SynCraft: An Integrated Web Server for ADMET-Aware Retrosynthesis and Molecular Design
1. SynCraft is a web server that unifies multi-step retrosynthetic planning with real-time ADMET evaluation, so every intermediate generated during route search is assessed for safety and drug-likeness without exporting molecules to separate tools.
2. The key practical feature is automatic, color-coded flagging of potentially hazardous intermediates during route exploration (e.g., genotoxicity-related alerts), addressing a common blind spot where conventional CASP tools optimize feasibility but ignore intermediate toxicity.
3. In an imatinib case study, SynCraft flags a well-known mutagenic intermediate, 4-methyl-1,2-phenylenediamine (ICH M7 Class 2), immediately when it appears in the tree (ClinTox 100%, ToxCast 0.18), while standard retrosynthesis outputs can present the same routes with no toxicity warning.
4. The retrosynthesis engine is template-based and deterministic: BFS search with InChIKey cycle detection, depth capped at 6 steps (chosen because 94.3% of molecules in a calibration set were solvable within 6), and termination when reaching a 22.4M commercial building-block database (ZINC15 eMolecules).
5. SynCraft uses a large reaction template library (384,512 templates) derived from USPTO-MIT plus Retro* templates, interleaved by frequency and weighted with an exponential decay scheme to balance solve rate vs runtime and reduce instability from rare templates.
6. Route ranking is multi-objective, combining synthetic accessibility (SA), synthetic complexity (SC), worst-intermediate ADMET signal, and step count via a Route Score; weights were tuned against chemist preference ratings on a held-out set (reported Spearman Ļ = 0.71).
7. ADMET prediction is powered by MolMVC, a multi-view contrastive learning framework combining 1D (Transformer on fingerprints), 2D (GIN Graph Transformer), and 3D (SchNet-based Graph Transformer on ETKDG/MMFF94 conformers), enabling intermediate-level predictions beyond simple 2D-only representations.
8. Safety flagging uses calibrated operational thresholds (e.g., ClinTox > 0.70; ToxCast < 0.40), motivated by ROC analysis and external validation; SynCraft also reports Lipinski compliance and QED for intermediates, plus SA (TwistDAN) and SCScore for synthesis difficulty context.
9. Benchmark and workflow results emphasize integration rather than higher solve rate: retrosynthesis performance is comparable to AiZynthFinder, but SynCraft evaluates all intermediates across all routes and reduces manual steps; a timing study reports ~84ā114 s end-to-end vs ~1,230ā1,410 s for a sequential retrosynthesis manual ADMET workflow (>91% reduction driven by eliminating per-intermediate manual evaluation and file handling).
š»Code:
github.com/Q-Aljanabi/SynCraā¦
šPaper:
doi.org/10.1093/nar/gkag463
#Retrosynthesis #ADMET #Cheminformatics #DrugDiscovery #ToxicityPrediction #MolecularMachineLearning #WebServer #ComputationalChemistry #MedicinalChemistry