Phytochemical profiling, in vitro biological activities, and in silico (molecular docking and absorption, distribution, metabolism, excretion, toxicity) studies of Polygonum cognatum Meissn.

Polygonum cognatum Meissn, a perennial herbaceous belonging to the Polygonaceae family, is an aromatic plant. High-performance liquid chromatography/diode array detector method was developed and validated for the phytochemical analysis of the plant. Also, various methods were used to investigate the antioxidant, antimicrobial, and cytotoxic activities of the methanolic extracts. Antioxidant activities were researched by 2,2'-diphenyl-1-picrylhydrazyl and cupric reducing antioxidant capacity methods. Among the tested standard microbial strains, Candida albicans was found to be more sensitive with a 24.60 ± 0.55 mm inhibition zone according to the diffusion tests. In the microdilution tests, the minimum inhibitory concentration and minimum bactericidal/fungicidal concentration values were 4.75 and ≥ 4.75 mg/mL, respectively, for all tested pathogens. Human colon carcinoma cells were used to investigate cytotoxicity by using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide analysis (IC50  = 2891 µg/mL for Plant A, IC50  = 3291 µg/mL for Plant B). Molecular docking and absorption, distribution, metabolism, excretion, and toxicity analysis were used to explain inhibition mechanisms of major phenolic compounds of plants against Tankyrase 1, Tankyrase 2 enzymes, and deoxyribonucleic acid gyrase subunit B and found compatible with experimental results.

Evaluation of biocidal efficacy of Chloramine T trihydrate on planktonic and sessile bacteria in a model cooling tower water system.

A model cooling tower system was experimentally seeded with Legionella pneumophila and real industrial cooling tower (CT) water has been run at the closest to full-scale system operating conditions. The water/biofilm samples were taken from the model system monthly, and the effectiveness of the different concentrations of Chloramine T trihydrate biocide was evaluated in terms of its ability to control both planktonic/sessile microbial populations. Although Chloramine T is a recommended commercial formulation for disinfecting CTs, there is a lack of published data on the efficacy of this compound against both planktonic and sessile populations in the cooling tower. Biocide response in both sessile/planktonic bacteria counts varied according to months. Tested biocide concentrations provided the clean tower conditions by reducing the concentration of heterotrophic plate count (HPC) below <104 cfu mL-1, L. pneumophila <10 cfu mL-1 and of adenosine triphosphate (ATP) values <300 relative light units (RLU), after 1, 3 and 24 h of exposure, during a 6-month period. There were no statistically significant differences in efficacy between concentrations in terms of reduction in the number of bacteria, decrease in ATP value and viability. The results revealed that Chloramine T can effectively control biofouling in cooling systems according to the limit values of the successful control program.