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

Cleistochlamys kirkii (Benth) Oliv. (Annonaceae) is a medicinal plant traditionally used in Mozambique to treat infectious diseases. The aim of this study was to find resistance modifiers in C. kirkii for Gram-positive and Gram-negative model bacterial strains. One of the most important resistance mechanisms in bacteria is the efflux pump-related multidrug resistance. Therefore, polycarpol (1), three C-benzylated flavanones (2-4), and acetylmelodorinol (5) were evaluated for their multidrug resistance-reverting activity on methicillin-susceptible and methicillin-resistant Staphylococcus aureus and Escherichia coli AG100 and AG100 A strains overexpressing and lacking the AcrAB-TolC efflux pump system. The combined effects of antibiotics and compounds (2 and 4) were also assessed by using the checkerboard microdilution method in both S. aureus strains. The relative gene expression of the efflux pump genes was determined by real-time reverse transcriptase quantitative polymerase chain reaction. The inhibition of quorum sensing was also investigated. The combined effect of the antibiotics and compound 2 or 4 on the methicillin-sensitive S. aureus resulted in synergism. The most active compounds 2 and 4 increased the expression of the efflux pump genes. These results suggested that C. kirkii constituents could be effective adjuvants in the antibiotic treatment of infections.

Background/Aim: Multidrug resistance (MDR) represents a significant impediment to successful cancer treatment. In this study, novel metal [Zn(II), Cu(II), Mg(II), Ni(II), Pd(II), and Ag(I)] complexes of 2-trifluoroacetonylbenzoxazole previously synthesized and characterized by our group were tested for their MDR-reversing activity in comparison with the free ligands in L5178Y mouse Tlymphoma (MDR) cells transfected with human ATP-binding cassette sub-family B member 1 (ABCB1; P-glycoprotein) gene. Materials and Methods: Cytotoxic and antiproliferative effects of the complexes were assessed by the thiazolyl blue tetrazolium bromide (MTT) method. Modulation of ABCB1 activity was measured by rhodamine 123 accumulation assay using flow cytometry. The apoptosis-inducing activity of some complexes was also tested on the multidrug resistant L5178Y mouse T-lymphoma cells, using the annexin-V/propidium iodide assay. Results: When compared to the free ligand, a remarkable enhancement in MDR reversal and cytotoxic activity was found for the Zn(II) and Cu(II) complexes. The activity of the complexes proved to be up to 29-and 5-fold higher than that of the ligands and the ABCB1 inhibitor verapamil as positive control, respectively. The complexes possessed a remarkable potential to induce apoptosis of MDR cells. Conclusion: Our results suggest that the Zn(II) and Cu(II) complexes display significant MDRreversing activity in a dose-dependent manner and possess strong cytotoxic activity and a remarkable potential to induce apoptosis in MDR L5178Y mouse T-lymphoma cells.

Objectives: Rheumatoid arthritis (RA) is a chronic, inflammatory joint disease with complex pathogenesis involving a variety of immunological events. Recently, it has been suggested that kynurenic acid (KYNA) might be a potential regulator of inflammatory processes in arthritis. KYNA has a definitive anti-inflammatory and immunosuppressive function. The aim of the present study is to investigate the complex effects of a newly synthesized KYNA analog—SZR72 on the in vitro production of tumor necrosis factor-α (TNF-α), tumor necrosis factor-stimulated gene-6 (TSG-6), calprotectin (SA1008/9), SA100 12 (EN-RAGE), and HNP1–3 (defensin-α) in the peripheral blood of patients with RA and the various effects of the disease.Methods: Patients with RA (n = 93) were selected based on the DAS28 score, medication, and their rheumatoid factor (RF) status, respectively. Peripheral blood samples from 93 patients with RA and 50 controls were obtained, and activated by heat-inactivated S. aureus. Parallel samples were pretreated before the activation with the KYNA analog N-(2-N, N-dimethylaminoethyl)-4-oxo-1H-quinoline-2-carboxamide hydrochloride. Following the incubation period (18 h), the supernatants were tested for TNF-α, TSG-6, calprotectin, S100A12, and HNP1–3 content by ELISA.Results: SZR72 inhibited the production of the following inflammatory mediators: TNF-α, calprotectin, S100A12, and HNP1–3 in whole blood cultures. This effect was observed in each group of patients in various phases of the disease. The basic (control) levels of these mediators were higher in the blood of patients than in healthy donors. In contrast, lower TSG-6 levels were detected in patients with RA compared to healthy controls. In addition, the KYNA analog exerted a stimulatory effect on the TSG-6 production ex vivo in human whole blood cultures of patients with RA in various phases of the disease.Conclusion: These data further support the immunomodulatory role of KYNA in RA resulting in anti-inflammatory effects and draw the attention to the importance of the synthesis of the KYNA analog, which might have a future therapeutic potential.

Background/Aim: Phenothiazines constitute a versatile family of compounds in terms of biological activity, which have also gained a considerable attention in cancer research. Materials and Methods: Three phenothiazines (promethazine, chlorpromazine and thioridazine) have been tested in combination with 11 active selenocompounds against MDR (ABCB1-overexpressing) mouse T-lymphoma cells to investigate their activity as combination chemotherapy and as antitumor adjuvants in vitro with a checkerboard combination assay. Results: Seven selenocompounds showed toxicity on mouse embryonic fibroblasts, while three showed selectivity towards tumor cells. Two compounds showed synergism with all tested phenothiazines in low concentration ranges (1.46-11.25 μM). Thioridazine was the most potent among the three phenothiazines. Conclusion: Phenothiazines belonging to different generations showed different levels of adjuvant activities. All the tested phenothiazines are already approved medicines with known pharmacological and toxicity profiles, therefore, their use as adjuvants in cancer may be considered as a potential drug repurposing strategy.