TCM HERBS AND DIABETES Lecture by Associate Professor Benny K H Tan

1. TCM HERBS AND DIABETES Lecture by Associate Professor Benny K H Tan Traditional Medicines and Natural Products Research Laboratory Department of Pharmacology Yong Loo Lin School of Medicine National University of Singapore

2. INTRODUCTION Definition –diabetes mellitus isa group of chronic metabolic disorders characterised by hyperglycemia with symptoms of polyuria and polydipsia. Two types – Type 1 (T1DM) and Type 2 (T2DM), each with different genetic factors. Type 2 is more common, and constitutes >95% of diabetic conditions. Type 1 – insulin deficiency, due to damaged pancreatic beta cells from damage by autoantibodies. Type 2 – insulin is sufficient but inefficient due to receptor insensitivity. Often associated with obesity.

3. Oxidative stress and its sequelae in diabetic states Hyperglycaemia stimulates the sorbitol dehydrogenase pathway, impairs mitochondrial electron transport, and leads to increased production of reactive oxygen species (ROS). Rosen et al. (2000) found increased ROS formation from the endothelium of aortae in diabetic rats when compared with normal rats. The pro-oxidant state in diabetes results in the oxidation of cellular proteins, lipids and DNA. In particular, oxidation of core lipids in lipoprotein particles is involved in the development of diabetic vascular complications.

4. Figure 1. Schema of Interacting Metabolic Factors in Diabetes Mellitus Endocrine disorders Body mass index Islet auto-antibodies and impaired insulin secretion Hypertension Obesity Insulin resistance Diabetes Impaired glucose tolerance Dyslipidaemia Pro-inflammatory state and oxidative stress DEATH Complications Blindness Heart disease Stroke Limb amputation Kidney failure Courtesy of Dr YC Ong, Faculty of Medicine, Monash University, Melbourne

5. Current treatment of diabetes and its associated conditions • Oral anti-diabetic agents (OADs) such as insulin secretagogues (sulphonylureas and meglitinides), insulin sensitisers like biguanides, thiazolidinediones and insulin “sparers” like the alpha-glucosidase inhibitors and/or with insulin injection as replacement therapy. • Lipid-lowering drugs, like statins and fibrates, are frequently co-administered with antidiabetic drugs to treat the accompanying hyperlipidaemia.

6. Limitations of antidiabetic drugs • Used singly or in combination, • blood sugar control is sub-optimal. • effectiveness of these treatments are known to decrease over time, for example, “secondary failure” occurs with the sulphonylureas. • complicationsdo not seem to be minimised withdrugs.

7. Summary comment on Western antidiabetic drugs: Current antidiabetic therapy does not adequately address the associated problems of the diabetic state, such as oxidative stress and co-attendant inflammatory and hyperlipidaemicconditions.

8. The challenge in diabetic treatment is thus to consider how such problems can be alleviated. • Role of complementary and alternative medicine • Traditional herbal medicinesmay provide a viable alternative or complementary treatment for diabetes because • their potential efficacy has been attested by long-term use, and • they cause less side-effects than Western drugs, when used appropriately. • 3. Last but not least, side-effects from Western drugs e.g., sulphonylureas and thiazolidinediones, include weight gain. This exacerbates the problems of obesity and insulin resistance.

9. HOW EFFECTIVE AND SAFE ARE TRADITIONAL HERBAL MEDICINES? The evidence in support of the efficacy of traditional medicines has been largely anecdotal. However, more recent evidence from studies in diabetic human subjects and animals with diabetes indicate that herbal medicines are not only efficacious but also safe (Mull et al., 2001; Al-Rowais, 2002).

10. Using herbal TCM for diabetes Fundamental to the principles of TCM is the goal of achieving balance among energy forces - yin, yang and qi – to achieve a healthy body state. In disease states and metabolic disorders, including diabetes, hypertension and hyperlipidaemia, an imbalance occurs among these forces. This corresponds to a state of oxidative stress, as understood in Western medicine.

11. A subtle difference in TCM over Western treatment is its holistic approach to the treatment of diabetes. While Western medicine targets the abnormality in blood sugar levels, TCM herbs treat the diabetic patient in an integrated manner, correcting the imbalance between yin, yang and qi forces in the patient to restore the state of health.

12. Table 1A.TCM herbs most frequently used in anti-diabetic compound recipes • Radix Astragali seu hedysari • Radix Rehmanniae and Radix Rehmanniae praeparata • Radix Trichosanthis • Radix Puerariae • Radix Ginseng • Radix Panacis quinquefolii • Rhizoma Polygonati • Rhizoma Polygonati odorati • Fructus coini • Fructus Lycii and Cortex Lycii radicis • Rhizoma Atractylodis • Rhizoma Anemarrhenae • Radix Ophiopogonis • Fructus Ligustri lucidi • Fructus Mori, Folium Mori and Cortex Mori radicis • Fructus Schisandrae • Gynostemmae herba • Radix Salviae miltiorrhizae • (from Li et al., 2004)

13. Table 1B. Natural products commonly used in traditional Chinese diets for the control and/or treatment of diabetes and its complications • Fructus Balsam pear • Rhizoma Dioscoreae • Stigma maydis • Semen Fagopyri cymosi • Semen Litchi • Pericarpium granati • Semen Coicis • Allii sativa bulbus • Allii cepa bulbus • Radix Asparrgi officinalis • Cordyceps sinensis • Ganoderma lucidum seu jap • (from Li et al., 2004)

14. Table 2. TCM-derived chemical compounds with anti-diabetic activity

15. Combining Western and herbal TCM – a new paradigm in antidiabetic treatment? The effectiveness of this treatment paradigm will lie in the ability to target the cluster of metabolic abnormalities that co-exist in the diabetic patient, such as obesity, hypertension, dyslipidaemia and insulin resistance. The challenge is to conduct comprehensive scientific research of traditional Chinese pharmacopoeias with the specific aim of identifying new antidiabetic therapeutics that have anti-hypertensive, obesity-altering, and/or lipid-lowering capabilities.

16. Objective of this study This study was done with the extract of a TCM herb, Herb X (which is used by TCM practitioners to treat diabetics), to demonstrate whether it: 1. has effects on glucose and lipid parameters as well as the antioxidant defence system in rats with experimental diabetes 2. enhances or potentiates the effects of metformin when given together.

17. MATERIALS AND METHODS Extraction of Herb X Induction of diabetes in male Wistar rats Experimental protocols 1 and 2 i. Dose-response study [oral glucose tolerance test (OGTT)] ii. Therapeutic study Determination of plasma glucose, insulin, leptin, total cholesterol (TC), triglyceride (TG) concentrations Preparation of liver samples Determination of catalase, SOD, GPx and GST activities in liver Determination of hepatic glucose-6-phosphatase (G-6-Pase) activity and glycogen content Statistical analysis

18. Statistical analysis The results are expressed as mean ± SEM (standard error of the mean). Statistical analysis was performed by two-way analysis of variance (ANOVA). Differences with p values < 0.05 were considered to be statistically significant.

19. RESULTS

20. Figure 2.Dose-response effects of ethanolic extract of Herb X on glucose tolerance in STZ-diabetic rats Administration of glucose (2g/kg bw) * p<0.05, compared to Control

21. Figure 3.Effects of Herb X, Metformin and Herb X+ metformin on mean fasting blood glucose levels in STZ- induced diabetic rats over 4 weeks (Each group, n=6 rats; values expressed as mean ± SEM)

22. Table 3. Changes in mean body weight of Herb X-, metformin- and Herb X + metformin- treated STZ-diabetic rats at week 4

23. Table 4. Plasma insulin, triglycerides, total cholesterol and leptin levels after 4 weeks of treatment * Values are expressed as mean ± SEM a p< 0.01 vs Diabetic control ; b p < 0.05 vs Diabetic control; c p < 0.05 vs Herb X; dp < 0.01 vs Non-diabetic control; ep < 0.05 vs Non-diabetic control; f p<0.05 vs Metformin;

24. Table 5.Effects of Herb X, metformin and Herb X + metformin on hepatic catalase, SOD, GPx and GST activities * Values expressed as mean ± SEM; nd = not done ap < 0.01 vs Diabetic control; bp < 0.05 vs Diabetic control; cp < 0.05 vs Herb X; d p< 0.01 vs non-diabetic control; e p< 0.05 vs non-diabetic control; f p< 0.01 vs Metformin

25. Table 6. Glucose–6-Phosphatase activity, hepatic glycogen content, and plasma C-Reactive Protein content after 4 weeks of treatment *Values expressed as mean ± SEM ap < 0.01 vs Diabetic control; bp < 0.05 vs Diabetic control; cp < 0.01 vs Herb X; d p<0.01 vs Non-diabetic conrol; f p<0.05 vs Metformin;

26. SUMMARY OF RESULTS • The ethanolic extract of the TCM herb, Herb X, has comparable effects to metformin in improving glucose tolerance, reducing plasma glucose and increasing insulin levels in the animal model of Type 1 diabetes. • Herb X, like metformin, also significantly lowered plasma triglyceride levels. • The rats treated with Herb X had significantly higher catalase, SOD, GPx and GST activities, compared with the metformin-treated and diabetic control groups. • 4. Herb X and metformin significantly reduced G-6-phosphatase activity.

27. Metformin + Herb X produced significantly • a. lower fasting blood sugar levels than either alone. • b. higher plasma insulin concentration and hepatic glycogen • content, compared with either alone. • c. greater anti-inflammatory activity than either alone. • d. higher elevation of catalase and SOD activities, compared • with either alone. • e. lower G-6-phosphatase activity than either alone.

28. Discussion ….. • The lowering effects of Herb X and metformin on triglycerides reflect improved insulin action. • 2. The greater decrease in fasting blood glucose levels in Herb X + metformin-treated rats may be partly due to the significantly reduced activity of hepatic G-6-phosphatase.

29. The increased glycogen content in Herb X + metformin-treated rats compared to Herb X- and metformin-treated rats is consistent with increased glycogen synthesis resulting from the increased hepatic glucose content. • 4. Herb X caused greater elevations in antioxidant enzyme actvities than metformin. These effects were significantly enhanced when herb X and metformin were given together, with catalase activity being comparable to that in non-diabetic rats. • Whether Herb X also promotes the synthesis of these enzymes needs to be confirmed by Western blot studies.

30. CONCLUSION This study provides promising evidence that the extract of the TCM herb, X, not only improves glucose profile but also reduces plasma triglycerides and has potent antioxidant potential. It appears to be useful in complementing or potentiating the effects of metformin in the treatment of experimental diabetes.

31. FUTURE STUDIES More studies are warranted to demonstrate such effects in the Type 2 animal model of diabetes, to identify the active chemical(s) responsible for such effects, and further elucidate their mechanism(s) of action.

32. Acknowledgments We thank the National University of Singapore for the Cross Faculty Grant (WBS R-184-000-117-712) for this study, and also the financial assistance to Viduranga Yashasvi Waisundara.

33. THANK YOU FOR YOUR ATTENTION!

34. Figure 4.Mean weekly food intake in Herb X- and metformin-treated STZ-diabetic rats Values are expressed as mean ± SEM;* F1140=37.82, p<0.05 vs Control (2-way ANOVA); ** F1140=295.13, p<0.01 vs Control (2-way ANOVA)

35. Figure 5.Mean weekly water intake in Herb X- and metformin- treated STZ-diabetic rats Values are expressed as mean ± SEM; * F1140=90.50, p<0.05 vs Control (2-way ANOVA);** F1140=1560.12, p<0.01 vs Control (2-way ANOVA)