Carvacrol partially reverses symptoms of diabetes in STZ-induced diabetic rats

Effects of Satureja Khuzestanica supplementation on glycemic indices and lipid profile in type 2 diabetes patients: a randomized controlled clinical-trial

BACKGROUND

Several studies showed the hypoglycemic and hypolipidemic effects of Satureja Khuzestanica (SK) in animal models. This study aimed to determine the effect of SK supplementation on glycemic and lipid outcomes of patients with type 2 diabetes mellitus (T2DM).

METHODS

The study was designed as a double-blind, placebo-controlled, randomized clinical trial using block randomization. Seventy-eight T2DM patients were randomly assigned to intervention (n = 39) or placebo (n = 39) groups. They received SK or placebo in 500 mg capsules daily for 12 weeks. Anthropometric, blood pressure, liver enzymes, glycemic, and lipid outcomes were measured before and after the intervention.

RESULTS

At baseline, there were no significant differences in age, sex, or glycated hemoglobin (HbA1c) levels between the groups. SK supplementation led to a significant decrease in FBS (-12.6 ± 20.7 mg/dl in the intervention group versus 3.5 ± 31.9 mg/dl; p = 0.007), HbA1c (-0.28 ± 0.45 in the intervention group versus 0.11 ± 0.54% in the placebo group; p = < 0.001), insulin (-1.65 ± 6.18 in the intervention group versus 2.09 ± 5.90 mIU/L in the placebo group; p = 0.03), total cholesterol (-14.6 ± 21.1 mg/dl in the intervention group versus 8.2 ± 30.9 mg/dl in the placebo group; p < 0.001), LDL-cholesterol (-4.6 ± 15.2 mg/dl in the intervention group versus 5.8 ± 14.6 mg/dl in placebo group; p < 0.001) levels, and significant increase in HDL-cholesterol (3.9 ± 4.9 mg/dl in the intervention group versus 0.9 ± 5.2 mg/dl in placebo group; p = 0.005).

CONCLUSION

Based on the study results, SK supplementation may improve glycemic indices and lipid profile of patients with T2DM. Our findings may provide novel complementary treatments without adverse effects for diabetes complications. These results need to be further confirmed in clinical trials.

REGISTRATION

This trial has been registered in the Iranian Registry of Clinical Trials (IRCT ID: IRCT20190715044214N1, registration date: 21/02/2021).

Carvacrol improves blood lipid and glucose in rats with type 2 diabetes mellitus by regulating short-chain fatty acids and the GPR41/43 pathway

Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia and dyslipidemia. Carvacrol (CAR) has demonstrated the potential to mitigate dyslipidemia. This study aims to investigate whether CAR can modulate blood glucose and lipid levels in a T2DM rat model by regulating short-chain fatty acids (SCFAs) and the GPR41/43 pathway. The T2DM rat model was induced by a high-fat diet combined with low-dose streptozocin injection and treated with oral CAR and/or mixed antibiotics. Fasting blood glucose, oral glucose tolerance, and insulin tolerance tests were assessed. Serum lipid parameters, hepatic and renal function indicators, tissue morphology, and SCFAs were measured. In vitro, high glucose (HG)-induced IEC-6 cells were treated with CAR, and optimal CAR concentration was determined. HG-induced IEC-6 cells were treated with SCFAs or/and GPR41/43 agonists. CAR significantly reduced blood lipid and glucose levels, improved tissue damage, and increased SCFA levels in feces and GPR41/43 expression in colonic tissues of T2DM rats. CAR also attenuated HG-induced apoptosis of IEC-6 cells and enhanced GPR41/43 expression. Overall, these findings suggest that CAR alleviates blood lipid and glucose abnormalities in T2DM rats by modulating SCFAs and the GPR41/43 pathway.

Role of polyphenols in the management of diabetic complications

BACKGROUND

Diabetes Mellitus is an endocrine disorder that will affect, about 693 million adults by 2045 worldwide, (>50% increase from 2017). The conventional treatment of the disease, include the oral hypoglycemic drugs which are given in combination with other drugs and are known to possess various adverse effects like gastrointestinal disturbance, nausea, water retention etc. PURPOSE: Due to the urgent need of combating this disorder without side effects, the alternative and complementary therapies should be explored due to their natural origins and comparable safety. Herbal sources serve as new leads, due to the presence of phytoconstituents with potential therapeutic properties, efficacy and safety. In this review, we tried to summarise the polyphenolic phytoconstituents effective in the treatment of diabetic complications.

METHODS

A systematic literature search was conducted using 4 databases (Google scholar, Pubmed, Scopus, Embase) for the identification of relevant data. Search was performed using various key words such as "diabetes", "polyphenols", "marine sources","anti-diabetic polyphenols". The in vitro studies involving the cell lines used in diabetes and animal models were also considered for inclusion. Additional research papers were identified by reviewing abstracts, scrutinizing reference lists, and reviewing previously published review articles.

RESULTS

Polyphenols, a group of phytoconstituents are known worldwide for their tremendous antioxidant potential. So, various research groups have explored their mechanism and therapeutic value in diabetic complications, to improve the insulin sensitivity and glucose metabolism, in controlling the glycemic conditions.

CONCLUSION

Polyphenols exhibit effective therapeutic potential in managing diabetic complications through their multifaceted mechanism of action. They exhibit antioxidative, anti-inflammatory, and anti-glycemic properties, which collectively contribute to their beneficial effects in mitigating diabetic complications. Thus, the inclusion of polyphenols into the diet, may be cosidered as an approach of managing diabetes on long term basis. In this review, we have tried to identify polyphenols effective in diabetes and summarize their mechanism of action along with their potential, for the treatment of diabetic complications.

Carvacrol is potential molecule for diabetes treatment

Diabetes is an important chronic disease that can lead to various negative consequences and complications. In recent years, several new alternative treatments have been developed to improve diabetes. Carvacrol found in essential oils of numerous plant species and has crucial potential effects on diabetes. The anti-diabetic effects of carvacrol have also been comprehensively studied in diabetic animal and cell models. In addition, carvacrol could improve diabetes through affecting diabetes-related enzymes, insulin resistance, insulin sensitivity, glucose uptake, anti-oxidant, and anti-inflammatory mechanisms. The use of carvacrol alone or in combination with anti-diabetic therapies could show a significant potential effect in the treatment of diabetes. This review contributes an overview of the effect of carvacrol in diabetes and anti-diabetic mechanisms.

Can Origanum be a hope for cancer treatment? A review on the potential of Origanum species in preventing and treating cancers

In this study, the potential of aromatic Origanum species belonging to Lamiaceae family to prevent and treat cancer was investigated. Since aromatic plants contain phytochemicals such as essential oils, phenolic acids, terpenoids, flavonoids, alkaloids, vitamins, enzymes and minerals with beneficial biological activities, they have become more interesting and important in medicine, pharmacy and industry. Publications/research between 1950 and 2022 were screened to investigate the effects of Origanum species on cancer, and the effects of their extracts and essential oils in cancer prevention and treatment. Essential phytochemicals found in plants provide efficacy in the prevention and treatment of many diseases. Besides, the essential oils found in these plant extracts are another reason that makes them important. Therefore, it is preferred in traditional medicine in the fight against many diseases as well as cancer. Essential oils of Origanum species mainly contain monoterpenes such as p-cymene, carvacrol, thymol and γ-terpinene. Since these compounds exhibit anticancer properties, Origanum species are becoming the plants of choice in the fight against cancer. In this context, Origanum majorana L. Origanum vulgare and Origanum munzurense are promising species, considering the composition of their extracts and essential oil.

Therapeutic application of carvacrol: A comprehensive review

Carvacrol is a major natural constituent and is significantly present as an essential oil in aromatic plants and is well known for its numerous biological activities. Therapeutic properties of carvacrol have been demonstrated as anti-oxidant, anticancer, diabetes prevention, cardioprotective, anti-obesity, hepatoprotective and reproductive role, antiaging, antimicrobial, and immunomodulatory properties. The carvacrol biosynthesis has been mediated through mevalonate pathway. Carvacrol has the anticancer ability against malignant cells via decreasing the expressions of matrix metalloprotease 2 and 9, inducing apoptosis, enhancing the expression of pro-apoptotic proteins, disrupting mitochondrial membrane, suppressing extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase signal transduction, and also decreasing the phosphoinositide 3-kinase/protein kinase B. It also decreased the concentrations of alanine aminotransferase, alkaline phosphatase and aspartate aminotransferase, and gamma-glutamyl transpeptidase as well as also restored liver function, insulin level, and plasma glucose level. Carvacrol also has been found to exert antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Coagulase-negative staphylococcus, Salmonella spp., Enterococcus sp. Shigella, and Escherichia coli. The current review article summarizes the health-promoting perspectives of carvacrol through various pathways.

Synthesis of Carvacrol Derivatives as Potential New Anticancer Agent against Lung Cancer

Lung cancer remains a major public health concern among all cancer diseases due to the toxicity and side-effects of the available commercially synthesized drugs. Natural product-derived synthesized anticancer drugs are now of promising interest to fight against cancer death. Carvacrol is a major component of most essential oil-bearing plants with potential pharmacological activity, especially against various cancer cell lines. Among the other organometallic compounds, copper complexes have been reported to be effective anticancer agents against various cancer cell lines, especially lung and leukemia cancers, due to the nontoxic nature of copper in normal cells since it is an endogenic metal. In this study, we synthesized three carvacrol derivatives, i.e., carvacrol aldehyde, Schiff base, and copper–Schiff base complex, through an established synthesis protocol and characterized the synthesized product using various spectroscopic techniques. The synthesized derivatives were evaluated for in vitro cytotoxic activity against different cancer cell lines, including human lung cancer (A549) and human fibroblast (BALB-3T3). Our findings showed that the copper–Schiff base complex derived from carvacrol inhibited the proliferation and migration of the A549 cell lines in a dose-dependent manner. This activity might be due to the inhibition of cell proliferation and migration at the G₂/M cell-cycle phase, as well as apoptosis, possibly through the activation of the mitochondrial apoptotic pathway. To our knowledge, this is the first report on the activity of the copper–Schiff base complex of carvacrol against A549 cell lines. Our result highlights that a new synthesized copper complex from carvacrol could be a novel potential drug in the treatment of lung cancer.

Actinidia deliciosa Mitigates Oxidative Stress and Changes in Pancreatic α-, β-, and δ-Cells and Immunohistochemical and Histological Architecture in Diabetic Rats

The present study evaluated the antioxidant capacity and antidiabetic effect of Actinidia deliciosa in diabetic rats. Rats were grouped as follows: control, Actinidia deliciosa aqueous extract (ADAE, 1 g/kg, daily and orally), streptozotocin (STZ, 50 mg/kg BW, single intraperitoneal dose), and STZ plus ADAE, respectively. Twenty-eight components were detected by GC-MS analysis with high phenolic contents and high DPPH scavenging activity. In vivo results revealed that rats treated with STZ showed a highly significant elevation in blood glucose and a decrease in insulin hormone levels. Thiobarbituric acid-reactive substances and hydrogen peroxide levels were elevated, while bodyweight, enzymatic, and nonenzymatic antioxidants were significantly decreased. Furthermore, histopathological and immunohistochemical insulin expression, besides ultrastructure microscopic variations (β-cells, α-cells, and δ-cells), were seen in pancreas sections supporting the obtained biochemical changes. Otherwise, rats supplemented with ADAE alone showed an improved antioxidant status and declined lipid peroxidation. Moreover, diabetic rats augmented with ADAE showed significant modulation in oxidative stress markers and different pancreatic tissue investigations compared to diabetic ones. Conclusively, ADAE has a potent antioxidant and hypoglycemic influence that may be utilized as a health-promoting complementary therapy in diabetes mellitus.

Gymnemic acid protects murine pancreatic β-cells by moderating hyperglycemic stress-induced inflammation and apoptosis in type 1 diabetic rats

Type 1 diabetes is a chronic immune-mediated disease caused by pancreatic β-cell dysfunction with consequent severe insulin deficiency. Exacerbated blood glucose levels can cause oxidative stress in the pancreatic β-cells, which leads to inflammation, and apoptosis resulting in islet dysfunction. Although massive studies have been carried out to elucidate the causative factors for β-cell damage in diabetes, the therapeutic approach to pancreatic β-cell damage has not been extensively studied. Hence, the present study has been designed to delineate the role of gymnemic acid (GA) in protecting pancreatic β-cells in diabetic animals, with special reference to inflammation and apoptosis. Our data revealed that the treatment with GA significantly reverted the alteration in both biochemical and histochemical observations in young diabetic rats. Moreover, treatment with the GA downregulates the expression of proinflammatory markers (nuclear factor-κB, tumor necrosis factor-α, interleukin-[IL]-6, and IL-1β), proapoptotic proteins (Bax, cytochrome c, and cleaved caspase-3), as well as upregulates the expression of antiapoptotic protein Bcl-2 in diabetic rats. These findings suggest that the anti-inflammatory and antiapoptotic nature of GA mitigates β-cell damage in hyperglycemic rats.

Hepatoprotective Effect of Actinidia deliciosa against Streptozotocin-Induced Oxidative Stress, Apoptosis, and Inflammations in Rats

The present research intended to assess the possible protective and hypoglycemic effect of Actinidia deliciosa fruit aqueous extract (ADAE) in diabetic rats. The scavenging antioxidant capabilities of ADAE were evaluated using GC-MS analysis. In addition, rats were divided into four groups: control, ADAE, streptozotocin-induced DM (STZ), and STZ-treated rats + ADAE in an in vivo investigation. GC-MS analysis of ADAE was shown to include major components with high total phenolic contents and high DPPH scavenging activity. In diabetic rats, significant elevation in blood glucose level, lipid peroxidation, bilirubin, and lactate dehydrogenase activity as well as a change in lipid profile was observed, while insulin, body and liver weights, enzymatic and nonenzymatic antioxidants, liver function biomarkers, and protein content were significantly decreased. Furthermore, changes in the expression of the peroxisome proliferator-activated receptor (PPAR-γ), apoptotic, and inflammation-related genes were found. In addition, histological differences in rat liver tissue architecture were discovered, corroborating the biochemical modifications. However, consuming ADAE alone reduced lipid peroxidation and improved antioxidant status. Furthermore, diabetic rats given ADAE showed significant reductions in oxidative stress indicators and biochemical parameters, as well as improved tissue structure, when compared to the diabetic rats’ group. Also, ADAE supplementation protects diabetic rats’ hepatic tissue by upregulating PPAR-γ and downregulating apoptotic and inflammatory-related gene expression. In conclusion, A. deliciosa has beneficial protective effects so, it might be used as a complementary therapy in diabetes mellitus.

Therapeutic Effect of P-Cymene on Lipid Profile, Liver Enzyme, and Akt/Mtor Pathway in Streptozotocin-Induced Diabetes Mellitus in Wistar Rats

Diabetes is a serious public health problem in low- and middle-income countries. There is a strong link between hyperglycemia, oxidative stress, inflammation, and the development of diabetes mellitus. PI3K/Akt/mTOR is the main signaling pathway of insulin for controlling lipid and glucose metabolism. P-cymene is an aromatic monoterpene with a widespread range of therapeutic properties including antioxidant and anti-inflammatory activity. In the present study, the antidiabetic effects of p-cymene were investigated. Diabetes was induced using streptozotocin in male Wistar rats. The effects of p-cymene and metformin were studied on levels of glucose (Glu), lipid profile, liver enzymes, oxidative stress, and the expression of Akt, phospho-Akt, and mTOR (mammalian target of rapamycin) proteins, using biochemical, histological, and immunohistochemical analysis. Data have shown that p-cymene can improve serum levels of Glu, total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL), alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA), and the expression of mTOR, Akt, and phospho-Akt protein in diabetic animals. These results suggest that p-cymene has hypoglycemia, hypolipidemia, and antioxidant properties. It can regulate Akt/mTOR pathway and reduce hepatic and pancreas injury. It can be suggested for diabetes management alone or simultaneously with metformin.

Anti-Inflammatory and Antioxidant Properties of Carvacrol and Magnolol, in Periodontal Disease and Diabetes Mellitus

Periodontal disease and diabetes mellitus are two pathologies that are extremely widespread worldwide and share the feature of chronic inflammation. Carvacrol is a phenolic monoterpenoid, produced by a variety of herbs, the most well-known of which is Origanum vulgare. Magnolol is a traditional polyphenolic compound isolated from the stem bark of Magnolia officinalis, mainly used in Chinese medicine. The purpose of this paper is to review the therapeutic properties of these bioactive compounds, in the treatment of periodontitis and diabetes. Based on our search strategy we conducted a literature search in the PubMed and Google Scholar databases to identify studies. A total of one hundred eighty-four papers were included in the current review. The results show that carvacrol and magnolol have anti-inflammatory, antioxidant, antimicrobial, anti-osteoclastic, and anti-diabetic properties that benefit both pathologies. Knowledge of the multiple activities of carvacrol and magnolol can assist with the development of new treatment strategies, and the design of clinical animal and human trials will maximize the potential benefits of these extracts in subjects suffering from periodontitis or diabetes.

Monoterpenes: current knowledge on food source, metabolism, and health effects

Monoterpenes, volatile metabolites produced by plants, are involved in the taste and aroma perception of fruits and vegetables and have been used for centuries in gastronomy, as food preservatives and for therapeutic purposes. Biological activities such as antimicrobial, analgesic and anti-inflammatory are well-established for some of these molecules. More recently, the ability of monoterpenes to regulate energy metabolism, and exert antidiabetic, anti-obesity and gut microbiota modulation activities have been described. Despite their promising health effects, the lack of reliable quantification of monoterpenes in food, hindered the investigation of their role as dietary bioactive compounds in epidemiological studies. Moreover, only few studies have documented the biotransformation of these compounds and identified the monoterpene metabolites with biological activity. This review presents up-to-date knowledge about the occurrence of monoterpenes in food, their bioavailability and potential role in the modulation of intermediate metabolism and inflammation, focusing on novel findings of molecular mechanisms, underlining research gaps and new avenues to be explored.

Investigating the effects of carvacrol in rats using oxygen-induced retinopathy model

Purpose:

Investigating the effects of intraperitoneal carvacrol administration in rats using the oxygen-induced retinopathy (OIR) model.

Methods:

A total of 28 newborn Sprague Dawley rats were used and the OIR model was created using the 50/10% oxygen model. The study composed of four groups in total. While the OIR model was not used in Group I (control group), it was created for Groups II, III, and IV. About 0.01 mL carvacrol, bevacizumab, or 0.9% NaCl was administered intraperitoneal (IP) to the rats in all groups on postnatal day (PND) 14 as follows: Group I and Group II were administered 0.9% NaCl, Group III was administered bevacizumab, and Group IV was administered carvacrol. On PND 18, rats were sacrificed and their right eyes were enucleated.

Results:

Histopathological and immunohistochemical studies showed that the number of vascular endothelial cells (VECs), vascular endothelial growth factor (VEGF), and tumor necrosis factor-α (TNF-α) decreased similarly in Group III and Group IV compared with Group II. VECs values for Group I, Group II, Group III, and Group IV were measured as 0 ± 0, 26.45 ± 4.57, 7.75 ± 1.98, and 5.78 ± 1.72, respectively, and it differed significantly between groups (P < 0.001). Likewise, VEGF levels were observed as 0.06 ± 0.01, 3.31 ± 0.53, 2.47 ± 0.44, and 2.49 ± 0.52, respectively, and it differed significantly between groups (P < 0.001). TNF-α levels were recorded as 0.06 ± 0.01, 3.58 ± 0.38, 2.46 ± 0.49, and 2.29 ± 0.25, respectively, and it differed significantly between groups (P < 0.001). VECs, VEGF, and TNF-α were similar between Group III and IV (range of P values were 0.486–0.998).

Conclusion:

The study demonstrated that carvacrol significantly reduced retinal pathological angiogenesis, NV, VEC nuclei count, VEGF, and TNF-α levels. Moreover, the observed effects were comparable to those of bevacizumab.

Protective effects of carvacrol against diabetes-induced reproductive damage in male rats: Modulation of Nrf2/HO-1 signalling pathway and inhibition of Nf-kB-mediated testicular apoptosis and inflammation

Diabetes mellitus, which causes many complications, also adversely affects reproductive system in men. Studies reported that natural antioxidants are effective in reducing important complication risks caused by diabetes. Carvacrol is an antioxidant phenolic monoterpene compound with therapeutic effect in various diseases found in essential oils of aromatic plants such as pepper, wild bergamot and thyme. We aimed to investigate the effects of carvacrol on diabetes-induced reproductive damage in male rats by evaluating the Nrf2/HO-1 pathway and Nf-kB-mediated apoptosis/inflammation and spermatological parameters. For this purpose, 74 Wistar albino male rats were used. The diabetes model was performed using single-dose intraperitoneal injection of streptozotocin 55 mg/kg. Rats were fed with carvacrol 75 mg/kg/daily/gavage for 4 and 8 weeks. Rats were divided into four groups: control group, diabetic group, carvacrol group which fed with carvacrol and the diabetic group which fed with carvacrol. It was determined that carvacrol significantly decreased malondialdehyde levels, Bax,COX-2,Nf-kB protein expression levels, Bax/Bcl-2 ratio and significantly increased glutathione peroxidase, catalase activities, Bcl-2, Nrf2,HO-1 protein expression levels and it was determined that had a positive effect on spermatological parameters. In conclusion, the negative effects of diabetes in the male reproductive system can be prevented and/or reduced by giving carvacrol.

Metformin protects against diabetes-induced heart injury and dunning prostate cancer model

In this study, both diabetes and Dunning prostate cancer were induced for the first time in Copenhagen rats in vivo. Thus, the effects of metformin against heart tissue damage of these rats were investigated by biochemical methods. Dunning prostate cancer was induced in Copenhagen rats using high metastatic MAT-LyLu cells. The rats were divided as follows: Control group: only injected with 0.9% NaCl for 14 days; Diabetic group: only injected single dose of streptozotocin (STZ) (65 mg/kg); Cancer group: subcutaneously (s.c) inoculated with 2 x 10⁴ MAT-LyLu cells only; Diabetic + cancer (DC) group: inoculated with 2 x 10⁴ MAT-LyLu cells and STZ injection, Cancer + metformin (CM) group: injected with metformin for 14 days after Mat-LyLu cells application; Diabetic + cancer + metformin (DCM) group: metformin administered for 14 days together with STZ and Mat-LyLu cells. At the end of the experimental period, heart tissues were taken. Reduced glutathione and total antioxidant status levels in heart tissues were decreased, whereas lipid peroxidation, advanced oxidized protein products, nitric oxide, homocysteine, and reactive oxygen species levels, total oxidant status and catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and xanthine oxidase activities increased in the diabetic, cancer and DC groups. Treatment with metformin reversed these effects. In conclusion, the present study shows that metformin has a protective effect against heart tissue damage in STZ-induced diabetic rats with Dunning prostate cancer.

Effect of long-term treatment of Carvacrol on glucose metabolism in Streptozotocin-induced diabetic mice

BACKGROUND

Carvacrol is a food additive with various bioactivities, including reducing the blood glucose level as well as improvement of heart function, in diabetic mice. We explored the antihyperglycemic effect of carvacrol and its effect on the key hepatic enzymes accounting for glucose metabolism.

METHODS

A streptozotocin (STZ)-induced diabetes-mellitus model in mice was used. Mice were divided randomly into a control group, diabetic group, low dose carvacrol-treated diabetic group (10 mg/kg body weight [BW]), and high dose carvacrol-treated diabetic group (20 mg/kg BW). Carvacrol was injected intraperitoneally (i.p.) in each carvacrol-treated group daily for 4 weeks and 6 weeks, respectively. The level of random plasma glucose, fasting plasma glucose, and plasma insulin was determined at 4 weeks and 6 weeks after carvacrol administration. The plasma level of total cholesterol (TC), triglycerides (TG), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and the activity of hepatic key enzymes related to glucose metabolism were determined.

RESULTS

Carvacrol treatment decreased the levels of random plasma glucose and fasting plasma glucose, significantly in a dose-dependent manner. A significant improvement in glucose tolerance and a significant decrease in the plasma level of TG were observed in carvacrol-treated diabetic mice at a dose of 20 mg/kg BW compared with that in vehicle-treated diabetic mice. There was no significant difference in the plasma level of TC and insulin between vehicle-treated diabetic mice and carvacrol-treated diabetic mice. Carvacrol treatment at a dose of 20 mg/kg BW significantly reduced the plasma level of LDH but not AST, ALT, or ALP, compared with that in the vehicle-treated diabetic group. The activity of hexokinase (HK), 6-phosphofructokinase (PFK), and citrate synthetase (CS) was increased by carvacrol treatment in diabetic mice.

CONCLUSIONS

Carvacrol exerted an anti-hyperglycemic effect in STZ-induced diabetic mice. This was achieved through regulating glucose metabolism by increasing the activity of the hepatic enzymes HK, PFK, and CS.

Carvacrol protects against diabetes-induced hypercontractility in the aorta through activation of the PI3K/Akt pathway

Vascular complications induced by diabetes constitute the principal cause of morbidity and mortality in diabetic patients. It has been reported that carvacrol (CAR) possesses a wide range of biological activities. The effects of CAR on diabetes-induced vasculopathy remain unknown. In this study, diabetic mice were created by the intraperitoneal injection of streptozotocin (STZ) in male C57BL/6 J mice to investigate whether CAR provided a protective effect against diabetes-induced vasculopathy and to investigate the underlying mechanisms. We found that CAR decreased blood glucose levels in diabetic mice. Moreover, CAR ameliorated diabetes-induced aortic morphological alterations, as evidenced by an increased thickness in the intima-media width and an increased number of vascular smooth muscle cells (VSMCs) layers. Further studies revealed that CAR inhibited hypercontractility in the aortas of diabetic mice and VSMCs in response to hyperglycemia, as evidenced by the relaxation of phenylephrine(PE)-induced vasoconstriction, the decreased expression of smooth muscle (SM)-α-actin, and the increased expression of Ki67 and proliferating cell nuclear antigen (PCNA). Furthermore, the PI3K/Akt signaling pathway was inhibited in the aortas of diabetic mice and VSMCs in response to hyperglycemia, while CAR treatment activated the PI3K/Akt signaling pathway. In conclusion, our results strongly suggest that CAR plays a protective role in diabetes-induced aortic hypercontractility, possibly by activating the PI3K/Akt signaling pathway. CAR is a potential drug for the treatment of diabetic vasculopathy.

Carvacrol Attenuates Diabetic Cardiomyopathy by Modulating the PI3K/AKT/GLUT4 Pathway in Diabetic Mice

Background: Diabetic cardiomyopathy (DCM), a common complication of diabetes mellitus, eventually leads to heart failure. Carvacrol is a food additive with diverse bioactivities. We aimed to study the protective effects and mechanisms of carvacrol in DCM.

Methods: We used a streptozotocin-induced and db/db mouse model of types 1 and 2 diabetes mellitus (T1DM and T2DM), respectively. Both study groups received daily intraperitoneal injections of carvacrol for 6 weeks. Cardiac remodeling was evaluated by histological analysis. We determined gene expression of cardiac remodeling markers (Nppa and Myh7) by quantitative real-time PCR and cardiac function by echocardiography. Changes of PI3K/AKT signaling were determined with Western blotting. GLUT4 translocation was evaluated by Western blotting and immunofluorescence staining.

Results: Compared with control mice, both T1DM and T2DM mice showed cardiac remodeling and left ventricular dysfunction. Carvacrol significantly reduced blood glucose levels and suppressed cardiac remodeling in mice with T1DM and T2DM. At the end of the treatment period, both T1DM and T2DM mice showed lesser cardiac hypertrophy, Nppa and Myh7 mRNA expressions, and cardiac fibrosis, compared to mice administered only the vehicle. Moreover, carvacrol significantly restored PI3K/AKT signaling, which was impaired in mice with T1DM and T2DM. Carvacrol increased levels of phosphorylated PI3K, PDK1, AKT, and AS160 and inhibited PTEN phosphorylation in mice with T1DM and T2DM. Carvacrol treatment promoted GLUT4 membrane translocation in mice with T1DM and T2DM. Metformin was used as the positive drug control in T2DM mice, and carvacrol showed comparable effects to that of metformin on cardiac remodeling and modulation of signaling pathways.

Conclusion: Carvacrol protected against DCM in mice with T1DM and T2DM by restoring PI3K/AKT signaling-mediated GLUT4 membrane translocation and is a potential treatment of DCM.

Sitagliptin attenuates myocardial apoptosis via activating LKB-1/AMPK/Akt pathway and suppressing the activity of GSK-3β and p38α/MAPK in a rat model of diabetic cardiomyopathy

The present study aimed to investigate the protective effect of sitagliptin, a dipeptidyl peptidase-4 inhibitor, on diabetic cardiomyopathy (DCM)-associated apoptosis and if this effect is mediated via modulating the activity of the survival kinases; AMP-activated protein kinase (AMPK) and Akt & the apoptotic kinases; glycogen synthase kinase-3 β (GSK-3β) and p38 mitogen-activated protein kinase (p38MAPK). Diabetes was induced by a single intraperitoneal injection of streptozotocin (55 mg/kg). Diabetic rats were treated with sitagliptin (10 mg/kg/day, p.o.) and metformin (200 mg/kg/day, p.o. as positive control) for six weeks. Chronic hyperglycemia resulted in elevation of serum cardiac biomarkers reflecting cardiac damage which was supported by H&E stain. The mRNA levels of collagen types I and III were augmented reflecting cardiac fibrosis and hypertrophy which was supported by Masson trichome stain and enhanced phosphorylation of p38MAPK. Cardiac protein levels of cleaved casapse-3, BAX were elevated, whereas, the levels of Bcl-2 and p-BAD were reduced indicating cardiac apoptosis which could be attributed to the diabetes-induced reduced phosphorylation of Akt and AMPK with concomitant augmented activation of GSK-3β and p38MAPK. Protein levels of liver kinase B-1, the upstream kinase of AMPK were also supressed. Sitagliptin administration alleviated the decreased phosphorylation of AMPK and Akt, inactivated the GSK-3β and p38 AMPK, therefore, attenuating the apoptosis and hypertrophy induced by hyperglycemia in the diabetic heart. In conclusion, sitagliptin exhibits valuable therapeutic potential in the management of DCM by attenuating apoptosis. The underlying mechanism may involve the modulating activity of AMPK, Akt, GSK-3β and p38MAPK.

Antidiabetic Potential of Monoterpenes: A Case of Small Molecules Punching above Their Weight

Monoterpenes belong to the terpenoids class of natural products and are bio-synthesized through the mevalonic acid pathway. Their small molecular weight coupled with high non-polar nature make them the most abundant components of essential oils which are often considered to have some general antioxidant and antimicrobial effects at fairly high concentrations. These compounds are however reported to have antidiabetic effects in recent years. Thanks to the ingenious biosynthetic machinery of nature, they also display a fair degree of structural complexity/diversity for further consideration in structure-activity studies. In the present communication, the merit of monoterpenes as antidiabetic agents is scrutinized by assessing recent in vitro and in vivo studies reported in the scientific literature. Both the aglycones and glycosides of these compounds of rather small structural size appear to display antidiabetic along with antiobesity and lipid lowering effects. The diversity of these effects vis-à-vis their structures and mechanisms of actions are discussed. Some key pharmacological targets include the insulin signaling pathways and/or the associated PI3K-AKT (protein kinase B), peroxisome proliferator activated receptor-γ (PPARγ), glucose transporter-4 (GLUT4) and adenosine monophosphate-activated protein kinase (AMPK) pathways; proinflammatory cytokines and the NF-κB pathway; glycogenolysis and gluconeogenesis in the liver; glucagon-like-1 receptor (GLP-1R); among others.

Essential Oils of Oregano: Biological Activity beyond Their Antimicrobial Properties

Essential oils of oregano are widely recognized for their antimicrobial activity, as well as their antiviral and antifungal properties. Nevertheless, recent investigations have demonstrated that these compounds are also potent antioxidant, anti-inflammatory, antidiabetic and cancer suppressor agents. These properties of oregano essential oils are of potential interest to the food, cosmetic and pharmaceutical industries. The aim of this manuscript is to review the latest evidence regarding essential oils of oregano and their beneficial effects on health.

Essential oil of Zygophyllum album inhibits key-digestive enzymes related to diabetes and hypertension and attenuates symptoms of diarrhea in alloxan-induced diabetic rats

CONTEXT

Zygophyllum album L. (Zygophyllaceae), commonly known as Bougriba, is widely used to treat diabetes, digestive tract spasm, and hypertension in folk medicine, in Tunisia.

OBJECTIVE

This study investigates the antidiabetic, antidiarrheal, and antihypertensive activities of the leaves of the essential oil from Zygophyllum album (OZA) in alloxan-induced diabetic rats.

MATERIALS AND METHODS

The oil was obtained by hydrodistillation and analyzed by GC-MS. Males rats were divided into four groups: control, diabetic-untreated group, diabetic-treated group with acarbose (10 mg/kg), and diabetic-treated rats with OZA (200 mg/kg) for 30 d.

RESULTS

At the end of the experimental period, the OZA significantly decreased the activity of α-amylase in pancreas and serum of the diabetic rats by 43% and 38%, respectively, which led to reduce the serum glucose level by 60% and lower of glycated hemoglobin (HbA1c) rate by 17% as compared with untreated diabetic animals. Moreover, the OZA treatment attenuated symptoms of diarrhea, improved lipid disorders, and hypertension through inhibiting the pancreatic lipase and angiotensin-converting enzyme (ACE) activities by 47% and 25%, respectively, in serum of diabetic rats.

CONCLUSION

OZA showed a good effect in the management of diabetes mellitus and exerted preventive action from related hypertension.

Potential Use of Turkish Medicinal Plants in the Treatment of Various Diseases

Medicinal plants are sources of health-promoting substances, including phytochemicals and phytoalexins that comprise polyphenols, flavonoids, carotenoids, vitamins A, C, E and several other constituents. Many studies have indicated that medicinal plants have been used to treat human diseases for thousands of years owing to their antimicrobial and antioxidant activities. Medicinal plants reduce the oxidative stress in cells and prevent cancer, cardiovascular and inflammatory diseases, neurodegenerative and digestive system disorders. These potential beneficial effects have been attributed to the presence of bioactive compounds that show antioxidant properties by acting as free radical scavengers or metal chelators, reducing the reactions that produce reactive oxygen and nitrogen species (ROS/RNS). Considering the importance of medicinal plants in terms of their beneficial health effects, some of the medicinally important plants grown in Turkey are covered in this review with respect to their antioxidant potential and phytochemical profile.

Ergosterol Alleviates Kidney Injury in Streptozotocin-Induced Diabetic Mice

Ergosterol (ERG) has been widely used in the development of novel drugs due to its unique physiological function. However, little is known about the protective effects of ERG on diabetes. Hence, the current study was designed to evaluate the positive role of ergosterol on streptozotocin- (STZ-) induced diabetes in mice. Oral glucose tolerance test (OGTT) was carried out to assess blood glucose level. Biochemical parameters such as uric acid, creatinine, serum insulin, triglycerides (TG), and total cholesterol (TC) were also measured. Pathological condition of kidney was examined by hematoxylin-eosin (H&E) staining. The expressions of PI3K, p-PI3K, Akt, p-Akt, NF-κBp65, p-NF-κBp65, IκBα, and p-IκBα were analyzed by western blot. ERG significantly reduced the concentrations of blood glucose, uric acid, creatinine, TG, and TC. Serum insulin was elevated with ERG treatment. In addition, renal pathologic changes of diabetes mice were also alleviated by ERG. Obtained data revealed that ERG restored the levels of PI3K/Akt/NF-κB signaling-related proteins in comparison with diabetes mice. Above all, it could be assumed that ERG might play a positive role in regulating STZ-induced diabetes through suppressing PI3K/Akt/NF-κB pathway.

Bacterial Flora Changes in Conjunctiva of Rats with Streptozotocin-Induced Type I Diabetes

Background

The microbiota of both humans and animals plays an important role in their health and the development of disease. Therefore, the bacterial flora of the conjunctiva may also be associated with some diseases. However, there are no reports on the alteration of bacterial flora in conjunctiva of diabetic rats in the literature. Therefore, we investigated the changes in bacterial flora in bulbar conjunctiva of rats with streptozotocin (STZ)-induced type I diabetes.

Methods

A high dose of STZ (60 mg/kg, i.p.) was injected into Sprague-Dawley (SD) rats to induce type I diabetes mellitus (T1DM). The diabetic rats were raised in the animal laboratory and at 8 months post-injection of STZ swab samples were taken from the bulbar conjunctiva for cultivation of aerobic bacteria. The bacterial isolates were identified by Gram staining and biochemical features. The identified bacteria from both diabetic and healthy rats were then compared.

Results

The diabetic and healthy rats had different bacterial flora present in their bulbar conjunctiva. In total, 10 and 8 bacterial species were found in the STZ and control groups, respectively, with only three species (Enterococcus faecium, Enterococcus gallinarum and Escherichia coli) shared between the two groups. Gram-positive bacteria were common in both groups and the most abundant was Enterococcus faecium. However, after the development of T1DM, the bacterial flora in the rat bulbar conjunctiva changed considerably, with a reduced complexity evident.

Conclusions

STZ-induced diabetes caused alterations of bacterial flora in the bulbar conjunctiva in rats, with some bacterial species disappearing and others emerging. Our results indicate that the conjunctival bacterial flora in diabetic humans should be surveyed for potential diagnostic markers or countermeasures to prevent eye infections in T1DM patients.

Carvacrol modulates oxidative stress and decreases cell injury in pancreas of rats with acute pancreatitis

Acute pancreatitis (AP) is considered as major problem around the world and the incidence of AP is increasing. Carvacrol (CAR), a monoterpenic phenol, has good antioxidant activity. This in vivo study was designed to evaluate whether CAR provide protection against AP that developed by pancreas injury. The rats were randomised into groups to receive (I) no therapy; (II) 50 µg/kg cerulein at 1 h intervals by four intraperitonally (i.p.) injections; (III) 50, 100 and 200 mg/kg CAR by one i.p. injection; and (IV) cerulein plus CAR after 2 h of cerulein administration. 12 h later, serum samples were obtained to assess pancreatic function, the lipase and amylase values. The oxidative stress markers were evaluated by changes in the amount of lipid peroxides measured as malondialdehyde (MDA) and changes in main tissue antioxidant enzyme levels including SOD, CAT and GSH-PX. Histopathological examination was performed using scoring systems. Additionally, oxidative DNA damage was determined by measuring the increases of 8-hydroxy-deoxyguanosine (8-OH-dG) formations. We found that the increasing doses of CAR decreased AP-induced MDA and 8-OH-dG levels. Moreover, the pancreas antioxidant enzyme activities were higher than that of the rats in the AP group when compared to the AP plus CAR group. In the treatment groups, the lipase and amylase were reduced. Besides, histopathological findings in the pancreatic tissue were alleviated (p < 0.05). We suggest that CAR could be a safe and potent new drug candidate for treating AP through its antioxidative mechanism of action for the treatment of a wide range of disorders related to pancreas.

Chemistry and multibeneficial bioactivities of carvacrol (4-isopropyl-2-methylphenol), a component of essential oils produced by aromatic plants and spices

Aromatic plants produce organic compounds that may be involved in the defense of plants against phytopathogenic insects, bacteria, fungi, and viruses. One of these compounds, called carvacrol, which is found in high concentrations in essential oils such as oregano, has been reported to exhibit numerous bioactivities in cells and animals. This integrated overview surveys and interprets our present knowledge of the chemistry and analysis of carvacrol and its beneficial bioactivities. These activities include its antioxidative properties in food (e.g., lard, sunflower oil) and in vivo and the inhibition of foodborne and human antibiotic-susceptible and antibiotic-resistant pathogenic bacteria, viruses, pathogenic fungi and parasites, and insects in vitro and in human foods (e.g., apple juice, eggs, leafy greens, meat and poultry products, milk, oysters) and food animal feeds and wastes. Also covered are inhibitions of microbial and fungal toxin production and the anti-inflammatory, analgesic, antiarthritic, antiallergic, anticarcinogenic, antidiabetic, cardioprotective, gastroprotective, hepatoprotective, and neuroprotective properties of carvacrol as well as metabolic, synergistic, and mechanistic aspects. Areas for future research are also suggested. The collated information and suggested research might contribute to a better understanding of agronomical, biosynthetic, chemical, physiological, and cellular mechanisms of the described health-promoting effects of carvacrol, and facilitate and guide further studies needed to optimize the use of carvacrol as a multifunctional food in pure and encapsulated forms, in edible antimicrobial films, and in combination with plant-derived and medical antibiotics to help prevent or treat animal and human diseases.

Carvacrol attenuates diabetes-associated cognitive deficits in rats

Carvacrol (CAR), a naturally occurring phenolic monoterpene, has been demonstrated to possess various biological actions. The present study was designed to investigate the neuroprotective effect of CAR on diabetes-associated cognitive deficit (DACD) in a rat model of diabetes and exploring its potential molecular mechanism. Diabetic rats were treated with CAR by the doses of 25, 50, and 100 mg/kg for 7 weeks. Morris water maze was used for behavioral evaluation of memory. Cytoplasmic and nuclear fractions of cerebral cortex and hippocampus were prepared for the quantification of oxidative stress (MDA, SOD, and GSH), NF-κB p65 unit, TNF-α, IL-1β, and caspase-3. After 7 weeks of streptozotocin injection, the rats produced remarkable increase in escape latency, coupled with increased oxidative stress (increased MDA level and decreased SOD as well as reduced GSH), NF-κB p65 unit, TNF-α, IL-1β, and caspase-3 in different regions of diabetic rat brain. Interestingly, coadministration of CAR significantly and dose-dependently prevented behavioral, biochemical, and molecular changes associated with diabetes. In summary, our findings provide the first evidence that CAR can remarkably attenuate DACD and suggest the involvement of oxidative stress, inflammation, and apoptotic cascades in the development of cognitive impairment caused by diabetes. The pharmacological effect of CAR suggests that it may be used as a promising agent for the treatment of conventional antihyperglycemic regiments as well as DACD.