Evaluation of Combination Study of Pterocarpus Marsupium and Tecoma Stans for Antidiabetic Action

Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia due to defects in insulin secretion or action. Despite numerous synthetic anti-diabetic drugs, many have limitations including side effects and limited efficacy, prompting the exploration of safer, plant-based alternatives. Pterocarpus marsupium, commonly known as Indian Kino tree, has been traditionally used in Ayurvedic medicine for managing diabetes. Its heartwood contains active compounds such as pterostilbene and marsupsin that have β-cell regenerative and insulinogenic properties. Tecoma stans, a yellow trumpetbush, has shown hypoglycemic effects in preliminary studies due to its flavonoid and alkaloid content. This study aims to scientifically evaluate the individual and combined effects of P. marsupium and T. stans in STZ-induced diabetic rats.

Role of Insulin in glucose homeostasis

In addition to the direct effects of hyperglycemia on the uptake of glucose into both the liver and peripheral tissues, the hormone Insulin plays a central role in regulating the blood glucose concentration. The islet cell is freely permeable to glucose via GLUT-2 transporter and the glucose is phosphorylated by the high-KM glucokinase. Therefore, the blood glucose concentration determines the flux through glycolysis, the citric acid cycle and the generation of ATP. The concentration of insulin in the blood parallels that of the blood glucose. Insulin has an immediate effect of increasing glucose uptake in tissues such as adipose tissue and muscle. This action is due to an enhancement of glucose transport through the cell membrane by requirement of glucose transporter from the interior of the cell to the plasma membrane. Insulin does indirectly enhance long-term uptake of glucose by the liver as a result of its actions on the synthesis of enzymes controlling glycolysis, glycogenesis and gluconeogenesis. Insulin has an immediate effect in activating glycogen synthase.

MATERIALS AND METHODS

1. 1. Plant Material

Pterocarpus marsupium heartwood and Tecoma stans leaf was collected, shade-dried, powdered, and extracted using ethanol/water (70:30) by Soxhlet extraction. The dose used was 250 mg/kg body weight based on previous studies.

1. 2. Animals

Adult Wistar rats weighing 150–180 g was used after one week of acclimatization.

1. 3. Diabetes Induction

Diabetes was induced by a single intraperitoneal injection of STZ (50 mg/kg) after overnight fasting. Rats with fasting blood glucose (FBG) > 250 mg/dL after 72 hours were included.

1. 4. Grouping and Treatment

Table 1.1 Grouping and Treatment (Pterocarpus marsupium) We arranged same numbers of rats in each group like normal control, diabetic control, Pterocarpus marsupium treated, Tecoma stans treated, combination dose of pterocarpus marsupium and tecoma stans treated and last group is treated by standard drug metformin

Treatment duration: 21 days; oral dosing once daily.

Table 1.2 Grouping and Treatment (Tecoma stans)

Table 1.3 Grouping and Treatment (Combination)

1. Parameters Evaluated

1. Primary Outcomes

Fasting Blood Glucose (Days 0, 7, 14, 21), Oral Glucose Tolerance Test (OGTT), HbA1c at Day 21

2. Secondary Outcomes

Lipid profile, Body weight, Pancreatic histopathology

2. Experimental Data

1. Fasting Blood Glucose (mg/dL) Fasting blood glucose (FBG) levels in normal, healthy rats typically range from 3.95 to 5.6 mmol/L (71 to 101 mg/dL). These levels can vary based on factors like fasting duration, sampling method, and the specific rat strain. 

Table 1.4 Fasting Blood Glucose (mg/dL) (Pterocarpus marsupium)

Table 1.5 Fasting Blood Glucose (mg/dL) (Tecoma stans)

Table 1.6 Fasting Blood Glucose (mg/dL) (Combination)

2. OGTT (mg/dL) - An Oral Glucose Tolerance Test (OGTT) in rats is a common method used to assess how well an animal's body processes glucose after consuming a measured amount of sugar. It's a valuable tool for studying diabetes, insulin resistance, and the effects of potential treatments for these conditions. 

Table 1.7 OGTT (mg/dL) (Pterocarpus marsupium)

Table 1.8 OGTT (mg/dL) (Tecoma stans)

Table 1.9 OGTT (mg/dL) (Combination)

3. HbA1c (%) at Day 21 - HbA1c (glycated hemoglobin) is a measure used to assess long-term blood glucose control, similar to its use in humans. It reflects the average blood glucose levels over the preceding weeks or months. HbA1c levels in rats can be elevated in diabetic models and reduced with interventions like insulin or other treatments. 

Table 1.10 HbA1c (%) at Day 21(Pterocarpus marsupium)

Table 1.11 HbA1c (%) at Day 21(Tecoma stans)

Table 1.12 HbA1c (%) at Day 21(Combination)

4. Lipid Profile (mg/dL)

Lipid Profile - assesses the levels of different fats (lipids) in their blood, including cholesterol and triglycerides. high density lipoprotein, low density lipoprotein and very low-density lipoprotein.

Table 1.13 (Pterocarpus marsupium) (mg/dL)

Table 1.14 Lipid Profile (mg/dL) (Tecoma stans)

1. 5. Body Weight (g) - Streptozotocin (STZ) induced diabetes in rats typically leads to weight loss due to the disease's impact on metabolism and fat/muscle tissue

Table 7.16 Body Weight(g) (Pterocarpus marsupium)

Table 1.17 Body Weight(g) (Tecoma stans)

Table 1.18 Body Weight(g) (Combination)

1. 6. Histopathology of Pancreas
1. (Pterocarpus marsupium)

Normal Control: Well-defined islets of Langerhans.

Diabetic Control: Degeneration and necrosis of pancreatic β-cells.

PM Treated: Moderate regeneration of β-cells and improved islet structure. Metformin Treated: Substantial recovery of islet morphology.

2. Tecoma stans

Normal Control: Healthy islets of Langerhans. Diabetic Control: Severe necrosis of β-cells.

TS Treated: Partial regeneration of β-cells and reduced necrosis. Metformin Treated: Almost normal islet architecture restored.

3. Combination

Normal Control: Intact islets of Langerhans.

Diabetic Control: Degeneration of β-cells and disorganized islets. Combination Treated: Improved β-cell population, near-normal islet structure. Metformin Treated: Reorganized islets, nearly complete recovery.

Figure 1: Pancreas of normal control rats showing normal acinar cells and Islet of Langerhans       (H&E10X)

Figure 2: Pancreas of normal rats treated with diabetic control acinar cells and Islet of Langerhans (H&E -10X)

Figure 3: Pancreas of STZ diabetic rats treated with pterocarpus marsupium acinar cells and Islet of Langerhans (H&E -10X)

Figure 4: Pancreas of STZ diabetic rats treated with Tecoma stans showing few diabetic changes and improved architecture of islet of Langerhans (H&E-10X).

Figure 5: Pancreas of STZ diabetic rats treated with combination of Tecoma stans and pterocarpus marsupium showing few diabetic changes and improved architecture of islet of Langerhans (H&E-10X).

Figure 6: Pancreas of STZ diabetic rats treated with metformin acinar cells and Islet of Langerhans (H&E -10X)