Thio-ProTide strategy: A novel H₂S donor–drug conjugate (DDC) alleviates hepatic injury via innate lysosomal targeting

Hydrogen sulfide (H₂S) is a gas signaling molecule with versatile bioactivities; however, its exploitation for disease treatment appears challenging. This study describes the design and characterization of a novel type of H₂S donor–drug conjugate (DDC) based on the thio-ProTide scaffold, an evolution of the ProTide strategy successfully used in drug discovery. The new H₂S DDCs achieved hepatic co-delivery of H₂S and an anti-fibrotic drug candidate named hydronidone, which synergistically attenuated liver injury and resulted in more sufficient intracellular drug exposure. The potent hepatoprotective effects were also attributed to the H₂S-mediated multipronged intervention in lipid peroxidation both at the whole cellular and lysosomal levels. Lysosomal H₂S accumulation and H₂S DDC activation were facilitated by the hydrolysis through the specific lysosomal hydrolase, representing a distinct mechanism for lysosomal targeting independent of the classical basic moieties. These findings provided a novel pattern for the design of optimally therapeutic H₂S DDC and organelle-targeting functional molecules.