The In Vitro Toxicity Profile of Nanoencapsulated Curcumin in a Chitosan–Alginate Gel Carrier Using Rabbit Lymphocytes: Preliminary Research

Curcumin is a natural bioactive compound of plant origin, characterised by a wide variety of properties that make it useful in numerous industries. Furthermore, due to its health-promoting properties, such as anti-inflammatory, antioxidant, and antimicrobial effects, it has found applications in medicine and animal husbandry. Unfortunately, curcumin has low bioavailability; its hydrophobic nature means it is poorly absorbed through the gastrointestinal tract, and it is rapidly metabolised in the liver. In recent years, research has been conducted into adding nanoencapsulated active ingredients, such as curcumin, to animal feed. This research aims to improve the bioavailability and stability of these ingredients, extend their shelf life, and enhance their absorption. These effects are expected to improve overall animal health, increase production efficiency, and enhance the quality of animal products. However, a significant challenge remains: the irreversible aggregation and chemical instability of bioactive substances due to the hydrolysis of their polymeric encapsulants, which can lead to toxic effects. This study utilised peripheral whole blood from five Blanc de Termonde rabbits. In vitro cell exposure was conducted using three distinct concentrations of nanoencapsulated curcumin (C1-C3: 10, 5.0, and 2.5 µg/mL) and a control. Cytotoxicity was determined by assessing viability using trypan blue exclusion, the comet assay, and the micronucleus assay. The results indicated that all tested concentrations of nanocurcumin significantly decreased the viability of blood cells to approximately 1-9%. In contrast, the encapsulation matrices themselves were not toxic (results were statistically significant). In the comet assay, the nanocurcumin formulations were toxic at all concentrations, and the results were statistically significant. Following exposure, the micronucleus assay revealed cell damage and a high percentage of apoptotic cells (up to 30% for Cur1 at 10 ug/mL). A significant number of binucleated cells with two micronuclei (BNCs + 2MN) were also observed, again for Cur1. In view of the considerable variation in the results from the individual tests, it is advisable to repeat the research using different matrix forms and concentrations of curcumin.