Antidiabetic and antioxidant properties of Boswellia sacra oleo-gum in streptozotocin-induced diabetic rats

Abstract

Background: Diabetes is a metabolic disorder requiring the administration of insulin or other oral hypoglycemic medicines. Although metformin is a popular prescription for type 2 diabetes, long-term use of chemotherapy-based diabetes medications can be hazardous. As a result, novel plant medicines with a high concentration of bioactive molecules, no harmful side effects, and potent pharmacological effects must be found. Edible Boswellia sacra (B. sacra) Flueck oleo-gum resin is widely utilized to treat many clinical diseases in traditional Arab, Chinese, African, and Ayurvedic medicine.

Objective: The goal of this study was to examine the possible therapeutic benefits of several B. sacra oleo-gum resin extracts on rat streptozotocin (STZ)-induced hyperglycemia (Type II).

Materials and methods: For 29 days, hyperglycemic rats are given either metformin (the reference drug; 250 mg/kg body weight per day) or several B. sacra extracts (ethanol, methanol, hydrodistilled, ethyl acetate, and acetone extracts) at doses of 200 or 400 mg/kg/day. Blood glucose levels and body weights were measured before the initiation and at 7, 11, 16, 22, and 29 days after oral treatment. Furthermore, an oral glucose tolerance test (OGTT) was carried out. At the end of the study, the rats were euthanized, and blood samples were obtained to evaluate cytokines (interleukin (IL-)2 and IL-8), reduced glutathione (GSH), superoxide dismutase (SOD), and serum insulin levels. The pancreas and liver tissues were rapidly excised, washed, fixed, and kept in a 10% formalin buffer for histological examination.

Results: B. sacra's ethanolic extract had the greatest concentration of total pentacyclic triterpenic acid (PTA) (391.52 mg/g) in comparison to the other extracts. The lower dose of B. sacra ethanol extract, 200 mg/kg/day, reduces blood glucose levels more efficiently than the higher dose of 400 mg/kg/day. In a 180-min OGTT, diabetic rats given ethanol extract (200 mg/kg) performed no better than control rats and even outperformed those given the reference medication metformin. Additionally, ethanol extract (200 mg/kg)- or metformin-treated diabetic rats gained weight. This was associated with a significant (p < 0.05) decrease in serum levels of IL-2 and IL-8, a reduction in oxidative stress as evidenced by a significant (p < 0.05) increase in SOD and GSH compared to the untreated diabetic group, and a significant (p < 0.05) increase in serum insulin levels compared to normal plasma rat levels. These discoveries, which were eventually confirmed by histochemical assays, indicated that the ethanol extract of B. sacra greatly enhanced the cellular architecture of pancreatic and liver cells.

Conclusion: The present investigation indicates that the ethanol extract of B. sacra oleo-gum resin, which contains a high proportion of acetyl-β-boswellic acid (β-ABA) and acetyl-11-keto-β-boswellic acid (AKBA), possesses antihyperglycemic, anti-inflammatory, and anti-oxidant properties for the first time to our knowledge. Additionally, it restores hepatic cells in STZ-induced diabetic rats and protects the pancreas against oxidative damage. Thus, the current study's results give a scientific rationale for the use of B. sacra in the medical management of diabetes and associated complications. More investigation into the metabolic profiles of these extracts must be conducted to establish the precise mechanism of action of the ethanol extract.

Keywords: Antioxidants; Boswellia sacra gum resin; Diabetes; Hypoglycemic agents.

Fig. 1

HPLC-DAD-MS/MS chromatograms of Pentacyclic Triterpenic Acids (PTAs) extracted from B. sacra.

Fig. 2A

(P–P8): (Color) Representative photographs of H&E-stained thin sections of rat pancreas, X400: (P1): Normal control rat pancreas with normal histological findings in pancreatic acinar cells; (P2) STZ-induced diabetic rat pancreas with islet endocrine cell damage and necrosis; Langerhans with islet shrinkage, degenerated acini cells, and islet of Langerhans. (P3–P7) Pancreas sections from rats given extracts at 200 or 400 mg/kg dosages after streptozotocin-induced diabetes: showing regeneration with restoration of Langerhans islets and pancreatic cells. (P8) pancreas of metformin-treated rat pancreas with a mild interstitial inflammatory cell infiltrate associated with acinar hyperplasia.

Fig. 2B

(L1-L8): (Color) Representative photographs of H&E-stained thin sections of rat liver, X400: (L1) Normal control of rat liver section demonstrating normal histological findings in the parenchymal cells of the liver; (L2) streptozotocin-induced diabetic rat liver section: demonstrating variable degree of bridging necrosis of hepatocytes, most prominent in centrilobular and mononuclear cellular infiltrate in the lobule. (L3-L7) After streptozotocin-induced diabetes, liver sections from rats treated with 200 or 400 mg/kg extracts exhibited centrilobular regeneration with restoration of the central vein, vacuole, sinusoidal spaces, and hepatocytes with mild necrosis. (L8) Metformin-treated rat liver with mild infiltration of inflammatory cells associated with steatosis.