Effect of Callistemon citrinus Phytosomes on Oxidative Stress in the Brains of Rats Fed a High-Fat-Fructose Diet

Abstract

Callistemon citrinus has shown antioxidant and anti-inflammatory properties in certain tissues. However, its impact on the brain remains unproven. This study investigates the effect of C. citrinus extract and phytosomes on the oxidative status of the brains of rats fed a high-fat-fructose diet (HFD). Fifty-four male Wistar rats were randomly divided into nine groups (n = 6). Groups 1, 2, and 3 received a standard chow diet; Group 2 also received the vehicle, and Group 3 was supplemented with C. citrinus extract (200 mg/kg). Groups 4, 5, 6, 7, 8, and 9 received a high-fat diet (HFD). Additionally, groups 5, 6, 7, 8, and 9 were supplemented with orlistat at 5 mg/kg, C. citrinus extract at 200 mg/kg, and phytosomes loaded with C. citrinus at doses of 50, 100, and 200 mg/kg, respectively. Administration was oral for 16 weeks. Antioxidant enzymes, biomarkers of oxidative stress, and fatty acid content in the brain were determined. A parallel artificial membrane permeability assay (PAMPA) was employed to identify compounds that can cross the intestinal and blood-brain barriers. The HFD group (group 4) increased body weight and adipose tissue, unlike the other groups. The brain fatty acid profile showed slight variations in all of the groups. On the other hand, group 4 showed a decrease in the activities of antioxidant enzymes SOD, CAT, and PON. It reduced GSH level, while increasing GPx activity as well as MDA, 4-HNE, and AOPP levels. C. citrinus extract and phytosomes restore the antioxidant enzyme activities and mitigate oxidative stress in the brain. C. citrinus modulates oxidative stress in brain tissue through 1.8-cineole and α-terpineol, which possess antioxidant and anti-inflammatory properties.

Keywords: Callistemon citrinus; antioxidant; brain; oxidative stress; phytosomes.

Figure 1

Scanning electron microscope images at 5000× (left) and 1000× (right) of phytosomes loaded with Callistemon citrinus leaf extract.

Figure 2

Weekly body weight in control rats and the different experimental treatments during the 16 weeks (A), and the percentage of total weight gained by control rats and various experimental treatments over 16 weeks is shown (B). Values are expressed as mean ± standard deviation (ANOVA followed by Tukey’s test, n = 6). Different letters (a,b) indicate significant differences between groups.

Figure 3

Effect of Callistemon citrinus extract and phytosomes on the lipid profile in brain tissue, (A) saturated fatty acids (SFAs), (B) monounsaturated fatty acids (MUFAs), (C) polyunsaturated fatty acids (PUFAs), and (D) dimethyl acetaldehyde (DMA) fatty acids. Control (C); control + vehicle (C + V); control + C. citrinus leaf extract (C + C.c, 200 mg/kg), high-fat diet (HFD), HFD + orlistat (HFD + Orl, 5 mg/kg), HFD + C. citrinus leaf extract (HFD + C.c, 250 mg/kg), HFD + phytosomes (HFD + P, 50 mg/kg, 100 mg/kg, and 200 mg/kg, respectively). Values are expressed as mean ± standard deviation (ANOVA followed by Tukey’s test, p < 0.05, n = 6).

Figure 4

GC/MS chromatogram (arbitrary units) of C. citrinus leaf extract showing compounds that could cross the intestinal barrier in vitro.

Figure 5

GC/MS chromatogram (arbitrary units) of C. citrinus leaf extract showing compounds that could cross the blood–brain barrier in vitro.

Figure 6

Effect of Callistemon citrinus extract and phytosomes on the generation of oxidative stress markers. Advanced oxidation protein products (AOPPs) (A), malondialdehyde (MDA) (B), 4-hydroxynonenal (4-HNE) (C), and reduced glutathione (GSH) (D). Control (C), control + vehicle (C + V), control + C. citrinus leaf extract (C + C.c, 200 mg/kg), high-fat diet (HFD), HFD + orlistat (HFD + Orl, 5 mg/kg), HFD + C. citrinus leaf extract (HFD + C.c, 250 mg/kg), HFD + phytosomes (HFD + P, 50, 100, and 200 mg/kg, respectively). Values are expressed as mean ± standard deviation (ANOVA followed by Tukey’s test, p < 0.001, n = 6). Different letters (a, b, c) indicate statistically significant differences between groups.

Figure 7

Effect of C. citrinus leaf extract and phytosomes on the activity of catalase (CAT) (A), glutathione peroxidase (GPx) (B), superoxide dismutase (SOD) (C), and paraoxonase (PON) (D) in brain tissue. Control (C), control + vehicle (C + V), control + C. citrinus leaf extract (C + C.c, 200 mg/kg), high-fat diet (HFD), HFD + orlistat (HFD + Orl, 5 mg/kg), HFD + C. citrinus leaf extract (HFD + C.c, 250 mg/kg), HFD + phytosomes (HFD + P, 50, 100, and 200 mg/kg, respectively). Values are expressed as mean ± standard deviation (ANOVA followed by Tukey’s test, p < 0.001, n = 6). Different letters (a, b, c) indicate statistically significant differences between groups.