Spectroscopic and Thermodynamic Exploration of Folic Acid’s Modulatory Impact on the Bimolecular Interactions of Hemoglobin with Pemetrexed

Pemetrexed (PEM) disrupts folate metabolism and may lead to blood-related side effects, such as anemia. Folic acid (FA) supplementation can be beneficial in reducing anemia caused by pemetrexed, as it helps replenish folate levels. FA plays a vital role in maintaining healthy red blood cells; its influence on the structural properties of hemoglobin (Hb) has not been clearly defined. This study involves the influence of the combined effects of PEM and FA on the structural and colloidal stability of Hb using spectroscopic techniques. Spectroscopic analysis indicates that PEM and FA associate with Hb without causing major changes to its structural stability. Notably, FA seems to help to maintain the secondary structure of Hb more effectively. The thermal stability assays demonstrated that Hb maintained and even improved its resilience when both PEM and FA were combined. Dynamic light scattering and transmission electron microscopy analyses demonstrate that Hb tends to aggregate when exposed to PEM, whereas it remains dispersed and does not aggregate in the presence of FA. The results show that FA counteracted the aggregation behavior of PEM on Hb's morphology. Therefore, the colloidal stability of Hb is balanced by FA in the presence of PEM. These results have proven and provided insights into how the mutual effect of PEM and FA is sufficient to protect proteins in therapeutic applications involving folate pathways, support the design of more such crucial effective drug delivery methods, and help in evolving biopharmaceutical formulations.