Formulation and Development of Ligustrazine-Loaded Liposomes: A promising drug Repurposing approach for treating Nephrotoxicity

Technical Summary: Formulation and Development of Ligustrazine-Loaded Liposomes for Nephrotoxicity

Problem Statement
Nephrotoxicity, characterized by kidney damage from exposure to chemicals, toxins, or pharmaceuticals, is a prevalent adverse effect leading to acute and chronic kidney injury. While phytoconstituents like Ligustrazine (an alkaloid from Ligusticum wallichii) demonstrate nephroprotective potential through anti-inflammatory and antioxidant mechanisms, their therapeutic efficacy is limited by poor bioavailability and non-specific distribution. Conventional therapies often suffer from inadequate drug delivery to the kidneys or excessive drug buildup, resulting in insufficient treatment and side effects. The study addresses the need for a targeted delivery system to enhance the renal accumulation of Ligustrazine and mitigate paracetamol-induced nephrotoxicity.

Methodology
The research employed a drug repurposing approach utilizing nanoformulation technology.

• Formulation Development: Ligustrazine-loaded liposomes (L-Liposomes) were prepared via the thin-film hydration method using phosphatidylcholine, cholesterol, and surfactants (Tween 80 and Span 60). A 2-factor, 3-level factorial design was used to optimize lipid and surfactant concentrations.
• Surface Modification: The optimized liposomes were coated with Polyethyleneimine (PEI), a cationic polymer, to create PEI-coated Ligustrazine-loaded liposomes (PCL-Liposomes). This coating aimed to enhance cellular uptake and renal targeting.
• Characterization: Formulations were evaluated for particle size, polydispersity index (PDI), zeta potential, entrapment efficiency (EE), and in vitro drug release. Morphological analysis was conducted using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Structural integrity and drug-polymer interactions were assessed via FTIR, DSC, and XRD.
• Computational Studies: Molecular docking simulations were performed to investigate the binding interactions of Ligustrazine with soluble epoxide hydrolase (sEH, PDB ID: 3ANS) and Nuclear Factor kappa-B (NF-κB, PDB ID: 1SVC).
• In Vivo Evaluation: A paracetamol-induced nephrotoxicity model was established in male Wistar rats. Animals were divided into five groups: negative control, positive control (paracetamol only), standard treatment (N-acetyl cysteine), Ligustrazine solution, and PCL-Liposomes. Treatments were administered for 7 days.
• Biochemical and Histopathological Analysis: Renal function was assessed via serum creatinine, blood urea nitrogen (BUN), TNF-α, and oxidative stress markers (MDA, SOD, CAT, GSH). Histopathological examination of kidney tissues was performed using H&E staining. Cytotoxicity was evaluated using an MTT assay on HEK293 cells.

Key Results

• Physicochemical Properties: The optimized PCL-Liposomes exhibited a particle size of approximately 152.8 nm, a PDI of 0.314, and a zeta potential of 14.4 mV. The PEI coating resulted in a slight increase in particle size compared to uncoated liposomes but maintained a spherical morphology.
• Encapsulation and Release: The entrapment efficiency of PCL-Liposomes was 94.1%, slightly higher than uncoated liposomes (93.3%), attributed to reduced drug leakage due to PEI interaction. In vitro release studies showed a cumulative release of 72% over 24 hours, fitting the Korsmeyer-Peppas model (non-Fickian diffusion).
• Molecular Docking: Ligustrazine demonstrated effective binding to sEH with a docking score of -5.184 kcal/mol, involving significant hydrophobic contacts. Binding to NF-κB yielded a score of -1.744 kcal/mol, indicating moderate affinity.
• In Vivo Efficacy: Paracetamol induction caused significant weight loss, elevated BUN, serum creatinine, and TNF-α levels, and reduced antioxidant enzyme levels (SOD, CAT, GSH). Treatment with PCL-Liposomes significantly mitigated these effects, restoring biochemical markers closer to control levels compared to the uncoated drug solution. Histopathology revealed that PCL-Liposome treated rats had well-preserved glomeruli and minimal tubular damage, contrasting with the necrosis and degeneration seen in the untreated nephrotoxic group.
• Safety: The MTT assay on HEK293 cells indicated that PCL-Liposomes maintained over 80% cell viability at higher concentrations, suggesting low cytotoxicity.
• Stability: The formulation remained stable at 4°C for three months, though aggregation was observed at 25°C and 37°C.

Significance and Claims
The paper posits that the developed PEI-coated Ligustrazine-loaded liposomes represent a promising strategy for the targeted treatment of drug-induced nephrotoxicity. The study claims that the nanoformulation successfully overcomes the limitations of free Ligustrazine by enhancing renal delivery and intracellular accumulation. The authors conclude that the formulation not only exhibits nephroprotective properties but also aids in the restoration of renal tissue from injury, offering a potential new approach for managing nephrotoxicity through drug repurposing and nanotechnology. The authors note that while the results are promising, additional clinical research is required to assess long-term safety.