Long-term effect of Trigonella foenum graecum and its combination with sodium orthovanadate in preventing histopathological and biochemical abnormalities in diabetic rat ocular tissues

Biological Consequences of Vanadium Effects on Formation of Reactive Oxygen Species and Lipid Peroxidation

Lipid peroxidation (LPO), a process that affects human health, can be induced by exposure to vanadium salts and compounds. LPO is often exacerbated by oxidation stress, with some forms of vanadium providing protective effects. The LPO reaction involves the oxidation of the alkene bonds, primarily in polyunsaturated fatty acids, in a chain reaction to form radical and reactive oxygen species (ROS). LPO reactions typically affect cellular membranes through direct effects on membrane structure and function as well as impacting other cellular functions due to increases in ROS. Although LPO effects on mitochondrial function have been studied in detail, other cellular components and organelles are affected. Because vanadium salts and complexes can induce ROS formation both directly and indirectly, the study of LPO arising from increased ROS should include investigations of both processes. This is made more challenging by the range of vanadium species that exist under physiological conditions and the diverse effects of these species. Thus, complex vanadium chemistry requires speciation studies of vanadium to evaluate the direct and indirect effects of the various species that are present during vanadium exposure. Undoubtedly, speciation is important in assessing how vanadium exerts effects in biological systems and is likely the underlying cause for some of the beneficial effects reported in cancerous, diabetic, neurodegenerative conditions and other diseased tissues impacted by LPO processes. Speciation of vanadium, together with investigations of ROS and LPO, should be considered in future biological studies evaluating vanadium effects on the formation of ROS and on LPO in cells, tissues, and organisms as discussed in this review.

Potential preventive and protective perspectives of different spice powders and their mixtures in rat model

BACKGROUND

The spices based dietary interventions are in lime light among the scientific community owing to their promising therapeutic perspective. The bioactive components in spices can be used to exert various health promoting functions in human body such as prompting weight loss, inhibit diet-induced obesity, hypercholesterolemia, hyperglycemia, allergies and various other maladies. In current study extraction and in vitro characterization of coriander seed (CS), black cumin seed (BCS) and fenugreek seed (FS) polyphenols was conducted for further development of dietary intervention against lipid and glycemia related abnormalities in experimental Sprague Dowley rats fed with control and different spice powder supplemented diets.

METHODS

Purposely, extraction of Coriander (CS), Black cumin (BCS) and Fenugreek seeds (FS) were carried out by using water and aqueous methanol (70:30 v/v). Afterwards, the resultant extracts were thoroughly investigated for their antioxidant potential through different indices like TPC, TFC, FRAP and β Carotene Bleaching Assay and ABTS. Furthermore, HPLC quantification were also conducted with special reference to thymoquinone, disogenin, chlorogenic acid, caffeic acid and kaempferol alongside in vitro pancreatic lipase inhibitory activity estimation. Bio-evaluation trial was consisting of three modules i.e. study-I (normal diet), study-II (high cholesterol diet) and study-III (high sucrose diet). Furthermore, rats were sub-divided in five groups in each module on the basis of diet provision including T₀ (control), T₁ (Diet containing CS), T₂ (Diet containing BCS), T₃ (Diet containing FS) and T₄ (Diet containing CSP + BCSP + FSP). At the beginning of trial, some rats were dissected to evaluate the baseline values whilst rest of the rats was killed at the termination (56th day). Feed and drink intakes were quantified on daily bases whereas, body weight was calculated weekly. Cholesterol level, serum low density lipoproteins (LDL), high density lipoproteins (HDL), triglycerides, glucose concentration and insulin level of collected sera was measured by standard procedures.

RESULTS

The in vitro characterization showed better extraction of spices antioxidant through aqueous methanol as compared to water. Among the spices, Black cumin seed alone or in combination revealed highest antioxidant activity in T2 (BCS) followed by T4 (CS + BCS), T7 (CS + BCS + FS), T1 (CS), T6 (BCS + FS), T5 (CS + FS) and lowest in T3 (FS). Likewise, the HPLC characterization showed the presence of thymoquinone in BCS, Dosignienin FGS and chlorogenic acid, caffeic acid and kaempferol in the other treatments. Furthermore, all the treatments showed dose dependent inhibition in Pancreatic lipase activity and order of inhibition was BCS > CS + BCS > CS + BCS + FS > CS > BCS + FC > CS + FS > FS. The maximum feed intake, drink intake and weight gain was observed in T0 (control) trailed by T1, T2, T3 and T4 group in experimental study I, II and III, respectively. The resultant diet T4 enhanced the high density lipoprotein from T0 (58.58 ± 2.51) to 61.71 ± 1.62 (T4) in hypercholesterolemia rats whereas in hyperglycaemia rats the HDL was varied from 38.77 ± 1.2 to 40.02 ± 0.99 in T0 and T4, respectively. Similarly, T2 significantly lowered the low density lipoprotein from 62.53 ± 1.22 (T1) & 46.53 ± 0.99 to 54.88 ± 0.52 & 40.94 ± 1.99 (T2) in hypercholesteraemic and diabetic rats. Moreover, T4 treatment showed maximum reduction as 10.01 & 11.53% in respective studies.

CONCLUSIONS

The diet prepared from the different combination of spices has been proven effective against Oxidative stress related physiological malfunctioning.

Investigation of synergistic mechanism and identification of interaction site of aldose reductase with the combination of gigantol and syringic acid for prevention of diabetic cataract

BACKGROUND

Gigantol and syringic acid (SA) have been shown to synergistically prevent formation of diabetic cataract (DC). However, the exact mechanism of this effect is unknown. Here, we investigate the effect of these compounds on the activity of aldose reductase (AR) and cataract formation.

METHODS

We examined the synergistic anti-cataract efficacy of gigantol and SA in the high glucose- and streptozotocin -induced DC rat model; synergism was evaluated using Jin's formula. We investigated possible mechanisms of action by measuring AR expression and activity and levels of sorbitol using enzyme kinetics, Western blot, and RT-PCR. Finally, we examined binding interaction between AR and both compounds using a combination of site-directed mutagenesis, recombinant expression of wild-type and mutant proteins, and enzyme kinetics.

RESULTS

Combination treatment of gigantol and SA synergistically protected both HLECs(human lens epithelial cells) grown in vitro and DC formation in STZ-induced rats in vivo. Synergism was attributed to inhibition of AR activity, downregulation of AR expression via impaired transcription, and decreased sorbitol levels. Enzyme kinetics studies showed that the activity of an AR Asn160Ala mutant protein was significantly decreased compared to wild-type AR, confirming that Asn160 is a key residue for interaction between AR and both compounds.

CONCLUSION

Combined administration of gigantol and SA synergize to enhance anti-cataract efficacy. The synergistic effect is mainly attributed to disruption of the polyol pathway and inhibition of AR activity.

Early Neurodegeneration of the Inner Retinal Layers in Type 1 Diabetes Mellitus

Purpose: This study explores retinal structural changes in type 1 diabetes without clinically diagnosed diabetic retinopathy (DR). Methods: Peripapillary retinal nerve fiber layer (RNFL) thickness, macular ganglion cell complex (GCC) thickness, and macular thickness (MT) were measured in 90 type 1 diabetic patients by using spectral domain optical coherence tomography. The values were compared with 100 sex- and age-matched healthy controls. The independent t test was used to assess differences in the mean age, mean diabetic and ocular parameters, and the thickness values between the diabetic and control groups. Multiple linear regression analysis was performed to investigate the correlation between the thickness values and diabetic and ocular parameters. Results: Whole-RNFL, the superior and inferior quadrants, and the superior half of the peripapillary RNFL thicknesses were significantly thinner in diabetic patients compared with controls (p < 0.05). GCC thicknesses in the average macular, outer temporal superior and outer temporal inferior sectors were significantly thinner in diabetic patients (p < 0.05). Central and average MTs were similar in both groups (p > 0.05). There were significant negative correlations of the duration of type 1 diabetes with the inner nasal MT, inner temporal superior GCC thickness, inner nasal inferior GCC thickness, and outer nasal superior GCC thickness (p < 0.05). Similarly, there were significant negative correlations of the level of HbA1c with the whole-RNFL thickness, superior-half-RNFL thickness, and superior-quadrant-RNFL thickness (p < 0.05). Conclusions: Type 1 diabetic patients without clinically diagnosed DR had neurodegeneration in the inner retinal layers compared with healthy controls.

Diabetes mellitus and its management with medicinal plants: A perspective based on Iranian research

ETHNOPHARMACOLOGICAL RELEVANCE

Complementary and alternative medicine has been increasingly used to treat chronic illnesses, such as diabetes mellitus. However, various limitations in terms of their application and efficacies exist. Furthermore, there is still much to be done to discover the right herbal medicine for diabetes.

AIM OF THE STUDY

This paper aims to evaluate previous herbal studies on the management of diabetes mellitus, to address their strengths and weaknesses and propose a general framework for future studies.

APPROACH AND METHODS

Data sources such as PubMed, ScienceDirect, Scopus, SpringerLink, and Wiley were searched, limited to Iran, using 36 search terms such as herbal, traditional, medicine, and phytopharmacy in combination with diabetes and related complications. Reviewed articles were evaluated regarding the use of botanical nomenclature and included information on (1) identity of plants and plant parts used, (2) the processing procedure, and (3) the extraction process. The main outcomes were extracted and then surveyed in terms of the efficacies of herbs in the management of diabetes mellitus. Then a comparative study was performed between Iranian and non-Iranian studies with respect to herbs best studied in Iran.

RESULTS

Of the 82 herbs studied in Iran, only six herbs were endemic and 19 were studied in detail. Although most of the reviewed herbs were found to decrease the level of blood glucose (BG) and/or glycated hemoglobin (HbA1C) in both Iranian and non-Iranian studies, information on their pharmacological mechanisms is scarce. However, the level of HbA1C was measured in a limited number of clinical trials or animal studies. Available information on both short- and long-term use of studied herbs on diabetes related complications and functions of involved organs as well as comorbid depression and/or simultaneous changes in lifestyle is also insufficient. Furthermore, little or no information on their phytochemical, toxicological, and herb-drug interaction properties is available. It is worth noting that the efficacy of the reviewed herbs has been studied scarcely in both humans and animals regarding both Iranian and non-Iranian studies. A significant number of reviewed articles failed to cite the scientific name of herbs and include information on the processing procedure and the extraction process.

CONCLUSIONS

Treatment of diabetes mellitus as a multifactorial disease using herbal medicines requires a comprehensive approach. In order to discover the right herbal medicine for the management of diabetes many other important factors than the levels of BG, HbA1C and insulin should be considered. According to our criteria, all the reviewed herbs suffered from inadequate investigation in human, animal and in vitro models in this respect, whereas they are worth investigating further. However, more research on endemic plants and the traditional history of herbal medicine is warranted. In our opinion, the pharmacological, toxicological, and phytochemical information should be obtained before clinical trials. Furthermore, information such as botanical scientific nomenclature, side effects, and toxicity will improve the quality and validity of publications in herbal research. In particular, designing a database covering all valid information about herbs and/or diseases will decrease unnecessary costs and increase the efficiency of research.

Identification of Novel Aldose Reductase Inhibitors from Spices: A Molecular Docking and Simulation Study

Hyperglycemia in diabetic patients results in a diverse range of complications such as diabetic retinopathy, neuropathy, nephropathy and cardiovascular diseases. The role of aldose reductase (AR), the key enzyme in the polyol pathway, in these complications is well established. Due to notable side-effects of several drugs, phytochemicals as an alternative has gained considerable importance for the treatment of several ailments. In order to evaluate the inhibitory effects of dietary spices on AR, a collection of phytochemicals were identified from Zingiber officinale (ginger), Curcuma longa (turmeric) Allium sativum (garlic) and Trigonella foenum graecum (fenugreek). Molecular docking was performed for lead identification and molecular dynamics simulations were performed to study the dynamic behaviour of these protein-ligand interactions. Gingerenones A, B and C, lariciresinol, quercetin and calebin A from these spices exhibited high docking score, binding affinity and sustained protein-ligand interactions. Rescoring of protein ligand interactions at the end of MD simulations produced binding scores that were better than the initially docked conformations. Docking results, ligand interactions and ADMET properties of these molecules were significantly better than commercially available AR inhibitors like epalrestat, sorbinil and ranirestat. Thus, these natural molecules could be potent AR inhibitors.

Loss of synaptic connectivity, particularly in second order neurons is a key feature of diabetic retinal neuropathy in the Ins2Akita mouse

Retinal neurodegeneration is a key component of diabetic retinopathy (DR), although the detailed neuronal damage remains ill-defined. Recent evidence suggests that in addition to amacrine and ganglion cell, diabetes may also impact on other retinal neurons. In this study, we examined retinal degenerative changes in Ins2^Akita diabetic mice. In scotopic electroretinograms (ERG), b-wave and oscillatory potentials were severely impaired in 9-month old Ins2^Akita mice. Despite no obvious pathology in fundoscopic examination, optical coherence tomography (OCT) revealed a progressive thinning of the retina from 3 months onwards. Cone but not rod photoreceptor loss was observed in 3-month-old diabetic mice. Severe impairment of synaptic connectivity at the outer plexiform layer (OPL) was detected in 9-month old Ins2^Akita mice. Specifically, photoreceptor presynaptic ribbons were reduced by 25% and postsynaptic boutons by 70%, although the density of horizontal, rod- and cone-bipolar cells remained similar to non-diabetic controls. Significant reductions in GABAergic and glycinergic amacrine cells and Brn3a⁺ retinal ganglion cells were also observed in 9-month old Ins2^Akita mice. In conclusion, the Ins2^Akita mouse develops cone photoreceptor degeneration and the impairment of synaptic connectivity at the OPL, predominately resulting from the loss of postsynaptic terminal boutons. Our findings suggest that the Ins2^Akita mouse is a good model to study diabetic retinal neuropathy.

Modulation of diabetic retinopathy pathophysiology by natural medicines through PPAR-γ-related pharmacology

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes and remains a major cause of preventable blindness among adults at working age. DR involves an abnormal pathology of major retinal cells, including retinal pigment epithelium, microaneurysms, inter-retinal oedema, haemorrhage, exudates (hard exudates) and intraocular neovascularization. The biochemical mechanisms associated with hyperglycaemic-induced DR are through multifactorial processes. Peroxisome proliferator-activated receptor-γ (PPAR-γ) plays an important role in the pathogenesis of DR by inhibiting diabetes-induced retinal leukostasis and leakage. Despite DR causing eventual blindness, only a few visual or ophthalmic symptoms are observed until visual loss develops. Therefore, early medical interventions and prevention are the current management strategies. Laser photocoagulation therapy is the most common treatment. However, this therapy may cause retinal damage and scarring. Herbal and traditional natural medicines may provide an alternative to prevent or delay the progression of DR. This review provides an analysis of the therapeutic potential of herbal and traditional natural medicines or their active components for the slowdown of progression of DR and their possible mechanism through the PPAR-γ pathway.

A pharmacological appraisal of medicinal plants with antidiabetic potential

Diabetes mellitus is a complicated metabolic disorder that has gravely troubled the human health and quality of life. Conventional agents are being used to control diabetes along with lifestyle management. However, they are not entirely effective and no one has ever been reported to have fully recovered from diabetes. Numerous medicinal plants have been used for the management of diabetes mellitus in various traditional systems of medicine worldwide as they are a great source of biological constituents and many of them are known to be effective against diabetes. Medicinal plants with antihyperglycemic activities are being more desired, owing to lesser side-effects and low cost. This review focuses on the various plants that have been reported to be effective in diabetes. A record of various medicinal plants with their established antidiabetic and other health benefits has been reported. These include Allium sativa, Eugenia jambolana, Panax ginseng, Gymnema sylvestre, Momrodica charantia, Ocimum sanctum, Phyllanthus amarus, Pterocarpus marsupium, Trigonella foenum graecum and Tinospora cordifolia. All of them have shown a certain degree of antidiabetic activity by different mechanisms of action.

Metabolic and molecular action of Trigonella foenum-graecum (fenugreek) and trace metals in experimental diabetic tissues

Diabetes mellitus is a heterogeneous metabolic disorder characterized by hyperglycaemia resulting in defective insulin secretion, resistance to insulin action or both. The use of biguanides, sulphonylurea and other drugs are valuable in the treatment of diabetes mellitus; their use, however, is restricted by their limited action, pharmacokinetic properties, secondary failure rates and side effects. Trigonella foenum-graecum, commonly known as fenugreek, is a plant that has been extensively used as a source of antidiabetic compounds from its seeds and leaf extracts. Preliminary human trials and animal experiments suggest possible hypoglycaemic and antihyperlipedemic properties of fenugreek seed powder taken orally. Our results show that the action of fenugreek in lowering blood glucose levels is almost comparable to the effect of insulin. Combination with trace metal showed that vanadium had additive effects and manganese had additive effects with insulin on in vitro system in control and diabetic animals of young and old ages using adipose tissue. The Trigonella and vanadium effects were studied in a number of tissues including liver, kidney, brain peripheral nerve, heart, red blood cells and skeletal muscle. Addition of Trigonella to vanadium significantly removed the toxicity of vanadium when used to reduce blood glucose levels. Administration of the various combinations of the antidiabetic compounds to diabetic animals was found to reverse most of the diabetic effects studied at physiological, biochemical, histochemical and molecular levels. Results of the key enzymes of metabolic pathways have been summarized together with glucose transporter, Glut-4 and insulin levels. Our findings illustrate and elucidate the antidiabetic/insulin mimetic effects of Trigonella, manganese and vanadium.

Mechanism of action of natural products used in the treatment of diabetes mellitus

Diabetes mellitus (DM) is a metabolic disorder caused by insufficient or inefficient insulin secretary response and it is characterized by increased blood glucose levels (hyperglycemia). DM is a heterogonous group of syndromes. Glucose is the main energy source for the body, and in the case of DM, management of glucose becomes irregular. There are three key defects in the onset of hyperglycemia in DM, namely increased hepatic glucose production, diminished insulin secretion, and impaired insulin action. Conventional drugs treat diabetes by improving insulin sensitivity, increasing insulin production and/or decreasing the amount of glucose in blood. This article provides a comprehensive review of the mode of action of most popular hypoglycemic herbs, such as ginseng, bitter melon, fenugreek, banaba, Gymnema sylvestre and Coptis chinensis. The herbs act by increasing insulin secretion, enhancing glucose uptake by adipose and skeletal muscle tissues, inhibiting intestinal glucose absorption and inhibiting hepatic glucose production. Although evidence from animals and humans consistently supports the therapeutic effect of these phytomedicines, multicenter large-scale clinical trials have not been conducted to evaluate the safety and efficacy of these herbal medicines and their interaction with conventional drugs when administered simultaneously.

Ginkgo biloba extract prevents against apoptosis induced by high glucose in human lens epithelial cells

AIM

To investigate the protective effects of Ginkgo biloba extract (GBE) on high glucose-induced apoptosis of human lens epithelial cells (HLEC) and the possible molecular mechanisms.

METHODS

The cultured HLEC were allotted into 6 groups: normal group, high glucose group, low-, moderate-, and high-dose GBE group, and the bendazac lysine group. Cell viability, cell apoptosis, the activities of cell antioxidases, aldose reductase, caspase-3, the levels of cell antioxidants, and the expressions of Bcl-2 and Bax were assessed by different methods.

RESULTS

After being incubated with high glucose for 24 h, HLEC underwent apoptosis and exhibited significant oxidative stress. In the presence of GBE at different doses, the rate of HLEC apoptosis was lower and the oxidative stress state was significantly ameliorated. The increased ratio of Bax to Bcl-2 was significantly reduced and the activation of caspase-3 was suppressed by GBE in a dose-dependent manner.

CONCLUSION

GBE prevents HLEC from high glucose-induced apoptosis through inhibiting oxidative stress, reducing the ratio of Bax to Bcl-2, and decreasing the activity of caspase-3. Therefore, GBE has a potential protective effect against diabetic cataract formation.

Clinical observation on trigonella foenum-graecum L. total saponins in combination with sulfonylureas in the treatment of type 2 diabetes mellitus

OBJECTIVE

To evaluate the efficacy and safety of trigonella foenum-graecum L. total saponins (TFGs) in combination with sulfonylureas (SU) in the treatment of patients with type 2 diabetes mellitus (T2DM) not well controlled by SU alone.

METHODS

Sixty-nine T2DM patients whose blood glucose levels were not well controlled by oral sulfonylureas hypoglycemic drug were randomly assigned to the treated group (46 cases) and the control group (23 cases), and were given TFGs or placebo three times per day, 6 pills each time for 12 weeks, respectively. Meanwhile, the patients continued taking their original hypoglycemic drugs. The following indexes, including effects on traditional Chinese medicine (TCM) symptoms, fast blood glucose (FBG), 2-h post-prandial blood glucose (2h PBG), glycosylated hemoglobin (HbA1c), clinical symptomatic quantitative scores (CSQS), body mass index (BMI), as well as hepatic and renal functions, were observed and compared before and after treatment.

RESULTS

The efficacy on TCM symptoms was obviously better in the treated group than that in the control group (P<0.01), and there were statistically remarkable decreases in aspect of FBG, 2h PBG, HbA1c and CSQS in the treated group as compared to those in the control group (P<0.05 or P<0.01), while no significant difference was found in BMI, hepatic and renal functions between the two groups (P>0.05).

CONCLUSION

The combined therapy of TFGs with sulfonylureas hypoglycemic drug could lower the blood glucose level and ameliorate clinical symptoms in the treatment of T2DM, and the therapy was relatively safe.

Proposal open for discussion: defining agreed diagnostic procedures in experimental diabetes research

BACKGROUND

Animal experimentation has a long tradition in diabetes research and has provided invaluable benefits with regard to insulin discovery and treatment assessment.

METHODS

The review focuses on chemical-induced diabetes in rats and surveys the protocols of diabetes induction, diabetes diagnosis, and glucose tolerance evaluation in a selection of recent research.

RESULTS

This brief review of techniques in experimental diabetes highlights that there is no uniformity, whereas standardisation of procedures is desirable so that comparability will exist among experiments carried out in different settings.

CONCLUSIONS

On this basis, questions are put and standards are proposed. It would be a platform to promote the exchange of ideas through expert consultation about practical issues related to animal research and a basis on which standards can be set according to user requirements and animal respect.