Development of plant extracts loaded lipid nanoparticles for potential glioblastoma treatment.

Abstract

Glioblastoma (GB) is a form of malignant brain tumours with extremely poor prognosis due to the difficulty in bypassing the blood brain barrier (BBB). Phytochemicals have shown potential for positive anti-cancer activity with two showing a promising potential for research those being epigallocatechin gallate (EPGC) and curcumin. Difficulties arose in delivery due to the BBB preventing entry to tumour sites in the brain. Nanostructured lipid carriers (NLC) show intrigue due to their ability in crossing the BBB. Encapsulation of these compounds inside NLC formulations was explored for their potential toxicity against GB cells U87MG and was compared to a control non-cancerous cell line (SVG P12).

A novel HPLC method was developed and optimised following ICH guidelines for curcumin and EPGC quantification. The methods showed accuracy ranging from 90-108% representing the high sensitivity of each method. The NLCs were optimised following a set of process and product parameters which include, increasing sonication time, and the inclusion of Solutol. Curcumin was optimized from F1 Cur-NLC to F2 Cur-NLC, to achieve a particle size of 132.9nm ± 22.2 and PDI of 0.181 ± 0.052, and zeta potential of -47.8mV ± 2.1. F2 Cur-NLC TD was 67.3% ± 4.4 and EE of 92% ± 1.2. F1 EPGC-NLC was characterised with a particle size of 148.3nm ± 6.5 with a uniform distribution of 0.209 ± 0.012. They also exhibited a zeta potential of -43.1mV ± 4.9. TGA and DSC highlighted the possibility that EPGC and Curcumin were embedded in NLCs in an amorphous state. FTIR showed encapsulation of curcumin inside the NLC, whilst the EPGC fingerprint region overlapped with peaks found in the formulation. All developed NLCs remained stable for up to 14 days, in a suspension form at ambient temperatures.

Data obtained from the In vitro studies suggested a reduced toxicity to SVG P12 cells lines between the phytochemical encapsulated NLC and the phytochemical alone at both 24 and 48 hours of treatment. This toxicity was reflected also on the scratch/wound assay data with F2 Cur-NLC showing an increased ability to inhibit the migration of U87MG cell lines when compared against both the control and the phytochemical alone. No change in cell cycle was observed in any of the U87MG cells treated with the chosen samples (F2 Blank-NLC, Curcumin, F2 Cur-NLC and EPGC) and followed a similar expression of G1, S and G2/M phase. While curcumin and EPGC exhibited a decrease in G1 phase when SVG P12 cells were tested. TNF-α was measured for both U87MG and SVG P12 cells with F2 cur-NLC inhibiting TNF-α to a significant degree when compared to the phytochemical alone.

The results presented in this project highlighted the potential benefits of using both curcumin and EPGC as a form of compounds loaded into a carrier system to improve BBB permeability and be used for GBs treatments.