Ortho vanillin

Most of the research chemicals were of analytical grade and used as received without further purification. Ortho vanillin (99%), Bromo-ortho vanillin (97%), and 2,2-dimethyl-1,3-diaminopropane (99%) were purchased directly from Sigma Aldrich Company, USA, and the methanol solvent was a spectroscopic grade.

Epithelial cells and fibroblasts were treated with flavoring chemicals such as acetoin (butter), diacetyl, pentanedione, maltol (malt), ortho-vanillin (vanilla), coumarin, and cinnamaldehyde (analytical grade >95% pure; Sigma). TNFα was used as positive control and untreated cells were used as controls. For flavoring chemical treatment, Beas2B, H292, and HFL-1 cells were grown to ∼85%–90% confluence. Cells were serum starved overnight in a suitable culture medium supplemented with low FBS (0.5%) and treated with appropriate flavoring chemicals (concentrations: 10 μM, 100 μM, and 1 mM) or (TNFα 10 ng/mL, positive control) for 24 hours at 37°C with 5% CO₂.
16-HBE cells were initially seeded in electric cell surface impedance sensing (ECIS) cultureware (8W10E+ PET) at a density of 1.75 × 10⁵ cells/well containing 400 μL complete medium (10% FBS). After 24–48 hours, low serum containing media (1% FBS) were added, a few hours later the cells were treated with different flavoring chemicals (1 mM) in batches. All the treatments were performed in separate eight-well ECIS cultureware, and nicotine (1 mM) was used as positive control. Transepithelial resistance (TEER) data were collected in real time pre- and post-treatment (15 hours) using ECIS Zθ 16-well array station (Applied Biophysics, Troy, NY).

Most of the research chemicals and solvents used in the current research works were reagents graded and used without further purification. The substances such as Cd(OAc)₂·2H₂O, DCM (dichloromethane), NaSCN, Ortho vanillin, salicylaldehyde, 1,2-propanediamine, and ethylenediamine were purchased from the Sigma-Aldrich Company, USA. Elemental (CHN) compositions were analyzed using a PerkinElmer 2400 CHN elemental analyzer. FT-IR/Raman spectra were recorded via KBr pellets (4000–400 cm⁻¹) using PerkinElmer spectrum RX 1 and BRUKER RFS 27 (4000–50 cm⁻¹) models. ¹H/¹³C NMR spectral analyses were performed on Bruker 400 MHz and 75.45 MHz FT-NMR spectrometers using TMS as an internal standard in DMSO-d₆ solvent. The EDX experiment was carried out on an EDX OXFORD XMX N using a W filament. The SEM images were recorded by a JEOL Model JSM-6390LV. A BRUKER AXS model and a GERMANY D8 FOCUS model with Cu Kα₋₁ radiation were used to perform PXRD. UV-visible spectra (200–1100 nm) were recorded using the popular Hitachi U-3501 spectrophotometer model.