Effects of Extended Treatment with Protium heptaphyllum Liposomes on Metabolic Parameters of Obese Rats

Abstract

Protium heptaphyllum (P. heptaphyllum), popularly known as "almacega" or "white pitch", is widely used in folk medicine due to its antioxidant, anti-inflammatory and healing properties, attributed to its richness in flavonoids and terpenes. Therefore, this study aimed to evaluate the effects of treatment for 28 days with liposomes containing P. heptaphyllum leaf extract in obese animals. Male Wistar rats, subjected to a hypercaloric diet for 8 weeks to induce obesity (hypercaloric chow and water enriched with 30% sucrose, ad libitum), were treated with the plant formulation (1 mg kg^-1day^-1, via gavage) for 28 days. The study investigated morphological, metabolic, redox state, immunological and histological parameters in adipose and liver tissue. Rats were divided into four groups: control (C), liposomes with extract (H), obese (O) and obese treated with liposomes containing extract (OH). The results indicated that the obese group (O) presented weight gain, hepatic steatosis and alterations in metabolic and inflammatory parameters. However, treatment with liposomes (OH) reduced glucose, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), creatinine and the lipid profile. In adipose tissue, the OH group showed decreased superoxide dismutase (SOD) activity and increased glutathione S-transferase (GST) activity, in contrast to the effects observed in liver GST. In the analysis of thiobarbituric-acid-reactive substances (TBARS), it was possible to observe an increase in all groups in adipose tissue and in group O in liver tissue, in addition to a reduction in TBARS in group OH in the liver, indicating modulation of oxidative stress. The treatment also increased the concentration of IL-10 and IL-17 in the liver and decreased that of IL-6 in adipose tissue. After 28 days of treatment, these results point to the therapeutic potential of treatment with P. heptaphyllum, not necessarily only against obesity, but also an effect per se of the liposomes, possibly due to the high concentration of flavonoids present in the plant extract.

Keywords: hypercaloric diet; oxidative stress; phytotherapeutic treatment; quercetrin.

Figure 1

Weight gain of rats in the negative control (C), liposomes (H), obese (O) and obese + liposomes (OH) groups between the 1st and 8th week of the experimental design. Data are expressed as mean ± standard deviation. Analysis was performed by ANOVA (Two-way) and Tukey’s test. * p < 0.05 compared with C; (n = 8).

Figure 2

Glycemic curve (A) and glucose decay constant (KITT) (B), generated by the intraperitoneal insulin tolerance test (IPITT), in the control (C), liposomes (H), obese (O) and obese + liposomes (OH) groups. Glycemic curve (C) and area under the curve (D), generated by the oral glucose tolerance test (OGTT) of the control (C), liposomes (H), obese (O) and obese + liposomes (OH) groups. Data are expressed as mean ± standard deviation. Analysis was performed by ANOVA (two-way) and Tukey’s test. * p < 0.05 compared with C; (n = 8).

Figure 3

Influence of liposomes containing P. heptaphyllum extract on adipose tissue of rats subjected to a hypercaloric diet. SOD: superoxide dismutase (A), CAT: catalase (B) and GST: glutathione S-transferase (C). Data are expressed as mean ± standard deviation. Analysis was performed by ANOVA (two-way) and Tukey’s test. ** p < 0.01 compared with C; #### p < 0.0001 compared with O; (n = 8).

Figure 4

Influence of liposomes containing P. heptaphyllum extract on liver tissue of rats fed a hypercaloric diet. SOD: superoxide dismutase (A), CAT: catalase (B), GST: glutathione S-transferase (C) and GPx: glutathione peroxidase (D). Data are expressed as mean ± standard deviation. Analysis was performed by ANOVA (two-way) and Tukey’s test. For SOD analysis, the Kruskal–Wallis test was used, and Dunn’s test, with data expressed as median and total range. * p < 0.05 compared with C; # p < 0.05 compared with O; (n = 8).

Figure 5

Photomicrograph of a sample of one specimen from each group of liver tissue, stained with hematoxylin and eosin (H&E), showing several morphological alterations in groups C (control), H (Liposomes), O (obese) and OH (Obese + Liposomes). Steatosis: lipid vacuoles in the adipose cytoplasm (arrows) in groups O and OH. Resolution: Bar 30 μm.