2,5-Diaryloxadiazoles and their precursors as novel inhibitors of cathepsins B, H and L

N-subsitutedbenzylidenebenzohydrazides and their cyclized derivatives i.e., 2,5-diaryl-1,3,4-oxadiazole are reported as novel inhibitors of cathepsin B, cathepsin H and cathepsin L with potency in nanomolar range. [Display omitted] •The present work details about some non-peptidyl inhibitors of cathepsins B, H and L.•Differential inhibitory effect of compounds on cathepsins B, H and L was observed.•Precursors and derivatives were found to inhibit differentially. High levels of cathepsins indicated in various pathological conditions like arthritis, cancer progressions, and atherosclerosis explains the need to explore potential inhibitors of these proteases which can be of great therapeutic significance. We, in the present work, report the synthesis of some 2,5-diaryloxadiazoles from N-subsitutedbenzylidenebenzohydrazides. The synthesized compounds were screened for their inhibitory potential on cathepsins B, H and L. Structure Activity Relationship studies show that 2,5-diaryloxadiazoles were less inhibitory than their precursors. 1i and 2k have been found to be most inhibitory to cathepsins B and L. Their Ki values have been calculated as 11.38×10−8M and 66.4×10−8M for cathepsin B and 4.2×10−9M and 47.31×10−9M for cathepsin L, respectively. However, cathepsin H activity was maximally inhibited by compounds, 1e and 2c with Ki values of 4.4×10−7M and 5.6×10−7M, respectively. Enzyme kinetic studies suggest that these compounds are competitive inhibitors to the enzymes. The results have been compared with docking results obtained using iGemDock.