Globally, people are highly affected by Cadmium (Cd), the most hazardous heavy metal. It has been implicated in various pathogeneses. Oxidative stress may be one the main reasons for Cd-induced disorders in the body. This article investigates the protective ability of Catharanthus roseus (CR) extract on oxidative stress in the kidney and liver of rats exposed to Cd. After 21 days, a significant increase in MDA concentration (6.81 ± 0.05), (6.64 ± 0.03) was observed in Cd-treated groups compared to the control (5.54 ± 0.02), (5.39 ± 0.04) for the kidney and liver, respectively, while significant changes were observed in the haematological parameters. Antioxidant enzymes, GPx, CAT, and SOD showed a significant decrease in their activity. We established that increasing the concentration of Cd in the presence of H₂O₂ was able to cause stand scission in pBR322 plasmid DNA, which may be due to the mediation of ROS generated in the process. The antioxidant ability of CR extract was tested in DPPH and H₂O₂ scavenging assay, depicted by the increase in the percentage inhibition. Upon treatment of CR extract to rats, MDA concentration was decreased for the kidney and liver compared to the Cd-treated groups. This was again confirmed by comet assay of both tissues, where the degree of cellular DNA breakage caused by Cd toxicity decreased significantly upon treatment with CR extract. Overall, the results suggest that Cd plays a major role as an effector metal ion, causing a decrease in the concentration and activity of AO enzymes and enhanced lipid peroxidation. ROS production resulted in oxidative DNA damage within the cell, whereas CR extract showed potential antioxidant activity against ROS-mediated DNA damage induced by Cd poisoning.

Background/Objectives: Protein misfolding and amyloid fibril formation underlie several degenerative diseases, including Alzheimer’s disease and Parkinson’s disease. Alpha-1 antitrypsin (A1AT), a serpin protein, is particularly prone to misfolding, with polymerization and aggregation implicated in alpha-1 antitrypsin deficiency and associated hepatic and pulmonary disorders. In this study, we examined the structural changes in A1AT induced by the fluorinated alcohol, trifluoroethanol (TFE), and assessed the inhibitory effects of two natural polyphenols, amentoflavone (AMF) and theaflavin (TF), on aggregation and fibril formation. Methods: A library of selected phytocompounds was virtually screened against the crystal structure of A1AT (PDB 3NE4) using AutoDock Vina to elucidate their binding affinity towards it. Based on binding affinities, two compounds, AMF and TF, were selected for further studies. Protein aggregation was induced with TFE, and the protective effects of AMF and TF were evaluated using protease inhibitory activity, intrinsic fluorescence, turbidity, Rayleigh scattering, ANS fluorescence, and ThT fluorescence assays. Furthermore, 100 ns molecular dynamics simulation and MM-PBSA calculations were performed to assess the stability and binding interactions of the A1AT–ligand complexes. Results: Pre-treatment of A1AT with AMF or TF significantly inhibited TFE-induced aggregation in a dose-dependent manner, with AMF being consistently more effective. ThT fluorescence analysis revealed a ~60–65% decrease in aggregate formation upon treatment with polyphenols, with IC₅₀ values estimated at ~40 µM for AMF and ~50 µM for TF, both of which are statistically significant. Molecular docking and 100 ns molecular dynamics simulation also revealed stable A1AT–polyphenol interactions, with AMF exhibiting greater binding affinity and greater attenuation of solvent-induced conformational perturbation. Conclusions: Collectively, our findings show that TFE causes A1AT misfolding via a molten globule-like intermediate, resulting in fibril formation at 30–40% TFE, and natural polyphenols AMF and TF inhibited aggregation in a concentration-dependent manner. These observations suggest the potential of AMF and TF as lead scaffolds for anti-aggregation strategies, as modulators of amyloidogenic processes.