Category: Formulation and Quality
Purpose: Chelerythrine chloride is a benzo[c]phenanthridine alkaloid that has been shown to suppress tumor activity. The anti-cancer activity of chelerythrine has been demonstrated in renal cancer, squamous cell carcinoma, prostate cancer and breast cancer. Chelerythrine exhibits its anti-cancer activity by inhibiting protein kinase c (PKC). Breast cancer is the most common cancer type among women in the United States and Triple negative Breast cancer (TNBC), is a subtype of breast cancer in which chelerythrine demonstrates anti-proliferative activity. As a PKC inhibitor in TNBC, chelerythrine has exhibited anti-proliferation of TNBC cell lines such as MDA-MB-231. Since TNBC subtype is not receptive to hormonal therapy or anti-HER2 treatment, chemotherapy is the primary option. Therefore, chelerythrine nanoparticles could serve as a potential treatment choice with lower off-target toxicity.
Methods: Chelerythrine nanoparticles were formulated using a biodegradable polymer poly(lactide-co-glycolide) (PLGA 50:50; acid terminated). Briefly, an emulsion containing an oil phase of PLGA and chelerythrine in dichloromethane was emulsified with an aqueous external phase of 1% w/v PVA. The formulation was subjected to ultra-sonication at 40% amplitude for 4 minutes (10 sec on/off cycle). The organic solvent was then removed by evaporation of the solvent using a rotary evaporator, followed by centrifugal washing to remove the unreacted polymers, unentrapped drug and excess PVA. To introduce the positive surface charge, the fabricated nanoformulation was further coated with 1% polyethylenimine (PEI). Introduction of PEI to the PLGA nanoparticles changed the zeta potential from negative to positive charge thereby increasing the cellular uptake in the breast cancer cell lines. Characterization of the final formulation included determination of particle size, zeta potential and percentage entrapment. Chelerythrine and chelerythrine nanoparticles were evaluated against MDA-MB-231 cells in an MTT assay by treating for 48 hours.
Results: The developed formulations possessed particle size < 200 nm (179.6±8.9 nm for uncoated, and 190.2±5.4 nm for PEI coated NPs) along with a narrow polydispersity index (< 0.06 for both the formulations), thus proving homogeneity of formulations. Since, a positive zeta potential governs a greater affinity of the drug to the negatively charged cancer cells with improved cellular uptake, PEI was incorporated to the formulation making the surface free charge of the nanoparticles more positive charged. The zeta potential changed from -24.2±1.9 mV to 40.0±8.6 mV. % drug entrapment in the developed formulation was found to be >35%. As indicated in the cytotoxicity data (Fig. 1), chelerythrine PEI-coated nanoformulation gave an IC50 value of 3.023±0.29 µM vs 4.179±1.61 µM.
Conclusion: This study has provided a method to fabricate chelerythrine nanoparticles that could possibly be utilized in the treatment of TNBC. Further in-vitro release studies will explore the efficacy of chelerythrine nanoformulation which can then be verified using other TNBC cell lines.