scopoletin and morin inhibit lactate dehydrogenase enzyme activity, which is critical for cancer metabolism

Background: lactate dehydrogenase (ldh) is a tetrameric enzyme that catalyzes the interconversion of pyruvate to l-lactate. the importance of this enzyme is because ldh isoenzymes are involved in cancer, heart, and liver diseases. inhibition of this enzyme can help prevent and treat different diseases. morin is a flavonoid found in the moraceae family and scopoletin is a coumarin found in scopolia genus. objectives: the aim of this study was to determine the effect of morin and scopoletin as two natural products on the activity and structure of lactate dehydrogenase enzyme. methods: morin and scopoletin were examined for inhibition of the activity of ldh in 100mmsodium phosphate buffer ph 7.5, at room temperature using uv-v spectrophotometry. fluorescence spectroscopy was used to characterize protein structural changes in the presence of morin and scopoletin. results: km and vmax of ldh for pyruvate were 11.69 mm and 1.258 mm/min, respectively. the kinetic results showed that morin and scopoletin are ldh inhibitors. the ki values of morin and scopoletin were determined as 1.78 µm and 0.8 µm, respectively, using a secondary plot. fluorescence intensity quenching and red shift of themaximumwavelength of emission in a concentrationdependent manner showed that morin and scopoletin bind to ldh and affect its structure. conclusions: the results suggest that morin and scopoletin bind to ldh, influence its conformation and inhibit its activity. scopoletin showed more effective inhibition of ldh activity and it can be a promising candidate in the field of tumor metabolism inhibitors.