AI-assisted identification of a novel vardenafil analog (KD-027) adulterated in capsules

Sexual dysfunction is a health issue that significantly affects adults. However, the increased demand for pharmacological treatments, such as sildenafil, tadalafil, and vardenafil has led to the emergence of counterfeit drugs, posing a serious public health concern. These counterfeit drugs and their analogs often lack clinical validation, leaving their effects on the human body largely unknown. In this case study, a suspected novel vardenafil analogue adulterated in sexual enhancement capsules was identified using gas chromatography-mass spectrometry (GC-MS). High-resolution mass spectrometry (LC-HRMS) was employed to determine the protonated molecular ion at m/z 562.2438 for the compound, and its possible elemental compositions were predicted. Based on AI-assisted analysis using ChatGPT-4o, the compound was inferred to be KD-027 (SLx-2101), a potential phosphodiesterase type 5 (PDE5) inhibitor. Following purification by column chromatography, nuclear magnetic resonance (NMR) spectroscopy confirmed this structure. In addition, evidence of coexisting E/Z tautomerism of KD-027 was observed in the NMR data. To the best of our knowledge, this is the first report to identify KD-027 in sexual enhancement products, providing its characteristic mass spectral fragments and NMR data, and demonstrating the utility of ChatGPT-4o in forensic investigations.