Effects of polyphenol-rich traditional herbal teas on obesity and oxidative stress in rats fed a high-fat-sugar diet

Abstract

Hibiscus rosa-sinensis and Zingiber officinalis teas are traditionally used for the therapies of various diseases, including obesity. The present research work was planned to appraise the potential of polyphenol-rich extracts of selected herbal plants in obesity and related biochemical parameters of high-fat-sugar diet-induced obese rats. Three herbal teas were prepared from Hibiscus rosa-sinensis flowers and Zingiber officinalis rhizomes and their mixture (3:1, respectively). Total phenolic contents (TPC) of Hibiscus rosa-sinensis and Zingiber officinalis extracts were found to be 5.82 and 1.45 mg/g of dry plant material, measured as GAE, while total flavonoid contents (TFC) were 9.17 and 1.95 mg/g of dry plant material, measured as CE, respectively. Two doses (250 and 500 mg/kg BW) of each tea were administered and body weight, BMI, kidney, liver, and atherogenic indices, TC, TG, HDL, LDL, VLDL, BT, AST, ALT, AP, SC, MDA, SOD, GSH, and TAC of rats groups were measured. Data showed that higher doses of Hibiscus rosa-sinensis significantly reduced the rat's BMI (0.50 g/cm²) in comparison with the high-fat-sugar diet group (0.79 g/cm²). All treatment groups, especially H-500 group, showed a significant decrease in the elevated kidney and liver weights and atherogenic index in comparison with HFSDC groups. Higher doses of Hibiscus rosa-sinensis significantly decreased the levels of AST, ALT, AP, and SC in comparison with the HFSDC group. A significant decrease in the levels of serum TC, TG, LDL, and VLDL was observed in all the treatment groups in comparison with the HFSDC group. Furthermore, all the teas, especially higher doses of Hibiscus rosa-sinensis, prevented the alterations in MDA, SOD, and GSH levels of experimental groups, thus showing the potential against oxidative stress. It can be concluded from these results that Hibiscus rosa-sinensis teas exhibited strong protective effects against obesity and oxidative stress, especially at higher doses.

Keywords: BMI; GSH; LDL and HDL; MDA; SOD; high‐fat diet; kidney index; liver index; nutraceutical; phenolic acids and flavonoids.

FIGURE 1

Typical HPLC chromatogram showing the separation of phenolic acids and flavonoids from hibiscus extracts

FIGURE 2

Effect of treatment on the lipid profile of different rat groups. HDL, high‐density lipoprotein; LDL, low‐density lipoprotein; TC, total cholesterol; TG, triglycerides; VLDL, very low‐density lipoprotein. *Significant (p ≤ .05) difference compared with NC. #Significant (p ≤ .05) difference compared with HFSDC among all the groups

FIGURE 3

Histopathological microscopic image showing the morphological changes of (a) liver and (b) kidney of different rat groups. G‐250 and G‐500, ginger 250 and 500 mg/kg BW; H‐250 and H‐500, hibiscus 250 and 500 mg/kg BW; HFSDC, high‐fat diet control; NC, normal control; PC, positive control