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Background and Objectives: In spite of the fact that antibiotics are considered to be the cornerstone of modern medicine, their use in the treatment of cancer remains controversial. In the present study, the main objective was to examine the effects of two antibiotics—tetracycline and ampicillin—on the viability, morphology, migration, and organization and structure of the nuclei and the actin fiber network of pharyngeal carcinoma cells—Detroit-562. Materials and Methods: In order to determine the viability of the cells, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method was applied after the cells were stimulated with five concentrations of tetracycline and ampicillin (10, 25, 50, 75, and 100 μM) for 72 h. A scratch assay was used to assess the migration ability of the cells. For the visualization of the nuclei and actin fibers, 4,6-diamidino-2-phenylindole (Dapi) and Rhodamine-Phalloidin were used. Results: There are different effects of tetracycline and ampicillin. Thus, tetracycline: (i) exhibited a concentration-dependent cytotoxic effect, decreasing cell viability to approximately 46%; (ii) inhibits cellular migration up to 16% compared to 60% for control cells; and (iii) induces changes in cell morphology as well as apoptotic changes in the nucleus and F-actin fibers. In contrast, in the case of ampicillin, an increase in viability up to 113% was observed at 10 μM, while a decrease in viability up to approximately 94% was observed at the highest concentration tested (100 μM). Conclusions: The results indicated a different effect regarding the impact on pharyngeal carcinoma cells. Thus, tetracycline has a concentration-dependent cytotoxic effect, while in the case of ampicillin a slight stimulation of cell viability was observed. [ABSTRACT FROM AUTHOR]

The present study was purported to assess the activities: (i) antibacterial and synergistic against three types of both Gram-positive and Gram-negative bacteria that are susceptible to drug resistance and (ii) cytotoxic and synergistic on colorectal adenocarcinoma cells, of thyme essential oil (TEo) in combination with tetracycline (Tcyc). Chemical composition of thyme essential oil was evaluated by gas chromatography-mass spectrometry (GC-MS) method, antioxidant capacity by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) assay, antibacterial and synergistic properties were determined by disk diffusion method and cytotoxic activity by quantifying viable cells by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Thyme essential oil has an elevated antioxidant activity, antibacterial potential against both Gram-positive and Gram-negative bacteria, especially on S. aureus and K. pneumoniae at the highest concentration tested (50µL/mL), also having a synergistic effect when combined with tetracycline (50µL/mL TEo with 10µg/mL Tcyc). Essential oil-treated cells showed a dosedependent reduction in colorectal adenocarcinoma cell viability, while combination with tetracycline leads to a significantly attenuated decrease in viability. [ABSTRACT FROM AUTHOR]

Antibiotics are considered as a cornerstone of modern medicine and their discovery offers the resolution to the infectious diseases problem. However, the excessive use of antibiotics worldwide has generated a critical public health issue and the bacterial resistance correlated with antibiotics inefficiency is still unsolved. Finding novel therapeutic approaches to overcome bacterial resistance is imperative, and natural compounds with antibacterial effects could be considered a promising option. The role played by antibiotics in tumorigenesis and their interrelation with the microbiota are still debatable and are far from being elucidated. Thus, the present manuscript offers a global perspective on antibiotics in terms of evolution from a historical perspective with an emphasis on the main classes of antibiotics and their adverse effects. It also highlights the connection between antibiotics and microbiota, focusing on the dual role played by antibiotics in tumorigenesis. In addition, using the natural compounds with antibacterial properties as potential alternatives for the classical antibiotic therapy is discussed. [ABSTRACT FROM AUTHOR]