Pharmacological evaluation of Thuja occidentalis for the attenuation of neuropathy via AGEs and TNF-α inhibition in diabetic neuropathic rats

When diabetes neuropathy occurs, the oxidative stress caused by chronic hyperglycemia may result in chronic neuronal damage. To mitigate the effects of hyperglycemia-induced neuronal damage, it may be beneficial to address oxidative stress and inflammation in the body. The current study evaluated the neuroprotective efficacy of Thuja occidentalis in streptozotocin (STZ)-nicotinamide (NAD)-induced diabetic neuropathy in male Wistar rats. A single dose of STZ (65 mg/kg, i.p.) was used to induce diabetic neuropathy in Wistar rats. Serum insulin, glucose, hyperalgesia, oxidative stress, inflammatory markers, and histopathology of the sciatic nerve were evaluated for neuropathy. Wistar rats were treated with varying doses of hydroalcoholic extracts of Thuja occidentalis (HAETO) and gabapentin for 30 days. Thuja occidentalis considerably corrected the levels of inflammatory markers and oxidative stress caused by hyperglycemia; also, it led to the restoration of neuronal functions, indicating that it is effective in treating diabetic neuropathy. Furthermore, the molecular docking of thujone at the active pockets of various inflammatory mediators (IL-1β, IL-6, TGF-β1, and TNF-α) has shown good interactions with critical amino acid residues. These findings indicate that the hydroalcoholic extract of Thuja occidentalis effectively inhibits the development of diabetic neuropathy. The hypoglycemic, antioxidant, anti-hyperalgesia, and anti-inflammatory properties of Thuja occidentalis are thought to be responsible for the neuroprotective benefit.

The Role of Polyphenol in Modulating Associated Genes in Diabetes-Induced Vascular Disorders

Diabetes-induced vascular disorder is considered one of the deadly risk factors among diabetic patients that are caused by persistent hyperglycemia that eventually leads to cardiovascular diseases. Elevated reactive oxygen species (ROS) due to high blood glucose levels activate signaling pathways such as AGE/RAGE, PKC, polyol, and hexosamine pathways. The activated signaling pathway triggers oxidative stress, inflammation, and apoptosis which later lead to vascular dysfunction induced by diabetes. Polyphenol is a bioactive compound that can be found abundantly in plants such as vegetables, fruits, whole grains, and nuts. This compound exerts therapeutic effects in alleviating diabetes-induced vascular disorder, mainly due to its potential as an anti-oxidative, anti-inflammatory, and anti-apoptotic agent. In this review, we sought to summarize the recent discovery of polyphenol treatments in modulating associated genes involved in the progression of diabetes-induced vascular disorder.

Animal models of diabetic microvascular complications: Relevance to clinical features

Diabetes has become more common in recent years worldwide, and this growth is projected to continue in the future. The primary concern with diabetes is developing various complications, which significantly contribute to the disease's mortality and morbidity. Over time, the condition progresses from the pre-diabetic to the diabetic stage and then to the development of complications. Years and enormous resources are required to evaluate pharmacological interventions to prevent or delay the progression of disease or complications in humans. Appropriate screening models are required to gain a better understanding of both pathogenesis and potential therapeutic agents. Different species of animals are used to evaluate the pharmacological potentials and study the pathogenesis of the disease. Animal models are essential for research because they represent most of the structural, functional, and biochemical characteristics of human diseases. An ideal screening model should mimic the pathogenesis of the disease with identifiable characteristics. A thorough understanding of animal models is required for the experimental design to select an appropriate model. Each animal model has certain advantages and limitations. The present manuscript describes the animal models and their diagnostic characteristics to evaluate microvascular diabetic complications.

Chlorophytum alismifolium mitigates microvascular complications of type 2 diabetes mellitus: the involvement of oxidative stress and aldose reductase

OBJECTIVES

Chlorophytum alismifolium (C. alismifolium) tubers are used in the management of diabetes. This research evaluated the effect of ethylacetate extract of C. alismifolium (EACA) on microvascular complications and the possible association of oxidative stress and aldose reductase in type 2 diabetic rats.

METHODS

C. alismifolium tubers were subjected to sequential extraction until ethylacetate extract was obtained using a soxhlet apparatus. The LD₅₀ was determined using the OECD 425 guideline. The animals were placed on high fat diet for 42 days and then induced with hyperglycaemia using 40 mg/kg of streptozotocin. Diabetic neuropathy was evaluated using thermal and mechanical methods. Serum was used for the assessment of oxidative stress markers and biochemical markers of retinopathy and nephropathy. Serum aldose reductase was investigated by utilizing the principle of enzyme-linked immunosorbent assay.

RESULTS

The median lethal dose of EACA was assessed to be above 5,000 mg/kg and it caused no mortality. Treatment with EACA significantly reduced the withdrawal times in both thermal and mechanical hyperalgesic methods (p<0.05). EACA also significantly reduced the levels of urea (p<0.001), albumin (p<0.05) and uric acid (p<0.001) in hyperglycaemic rats. EACA significantly decreased the amounts of low density lipoprotein and triglycerides (p<0.001). There was a remarkable elevation in the levels of high density lipoprotein (p<0.05). A significant (p<0.05) increase in the levels of magnesium was observed in the EACA-treated groups. EACA significantly increased catalase (p<0.05) and reduced malondialdehyde levels (p<0.05). The levels of aldose reductase was significantly (p<0.001) reduced by EACA compared to the hyperglycaemic control.

CONCLUSIONS

The ethylacetate extract of C. alismifolium has beneficial effects in alleviating microvascular complications of diabetes through the inhibition of oxidative stress and aldose reductase in diabetic rats.

Chlorophytum alismifolium mitigates microvascular complications of type 2 diabetes mellitus: the involvement of oxidative stress and aldose reductase

OBJECTIVES

Chlorophytum alismifolium (C. alismifolium) tubers are used in the management of diabetes. This research evaluated the effect of ethylacetate extract of C. alismifolium (EACA) on microvascular complications and the possible association of oxidative stress and aldose reductase in type 2 diabetic rats.

METHODS

C. alismifolium tubers were subjected to sequential extraction until ethylacetate extract was obtained using a soxhlet apparatus. The LD50 was determined using the OECD 425 guideline. The animals were placed on high fat diet for 42 days and then induced with hyperglycaemia using 40 mg/kg of streptozotocin. Diabetic neuropathy was evaluated using thermal and mechanical methods. Serum was used for the assessment of oxidative stress markers and biochemical markers of retinopathy and nephropathy. Serum aldose reductase was investigated by utilizing the principle of enzyme-linked immunosorbent assay.

RESULTS

The median lethal dose of EACA was assessed to be above 5,000 mg/kg and it caused no mortality. Treatment with EACA significantly reduced the withdrawal times in both thermal and mechanical hyperalgesic methods (p<0.05). EACA also significantly reduced the levels of urea (p<0.001), albumin (p<0.05) and uric acid (p<0.001) in hyperglycaemic rats. EACA significantly decreased the amounts of low density lipoprotein and triglycerides (p<0.001). There was a remarkable elevation in the levels of high density lipoprotein (p<0.05). A significant (p<0.05) increase in the levels of magnesium was observed in the EACA-treated groups. EACA significantly increased catalase (p<0.05) and reduced malondialdehyde levels (p<0.05). The levels of aldose reductase was significantly (p<0.001) reduced by EACA compared to the hyperglycaemic control.

CONCLUSIONS

The ethylacetate extract of C. alismifolium has beneficial effects in alleviating microvascular complications of diabetes through the inhibition of oxidative stress and aldose reductase in diabetic rats.

Emerging role of protein kinases in diabetes mellitus: From mechanism to therapy

Diabetes mellitus has emerged as a severe burden on the medical health system across the globe. Presently, around 422 million people are suffering from diabetes which is speculated to be expanded to about 600 million by 2035. Patients with type 2 diabetes are at increased risk of developing detrimental metabolic and cardiovascular complications. The scientific understanding of this chronic disease and its underlying root cause is not yet fully unraveled. Protein kinases are well known to regulate almost every cellular process through phosphorylation of target protein in diverse signaling pathways. The important role of several protein kinases including AMP-activated protein kinase, IκB kinase and protein kinase C have been well demonstrated in various animal models. They modulate glucose tolerance, inflammation and insulin resistance in the cells via acting on diverse downstream targets and signaling pathways. Thus, modulating the activity of potential human kinases which are significantly involved in diabetes by targeting with small molecule inhibitors could be an attractive therapeutic strategy to tackle diabetes. In this chapter, we have discussed the potential role of protein kinases in glucose metabolism and insulin sensitivity, and in the pathogenesis of diabetes mellitus. Furthermore, the small molecules reported in the literature that can be potentially used for the treatment of diabetes have been discussed in detail.

Comparing the incidence of major cardiovascular events and severe microvascular complications in patients with type 2 diabetes mellitus: A systematic review and meta-analysis

BACKGROUND

Type 2 diabetes mellitus (T2DM) causes both macrovascular and microvascular complications. However, currently, selection of glycemic measures and their thresholds to diagnose T2DM, and efficacy outcomes in evaluation of anti-diabetic drugs is predominantly informed by the relation of T2DM to microvascular complications. We can be severely mistaken on T2DM by neglecting macrovascular complications which are generally more severe, if they also occur more commonly than microvascular complications.

AIM

To compare the incidence of major cardiovascular events (MACEs) and severe microvascular complications (SMICs) in T2DM patients.

METHODS

MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials were searched from inception to September 2017. Cohort studies or trials of T2DM patients aged 18 years or older that reported incidence of both MACEs and SMICs were included. MACEs were defined as nonfatal myocardial infarction and stroke, and cardiovascular death, while SMICs included serious retinopathy, nephropathy and diabetic disorder. The relative risk (RR) was estimated as the incidence of MACEs divided by that of SMICs in same patients and combined with meta-analysis in a random-effect model.

RESULTS

Twelve studies with a total of 16 cohorts and 387376 patients were included, and the combined RR was 2.02 (95%CI: 1.46–2.79). The higher incidence of MACEs remained in various subgroup and sensitivity analyses.

CONCLUSION

Patients with T2DM are much more likely to develop MACEs than SMICs. By taking more serious consequences and relatively higher incidence into consideration, macrovascular complications deserve more emphasis in developing the diagnostic criteria of T2DM and in evaluating the efficacy of anti-diabetic drugs.