Free and nanoencapsulated curcumin prevents scopolamine-induced cognitive impairment in adult zebrafish

Cognitive dysfunctions are the main symptoms associated with Alzheimer's disease (AD). In the last decade, the use of natural substances to prevent or alleviate neurological symptoms have attracted great interest. Curcumin, the main polyphenolic component of turmeric (Curcuma longa) rhizomes, has a variety of beneficial properties, including potent antioxidant and anti-inflammatory properties. Despite the therapeutic potential for neurodegenerative diseases including AD, the use of this natural compound as a drug in therapies has huge limitations due to its low water solubility, physicochemical instability, and poor bioavailability. Nanotechnology is an important tool to overcome these drawbacks. Here, the safety of curcumin and its nanoencapsulated form was evaluated using zebrafish embryos. We also investigated the potential protective effect of curcumin and nanoencapsulated curcumin (50 mg/kg, single injection, i.p.) against scopolamine-induced memory deficits in adult zebrafish. The embryotoxicity test revealed that the formulations in any dose tested did not cause embryo mortality or affect the hatching rate. Data showed that both curcumin and nanoencapsulated curcumin are effective in preventing scopolamine-induced cognitive impairments without altering the animals' locomotion. These findings suggest that these treatments are safe and could be useful for enhancing memory function in AD or other age-related disorders.