Unveiling molecular moieties through hierarchical Grad-CAM graph explainability

Background Virtual Screening (VS) has become an essential tool in drug discovery, enabling the rapid and cost-effective identification of potential bioactive molecules. Among recent advancements, Graph Neural Networks (GNNs) have gained prominence for their ability to model complex molecular structu...

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Veröffentlicht in:BMC bioinformatics Jg. 26; H. 1; S. 261 - 23
Hauptverfasser: Contino, Salvatore, Sortino, Paolo, Gulotta, Maria Rita, Perricone, Ugo, Pirrone, Roberto
Format: Journal Article
Sprache:Englisch
Veröffentlicht: London BioMed Central 23.10.2025
BioMed Central Ltd
Springer Nature B.V
BMC
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ISSN:1471-2105, 1471-2105
Online-Zugang:Volltext
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Zusammenfassung:Background Virtual Screening (VS) has become an essential tool in drug discovery, enabling the rapid and cost-effective identification of potential bioactive molecules. Among recent advancements, Graph Neural Networks (GNNs) have gained prominence for their ability to model complex molecular structures using graph-based representations. However, the integration of explainable methods to elucidate the specific contributions of molecular substructures to biological activity remains a significant challenge. This limitation hampers both the interpretability of predictive models and the rational design of novel therapeutics. Results We trained 20 GNN models on a dataset of small molecules with the goal of predicting their activity on 20 distinct protein targets from the Kinase family. These classifiers achieved state-of-the-art performance in virtual screening tasks, demonstrating high accuracy and robustness on different targets. Building upon these models, we implemented the Hierarchical Grad-CAM graph Explainer (HGE) framework, enabling an in-depth analysis of the molecular moieties driving protein-ligand binding stabilization. HGE exploits Grad-CAM explanations at the atom, ring, and whole-molecule levels, leveraging the message-passing mechanism to highlight the most relevant chemical moieties. Validation against experimental data from the literature confirmed the ability of the explainer to recognize a molecular pattern of drugs and correctly annotate them to the known target. Conclusions Our approach may represent a valid support to shorten both the screening and the hit discovery process. Detailed knowledge of the molecular substructures that play a role in the binding process can help the computational chemist to gain insights into the structure optimization, as well as in drug repurposing tasks.
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ISSN:1471-2105
1471-2105
DOI:10.1186/s12859-025-06208-y