pharmacological properties have emerged from time to time; thus, they have an important role in many areas of medicine and beyond. This is why phenothiazines are basic compounds in pharmacology. The history of these compounds goes back to the second half of the 19th century, when a German chemist, Heinrich August Bernthsen began to study the structure of methylene blue, which was first synthesized in 1876 by Heinrich Caro. In 1885, two years after Bernthsen first managed to produce phenothiazine, he also succeeded in describing the structure of methylene blue (1). At the same time, Paul Ehrlich began to investigate the possible therapeutic use of methylene blue in malaria infections, which he first published in 1891 (2). Due to this, methylene blue was often prescribed for patients with malaria in the subsequent period (3).Research conducted in the 1930s and '40s proved the potential wide use of phenothiazines. The insecticidal (4), antihelmintic (5, 6), and antibacterial (7) effects of the compound were detected; however, it was not widely used for these purposes. In the 1940s, another novel phenothiazine derivative, namely promethazine was brought to the forefront of attention; it was investigated by Paul Charpentier at the Rhone-Poulenc laboratory in Paris (8). It was shown that promethazine had an antihistamine effect (9), which was later used in the therapy of allergic diseases and in anesthesia (10,11). A few years later in the same laboratory, chlorpromazine was discovered, which has strong anxiolytic and antipsychotic effect along with its antihistaminic effect (12). Psychiatry fully exploited this feature in psychotic patients (13), which resulted in the almost complete emptying of psychiatric hospitals in the 1950s. As a result, the discovery of chlorpromazine and the beginning of its use as an antipsychotic are considered the beginning of modern psychiatry and psychopharmacology.Since then, several antipsychotic phenothiazine compounds have been used in clinical practice, although research conducted in the last couple of decades indicated that phenothiazine compounds could have an important role in other fields of medicine as well, such as in the treatment of tumorous, infectious, or neurodegenerative diseases (3). 5983

Thioridazine (TZ), an antipsychotic drug, renders multidrug-resistant (MDR) cancer cells susceptible to cytotoxic agents to which they were initially resistant, has anti-prolilferative activity and apoptosis-inducing properties in various tumor cell lines and cancer stem cells. Whereas the anti-proliferative activity takes place at high concentrations that ensure the intercalation of the compound between nucleic bases (especially rich in G/C bases), much lower concentrations inhibit the export function of the ABCB1 (P-glycoprotein), which is responsible for the MDR phenotype of the cancer cell. The co-administration of TZ with doxorubicin inhibits efflux of doxorubicin and, hence, increases the intracellular concentration of anticancer drug. The (+) and (-) enantiomers of TZ have the same activities as TZ. The main focus of this review is to present extensive evidence provided by our work, confirmed by much later studies, as it supports adjuvant use of TZ with an anticancer drug for MDR cancer therapy.

Estrogen deficiency is one of the main causes of age-associated diseases in the cardiovascular system. Female Wistar rats were divided into four experimental groups: pharmacologically ovariectomized, surgically ovariectomized, and 24-month-old intact aging animals were compared with a control group. The activity and expression of heme oxygenases (HO) in the cardiac left ventricle, the concentrations of cardiac interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), the myeloperoxidase (MPO) activity in the cardiac left ventricle, and the effects of heme oxygenase blockade (by 24-hour and 1-hour pretreatment with tin-protoporphyrin IX, SnPP) on the epinephrine and phentolamine-induced electrocardiogram ST segment changes in vivo were investigated. The cardiac HO activity and the expression of HO-1 and HO-2 were significantly decreased in the aged rats and after ovariectomy. Estrogen depletion was accompanied by significant increases in the expression of IL-6 and TNF-α. The aged and ovariectomized animals exhibited a significantly elevated MPO activity and a significant ST segment depression. After pretreatment with SnPP augmented ST segment changes were determined. These findings demonstrate that the sensitivity to cardiac ischemia in estrogen depletion models is associated with suppression of the activity and expression of the HO system and increases in the secretion of proinflammatory cytokines and biomarkers.

The estrogen deficiency after menopause leads to overweight or obesity, and physical exercise is one of the important modulators of this body weight gain. Female Wistar rats underwent ovariectomy surgery (OVX) or sham operation (SO). OVX and SO groups were randomized into new groups based on the voluntary physical activity (with or without running) and the type of diet for 12 weeks. Rats were fed standard chow (CTRL), high triglyceride diet (HT), or restricted diet (CR). The metabolic syndrome was assessed by measuring the body weight gain, the glucose sensitivity, and the levels of insulin, triglyceride, leptin, and aspartate aminotransferase transaminase (AST) and alanine aminotransferase (ALT). The exercise training combined with the CR resulted in improvements in the glucose tolerance and the insulin sensitivity. Plasma TG, AST, and ALT levels were significantly higher in OVX rats fed with HT but these high values were suppressed by exercise and CR. Compared to SO animals, estrogen deprivation with HT caused a significant increase in leptin level. Our data provide evidence that CR combined with voluntary physical exercise can be a very effective strategy to prevent the development of a metabolic syndrome induced by high calorie diet.

Protein phosphatase 4 (PP4) is an evolutionarily conserved and essential Ser/Thr phosphatase that regulates cell division, development and DNA repair in eukaryotes. The major form of PP4, present from yeast to human, is the PP4c-R2-R3 heterotrimeric complex. The R3 subunit is responsible for substrate-recognition via its EVH1 domain. In typical EVH1 domains, conserved phenylalanine, tyrosine and tryptophan residues form the specific recognition site for their target's proline-rich sequences. Here, we identify novel binding partners of the EVH1 domain of the Drosophila R3 subunit, Falafel, and demonstrate that instead of binding to proline-rich sequences this EVH1 variant specifically recognizes atypical ligands, namely the FxxP and MxPP short linear consensus motifs. This interaction is dependent on an exclusively conserved leucine that replaces the phenylalanine invariant of all canonical EVH1 domains. We propose that the EVH1 domain of PP4 represents a new class of the EVH1 family that can accommodate low proline content sequences, such as the FxxP motif. Finally, our data implicate the conserved Smk-1 domain of Falafel in target-binding. These findings greatly enhance our understanding of the substrate-recognition mechanisms and function of PP4.