## 4 Conclusions  
Here, we report the antimicrobial (antibacterial and antifungal) and antiproliferative activities of 19 chloropyrazine-tethered pyrimidine hybrids (**22**-**40**) synthesized previously by replacing the 1,5-benzothazepine scaffold of chloropyrazine-linked 1,5-benzothazepine derivatives. The tested analogues (**22**-**40**) showed more antiproliferative activity and less antimicrobial activity than the corresponding chloropyrazine-linked 1,5-benzothazepine derivatives. The results indicated that the electron-withdrawing atoms/groups on the phenyl ring of the chloropyrazine-tethered pyrimidine hybrids are vital for improving the antimicrobial, whereas the biososteric heteroaryl scaffold 2\({}^{\prime\prime}\)-pyridinyl substitutions are vital for antiproliferative activity. Compound **31**, containing a 2\({}^{\prime\prime}\),4\({}^{\prime\prime}\)-dichlorophenyl ring, showed the most potent antibacterial and antifungal activities with an MIC value of 45.37 \(\upmu\)M, while compounds **25** and **30**, containing 4\({}^{\prime\prime}\)-nitrophenyl and 2\({}^{\prime\prime}\),4\({}^{\prime\prime}\)-difluorophenyl moieties, had MIC values of 48.67 \(\upmu\)M and 50.04 \(\upmu\)M, respectively. Compound **35**, containing a 2\({}^{\prime\prime}\)-pyridinyl ring, showed the most potent IC\({}_{50}\) value of 5 \(\pm\) 1 \(\upmu\)g/mL against DU-145. All compounds can be considered safe as they had less selectivity to LO2 normal human liver cells compared to the cancerous cells. Molecular docking results for compound **35** showed major binding interactions at the binding site, correlating with the in vitro antiproliferative activity as well as the SwissADME results of **35** for drug-likeness, suggesting the usefulness of computational studies in the development of new drug-like candidates. The potential lead compounds identified through this work will be useful in the further design and optimization of drug candidates against antimicrobial activities, and compound **35** is a potential lead compound for the development of new anticancer agents.  
Conceptualization, R.R.B. and A.B.S.; methodology, A.B.S.; software, R.R.B.; validation, R.R.B. and A.B.S.; formal analysis, R.R.B. and A.B.S.; investigation, A.B.S.; resources, R.R.B. and A.B.S.; data curation, A.B.S.; writing--original draft preparation, R.R.B. and A.B.S.; writing--review and editing, R.R.B. and A.B.S.; visualization, A.B.S.; supervision, A.B.S.; project administration, R.R.B. and A.B.S.; funding acquisition, R.R.B. and A.B.S. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research received no external funding. RRB is thankful to the Deanship of Graduate Studies and Research (DGSR), Ajman University, for providing partial funding for the article processing charges.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** [PERSON] would like to thank the Dean's Office of the College of Pharmacy and Health Sciences, Ajman University, United Arab Emirates, and [PERSON] extends his thanks to Vignan Pharmacy College, Vadlamudi, Andhra Pradesh, India. [PERSON] would like to thank the Deanship of Graduate Studies and Research, Ajman University for providing partial funding of article processing charges.  
**Conflicts of Interest:** The authors declare no conflict of interest.  
**Sample Availability:** Samples of the compounds were utilized for spectral characterization and biological evaluation; hence, the samples are currently unavailable from the authors.