A novel acid–base nanocatalyst (MNPs@Alg-Pr-His) was synthesized using available materials (nanomagnetic alginate core and histidine) via a facile strategy. After characterization, its efciency was investigated in the synthesis of 2-amino- 4H-chromene and 1,2,3,6-tetrahydropyrimidine derivatives. This nanobiocatalyst showed remarkable catalytic efciency in both reactions (the reaction yields for the frst reaction: 89–96% and for the second reaction: 68–85%). This catalyst was reusable and recyclable and still showed good activity after fve runs. The antibacterial efect of the histidine, alginate, and MNPs@Alg-Pr-His was evaluated against a Gram-positive bacterium (S.aureus) and a Gram-negative bacterium (E. coli) by the disk difusion method. It is noticeable that MNPs@Alg-Pr-His, unlike histidine and alginate, showed more antibacterial activity against Gram-negative bacterium (28.0 ±1.4) than Gram-positive bacterium (19.0±1.4).
