## Flavonols Found in Common Foods May Combat drug Resistance
New research shows that certain flavonols from everyday foods can shut down the bodyS drug-resistance machinery, potentially paving the way for more effective treatments, but clinical hurdles remain.
study: Inhibition of breast cancer resistance protein by flavonols: in vitro, in vivo, and in silico implications of the interactions. Image Credit: Danijela Maksimovic / Shutterstock
In a recent study published in the journal Scientific reports, a group of researchers identified flavonols that inhibit Breast Cancer Resistance Protein (BCRP), encoded by Adenosine triphosphate (ATP)-binding cassette subfamily G member 2 (ABCG2), and tested whether they reverse drug resistance in vitro and increase exposure to a BCRP substrate in vivo. The study also highlights critically important limitations and the need for caution when considering clinical applications.
## Background
Why do some medicines fail just when patients need them most? One reason is BCRP, an ATP-driven efflux pump that lowers intestinal drug absorption, limits tissue penetration at barriers like the brain and placenta, and speeds drug elimination, altering efficacy and side effects. Diet-derived flavonoids are widely consumed, and some can block BCRP, but their specific inhibitory patterns and practical impact remain unclear. Understanding which flavonols inhibit BCRP, and how strongly, matters for real-world issues like chemotherapy resistance and statin exposure. The central question: can selected flavonols overcome transporter-mediated resistance and boost exposure to BCRP substrates without undue toxicity? Further research is needed to link these mechanistic findings to clinical use and to clarify the impact of species differences and the low oral bioavailability of flavonols observed in this study.
## About the study
Flavonol screening was performed in Madin-Darby Canine Kidney II (MDCKII) cells stably expressing human BCRP and MDCKII-mock controls, maintained in Dulbecco’s Modified Eagle’s Medium (DMEM) with Fetal Bovine Serum (FBS), Nonessential Amino Acids (NEAA), and penicillin/streptomycin at 37°C in 5% carbon dioxide (CO).BCRP activity was quantified by a prazosin accumulation assay in Hanks’ Balanced Salt Solut“`html
Reverse Transcriptase Inhibitors: Development and Molecular Docking
Table of Contents
Reverse transcriptase inhibitors (RTIs) are a crucial class of antiretroviral drugs used to treat Human Immunodeficiency Virus (HIV) infection. These drugs work by selectively inhibiting reverse transcriptase, an enzyme vital for HIV replication. Understanding the development and mechanisms of these inhibitors, especially through techniques like molecular docking, is key to designing more effective treatments.
How Reverse Transcriptase Works and Why It’s a Target
HIV is a retrovirus, meaning it uses RNA as its genetic material. To replicate, HIV must first convert its RNA into DNA using reverse transcriptase. This DNA than integrates into the host cell’s genome,allowing the virus to produce more copies of itself. Blocking reverse transcriptase prevents this crucial step, halting viral replication.Because reverse transcriptase is unique to retroviruses like HIV, inhibiting it has minimal impact on the host cell.
Classes of Reverse Transcriptase Inhibitors
RTIs are broadly categorized into two main classes: Nucleoside/Nucleotide Reverse Transcriptase Inhibitors (NRTIs) and Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs).
Nucleoside/Nucleotide Reverse Transcriptase Inhibitors (nrtis)
NRTIs are analogs of natural nucleosides,the building blocks of DNA. They work by being incorporated into the growing viral DNA chain, but because they lack a 3′-hydroxyl group, they cause chain termination, preventing further DNA synthesis. Examples include zidovudine (AZT), lamivudine (3TC), and tenofovir. HIV.gov provides detailed details on NRTIs.
Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
NNRTIs bind directly to reverse transcriptase,causing a conformational change that inhibits its activity. They do not require phosphorylation like NRTIs. Examples include efavirenz, nevirapine, and rilpivirine. NIH’s AIDSinfo offers comprehensive details on NNRTIs.
recent Developments and Research
Recent research focuses on developing new RTIs with improved potency, fewer side effects, and increased resistance profiles. One area of investigation involves exploring novel chemical scaffolds and optimizing existing structures. studies have shown that certain compounds can induce conformational changes in reverse transcriptase, leading to near-complete inhibition.
A recent study investigated 14 potent inhibitors, observing varying degrees of reversal in enzyme activity – some reaching mock-like levels, indicating near-complete reversal. Others produced partial reversal, reflected in total reverse fold (RFt) values depending on structure. (Source: PubMed – specific study details can be found here)
Molecular docking backed up the lab results. All 14 potent inhibitors sat in the active site of the enzyme.
molecular Docking: A Computational Approach
Molecular docking is a computational technique used to predict the preferred orientation of a molecule (like a drug candidate) when bound to a target protein (like reverse transcriptase). this allows researchers to visualize the interactions between the drug and the enzyme, understand the binding affinity, and identify key residues involved in the interaction.This information is crucial for rational drug design, allowing scientists to optimize drug structures for improved potency and selectivity.
how Molecular Docking Works
- Protein Readiness: The 3D structure of the target protein (reverse transcriptase) is obtained, frequently enough from the Protein Data Bank (PDB).
- Ligand Preparation: The 3D structure of the potential inhibitor is prepared.
- Docking Simulation: The ligand is “docked” into the active site of the protein using computational algorithms.
- Scoring: The docking software scores the different possible binding poses based on factors like binding affinity and steric clashes.
- Analysis: The best-scoring poses are analyzed to understand the interactions between the drug and the enzyme.
Future Directions