Anti-Diabetic Effects of Cordyceps Militaris Extract on Weight, Blood Glucose, and Insulin Resistance in Diabetic Model Mice
Article information
Abstract
Objectives
This study investigates the anti-diabetic effects of Cordyceps militaris extract on diabetic model mice (db/db mouse).
Methods
Diabetic mice (db/db) were compared to normal control group (NC). The positive control group received Metformin (Met), while other groups received Cordyceps militaris extract, including ARA301_L. Body weight, fasting blood glucose levels (FBGL), oral glucose tolerance tests (OGTT), insulin tolerance tests (ITT), blood lipid profiles, and tissue analysis were conducted.
Results
Diabetic mice showed significantly higher body weight compared to normal mice. The positive control group maintained stable weight over 56 days, while the Cordyceps militaris extract groups showed slight weight decreases, with a marked reduction in the ARA301_L group. FBGLs were significantly lower in treated groups than in control groups. OGTT indicated better glucose regulation in treated groups, though differences among them were not significant. ITT showed lower blood glucose levels in treated groups, indicating improved insulin resistance. Blood lipid profiles revealed significant reductions in total cholesterol (TC) and AST in the ARA301_L group. Liver tissue analysis showed decreased expression of lipid metabolism and inflammation-related genes, particularly PPARγ and SREBP-1c. Muscle and adipose tissues displayed increased GLUT4 protein and reduced inflammatory gene expression.
Conclusions
Cordyceps militaris extract has more positive effects than metformin on body weight, insulin resistance, sugar metabolism, fatty liver, and inflammation in diabetic mice. It also has a similar positive effect as metformin on blood lipid concentration and liver damage. This suggests the potential of diabetes management in Cordyceps militaris extract.
Introduction
Diabetes is a prominent chronic disease and a major cause of mortality in modern society, with the risk increasing with age. In 2022, the mortality rate due to diabetes in South Korea was 21.6 per 100,000 population1), and the prevalence of diabetes among individuals aged 19 and older rose steadily from 10.3% in 2011 to 12.5% in 2022, indicating that approximately one in eight adults in South Korea suffers from this common chronic condition. Furthermore, the prevalence of diabetes among South Koreans aged 65 and older reached 28% in the same year, confirming that the incidence of diabetes is higher in older populations2). Additionally, the proportion of individuals aged 65 and older in South Korea has rapidly increased from 11.9% in 2013 to 17.4% in 20223), raising concerns about continued growth in this demographic.
Diabetes is a metabolic disorder characterized by insufficient insulin secretion or impaired insulin function, classified into Type 1 and Type 2 diabetes. Type 1 diabetes mellitus (T1DM) accounts for approximately 5–10% of all diabetes cases and is often referred to as insulin-dependent diabetes. It occurs when β-cells (insulin-secreting cells) in the pancreas are destroyed for various reasons, and currently, there are no alternatives to insulin treatment, or any available options have severe side effects4,5).
Type 2 diabetes mellitus (T2DM) accounts for approximately 90–95% of all diabetes cases and is commonly referred to as insulin-independent diabetes. The pathophysiology of Type 2 diabetes involves increased insulin resistance, which means the body either fails to secrete insulin effectively or develops a tolerance to it. Preventive measures include maintaining a healthy lifestyle and normal body weight4,5).
However, the obesity rate among South Korean adults reached 37.2% in 20226), making it challenging to achieve these preventive measures without fundamentally changing dietary habits and lifestyles. Therefore, pharmacological interventions are necessary. Furthermore, most currently available diabetes medications primarily target Type 2 diabetes4,5).
Among the currently used medications for Type 2 diabetes, metformin, a biguanide oral hypoglycemic agent, is the most recommended7). While it is effective in improving insulin resistance, long-term use can lead to gastrointestinal side effects such as diarrhea, vomiting, and abdominal distension, as well as potential liver or kidney dysfunction8,9). Consequently, there is ongoing research into various candidate substances for the development of natural compounds that have few or no side effects for the treatment of Type 2 diabetes or for improving insulin resistance10,11,12,13,14,15,16,17).
In the process of finding these antidiabetic substances, Cordyceps militaris’s antidiabetic -related research results18,19) discovered the possibility of natural product-derived type 2 diabetes treatments in these substances. However, each study had limitations such as high production difficulty and unit price using the extract as dry powder, melting it again18), or using the extract as it is, but only confirming the antidiabetic effect19), or not confirming insulin resistance18,19).
The purpose of this study is to comprehensively verify the efficacy of the Cordyceps militaris extract against diabetes and its complications, including insulin resistance not covered in previous studies.
Method
1. Sample source and manufacturing process
Cordyceps militaris extract was provided by BIOARA Co., Ltd., derived from cultivated Cordyceps militaris. The sample was obtained from strains that had been grown for 60 days (strain name: ARA301) and was prepared by extracting the mushroom with hot water at 80°C for 24 hours. The extract was then filtered using a 22 μ filter.
2. Animal Experiment (Mouse)
The study design for investigating the efficacy and mechanisms of Cordyceps militaris extract in diabetic model mice (db/db mice) is presented in Table 1.
A Study Design to Study the Efficacy and Mechanism of Cordyceps Militaris Extract in Diabetic Mouse Model (db/db mouse)
1) Experimental animals and rearing period
A total of 32 eight-week-old diabetic model mice (BKS.Cg-Dock7m +/+ Leprdb/J, hereafter referred to as db/db mice) and 8 eight-week-old normal mice (B6.BKS(D)-Leprdb/J, hereafter referred to as db/+ mice or control group (NC)) were purchased from The Jackson Laboratory (Maine, USA) and reared in SPF facilities for a duration of 10 weeks.
2) Diet and rearing conditions
After a 2-week adaptation period on solid feed, the control group (NC) maintained a solid diet, while the db/db mice were fed D10001 (AIN-76A) (Research Diets, Inc., New Brunswick, USA) for 8 weeks. The db/db mice were classified using a randomized complete block design (n=8) and divided into four groups. The positive control group (Met) received metformin at 200 mg/kg administered orally once daily. The low-dose Cordyceps militaris extract group (ARA301_L) and the high-dose Cordyceps militaris extract group (ARA301_H) received daily oral doses of 100 mg/kg and 250 mg/kg of the extract, respectively.
During the experimental period, water and feed were available ad libitum, and body weight, blood glucose levels, feed intake, and water intake were measured weekly. The rearing room was maintained at a temperature of 23°C and a humidity of 50–60%, with a light-dark cycle of 12 hours (09:00–21:00).
3) Oral glucose tolerance test
At the 6-week mark of the experiment, an oral glucose tolerance test (OGTT) was conducted to evaluate improvements in insulin secretion regulation. After a 12-hour fasting period, baseline blood glucose levels were measured. Subsequently, a glucose solution (2 g/kg) was administered orally, and blood glucose levels were measured at 15 minutes, 30 minutes, 60 minutes, and 120 minutes post-administration.
4) Insulin tolerance test
At the 7-week mark of the experiment, an insulin tolerance test (ITT) was conducted to assess improvements in insulin resistance. After a 12-hour fasting period, baseline blood glucose levels were measured. Insulin (1 U/kg) was then administered subcutaneously, and blood glucose levels were measured at 15 minutes, 30 minutes, and 60 minutes post-administration. However, in the control group (NC), due to the risk of hypoglycemia, a glucose solution was administered orally after measuring blood glucose levels at the 60-minute mark.
5) Comply with animal experiment ethics
All procedures involving animal experiments were conducted in accordance with the approval from the Animal Experiment Ethics Committee (GU1-2021-IA0017-00).
3. Euthanasia of experimental animals and sample collection
At the end of the rearing period, the experimental animals were fasted for 12 hours before euthanasia (December 29, 2021). Blood was collected via the vertebral vein and centrifuged at 3,000 rpm for 15 minutes at 4°C to obtain serum, which was stored at −80°C until analysis. The liver, thigh muscle, and epididymal fat were immediately excised after blood collection, rinsed with physiological saline, dried with filter paper, and weighed. All samples were subsequently stored in a deep freezer at −80°C for future use.
4. Morphological observation of lipid droplets in liver tissue
Liver tissue was fixed using 10% neutral buffered formalin, followed by dehydration and embedding to create paraffin blocks. Sections of 4 μm thickness were prepared, and the paraffin was removed using xylene. The sections were then stained with hematoxylin and eosin (H&E) and observed under an optical microscope (Nikon, Tokyo, Japan).
5. Analysis of serum lipid profile and liver function parameters
To assess the serum lipid profile, serum triglycerides (TG) and total cholesterol (TC) were analyzed using enzymatic methods (Asan Pharm. Co., Seoul, Korea). For liver function analysis, the activities of aspartate transaminase (AST) and alanine transaminase (ALT) were measured as key liver function indicators. The activities of these enzymes were determined using the Asan set GOT Assay kit (Manual GOT (AST)) and the Asan set GPT Assay kit (Manual GPT (ALT)) (Asan Pharm Co., Seoul, Korea).
For the assays, 20 μL of serum was mixed with 100 μL of substrate solution for AST and ALT, which had been preincubated at 37°C. The AST mixture was incubated for 60 minutes, while the ALT mixture was incubated for 30 minutes in a 37°C water bath. Following incubation, 100 μL of 2,4-dinitrophenylhydrazine was added to each mixture and allowed to react at room temperature for 20 minutes. After the reaction, 1 mL of 0.4 N NaOH was added to stop the enzymatic reaction, and the absorbance of the resulting hydrazone was measured at 505 nm using a UV-1800 spectrophotometer (Shimadzu Scientific Korea Co., Seoul, Korea)
6. Measurement of mRNA expression of antidiabetic, lipid metabolism, and anti-inflammatory genes
To evaluate lipid metabolism, mRNA was extracted from various tissues and analyzed for expression. The following mRNA was extracted from specific tissues: peroxisome proliferator-activated receptor gamma (PPARγ) from liver and epididymal fat tissue; peroxisome proliferator-activated receptor alpha (PPARα) from liver tissue; sterol regulatory element-binding protein-1 (SREBP-1c) from liver, muscle, and epididymal fat tissue; fatty acid synthase (FAS) from liver tissue; and stearoyl-CoA desaturase 1 (SCD1) from liver tissue.
To assess the antidiabetic effects, mRNA was extracted and analyzed for expression in various tissues. The following mRNA was extracted: glucose transporter 4 (GLUT4) from muscle and epididymal fat tissue; glucose transporter 2 (GLUT2), insulin receptor (IR), and insulin receptor substrate (IRS) from liver tissue.
To evaluate the anti-inflammatory effects, mRNA was extracted and analyzed for expression in different tissues. The following mRNA was extracted: tumor necrosis factor-alpha (TNF-α) from liver and muscle tissue; and interleukin 6 (IL-6) from liver tissue.
Each tissue was homogenized using a Polyton PT-MR 3100 homogenizer (Kinematica AG, Luzern, Switzerland), and total RNA was isolated using an RNA Extraction kit (iNtRON Biotechnology, Gyeonggi-do, Korea). Subsequently, cDNA was synthesized using the iScript cDNA Synthesis Kit (BioRad, California, USA). Real-time reverse transcription polymerase chain reaction (rRT-PCR) was conducted with the extracted total RNA and synthesized cDNA, using SYBR Green Master Mix (TaKaRa Bio, Otsu, Japan) and analyzed with the ABI QuantStudio 3 (Applied Biosystems, Massachusetts, USA). The primer sequences used in the experiments are shown in Table 2, and mRNA expression was normalized to GAPDH.
Primer Sequences used in real-time reverse transcription PCR quantification of mRNA
7. Analysis of protein expression related to lipid metabolism and antidiabetic Effects
Liver and muscle tissues were washed twice with ice-cold 1x PBS and then homogenized using the PRO-PREP Protein Purification Kit (iNtRON Biotechnology, Gyeonggi-do, Korea). Protein concentrations were measured using the BCA Protein Assay Kit (Thermo Fisher Scientific, Massachusetts, USA). Tissue lysates containing 30 μg of protein were loaded onto a 10% SDS-PAGE gel for electrophoresis to separate the proteins, which were subsequently transferred to a PVDF western blotting membrane (Merck Millipore, Massachusetts, USA).
To evaluate lipid metabolism in liver tissue, the protein expressions of SREBP-1c and FAS were measured. For assessing the antidiabetic effects in muscle tissue, the protein expressions of PPARα and GLUT4 were analyzed. β-actin was used as a loading control for protein expression. All primary antibodies for the proteins measured were purchased from Abcam Limited (Cambridge, UK) and incubated overnight at 4°C. Following this, horseradish peroxidase-conjugated secondary antibodies (Promega, Wisconsin, USA) were applied, and the resulting enhanced chemiluminescence was measured using the ImageQuant LAS500 (GE Healthcare, Illinois, USA).
8. Statistical analysis
All statistical analyses were conducted using Prism 9.02 software (GraphPad Software Inc., California, USA), and results are presented as means and standard errors (SE). To evaluate the significance between experimental groups, one-way ANOVA was performed, and a p-value of less than 0.05 was considered statistically significant.
Results
1. Changes in body weight and fasting blood glucose level (FBGL) after administration of a Cordyceps militaris extract
The body weight measurements indicated that the diabetes model mice (db/db mouse) had significantly higher weights compared to the normal control group (NC). In the positive control group (Met), body weight was maintained or increased throughout the experimental period compared to the control group (Con). In contrast, both groups administered with Cordyceps militaris extract (ARA301_L, ARA301_H) showed similar or decreased body weights compared to the Con group, with the low-dose Cordyceps militaris extract group (ARA301_L) exhibiting a greater tendency for weight loss (Figure 1-A).
Changes in Body Weight and Fasting Blood Glucose Level after Administration of a Cordyceps Militaris Extract
(A) Weight change (B) fasting blood glucose level(FBGL) change
Fasting blood glucose level (FBGL) measurements revealed that the Con group displayed higher blood glucose levels compared to the NC, with glucose levels increasing over time. The treatment groups (Met, ARA301_L, ARA301_H) showed a smaller increase in blood glucose levels up to the second week of the experiment; however, as the experiment progressed, their blood glucose levels converged to values similar to those of the control group. Notably, metformin maintained significantly lower blood glucose levels compared to the control group until the end of the experiment (Figure 1-B).
2. Oral glucose tolerance test and insulin tolerance test
In the oral glucose tolerance test (OGTT), the normal control group (NC) returned to blood glucose levels similar to baseline after 2 hours following glucose solution administration. In contrast, the db/db mice exhibited elevated blood glucose levels at 2 hours post-administration compared to baseline, with no statistically significant differences observed among the db/db mice (Figure 2-A).
Oral Glucose Tolerance Test and Insulin Tolerance Test
(A) Results of oral glucose tolerance test (OGTT) after 6 weeks of administration (B) OGTT-area under the curve (AUC) (C) Results of insulin tolerance test (ITT) after 7 weeks of administration (D) ITT-AUC *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001
When comparing the area under the curve (AUC) for the OGTT results, there was a statistically significant difference between the NC and db/db mice (p < 0.0001), while no significant differences were found when comparing the db/db mice to one another (Figure 2-B).
In the insulin tolerance test (ITT), the NC group showed a continuous decrease in blood glucose levels following insulin administration. Conversely, the control group (Con) and the high-dose Cordyceps militaris extract group (ARA301_H) exhibited an increase in blood glucose levels for 15 minutes, while the positive control group (Met) and the low-dose group (ARA301_L) showed an increase for 30 minutes before decreasing. The Con group had the highest blood glucose levels at all time points, except for the initial measurement (0 min). At the final measurement (60 min), ARA301_H exhibited the lowest blood glucose levels after the NC group. When comparing initial (0 min) and final (60 min) blood glucose levels, only the normal group showed a decrease. ARA301_L had similar values for initial and final blood glucose, while the other groups (Con, Met, ARA301_H) showed an increase in final blood glucose compared to initial levels (Figure 2-C).
AUC comparisons for the ITT results indicated a marked difference between NC and Con (p < 0.0001). Both Met and ARA301_L showed smaller AUCs compared to Con (p < 0.05), and ARA301_H demonstrated an even smaller AUC, indicating a significant difference from Con (p < 0.01) (Figure 2-D).
3. Changes in serum lipid profile and liver enzyme levels
All db/db mice exhibited significantly higher serum lipid concentrations (total cholesterol [TC] and triglycerides [TG]) and liver enzyme levels (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]) compared to the normal control group (NC) (p < 0.05 to p < 0.0001). For TC, the low-dose Cordyceps militaris extract group (ARA301_L) showed a significant reduction compared to the control group (Con) (p < 0.05) (Figure 3-A).
Changes in Serum Lipid Profile and Liver Enzyme Levels
(A) Serum total cholesterol (TC) (B) Serum triglyceride (TG) (C) Serum aspartate transaminase (AST) (D) Serum alanine transaminase (ALT) *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001
Regarding TG, no significant differences were observed among all db/db mouse groups (p > 0.05) (Figure 3-B). Although AST levels were lower in the ARA301_L group among the db/db mice, the difference was not statistically significant (p > 0.05) (Figure 3-C). Similarly, no significant differences in ALT levels were found among all db/db mouse groups (p > 0.05) (Figure 3-D).
4. Hematoxylin-Eosin (H&E) Staining of Liver Tissue
Compared to the normal control group (NC), the liver tissue of the control group (Con) exhibited a significant presence of lipid vacuoles. In the metformin and Cordyceps militaris extract treatment groups, both the size and number of lipid vacuoles were reduced compared to the Con group, with areas showing partial resemblance to the NC (Figure 4).
Hematoxylin-Eosin (H&E) Staining of Liver Tissue
Scale bar = 100 μm
5. Comparison of lipid metabolism-related gene expression in liver tissue
In terms of PPARγ gene expression, both the control group (Con) and metformin group (Met) showed significantly higher levels compared to the normal control group (NC) (p < 0.0001). Additionally, expression levels in the low-dose (ARA301_L) and high-dose (ARA301_H) Cordyceps militaris extract groups were significantly reduced compared to the Con group (p < 0.001, p < 0.01) (Figure 5-A).
Comparison of Lipid Metabolism-Related Gene Expression in Liver Tissue
(A) Peroxisome proliferator-activated receptor gamma (PPARγ) (B) Sterol regulatory element-binding protein-1 (SREBP-1c) (C) Fatty acid synthase (FAS) (D) Stearoyl-CoA desaturase 1 (SCD1) *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001
For the SREBP-1c gene, both the Met and Cordyceps militaris extract treatment groups exhibited significant reductions compared to the Con group (p < 0.05), with ARA301_L showing a particularly pronounced decrease (p < 0.01) (Figure 5-B).
For the SREBP-1c gene, both the Met and Cordyceps militaris extract treatment groups exhibited significant reductions compared to the Con group (p < 0.05), with ARA301_L showing a particularly pronounced decrease (p < 0.01) (Figure 5-C). For SCD1, a decrease was observed in ARA301_L compared to the Con group (p < 0.05), while no significant differences were noted in the Met and ARA301_H groups (p > 0.05) (Figure 5-D).
6. Comparison of anti-inflammatory gene expression in liver tissue
Compared to the normal control group (NC), the expression levels of TNF-α and IL-6 genes were significantly higher in the control group (Con) (p < 0.001, p < 0.05). When compared to the Con group, both the metformin group (Met) and the Cordyceps militaris extract treatment groups (CME) exhibited significantly lower expression levels of TNF-α and IL-6 genes. The change in IL-6 expression relative to the Con group was similar across all treatment groups (p < 0.0001).
The improvement in TNF-α gene expression was ranked in terms of effectiveness as follows: ARA301_L (p < 0.0001), ARA301_H (p < 0.001), and Met (p < 0.01) (Figure 6).
Comparison of Anti-Inflammatory Gene Expression in Liver Tissue
(A) Tumor necrosis factor-α(TNF-α) (B) Interleukin-6 (IL-6) *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001
7. Comparison of antidiabetic and lipid metabolism-related gene expression in liver tissue
Compared to the normal control group (NC), the expression of antidiabetic genes (GLUT2, IR, IRS) and the lipid metabolism-related gene (PPARα) was significantly lower in the db/db mice (p < 0.0001). Metformin (Met) showed improvement in the gene expression of GLUT2 and PPARα, while no improvement was observed for IR and IRS expression.
In contrast, the Cordyceps militaris extract treatment groups did not demonstrate improvement in GLUT2, PPARα, or IRS expression, but did show improvement in IR expression, with a more pronounced effect observed in the high-dose group (ARA301_H) (Figure 7).
Comparison of Antidiabetic and Lipid Metabolism-Related Gene Expression in Liver Tissue
(A) Glucose transporter 2 (GLUT2) (B) Insulin receptor (IR) (C) Insulin receptor substrate (IRS) (D) Peroxisome proliferator-activated receptor alpha (PPARα) *p < 0.05, ***p < 0.001, ****p < 0.0001
8. Comparison of lipid metabolism, anti-Inflammatory, and antidiabetic gene expression in muscle tissue
In muscle tissue, the expressions of SREBP-1c (lipid metabolism-related gene) and TNF-α (inflammatory gene) were significantly higher in the control group (Con) compared to the normal control group (NC). Improvement in gene expression was observed in the Met, ARA301_L, and ARA301_H groups. ARA301_H exhibited effects similar to those of Met, while ARA301_L demonstrated a stronger improvement effect, regulating gene expression to levels comparable to those of the normal group (Figure 8-A, B).
Comparison of Lipid Metabolism, Anti-Inflammatory, and Antidiabetic Gene Expression in Muscle Tissue
(A) Sterol regulatory element-binding protein-1 (SREBP-1c) (B) Tumor necrosis factor-α (TNF-α) (C) Glucose transporter 4 (GLUT4) *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001
The expression of GLUT4 was lower in the Con group compared to the NC group. The treatment groups showed improved gene expression compared to the Con group, with ARA301_H, ARA301_L, and Met demonstrating progressively higher levels of improvement (Figure 8-C).
9. Comparison of lipid metabolism and antidiabetic gene expression in adipose tissue
In the epididymal adipose tissue, the expression of the SREBP-1c gene was higher in the control group (Con) compared to the normal control group (NC). The gene expression levels in the Cordyceps militaris extract treatment groups were lower than those in the Con group, with a particularly marked decrease observed in the low-dose group (ARA301_L) (Figure 9-A).
Comparison of Lipid Metabolism and Antidiabetic Gene Expression in Adipose Tissue
(A) Sterol regulatory element-binding protein-1 (SREBP-1c) (B) Peroxisome proliferator-activated receptor gamma (PPARγ) (C) Glucose transporter 4 (GLUT4) *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001
The expression of the PPARγgene was lower in db/db mice compared to the NC, and no statistically significant differences in gene expression were found among the db/db mouse groups (Figure 9-B). Additionally, the expression of the GLUT4 gene did not show statistically significant differences across all experimental groups (Figure 9-C).
10. Comparison of lipid metabolism and antidiabetic protein expression in liver and muscle tissues
In liver tissue, the protein expression of SREBP-1c and FAS was measured. For SREBP-1c, both the metformin (Met) and low-dose Cordyceps militaris extract (ARA301_L) groups showed significantly reduced expression compared to the control group (Con), with ARA301_L exhibiting the largest decrease. In contrast, ARA301_H did not show statistically significant differences compared to the control group (Figure 10-A). Regarding FAS, no statistically significant differences were observed among the db/db mice (Figure 10-B).
Comparison of Lipid Metabolism and Antidiabetic Protein Expression in Liver and Muscle Tissues
(A) Comparison of sterol regulatory element-binding protein-1 (SREBP-1c) in liver tissue (B) Comparison of fatty acid synthetase (FAS) in liver tissue (C) Comparison of glucose transporter 4 (GLUT4) in muscle tissue (D) Comparison of peroxisome proliferator-activated receptor alpha (PPARα in muscle tissue *p < 0.05, ***p < 0.001
In muscle tissue, the protein expression of GLUT4 and PPARα was assessed. GLUT4 expression decreased in the Met group compared to the Con group. Conversely, both ARA301_L and ARA301_H groups showed increased protein expression relative to the Con group, with ARA301_H demonstrating a greater increase (Figure 10-C). For PPARα, all treatment groups (Met, ARA301_L, ARA301_H) exhibited increased expression, with ARA301_L showing the highest levels, followed by ARA301_H and Met (Figure 10-D).
Discussion
1. Changes in body weight and fasting blood glucose in diabetic animal models (db/db mouse) after administration of the Cordyceps militaris extract
Body weight measurements revealed that both the low-dose (100 mg/kg) and high-dose (250 mg/kg) Cordyceps militaris extract groups exhibited weight loss effects, with the low-dose group (ARA301_L) showing a more pronounced effect. In contrast, the positive control group (Met) experienced weight gain compared to the control group (Con), indicating a negative impact on weight reduction.
Regarding fasting blood glucose levels (FBGL), the groups administered with Cordyceps militaris extract demonstrated significant reductions up to the second week of the experiment. However, after that period, their blood glucose levels converged to values similar to those of the Con group over time. This suggests that both metformin and Cordyceps militaris extract functioned as effective hypoglycemic agents during the short-term administration of less than two weeks. Notably, up to one week after administration, the hypoglycemic effect of Cordyceps militaris extract was stronger than that of metformin. Conversely, metformin maintained its blood glucose improvement effects until the end of the experiment.
These results, along with findings from previous studies18), indicate that the hypoglycemic function of Cordyceps militaris extract is superior to that of metformin during short-term use (one week), and that this effect increases in a dose-dependent manner within the range of 100 mg/kg to 1,000 mg/kg. However, in terms of long-term administration, metformin demonstrated superior hypoglycemic effects.
2. Comparison of insulin resistance improvement and glucose antidiabetic effect
The results from the oral glucose tolerance test (OGTT) indicated that both metformin and Cordyceps militaris extract were ineffective in enhancing insulin production. However, the insulin tolerance test (ITT) demonstrated that the treatment groups significantly improved insulin resistance, suggesting that Cordyceps militaris extract may be a more effective agent for improving insulin resistance compared to metformin. Furthermore, it was confirmed that administering a higher dose of Cordyceps militaris extract resulted in a stronger effect on insulin resistance improvement than the lower dose.
The study also evaluated the effects on the expression of proteins and mRNA involved in insulin resistance and glucose metabolism. The findings revealed that while metformin improved the expression of glucose metabolism-related genes, it did not enhance protein expression or show any improvement in insulin resistance. In contrast, Cordyceps militaris extract did not demonstrate significant effects on the expression of glucose metabolism-related genes; however, it did improve the expression of proteins associated with glucose metabolism and enhanced the expression of insulin resistance-related genes, supporting the earlier ITT results.
These experimental outcomes were not addressed in previous studies18,19). Analysis of the results indicated that metformin has a stronger function as a hypoglycemic agent compared to Cordyceps militaris extract. Nevertheless, Cordyceps militaris extract shows potential for improving insulin resistance and glucose metabolism, suggesting its promise as a long-term therapeutic agent for diabetes management and amelioration.
3. Comparison of blood lipid profile and liver damage improvement effect
The results of this study on serum lipid concentrations (total cholesterol [TC] and triglycerides [TG]) and liver damage markers (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]) indicate that both metformin and Cordyceps militaris extract demonstrate improvements in serum lipid levels and liver damage, despite some variability in their effects.
The intensity of the improvement effect was similar in Met, ARA301_L, and ARA301_H, and comparative analysis with previous paper19), showed that the improvement effect of the extract was greater than that of cordycepin, which is known as an active ingredient in Cordyceps militaris, and the effect is concentration-dependent.
4. Comparison of the hepatoprotective effects on fatty liver
H&E staining results of liver tissue confirmed that Met, ARA301_L, and ARA301_H exhibited significant improvement effects on fatty liver, with similar intensities of effect across these groups.
A comparative analysis of the effects of metformin and Cordyceps militaris extract on the expression of lipid metabolism-related genes and proteins (PPARα, PPARγ, FAS, SCD1, SREBP-1c) in liver, muscle, and adipose tissues revealed that the Cordyceps militaris extract demonstrated comparable or superior lipid metabolism improvement effects compared to metformin. Taken together, these findings indicate that the Cordyceps militaris extract exhibits superior efficacy in improving fatty liver compared to metformin.
5. Anti-inflammatory efficacy comparison
Inflammation-related genes TNF-α and IL-6 showed improvement effects with both metformin and Cordyceps militaris extract. While the intensity of the improvement effects was generally similar, the effect on TNF-α was significantly pronounced in the ARA301_L group. This finding contrasts with previous studies, which reported a dose-dependent enhancement of effects19).
Considering that the doses in that study were 1 g/kg and 1.5 g/kg, the observed differences may suggest that at higher concentrations, the improvement effects become more pronounced in a dose-dependent manner. Overall, these results indicate that the anti-inflammatory effects of Cordyceps militaris extract are stronger than those of metformin, and that at doses exceeding 1 g/kg, the effects intensify in a dose-dependent manner.
Conclusion
Diabetes has become a significant social issue in South Korea, particularly due to the increasing rates of obesity and an aging population. Among the recommended treatments and interventions, metformin is widely used; however, it is associated with various side effects when taken over long periods. As a result, there is a growing demand for natural products that can serve as diabetes treatments or improvements with minimal or no side effects.
In response to this social demand, a review of various natural products was conducted, revealing the potential of Coryceps militaris as a treatment or improvement for type 2 diabetes. However, previous studies have been limited by the high production difficulty and cost of the substances used, or they focused solely on confirming anti-diabetic effects. Additionally, they failed to explore the potential for improving insulin resistance, a mechanism associated with metformin. Therefore, this study aims to compare the effects of Coryceps militaris on insulin resistance and diabetes-related complications with those of metformin, addressing gaps identified in previous research.
Analysis results indicated that Cordyceps militaris extract demonstrated superior effects compared to metformin in improving body weight, insulin resistance, glucose metabolism, fatty liver, and inflammation. Both Cordyceps militaris extract and metformin exhibited similar effects on blood lipid levels and liver damage improvement. However, metformin showed greater efficacy in improving fasting blood glucose levels.
In summary, the results indicate that Cordyceps militaris extract exhibits similar or stronger improvement effects compared to metformin for most anti-diabetic outcomes and related complications. Thus, the overall efficacy of Cordyceps militaris extract in improving diabetes and its complications appears to be more beneficial than that of metformin.
Furthermore, comparative analyses with previous studies18,19) suggest that consuming the extract is more effective than ingesting only cordycepin, the active component of Cordyceps militaris, and generally, higher oral dosages lead to stronger improvement effects. This suggests the potential of Cordyceps militaris extract as a natural therapy or supplement with mechanisms and effects comparable to or superior to those of metformin for type 2 diabetes and its complications. However, since these findings are based on animal studies, further validation through clinical trials is necessary.
Acknowledgment
This study was conducted with the support of the Korean Medicine Industry Innovation Growth Support Project funded by the National Institute for Korean Medicine Development in 2021. We would like to express our gratitude to Pohang Bio Park for their collaboration and to Director Jung Chul of Namsangcheon Korean Medicine Clinic, Director Han Seung-seop of Kumsanmihak Korean Medicine Clinic, Professor Seo Young-bae of Daejeon University College of Korean Medicine, Professor Ahn Deok-gyun of Kyunghee Cyber University of Korean Medicine, and the officials and staff of the Korea Health Industry Development Institute for their assistance.