Mechanism-based inactivation of cytochrome P450 2D6 by Notopterol

Synergistic effect of osthole and notopterol combination against Alzheimer's disease and osteoporosis by applying zebrafish AD/OP comorbidity model

Alzheimer's disease (AD) and osteoporosis (OP) are both serious degenerative diseases, with the potential for concurrent occurrence in clinical settings, and they share certain pathological correlations. Osthole (OST) and notopterol (NOT) are the main active ingredients in traditional Chinese medicine, Angelica pubescens and Notopterygium incisum, respectively, and they exhibit neuroprotective and osteoprotective effects. However, whether the combination of OST and NOT produces a synergistic effect against AD and/or OP remains unclear. The aim of this study was to investigate whether the combination of OST and NOT could produce synergistic anti-AD and/or OP effects using the previously constructed zebrafish AD/OP comorbidity model. Active compounds with anti-AD and OP effects were screened from Angelica pubescens and Notopterygium incisum through network pharmacology, identifying OST and NOT, respectively. Then, the AlCl3-induced (Aluminum chloride, AlCl3) AD combined with OP zebrafish model, in conjunction with the Chou-Talalay synergy evaluation model, was employed to assess whether the OST and NOT combination produced synergistic effects against AD and/or OP. Furthermore, a CuSO4-induced (Copper sulfate, CuSO4) inflammation zebrafish model was used to investigate whether the combination of OST and NOT produced synergistic anti-inflammatory effects, thereby resulting in synergistic anti-AD and/or OP effects. The results demonstrated that the OST-NOT combined treatment produced a synergistic anti-AD and OP effect. Moreover, the combined treatment of OST and NOT significantly inhibited nitric oxide (NO) and reactive oxygen species (ROS) release more effectively than OST or NOT alone, indicating a synergistic anti-inflammatory effect of the OST and NOT combined treatment.

Phytochemistry and Biological Profile of the Chinese Endemic Herb Genus Notopterygium

Notopterygium, a plant genus belonging to the Apiaceae family, is utilized in traditional Chinese medicine for its medicinal properties. Specifically, the roots and rhizomes of these plants are employed in phytotherapy to alleviate inflammatory conditions and headaches. This review provides a concise overview of the existing information regarding the botanical description, phytochemistry, pharmacology, and molecular mechanisms of the two Notopterygium species: Notopterygium incisum and N. franchetii. More than 500 distinct compounds have been derived from these plants, with the root being the primary source. These components include volatile oils, coumarins, enynes, sesquiterpenes, organic acids and esters, flavonoids, and various other compounds. Research suggests that Notopterygium incisum and N. franchetii exhibit a diverse array of pharmacological effects, encompassing antipyretic, analgesic, anti-inflammatory, antiarrhythmic, anticoagulant, antibacterial, antioxidant, and anticancer properties on various organs such as the brain, heart, digestive system, and respiratory system. Building activity screening models based on the pharmacological effects of Notopterygium species, as well as discovering and studying the pharmacological mechanisms of novel active ingredients, will constitute the primary development focus of Notopterygium medicinal research in the future.

Mechanistic Study of Xanthotoxin-Mediated Inactivation of CYP1A2 and Related Drug-Drug Interaction with Tacrine

Xanthotoxin (XTT) is a biologically active furanocoumarin widely present in foods and plants. The present study is designed to systematically investigate the enzymatic interaction of XTT with CYP1A2, along with pharmacokinetic alteration of tacrine resulting from the co-administration of XTT. The results showed that XTT induced a time-, concentration-, and NADPH-dependent inhibition of CYP1A2, and the inhibition was irreversible. Co-incubation of glutathione (GSH) and catalase/superoxide dismutase was unable to prevent enzyme inactivation. Nevertheless, competitive inhibitor fluvoxamine exhibited a concentration-dependent protective effect against the XTT-induced CYP1A2 inactivation. A GSH trapping experiment provided strong evidence for the production of epoxide or/and γ-ketoenal intermediates resulting from the metabolic activation of XTT. Furthermore, pretreatment of rats with XTT was found to significantly increase the C_max and area under the curve of plasma tacrine relative to those of tacrine administration alone.

Mechanism-based inactivation of cytochrome P450 enzymes by natural products based on metabolic activation

Cytochrome P450 enzymes (P450 enzymes) are the most common and important phase I metabolic enzymes and are responsible for the majority of the metabolism of clinical drugs and other xenobiotics. Drug-drug interactions (DDIs) can occur when the activities of P450 enzymes are inhibited. In particular, irreversible inhibition of P450 enzymes may lead to severe adverse interactions, compared to reversible inhibition. Many natural products have been shown to be irreversible inhibitors of P450 enzymes. The risks for intake of naturally occurring irreversible P450 enzyme inhibitors have been rising due to the rapid growth of the global consumption of natural products. Irreversible inhibition is usually called mechanism-based inactivation, which is time-, concentration- and NADPH- dependent. Generally, the formation of electrophilic intermediates is fundamental for the inactivation of P450 enzymes. This review comprehensively classifies natural P450 enzyme inactivators, including terpenoids, phenylpropanoids, flavonoids, alkaloids, and quinones obtained from herbs or foods. Moreover, the structure - activity correlations according to the IC₅₀ (or K_i) values reported in the literature as well as the underlying mechanisms based on metabolic activation are highlighted in depth.

The Grapefruit Effect: Interaction between Cytochrome P450 and Coumarin Food Components, Bergamottin, Fraxidin and Osthole. X-ray Crystal Structure and DFT Studies

Coumarins are plant-derived secondary metabolites. The crystal structure of three coumarins—bergamottin, osthole and fraxidin—are described and we analyze intermolecular interactions and their role in crystal formation. Bergamottin is a furanocoumarin found in citrus plants, which is a strong inhibitor of the principal human metabolizing enzyme, cytochrome P450 3A4 (CYP3A4). The crystal structure determinations of three coumarins give us the geometrical parameters and reveal the parallel-displaced π–π stacking and hydrogen bonding intermolecular interactions used for molecular assembly in the crystal structure. A quite strong (less than 3.4 Å) stacking interaction of bergamottin appears to be a determining feature that distinguishes it from other coumarins studied in this work. Our DFT computational studies on the three natural products of the same coumarin family docked into the active site of CYP3A4 (PDB 4D78) show different behavior for these coumarins at the active site. When the substrate is bergamottin, the importance of π-π stacking and hydrogen bonding, which can anchor the substrate in place, appears fundamental. In contrast, fraxidin and osthole show carbonyl coordination to iron. Our docking calculations show that the bergamottin tendency towards π–π stacking is important and likely influences its interactions with the heme group of CYP3A4.