Assessing the In Vitro and In Vivo Performance of L-Carnitine-Loaded Nanoparticles in Combating Obesity

Abstract

Addressing obesity is a critical health concern of the century, necessitating urgent attention. L-carnitine (LC), an essential water-soluble compound, plays a pivotal role in lipid breakdown via β-oxidation and facilitates the transport of long-chain fatty acids across mitochondrial membranes. However, LC's high hydrophilicity poses challenges to its diffusion through bilayers, resulting in limited bioavailability, a short half-life, and a lack of storage within the body, mandating frequent dosing. In our research, we developed LC-loaded nanoparticle lipid carriers (LC-NLCs) using economically viable and tissue-localized nanostructured lipid carriers (NLCs) to address these limitations. Employing the central composite design model, we optimized the formulation, employing the high-pressure homogenization (HPH) method and incorporating Poloxamer^® 407 (surfactant), Compritol^® 888 ATO (solid lipid), and oleic acid (liquid oil). A comprehensive assessment of nanoparticle physical attributes was performed, and an open-field test (OFT) was conducted on rats. We employed immunofluorescence assays targeting CRP and PPAR-γ, along with an in vivo rat study utilizing an isolated fat cell line to assess adipogenesis. The optimal formulation, with an average size of 76.4 ± 3.4 nm, was selected due to its significant efficacy in activating the PPAR-γ pathway. Our findings from the OFT revealed noteworthy impacts of LC-NLC formulations (0.1 mg/mL and 0.2 mg/mL) on adipocyte cells, surpassing regular L-carnitine formulations' effects (0.1 mg/mL and 0.2 mg/mL) by 169.26% and 156.63%, respectively (p < 0.05).

Keywords: NLC; carnitine; cell culture; obesity; open-field test.

Figure 1

SEM images of LC-NLC nanoparticles: (A) 0.2 mg/mL, (B) 0.2 mg/mL loaded NLC formulation, (C) 0.1 mg/mL loaded NLC formulation, (D) 0.1 mg/mL loaded NLC formulation.

Figure 2

Release profiles of pure LC (control) and LC-NLC formulations.

Figure 3

Evaluation of the body weight and fat of the rats up to the end of the experiment. (A) Weight variation, (B) body weight index change, and (C) differentiation of fat weight.

Figure 4

Open-field test results: (A) pathway of the rats and (B) distance travelled by rats (60.DAY represents the end of the three days’ treatment).

Figure 5

Protein levels from the isolated adipose tissue of rats: (A) CRP level and (B) PPAR-γ level.

Figure 6

Cell viability study with NIH-3T3 cells. (A) Flow cytometry results, (B) graphical expression of the results, and (C) IC50 values (*** represents p < 0.001).