Characterization of PKC-rutin interactions and their application as a treatment strategy for pulmonary arterial hypertension by inhibiting ferroptosis

As a common plant-derived dietary flavonoid, rutin receives widespread attention because of its good antioxidant bioactivities. Protein kinase C alpha (PKC alpha) is a serine/threonine kinase that is involved in uncountable cellular processes, among which ferroptosis, a novel form of cell death, is triggered by lipid peroxidation and has been reported to be associated with pulmonary arterial hypertension (PAH). But it is still not well appreciated how rutin inhibits ferroptosis in PAH and what function PKC alpha has in this process. In this study, we first observed whether rutin could prevent PAH by attenuating ferroptosis with a PAH animal model and pulmonary artery smooth muscle cells (PASMCs) under hypoxia. Mitochondrial metabolomics and network pharmacology were employed to clarify the metabolic alterations and screen target proteins, and the results showed that PKC alpha was a vital node in rutin regulating mitochondrial metabolism related to ferroptosis in PAH. Based on molecular docking and multispectral analysis, we found that rutin could directly interact with PKC alpha through hydrogen bonds, which could induce static quenching, and then influence the secondary structure of PKC alpha. In conclusion, these findings mainly point to a novel mechanism that rutin protects PAH rats by modifying the structure and altering the activity of PKC alpha, and thus suppressing ferroptosis. This work reveals that the interaction behaviors between small molecules and bio-macromolecules are a critical factor to develop natural biological active ingredients and gives an insight into the potential applications of flavonoids in health and disease. In this work, rutin was found to have great potential to regulate mitochondrial metabolism by targeting PKC alpha to suppress ferroptosis, and thus protect against PAH.