Inhibitors of 11β-Hydroxysteroid Dehydrogenase Type 1 as Potential Drugs for Type 2 Diabetes Mellitus—A Systematic Review of Clinical and In Vivo Preclinical Studies

Pistacia lentiscus: Phytochemistry and Antidiabetic Properties

Pistacia lentiscus L. (P. lentiscus) is an evergreen shrub (Anacardiaceae family) primarily found in the Mediterranean region. The plant has been thoroughly characterized, resulting in a high concentration of bioactive compounds as flavonoids and phenolics. Moreover, P. lentiscus was revealed to possess a great nutritional and industrial importance because of its variety of biological activities, including antibacterial, anti-inflammatory, anti-atherogenic and antioxidant properties. Many of its beneficial health properties and applications date back to antiquity, and the European Medicines Agency officially acknowledged it as an herbal medicinal product. Indeed, it is widely employed in conventional medicine to treat several diseases, including type 2 diabetes (T2D). On this basis, this review aims to summarize and describe the chemical composition of different parts of the plant and highlight the potential of P. lentiscus, focusing on its antidiabetic activities. The plant kingdom is drawing increasing attention because of its complexity of natural molecules in the research of novel bioactive compounds for drug development. In this context, P. lentiscus demonstrated several in vitro and in vivo antidiabetic effects, acting upon many therapeutic T2D targets. Therefore, the information available in this review highlighted the multitarget effects of P. lentiscus and its great potential in T2D treatment.

11β-Hydroxysteroid dehydrogenase and the brain: Not (yet) lost in translation

11-beta-hydroxysteroid dehydrogenases (11β-HSDs) catalyse the conversion of active 11-hydroxy glucocorticoids (cortisol, corticosterone) and their inert 11-keto forms (cortisone, 11-dehydrocorticosterone). They were first reported in the body and brain 70 years ago, but only recently have they become of interest. 11β-HSD2 is a dehydrogenase, potently inactivating glucocorticoids. In the kidney, 11β-HSD2 generates the aldosterone-specificity of intrinsically non-selective mineralocorticoid receptors. 11β-HSD2 also protects the developing foetal brain and body from premature glucocorticoid exposure, which otherwise engenders the programming of neuropsychiatric and cardio-metabolic disease risks. In the adult CNS, 11β-HSD2 is confined to a part of the brain stem where it generates aldosterone-specific central control of salt appetite and perhaps blood pressure. 11β-HSD1 is a reductase, amplifying active glucocorticoid levels within brain cells, notably in the cortex, hippocampus and amygdala, paralleling its metabolic functions in peripheral tissues. 11β-HSD1 is elevated in the ageing rodent and, less certainly, human forebrain. Transgenic models show this rise contributes to age-related cognitive decline, at least in mice. 11β-HSD1 inhibition robustly improves memory in healthy and pathological ageing rodent models and is showing initial promising results in phase II studies of healthy elderly people. Larger trials are needed to confirm and clarify the magnitude of effect and define target populations. The next decade will be crucial in determining how this tale ends - in new treatments or disappointment.

P. Discovery of novel inhibitor of 11 beta-hydroxysteroid dehydrogenase type 1 using in silico structure-based screening approach for the treatment of type 2 diabetes

Purpose

The current study is aimed to perform structure-based screening of FDA-approved drugs that can act as novel inhibitor of the 11beta- hydroxysteroid dehydrogenase type 1 (11β-HSD1) enzyme.

Methods

Structural analogs of carbenoxolone (CBX) were selected from DrugBank database and their Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) parameters were investigated by SwissADME. Molecular docking of CBX analogs against 11β-HSD1 was performed by AutoDock tool, their binding patterns were visualized using PyMOL and the interacting amino acids were determined by ProteinPlus tool. Molecular dynamics simulation was performed on the docked structure of 11β-HSD1 (Protein Data Bank (PDB) code: 2ILT) using GROMACS 2018.1.

Results

The binding energies of hydrocortisone succinate, medroxyprogesterone acetate, testolactone, hydrocortisone cypionate, deoxycorticosterone acetate, and hydrocortisone probutate were lower than that of substrate corticosterone. The molecular dynamics simulation of 11β-HSD1 and hydrocortisone cypionate docked structure showed that it formed a stable complex with the inhibitor. The Root mean square deviation (RMSD) of the protein (0.37 ± 0.05 nm) and ligand (0.41 ± 0.06 nm) shows the stability of the ligand-protein interaction.

Conclusion

The docking study revealed that hydrocortisone cypionate has a higher binding affinity than carbenoxolone and its other analogs. The molecular dynamics simulation indicated the stability of the docked complex of 11β-HSD1 and hydrocortisone cypionate. These findings indicate the potential use of this FDA approved drug in the treatment of type 2 diabetes. However, validation by in vitro inhibitory studies and clinical trials on type 2 diabetes patients is essential to confirm the current findings.

The Impact of Obesity on the Excretion of Steroid Metabolites in Boys and Girls: A Comparison with Normal-Weight Children

Obesity in childhood is associated with several steroid changes, which result from excess body mass. The aim of this study was to evaluate steroid metabolism in children with obesity compared with those with normal weight, especially in relation to sex and puberty progress. We analyzed the clinical data of 191 children, aged between 5 and 18 years, with 115 affected (64 girls and 51 boys) and 76 unaffected (35 girls and 41 boys) by obesity. Routine clinical assessment and pubertal stage evaluation based upon Tanner's scale were performed. In addition, to evaluate the impact of puberty, children with pre-adolescence and advanced puberty were divided into separate subgroups. Then, 24 h urine steroid excretion profiles were analyzed by gas chromatography/mass spectrometry. Significant differences in the excretion of steroid metabolites were found between normal weight children and children with obesity, especially in the prepubertal cohort. In this group, we observed enhanced activity in all the pathways of adrenal steroidogenesis. Raised excretion of mineralocorticoid derivatives such as tetrahydro-11-deoxycorticosterone, tetrahydrocorticosterone, and 5α-tetrahydrocorticosterone supported increased activity of this track. No significant differences were detected in the excreted free forms of cortisol and cortisone, while the excretion of their characteristic tetrahydro-derivatives was different. In pre-adolescent children with obesity, α-cortol and especially α-cortolone appeared to be excreted more abundantly than β-cortol or β-cortolone. Furthermore, in children with obesity, we observed elevated androgen excretion with an enhanced backdoor pathway. As puberty progressed, remarkable reduction in the differences between adolescents with and without obesity was demonstrated.

Antihyperglycemic Potential of Spondias mangifera Fruits via Inhibition of 11β-HSD Type 1 Enzyme: In Silico and In Vivo Approach

The 11 β- hydroxysteroid dehydrogenase 1 (11 β-HSD1) is hypothesized to play a role in the pathogenesis of type 2 diabetes and its related complications. Because high glucocorticoid levels are a risk factor for metabolic disorders, 11β-HSD1 might be a viable therapeutic target. In this investigation, docking experiments were performed on the main constituents of Spondias mangifera (SM) oleanolic acid, β-amyrin, and β-sitosterol to ascertain their affinity and binding interaction in the human 11β-hydroxysteroid dehydrogenase-1 enzyme’s active region. The results of in vitro 11β HSD1 inhibitory assay demonstrated that the extract of S. mangifera had a significant (p < 0.05) decrease in the 11-HSD1% inhibition (63.97%) in comparison to STZ (31.79%). Additionally, a non-insulin-dependent diabetic mice model was used to examine the sub-acute anti-hyperlipidemic and anti-diabetic effects of SM fruits. Results revealed that, in comparison to the diabetic control group, SM fruit extract (SMFE) extract at doses of 200 and 400 mg/kg body weight considerably (p < 0.05 and p < 0.01) lowered blood glucose levels at 21 and 28 days, as well as significantly decreased total cholesterol (TC) and triglycerides (TG) and enhanced the levels of high-density lipoprotein (HDL). After 120 and 180 s of receiving 200 and 400 mg/kg SMFE, respectively, disease control mice showed significantly poorer blood glucose tolerance (p < 0.05 and p < 0.01). SMFE extract 200 (p < 0.05), SMFE extract 400 (p < 0.01), and Glibenclamide at a dosage of 5 mg/kg body weight all resulted in statistically significant weight increase (p < 0.01) when compared to the diabetic control group after 28 days of treatment. According to in silico, in vitro, and in vivo validation, SMFE is a prospective medication with anti-diabetic and hypoglycemic effects.

The Genus Walsura: A Rich Resource of Bioactive Limonoids, Triterpenoids, and Other Types of Compounds

Medicinal plants of the genus Walsura (family Meliaceae) are native to tropical zones of a number of Asian countries, and have been used in systems of folk medicine. Several original research articles on Walsura species are available, but an overview highlighting the phytochemical and biological aspects of the compounds isolated to date is so far absent. Since the 1970s, phytochemical investigations on the genus Walsura have been undertaken, and more than 220 compounds from ten species have been identified. Natural products from Walsura species that have received the most attention are limonoids (114 compounds) and triterpenoids (72 compounds). Walsura limonoids have been characterized structurally as having diverse skeletons and more than 100 such compounds are new to the literature, while dammaranes, tirucallanes, and apotirucallanes are the main triterpenoid types from this genus. Other Walsura constituents comprise sesquiterpenoids, flavonoids, sterols, lignans, xanthones, and anthraquinones. Walsura species constituents have also been studied in natural product drug discovery screening programs. Many in vitro biological and some in vivo pharmacological investigations have been carried out on Walsura species isolated compounds. Walsura components display properties such as cancer cell cytotoxicity, antimicrobial, antidiabetes, anti-inflammatory, antioxidant, antifeedant, antifertility, ichthyotoxic, and neuroprotection activities.

Celastrol attenuates high-fructose diet-induced inflammation and insulin resistance via inhibition of 11β-hydroxysteroid dehydrogenase type 1 activity in rat adipose tissues

High fructose consumption has been linked to low-grade inflammation and insulin resistance that results in increased intracellular 11ß-hydroxysteroid dehydrogenase type 1 (11β-HSD1) activity. Celastrol, a pentacyclic triterpene, has been demonstrated to exhibit multifaceted targets to attenuate various metabolic diseases associated with inflammation. However, the underlying mechanisms by which celastrol exerts its attributive properties on high fructose diet (HFrD)-induced metabolic syndrome remain elusive. Herein, the present study was aimed to elucidate the mechanistic targets of celastrol co-administrations upon HFrD in rats and evaluate its potential to modulate 11β-HSD1 activity. Celastrol remarkably improved glucose tolerance, lipid profiles, and insulin sensitivity along with suppression of hepatic glucose production. In rat adipose tissues, celastrol attenuated nuclear factor-kappa B (NF-κB)-driven inflammation, reduced c-Jun N-terminal kinases (JNK) phosphorylation, and mitigated oxidative stress via upregulated genes expression involved in mitochondrial biogenesis. Furthermore, insulin signaling pathways were significantly improved through the restoration of Akt phosphorylation levels at Ser473 and Thr308 residues. Celastrol exhibited a potent, selective and specific inhibitor of intracellular 11β-HSD1 towards oxidoreductase activity (IC₅₀ value = 4.3 nM) in comparison to other HSD-related enzymes. Inhibition of 11β-HSD1 expression in rat adipose microsomes reduced the availability of its cofactor NADPH and substrate H6PDH in couple to upregulated mRNA and protein expressions of glucocorticoid receptor. In conclusion, our results underscore the most likely conceivable mechanisms exhibited by celastrol against HFrD-induced metabolic dysregulations mainly through attenuating inflammation and insulin resistance, at least via specific inhibitions on 11β-HSD1 activity in adipose tissues.

Lower synaptic density is associated with psychiatric and cognitive alterations in obesity

Obesity is a serious medical condition that often co-occurs with stress-related psychiatric disorders. It is recognized that the brain plays a key role in the (patho)physiology of obesity and that there is a bidirectional relationship between obesity and psychopathology, yet molecular mechanisms altered in obesity have not been fully elucidated. Thus, we investigated relationships between obesity and synaptic density in vivo using the radioligand [11C]UCB-J (which binds to synaptic glycoprotein SV2A) and positron emission tomography in individuals with obesity, and with or without stress-related psychiatric disorders. Regions of interest were the dorsolateral prefrontal cortex, orbitofrontal cortex, ventromedial, amygdala, hippocampus, and cerebellum. Forty individuals with a body mass index (BMI) ≥ 25 kg/m2 (overweight/obese), with (n = 28) or without (n = 12) psychiatric diagnosis, were compared to 30 age- and sex-matched normal weight individuals (BMI < 25), with (n = 14) or without (n = 16) psychiatric diagnosis. Overall, significantly lower synaptic density was observed in overweight/obese relative to normal weight participants (ηp2 = 0.193, F = 2.35, p = 0.042). Importantly, in participants with stress-related psychiatric diagnoses, we found BMI to be negatively correlated with synaptic density in all regions of interest (p ≤ 0.03), but no such relationship observed for mentally healthy controls (p ≥ 0.68). In the stress-related psychiatric groups, dorsolateral prefrontal cortex synaptic density was negatively associated with measures of worry (r = -0.46, p = 0.01), tension/anxiety (r = -0.38, p = 0.04), fatigue (r = -0.44, p = 0.02), and attentional difficulties (r = -0.44, p = 0.02). In summary, the findings of this novel in vivo experiment suggest compounding effects of obesity and stress-related psychopathology on the brain and the associated symptomatology that may impact functioning. This offers a novel biological mechanism for the relationship between overweight/obesity and stress-related psychiatric disorders that may guide future intervention development efforts.

Comparative Effect of Vitamin D3 and Carbenoxolone Treatments in Metabolic Syndrome Rats

Metabolic syndrome (MetS) is a cluster of cardiovascular risk factors including central obesity, hypertension, insulin resistance, dyslipidemia, and hyperglyemia. MetS is found to be a positive predictor of cardiovascular morbidity and mortality. The present study was planned to test the efficacy of vitamin D3 supplementation as compared to cortisol inhibition on MetS parameters. Wistar rats were allocated into four groups: controls, untreated MetS, and MetS treated with either vitamin D3 (10 μg/kg), or carbenoxolone (50 mg/kg). MetS was induced by combination of high fat diet and oral fructose. After the induction period (8 weeks), MetS was confirmed and treatment modalities started for a further 4 weeks. Compared to untreated MetS, vitamin D3 and carbenoxolone treated rats showed significant reduction in blood pressure, body mass index, lee index, waist circumference, retroperitoneal fat, and improvement of dyslipidemia. Meanwhile, treatment with carbenoxolone significantly lowered the elevated liver enzymes, vitamin D3 resulted in improved insulin sensitivity, enhanced glucose uptake by muscles and replenished glycogen content in the liver and muscles near control levels. In conclusion, although treatment with vitamin D3 or carbenoxolone reduced the risk factors associated with MetS, vitamin D3 was effective in ameliorating insulin resistance which is the hallmark of MetS.