Evaluation of the effect of new compounds 1,3,4-thiadazole derivates on various pathogenic bacterial isolates

Due to the misuse of antibiotics and caused antibiotic-resistant bacteria, scientists have been trying to produce alternative substant to antibiotics used in hospitals. Therefore, this study aimed to produce a new compound, 1,3,4-thiadiazole derivatives compounds, and to evaluate the biological effects of bacteria collected from patients of different hospitals in Iraq. The bacterial detected samples were collected from 29% wounds, 29% burns, 26% urine, 19% sputum, 17% ear swabs, and 9% stool specimens from the patients which of the Central Child Hospital, Al-Kindi Teaching Hospital, Ibn Al-Baladi Women's Hospital, and the Children's Hospital of Al-Numan (Iraq). Among the bacterial samples, 50% of Pseudomonas aeruginosa and 50% of Staphylococcus aureus were detected. The biofilm features of bacteria were also detected in 80% of P. aeruginosa and 76% of S. aureus. After synthesizing the 1,3,4-thiadiazoles, they were applied to bacterial strains. While the compound had few biological activities against P. aeruginosa, great biological activities were found against S. aureus. The results of the study showed that alternative compounds for antibiotics have important effects on bacterial strains. Compund 1: After dissolving 2.20 g of 5- Bromo-2-aminobenzothiazol, in 5 mL of ethyl alcohol with the addition of 3-5 drops of glacial acetic acid in a circular flask, P-aminoacetophenone was added as 1.99 g into solution and the flask was stirred for 7 hours at 67°C. Then, the solution was poured into another bottle and left to evaporate the alcohol. The precipitate was collected, dried, and then washed with water. Then, it was recrystallized using ethanol. The completeness of the reaction and the purity of the obtained product were tested by mobile phase TLC (hexane: ethyl acetate, 6:4, V:V). Compound 2: The compound 1 (0.47 g) was dissolved by heating and stirring in 8 mL of 85% phosphoric acid. Then the solution was cooled to 0°C in an ice bath, then 4 mL of concentrated nitric acid was added to the solution. The 0.13 g of sodium nitrite dissolved in 2 mL of distilled water. Then, sodium nitrite solution was added dropwise with vigorous stirring and cooling at -5°C for about 5 minutes. Then, drops of 2-hydroxy-1-naphthaldehyde solution prepared from 0.3 g of 2-hydroxy-1- naphthaldehyde in 0.5ml of distilled water were added with vigorous stirring. Then, the mixture was poured reaction in 100 mL of cold water, The precipitate was filtered and washed with cold water for several times and recrystallized using ethanol, and the reaction process was followed up and the purity of the compound was confirmed using TLC and using the mobile phase (ethyl acetate: hexane, 4:5, V:V). Compound 3, 4 and 5: The 0.4 g of 5-Bromo-2-aminobenzothiazol was added to a solution consisting of dissolving 0.5 g of the prepared compound 2 in 5 ml ethanol with added 5 of drops of glacial acetic acid to product compound 3. In the same way to product compound 4 and 5, when using 6-Hydroxy-2-aminobenzothiazol or 6- Nitro-2 - Aminobenzothiazol added to it. The mixture was raised at a temperature of 90°C for 7 hours with stirring. The resulting solution was poured into another bottle and left for alcohol to evaporate. The precipitate was collected, dried, and then washed with water. After that, the crystallization was done using ethanol, the completeness of the reaction and the purity of the obtained product were tested using TLC by the mobile phase (hexane: ethyl acetate, 6:4, V: V).