Plastic waste presents a persistent environmental burden, yet its constituent polymers represent structurally valuable chemical feedstocks. Mechanical recycling remains limited due to polymer degradation, additive contamination, and material downcycling, underscoring the need for alternative strategies. Chemical upcycling offers pathways to convert post-consumer plastics into higher-value monomers, functional chemicals, and bioactive or pharmaceutical precursors by exploiting inherent structural motifs such as aromatic rings, ester linkages, and heteroatom-containing backbones. Approaches such as catalytic depolymerization, molecular functionalization, microbial and enzymatic transformation, and scaffold repurposing enable the recovery of polymer-derived building blocks with improved functional value. Case studies illustrating the conversion of discarded plastics into advanced materials and biologically relevant small molecules demonstrate the potential of these approaches to stimulate innovation and expand sustainable chemical practices. Collectively, such developments align with green chemistry principles, support emerging circular chemical economies, and contribute to global sustainability priorities reflected in the United Nations Sustainable Development Goals. This review aims to outline the guiding principles of chemical upcycling and highlight the challenges in chemical design, encouraging the modern chemistry community to tap into the hidden potential of waste plastics.
A library of 4-aminoquinoline derivatives and benzoxaborole-4-aminoquinoline hybrids, linked through amide and 1H-1,2,3-triazole spacers, was synthesized and evaluated against both chloroquine-sensitive (3D7) and -resistant (W2) strains of Plasmodium falciparum. Structure–activity relationship studies revealed that antiplasmodial potency was strongly influenced by the length of the alkyl chain and by the nature of the terminal functional group (azido, aldehyde, or benzyl alcohol). Notably, incorporation of the benzoxaborole core significantly enhanced activity relative to the parent 4-aminoquinoline derivatives. Among the series, hybrid 8b emerged as the most potent analogue, displaying superior activity against the CQ-resistant W2 strain compared with the reference antimalarials quinine and chloroquine. The hybrids exhibited negligible cytotoxicity toward HEK-293 cells, affording selectivity indices of up to ∼700. UV-visible spectroscopic titrations demonstrated that compound 8b binds monomeric heme more selectively than CQ at both physiological and digestive vacuole pH, supporting inhibition of hemozoin formation as its primary mode of action. Furthermore, homology modelling, induced-fit docking, and molecular dynamics simulations with both wild-type and benzoxaborole-resistant (H36Y/D470N) PfCPSF3 suggested that the scaffold can maintain a stable Zn2+-coordinated binding mode in both protein variants. These findings indicate a potential dual mechanism involving hemozoin inhibition and PfCPSF3 targeting, warranting further experimental validation.
Anuradha Saini, Sumit Kumar, B. Pradines et al.· RSC Advances· 0 citations
Overall, the cytotoxic effects of 7k on MV4-11 cells are attributed to the coordinated induction of ROS-mediated oxidative stress, G0/G1 cell cycle arrest, and caspase-dependent apoptosis, highlighting its promising antiproliferative potential.