Antioxidant and anti-inflammatory activities of freeze-dried grapefruit phenolics as affected by gum arabic and bamboo fibre addition and microwave pretreatment

Preparation, characterization and therapeutic properties of gum arabic-stabilized gallic acid nanoparticles

Gallic acid (GA) is a natural phenolic compound with therapeutic effects that are often challenged by its rapid metabolism and clearance. Therefore,  GA was encapsulated using gum arabic into nanoparticles to increase its bioavailability. The formulated nanoparticles (GANPs) were characterized for physicochemical properties and size and were then evaluated for antioxidant and antihypertensive effects using various established in vitro assays, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide scavenging (NO), β-carotene bleaching and angiotensin-converting enzyme (ACE) inhibitory assays. The GANPs were further evaluated for the in vitro cytotoxicity, cell uptake and cell migration in four types of human cancer cell lines including (MCF-7, MDA-MB231) breast adenocarcinoma, HepG2 hepatocellular cancer, HT-29 colorectal adenocarcinoma, and MCF-10A breast epithelial cell lines. The GANPs demonstrated potent antioxidant effects and have shown promising anti-cancer properties in a dose-dependent manner with a predilection toward HepG2 and MCF7 cancer cells. The uptake of GANPs was successful in the majority of cancer cells with a propensity to accumulate in the nuclear region of the cells. The HepG2 and MCF7 cancer cells also had a significantly higher percentage of apoptosis and were more sensitive to gallic acid nanoparticle treatment in the cell migration assay. This study is the first to confirm the synergistic effects of gum arabic in the encapsulation of gallic acid by increasing the selectivity towards cancer cells and enhancing  the antioxidant properties. The formulated nanoparticles also had remarkably low toxicity in normal cells. Based on these findings, GANPs may have promising therapeutic applications towards the development of more effective treatments with a probable targeting precision in cancer cells.

Insights into the development of grapefruit nutraceutical powder by spray drying: physical characterization, chemical composition and 3D intestinal permeability

BACKGROUND

The development of functional and nutraceutical foods comes from a greater awareness of the relationship between food and health by consumers. In recent years, the idea of purifying and encapsulating bioactive compounds through techniques such as spray drying has been well received by the food industry. The development and characterization of a grapefruit (Citrus paradisi) nutraceutical powder obtained by spray drying is of great interest owing to the different bioactive compounds and the potential health effects.

RESULTS

The grapefruit powder was characterized by a low water amount (1.5 g water per 100 g powder) and a high porosity (75%). The color parameters were L* = 80.0 ± 1.8, h_ab * = 61.7 ± 0.4 and C_ab * = 11.4 ± 0.6. The IC₅₀ values determined for the freeze-dried oxalic acid extract (FDOA) and the freeze-dried methanol-water extract (FDMW) were 0.48 and 0.72 mg mL^-1 respectively, while the total phenolic content (TPC) ranged between 1274 and 1294 mg gallic acid equivalent (GAE) per 100 g dry basis (d.b.). Regarding total flavonoid content (TFC), FDOA presented the highest amount (6592 mg quercetin equivalent (QE) per 100 g d.b.). For both extracts, the cell viability in Caco-2 and HT29-MTX was above 90% at 100 μg mL^-1 . The bioavailability of the bioactive compounds was analyzed through a 3D intestinal model. Delphenidin-3-glucoside and hesperitin-7-O-glucoside presented a permeation higher than 50%, followed by hesperidin which was close to 30%.

CONCLUSION

This work allows to establish that the formulation of grapefruit powder has great potential as a nutraceutical food, with spray drying being a good alternative technique in the food industry. © 2019 Society of Chemical Industry.