Plants from the genus Trifolium have been utilized in the treatment of chronic diseases by many cultures. The aim of this study was to investigate the antioxidant activity of flavonoids isolated from Trifolium resupinatum L. using an in vitro radical scavenging assay and a computational study of the structure–antioxidant activity relationship (SAR). A phytochemical fractionation of the ethanolic extract of T. resupinatum resulted in the isolation of one new flavonoid along with six known flavonoids. The structure of the isolated compounds was elucidated by data obtained from UV, IR, MS, 1D NMR and 2D NMR spectra. The order of antioxidant efficacies of the isolated flavonoids, obtained by DPPH assay, was correlated to that predicted by the computational analysis. To verify the antioxidant potential, the effect of T. resupinatum on oxidative stress, and the expression of the antioxidant enzymes and the redox sensitive nuclear factor erythroid 2-related factor 2 (Nrf2), in a cyclophosphamide-induced hepatotoxicity rat model was investigated. T. resupinatum protected against cyclophosphamide-induced liver injury through attenuation of oxidative stress and inflammation, and up-regulation of Nrf2. Therefore, the present study provides the first clarification of the detailed antioxidant SARs of T. resupinatum flavonoids and points to the involvement of Nrf2 in their hepatoprotective activity.

Centaurea scoparia flavonoids bind to the appropriate binding site on β-lactoglobulin via polar and hydrophobic interactions and bind to and inhibit xanthine oxidase.

Seaweeds are rich in structurally diverse bioactive compounds with promising therapeutic effects. This study aimed to isolate and identify terpenes from the brown alga Padina pavonia and to investigate its antidiabetic activity, pointing to the possible involvement of peroxisome proliferator-activated receptor (PPAR)γ. Type 2 diabetes was induced by feeding rats a high fat diet (HFD) for 4 weeks followed by injection of 35 mg/kg streptozotocin (STZ). The diabetic rats received P. pavonia extract (PPE; 50, 100 and 200 mg/kg) for 4 weeks and samples were collected for analyses. HFD/STZ-induced rats showed hyperglycemia, dyslipidemia, impaired glucose tolerance, decreased insulin, and increased HbA1c and HOMA-IR. PPE ameliorated hyperglycemia and dyslipidemia, and improved glucose tolerance and insulin sensitivity in diabetic rats. Treatment with PPE increased hepatic hexokinase activity and glycogen, suppressed glucose-6-phosphatase, fructose-1,6-biphosphatase, and glycogen phosphorylase, and attenuated oxidative stress, inflammation, and liver injury and lipid infiltration in HFD/STZ-induced rats. In addition, PPE boosted antioxidants and upregulated PPARγ gene and protein expression in the liver of diabetic rats. Phytochemical investigation resulted in the isolation of six terpenes from PPE and in silico analysis revealed their binding affinity toward PPARγ. In conclusion, P. pavonia-derived terpenes attenuated hyperglycemia, dyslipidemia, oxidative stress, and inflammation, and improved insulin sensitivity and carbohydrate metabolism in type 2 diabetic rats. These beneficial effects are mediated via PPARγ activation. However, further studies to explore the exact mechanisms underlying the antidiabetic effect of PPE are recommended.

This study provides a comprehensive computational exploration of the inhibitory activity and metabolic pathways of 8-methoxypsoralen (8-MP), a furocoumarin derivative used for treating various skin disorders, on cytochrome P450 (P450). Employing quantum chemical DFT calculations, molecular docking, and molecular dynamics (MD) simulations analyses, the biotransformation mechanisms and the active site binding profile of 8-MP in CYP1B1 were investigated. Three plausible inactivation mechanisms were minutely scrutinized. Further analysis explored the formation of reactive metabolites in subsequent P450 metabolic processes, including covalent adduct formation through nucleophilic addition to the epoxide, 8-MP epoxide hydrolysis, and non-CYP-catalyzed epoxide ring opening. Special attention was paid to the catalytic effect of residue Phe268 on the mechanism-based inactivation (MBI) of P450 by 8-MP. Energetic profiles and facilitating conditions revealed a slight preference for the C4′=C5′ epoxidation pathway, while recognizing a potential kinetic competition with the 8-OMe demethylation pathway due to comparable energy demands. The formation of covalent adducts via nucleophilic addition, particularly by phenylalanine, and the generation of potentially harmful reactive metabolites through autocatalyzed ring cleavage are likely to contribute significantly to P450 metabolism of 8-MP. Our findings highlight the key role of Phe268 in retaining 8-MP within the active site of CYP1B1, thereby facilitating initial oxygen addition transition states. This research offers crucial molecular-level insights that may guide the early stages of drug discovery and risk assessment related to the use of 8-MP.