Scopoletin and Morin Inhibit Lactate Dehydrogenase Enzyme Activity, Which Is Critical for Cancer Metabolism

Abstract

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 100 mM sodium 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 the maximum wavelength 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.

Enzymatic activation of pyruvate kinase increases cytosolic oxaloacetate to inhibit the Warburg effect

“…The K d was calculated by plotting the log(fluorescence change/fluorescence intensity) versus log(oxaloacetate concentration). K d was calculated by the modified form of a Stern-Volmer plot in which the vertical intercept is log(1/K d ) 49 . The assay was performed at room temperature.…”

“…280 nm, em. 340 nm) from tryptophan was measured and the K d was calculated by the modified form of a Stern-Volmer plot in which the vertical intercept is log(1/K d ) 49 . f 0 : fluorescence intensity without OAA treatment, f: fluorescence intensity with OAA treatment at the indicated concentrations.…”

Flavonoids against the Warburg phenotype—concepts of predictive, preventive and personalised medicine to cut the Gordian knot of cancer cell metabolism

“…Morin (MO), a flavonoid isolated from the Moraceae family, inhibited the enzymatic activity of LDH. MO modulated the conformation and inhibited the catalytic activity of LDH [144]. Furthermore, QUE effectively suppressed cancer growth and proliferation in MCF-7 and MDA-MB-231 cells and decreased the level of glycolysis-related enzymes including LDHA [119].…”