Investigation of Liposomal Encapsulation of Fractionated Black Raspberry Phytochemicals

Objectives: Background and Objective: In vitro, in vivo and human clinical studies show that black raspberry (BRB) phytochemicals exhibit significant anticancer activities in oral cancer tissues. These properties are attributed to the complex mixture of phytochemicals present in ripe BRBs and their combinatorial interactions. These studies aim to engineer, characterize, and optimize a delivery vehicle for complex BRB phytochemical fractions. We hypothesize that BRB phytochemical encapsulation employing liposomal nanoparticles (LNs) will improve in vitro bioavailability, facilitate growth inhibition, modulate release kinetics, and regulate gene expression signatures in premalignant cells that support oral cancer chemopreventive activities.
Methods: Methods: LN formulations were designed and evaluated for their capacity to efficiently encapsulate Quercetin, ethanol and hexane extracts of powdered freeze-dried BRBs. LNs were made by the ethanol injection method using PHOSAL^® 35 SB (Lipoid GmbH) or egg phosphatidylcholine, cholesterol, and Tween 80 (PCCT80, 60:35:5 mole ratios). Particle size was evaluated by dynamic light scattering (DLS). Thin-film hydration (TFH) and extrusion (polycarbonate film, 0.2µm) were implemented to evaluate size and stability. Encapsulation efficiency and physical and chemical stability of LNs and phytochemical compounds were characterized utilizing standard curves, DLS and UV-VIS spectroscopy.
Results: Results and Discussion: PHOSAL^® LN diameters ranged from 200–600nm, while PCCT80 LNs had 100–200nm diameters. LNs formed by ethanol injection proved unstable; therefore, TFH and extrusion techniques were implemented. Applying sonication and extrusion resulted in consistent particle sizing and nominal instability during storage. UV-VIS spectroscopy was not sensitive enough to reproducibly detect and quantify extract composition.
Conclusions: Conclusions: Preliminary results demonstrate that LNs using the modified PCCT80 formulation, TFH, and extrusion are better suited for BRB phytochemical encapsulation. Further analysis is being conducted to accurately evaluate encapsulation efficiency. LNs created in this study will be optimized in in vitro testing to evaluate biological activity in human oral epithelial cell types.