Comparative In Vitro and In Silico Biological Evaluation of o-Phenylenediamine Conjugates Based on Isofunctional-Surfaced Polyanhydride and Citric Acid-Derived Carbon Quantum Nanodots

This study aimed to comparatively evaluate the anticancer and antimicrobial activities of conjugates formed from poly(maleic anhydride-co-vinyl acetate) (MAVA) and carbon quantum dots (CNDs) with o-phenylenediamine (o-PDA). o-PDA was chosen as the conjugation agent due to its status as a significant aromatic six-membered diamine, which enables specific reactions in the field of drug discovery. MAVA and CNDs, which are low-toxicity carrier systems, were prepared according to a previously developed protocol and conjugated with o-PDA to yield MAVA/o-PDA and CNDs/o-PDA. The structural characteristics of the conjugates were confirmed by ATR-FTIR and 1H-NMR analyses. The cytotoxic effects of the obtained conjugates on MG-63, A549, and MCF-7 cancer cell lines and healthy WI-38 cells, as well as their antimicrobial activities against various Gram-positive and Gram-negative bacteria, were evaluated. Additionally, ADMET properties and drug-likeness profiles were analyzed in silico to support the biological findings. While neither conjugate induced significant cytotoxicity in healthy WI-38 cells, they exhibited a stronger cytotoxic effect in cancer cells compared to o-PDA alone and the carrier systems. CNDs/o-PDA was found to be more effective than MAVA/o-PDA in MG-63, A549, and MCF-7 cells, whereas MAVA/o-PDA exhibited stronger activity in C6 cells. The conjugates also exhibited higher antimicrobial activity than their individual components, particularly against Gram-negative bacteria. In general, it has been observed that conjugation with o-PDA can enhance the biological activities of MAVA and CNDs while limiting toxicity in normal cells.