Linalool exerts antioxidant activity in a rat model of diabetes by increasing catalase activity without antihyperglycemic effect.

Diabetes mellitus (DM) is a prevalent metabolic disorder often accompanied by oxidative stress, which contributes to various diabetic complications. Investigating the antioxidant activity of linalool (LIN) is crucial as it may offer a natural therapeutic approach to mitigate oxidative damage in DM. The aim of the present study was to investigate the antioxidant activity of LIN in a DM rat model. A total of 40 male Wistar albino rats (age, 8 weeks; weight, 250-300 g) were used. CONTROL and DM groups were administered physiological saline solution by oral gavage for 21 days. In rats in the DM + LIN and LIN groups, 100 mg/kg LIN was administered intragastrically after streptozotocin injection (n=10 per group). In the first (48 h after STZ injection), second (1 week later), third (2 weeks later), and fourth (3 weeks later) blood glucose measurements, a statistically significant increase was found in the blood glucose values of the DM and DM + LIN groups compared with those of the CONTROL group. During the 21-day experimental period, there was no reduction in blood glucose levels of the DM + LIN group. Consequently, no discernible anti-hyperglycemic effect of LIN was observed. Catalase enzyme activity, superoxide dismutase (SOD) enzyme activity, malondialdehyde (MDA) levels and glutathione (GSH) levels were measured spectrophotometrically. All assays were conducted according to the protocols provided in the respective kits. The results were analyzed to assess the oxidative status and antioxidant capacity in the experimental groups. Catalase (CAT) activity was decreased in the DM group compared with that in the CONTROL group in both the serum and liver. However, LIN administration restored CAT activity in the DM + LIN group to the level of the CONTROL group. In the liver, the DM + LIN-treated group showed a notable reduction in malondialdehyde (MDA) levels compared with those in the DM group. In conclusion, the present results suggest that the antioxidant properties of LIN may have a regulatory effect on the oxidative status in diabetes-affected systems, potentially offering therapeutic benefits in managing oxidative stress associated with diabetes.