) were added to each tube followed by 10 s agitation. Thirty min later, three 100 μL aliquots of each tube were transferred to a 96-well plate and the absorbance of the test and blank tubes was measured at 655 nm wavelength with the ELISA plate reader (Thermo Plate). Total protein production was calculated from a standard curve created using known protein concentrations. Analysis of ALP activity was performed using the colorimetric endpoint assay (ALP Kit; Labtest Diagnóstico S.A.,

Lagoa Santa, MG, PR-171 cell line Brazil) employed in previous studies.20 This test uses a thymolphthalein monophosphate substrate, which is a phosphoric acid ester substrate. ALP hydrolyzes the thymolphthalein monophosphate substrate, releasing thymolphthalein. Therefore, it is possible to measure directly the product

of hydrolysis, altering the pH. The altered pH interrupts Panobinostat supplier the enzymatic activity and provides bluish colour to the solution, which is characteristic of the reaction. The intensity of the resulting colour is directly proportional to the enzymatic activity and is analyzed spectrophotometrically. After 24 h incubation of the cells in contact with DMEM alone (control group) or containing the two ZOL concentrations (experimental groups), the culture medium with ZOL was aspirated and the cells were washed three times with 1 mL PBS at 37 °C. An amount of 1 mL of 0.1% sodium lauryl sulphate (Sigma Aldrich Corp.) were added to each well and maintained for 40 min at room temperature to produce cell lysis. The test was performed according to the instructions of the Kit’s manufacturer. The absorbance of the samples was measured at 590 nm wavelength with a spectrophotometer (Thermo Plate). ALP activity was calculated by a standard curve using known concentrations of the enzyme. SEM

analysis was used to identify possible morphological alterations caused by the addition of different concentrations of ZOL to DMEM culture medium in which the MDPC-23 cells were cultured. The following protocol used in previous Tenoxicam studies was employed.20 and 21 Sterile 13-mm-diameter cover glasses (Fisher Scientific, Pittsburgh, PA, USA) were sterilized in 70% ethanol for 24 h and placed on the bottom of the wells immediately before seeding the cells. After 24 h of incubation of the cells in contact with DMEM alone (control group) or containing the two ZOL concentrations (experimental groups), the culture medium with ZOL was aspirated and the cells were fixed in 1 mL of 2.5% glutaraldehyde in PBS for 1 h. Then, the glutaraldehyde was removed and the cells were washed with PBS and post-fixed with 1% osmium tetroxide for 1 h at room temperature.