Formulation of a Bioactive Nanoemulsion of Gamma Linolenic Acid for Anti-Glioblastoma Activity

Background

Glioblastoma (GBM), a highly aggressive primary brain tumor, presents significant therapeutic challenges due to its inherent chemoresistance, neurotoxicity concerns, and the formidable blood-brain barrier. Gamma Linolenic Acid (GLA), a promising anti-cancer agent, is currently limited by poor water solubility and non-specific effects, hindering its clinical application for such malignancies.

Aim and Objectives

This research aimed to develop and evaluate a Nanoemulsion (GLA-NE) utilizing borage seed oil to enhance the delivery of GLA to tumors, with a specific focus on its anti-glioblastoma activity.

Materials and Methods

A GLA-NE was formulated and optimized, followed by comprehensive characterization including particle size, stability, in vitro drug release kinetics, and hemocompatibility. The in vitro anti-cancer activity of GLA-NE was rigorously evaluated against U-373MG glioblastoma cell lines. Further, in vivo studies in a DMBA-induced solid tumor rat model compared the pharmacokinetics, tumor growth inhibition, and organ toxicity of GLA-NE versus free GLA. Long-term stability of GLA-NE was assessed over 6 months under specific storage conditions.

Results

The optimized GLA-NE exhibited a mean particle size of 180.2 ± 4.5 nm, a Polydispersity Index (PDI) of 0.178 ± 0.01, and a zeta potential ranging from -33.7 ± 1.9 mV to -35.7 ± 1.5 mV, indicative of robust colloidal stability and uniform particle distribution. In vitro release studies demonstrated a biphasic pattern with an initial burst release of approximately 29% within 2 hr, followed by a sustained release of 67.04% over 24 hr, governed by Fickian diffusion (Korsemeyer-Peppas model, n=0.1075, R²=0.956). The formulation displayed excellent hemocompatibility with hemolysis percentages ranging from 1.9 ± 0.1% to 3.4 ± 1.5%, well below the 5% safety threshold for intravenous administration. Notably, GLA-NE retained in vitro cytotoxicity against U-373MG glioblastoma cells, with an IC₅₀ of 17.34 μg/mL compared to 10.48 μg/mL for pure GLA. In vivo studies in a solid tumor model demonstrated improved drug retention, protracted plasma levels (detectable up to 14 hr for GLA-NE vs. 12 hr for pure GLA), and significant tumor growth inhibition, with GLA-NE cohorts experiencing tumor volume reductions of 1.24-fold, 2.01-fold, and 3.84-fold relative to GLA, marketed, and control groups, respectively. Reduced liver and kidney toxicity was also observed with GLA-NE treatment. The nanoemulsion maintained stability for 6 months, showing minimal changes in physical characteristics.

Discussion

The formulated GLA-NE exhibited superior physicochemical stability, biocompatibility, and sustained release kinetics, culminating in enhanced pharmacokinetic performance and pronounced tumor suppression. Its optimized nanoscale architecture mitigated systemic toxicity while preserving anti-glioblastoma potency, underscoring its translational viability as a rationally engineered nanotherapeutic platform for glioblastoma intervention.

Conclusion

This study demonstrates that the developed GLA-NE is a promising nanocarrier system, offering improved drug delivery, retained in vitro anti-glioblastoma cytotoxicity, and significant in vivo anti-tumor efficacy with reduced systemic toxicity compared to free GLA. The formulation's stability further supports its potential for clinical translation in cancer therapy.