Inhibition studies of enzymes in the pentose phosphate pathway (PPP) have recently emerged as a promising technique for pharmacological intervention in several illnesses. Glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) are the most important enzymes of the PPP. For this purpose, in the current study, we examined the effect of some fluorophenylthiourea on G6PD and 6PGD enzyme activity. These compounds exhibited moderate inhibitory activity against G6PD and 6PGD with K I values ranging from 21.60 ± 8.42 to 39.70 ± 11.26 μM, and 15.82 ± 1.54 to 29.97 ± 5.72 μM, respectively.2,6-difluorophenylthiourea displayed the most potent inhibitory effect for G6PD, and 2-fluorophenylthiourea demonstrated the most substantial inhibitory effect for 6PGD. Furthermore, the molecular docking analyses of the fluorophenylthioureas, competitive inhibitors, were performed to understand the binding interactions at the enzymes' binding site.6-phosphogluconate dehydrogenase, fluorophenylthiourea, glucose 6-phosphate dehydrogenase, molecular docking | INTRODUCTIONOne of the main intracellular reducing agents, nicotinamide adenine dinucleotide phosphate (NADPH), is mainly produced by the pentose phosphate pathway (PPP) and is crucial for the thioredoxin and glutathione systems. 1-4 PPP is the main pathway for glucose catabolism and the biosynthesis of aromatic amino acids, nucleic acids, glucose 6-phosphate dehydrogenase (G6PD), and 6-phosphogluconate dehydrogenase (6PGD) enzymes. These enzymes are the most important enzymes of the PPP play an essential role in the formation of NADPH. [5][6][7][8] On the other hand, an activated PPP affects tumor metabolism, such as angiogenesis, favoring tumor metastasis, promoting malignant transformation, protecting cells from apoptosis, and increasing tumor progression. [9][10][11][12] In recent years, overexpression of PPP enzymes in many types of cancer has been the focus of interest for researchers. The mechanism of PPP enzymes associated with cancer progression is still under investigation. The research found that 6PGD was regulated in many types of cancer, such as colon, leukemia, breast, ovarian, liver, and thyroid. [13][14][15] Thiourea structures have several biological activities, like anticancer and antibacterial activities, and especially on the central nervous system of rodents, they have a high impact. [16][17][18] The thiourea skeleton has an essential role in pharmaceutical chemistry. Studies have shown solid cytotoxic activity against cancer cells. [19][20][21] The desired inhibitory activity of these drugs against various inhibitors is crucial in the death of cancer cells. Recently, evaluation of novel derivatives of thiourea as anti-angiogenic and antitumor agents has been published. [22][23][24]