New grapefruit cultivars exhibit low cytochrome P4503A4-Inhibition activity

Interactions between grapefruit juice and psychotropic medications: an update of the literature and an original case series

INTRODUCTION

There is a large body of preclinical data implicating that grapefruit juice (GJ) inhibits many CYP 450 isoforms. The potential of GJ-to-drug is of high relevance to clinical psychiatry, because a wide range of psychotropic medicines undergo CYP 450 metabolism and P-gp transport.

AREAS COVERED

Relevant data were identified by searching the electronic databases up to February 2024. This work constitutes a summary of preclinical and clinical data on GJ impact on CYP 450 metabolism, P-glycoprotein, and organic anion-transporting polypeptides (OATPs), with focus on studies that assessed GJ-to-psychotropic drug interactions. Additionally, an unpublished case series of nine patients is provided.

EXPERT OPINION

The impact of GJ on CYP 3A4 appears to be the critical mechanism for the majority of GJ-to-psychopharmacotherapy interactions described in human studies or case reports. However, there are studies and cases of patients clearly showing that this is not the only route explaining the GJ effect, and at times, this particular is of no relevance and that other CYP 450 isoforms as well as drug transporting proteins might be involved. The risk of GJ-to-psychotropic drugs needs to be further evaluated in a 'real-world' setting and apply not only measures of pharmacokinetics but also treatment effectiveness and safety.

Colchicine Drug Interaction Errors and Misunderstandings: Recommendations for Improved Evidence-Based Management

Colchicine is useful for the prevention and treatment of gout and a variety of other disorders. It is a substrate for CYP3A4 and P-glycoprotein (P-gp), and concomitant administration with CYP3A4/P-gp inhibitors can cause life-threatening drug-drug interactions (DDIs) such as pancytopenia, multiorgan failure, and cardiac arrhythmias. Colchicine can also cause myotoxicity, and coadministration with other myotoxic drugs may increase the risk of myopathy and rhabdomyolysis. Many sources of DDI information including journal publications, product labels, and online sources have errors or misleading statements regarding which drugs interact with colchicine, as well as suboptimal recommendations for managing the DDIs to minimize patient harm. Furthermore, assessment of the clinical importance of specific colchicine DDIs can vary dramatically from one source to another. In this paper we provide an evidence-based evaluation of which drugs can be expected to interact with colchicine, and which drugs have been stated to interact with colchicine but are unlikely to do so. Based on these evaluations we suggest management options for reducing the risk of potentially severe adverse outcomes from colchicine DDIs. The common recommendation to reduce the dose of colchicine when given with CYP3A4/P-gp inhibitors is likely to result in colchicine toxicity in some patients and therapeutic failure in others. A comprehensive evaluation of the almost 100 reported cases of colchicine DDIs is included in table form in the electronic supplementary material. Colchicine is a valuable drug, but improvements in the information about colchicine DDIs are needed in order to minimize the risk of serious adverse outcomes.

Computer-Aided (In Silico) Modeling of Cytochrome P450-Mediated Food–Drug Interactions (FDI)

Modifications of the activity of Cytochrome 450 (CYP) enzymes by compounds in food might impair medical treatments. These CYP-mediated food–drug interactions (FDI) play a major role in drug clearance in the intestine and liver. Inter-individual variation in both CYP expression and structure is an important determinant of FDI. Traditional targeted approaches have highlighted a limited number of dietary inhibitors and single-nucleotide variations (SNVs), each determining personal CYP activity and inhibition. These approaches are costly in time, money and labor. Here, we review computational tools and databases that are already available and are relevant to predicting CYP-mediated FDIs. Computer-aided approaches such as protein–ligand interaction modeling and the virtual screening of big data narrow down hundreds of thousands of items in databanks to a few putative targets, to which the research resources could be further directed. Structure-based methods are used to explore the structural nature of the interaction between compounds and CYP enzymes. However, while collections of chemical, biochemical and genetic data are available today and call for the implementation of big-data approaches, ligand-based machine-learning approaches for virtual screening are still scarcely used for FDI studies. This review of CYP-mediated FDIs promises to attract scientists and the general public.

Dietary Inhibitors of CYP3A4 Are Revealed Using Virtual Screening by Using a New Deep-Learning Classifier

CYP3A4 is the main human enzyme responsible for phase I metabolism of dietary compounds, prescribed drugs and xenobiotics, steroid hormones, and bile acids. The inhibition of CYP3A4 activity might impair physiological mechanisms, including the endocrine system and response to drug admission. Here, we aimed to discover new CYP3A4 inhibitors from food and dietary supplements. A deep-learning model was built that classifies compounds as either an inhibitor or noninhibitor, with a high specificity of 0.997. We used this classifier to virtually screen ∼60,000 dietary compounds. Of the 115 identified potential inhibitors, only 31 were previously suggested. Many herbals, as predicted here, might cause impaired metabolism of drugs, and endogenous hormones and bile acids. Additionally, by applying Lipinski's rules of five, 17 compounds were also classified as potential intestine local inhibitors. New CYP3A4 inhibitors predicted by the model, bilobetin and picropodophyllin, were assayed in vitro.

Mechanistic study of bergamottin-induced inactivation of CYP2C9

Bergamottin (BGM) is a major furanocoumarin constituent of grapefruit and is reported to have inhibitory effects on cytochrome P450 enzymes. This study investigated the chemical interactions between BGM and the enzyme CYP2C9. BGM exhibited time-, concentration-, and NADPH-dependent inhibition of CYP2C9. Co-incubation with diclofenac, a reversible inhibitor of CYP2C9, attenuated the time-dependent enzyme inhibition. Exhaustive dialysis did not restore enzyme activity post-inhibition. Glutathione (GSH) and catalase/superoxide dismutase failed to reverse BGM-induced CYP2C9 inactivation. A GSH trapping study suggested that BGM was metabolized to an epoxide and/or γ-ketoenal that may have been responsible for the enzyme inactivation. In conclusion, BGM can be characterized as a mechanism-based inactivator of CYP2C9 acting via the formation of an epoxide and/or γ-ketoenal.

Outgoing and potential trends of composition, health benefits, juice production and waste management of the multi-faceted Grapefruit Citrus Χ paradisi: A comprehensive review for maximizing its value

Grapefruit (GF) Citrus Χ paradisi Macfad (F. Rutaceae) is one of the major citrus fruits that encompass a myriad of bioactive chemicals and most unique among citrus fruits. Nevertheless, no study has yet to assess comprehensively its multitudinous constituents, health benefits, and valuable waste products. Hereto, the present review provides an updated comprehensive review on the different aspects of GF, its juice production, waste valorization, enhancement of its byproducts quality, and compared to other citrus fruits. Grapefruit uniqueness among other citrus fruits stands from its unique taste, flavor, and underlying complex chemical composition. Despite limonene abundance in peel oil and grapefruit juice (GFJ) aroma, nootkatone and sulfur compounds are the key determinants of its flavor, whereas flavanones contribute to its bitter taste and in conjunction with limonoids. Different postharvest treatments and juice processing are reviewed and in context to its influence on final product quality and or biological effects. Flavanones, furanocoumarins, and limonoids appear as the most prominent in GF drug interactions affecting its metabolism and or excretion. Valorization of GF peel is overviewed for its utilization as biosrobent, its oil in aromatherapy, limonene as antimicrobial or in cosmetics, fruit pectin for bioethanol production, or as biosorbent, and peel phenolics biotransformation. The present review capitalizes on all of the aforementioned aspects in GF and further explore novel aspects of its juice quality presenting the full potential of this valued multi-faceted citrus fruit.