Leaf Extract of Eugenia uniflora L. Prevents Episodic Memory Impairment Induced by Streptozotocin in Rats

Background: Eugenia uniflora is a plant found in several countries of South America and is traditionally used in folk medicine as an antimicrobial, anti‑inflammatory, and antihypertensive agent. Objective: This study aimed to investigate the neuroprotective effect of the ethanolic extract of E. uniflora leaves on memory impairment induced by streptozotocin (STZ) in rats. Materials and Methods: The ethanolic extract of E. uniflora leaves was used to treat Wistar rats which received intracerebroventricular (ICV)‑STZ. Animals were allocated to the control group (n = 10), i.e., ICV vehicle solution + ethanol 10%; STZ group (n = 10), i.e., ICV‑STZ + ethanol 10%; STZ + E. uniflora (300 mg/kg) group (n = 10), i.e., ICV‑STZ +300 mg/kg of leaf extract of E. uniflora; and STZ + E. uniflora (1000 mg/kg) group (n = 10), i.e., ICV‑STZ +1000 mg/kg of leaf extract of E. uniflora. The animals were submitted to the treatments 24 h after receiving ICV‑STZ. The treatments were performed on alternate days over a 30‑day period. After this period, the animals were tested in the elevated plus maze to assess learning and memory. Results: The STZ group presented a higher transfer latency (P < 0.001) which impaired memory regarding the aversive characteristics of the apparatus. The performance in the sessions regarding this parameter of the groups treated with the leaf extract of E. uniflora was similar to the control group (P > 0.05) for both the doses. Conclusion: The leaf extract of E. uniflora showed a neuroprotective effect on memory impairment induced by STZ in rats.