Cathepsins B and L are papain-like cysteine peptidases and are expressed in all human tissues. Both enzymes take part in nonspecific protein degradation and processing of antigens. Their excessive activity is linked to several diseases, such as tumour metastasis, atherosclerosis and rheumatoid diseases. The goal of our research was to test the effect of selected plant phenols on the activity of both enzymes. Inhibition of cathepsin C with two of those phenols – chlorogenic and caffeic acid – has been reported previously. We wanted to determine the relationship between the structure of phenols and their inhibitory activity. We tested eight plant phenols and determined, that the presence of two or at least two hydroxyl groups on the common phenolic framework is most probably responsible for stronger cathepsin B and L inhibition. The strongest inhibitors were resveratrol, caffeic and chlorogenic acid, therefore we also determined their mechanism of inhibition of both cathepsins. We also predicted the binding of these three phenols on cathepsins by using AutoDock Vina. All of them docked into the S’ sites in the binding pocket of cathepsins B and L.
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