Understanding the mode-of-action of Cassia auriculata via in silico and in vivo studies towards validating it as a long term therapy for type II diabetes

Procyanidins: A promising anti-diabetic agent with potential benefits on glucose metabolism and diabetes complications

Diabetes mellitus (DM) is a complex disease with alarming worldwide health implications and high mortality rates, largely due to its complications such as cardiovascular disease, nephropathy, neuropathy, and retinopathy. Recent research has shown that procyanidins (PC), a type of flavonoid, have strong antioxidant and free radical elimination effects, and may be useful in improving glucose metabolism, enhancing pancreatic islet cell activity, and decreasing the prevalence of DM complications. This review article presents a systematic search for peer-reviewed articles on the use of PC in the treatment of DM, without any language restrictions. The article also discusses the potential for PC to sensitise DM medications and improve their efficacy. Recent in vivo and in vitro studies have demonstrated promising results in improving the biological activity and bioavailability of PC for the treatment of DM. The article concludes by highlighting the potential for novel materials and targeted drug delivery methods to enhance the pharmacokinetics and bioactivity of PC, leading to the creation of safer and more effective anti-DM medications in the future.

Herbal Extracts Encapsulated Nanoliposomes as Potential Glucose-lowering Agents: An in Vitro and in Vivo Approach Using Three Herbal Extracts

Encapsulation of polyphenol-rich herbal extracts into nanoliposomes is a promising strategy for the development of novel therapeutic agents against type 2 diabetes mellitus. An attempt was made to encapsulate aqueous, ethanol, and aqueous ethanol (70% v/v) extracts of Senna auriculata (L.) Roxb., Murraya koenigii (L.) Spreng,. and Coccinia grandis (L.) Voigt into nanoliposomes and to screen acute bioactivities in vitro and in vivo. A wide spectrum of bioactivity was observed of which aqueous extracts encapsulated nanoliposomes of all three plants showed high bioactivity in terms of in vivo glucose-lowering activity in high-fat diet-fed streptozotocin induced Wistar rats, compared to respective free extracts. The particle size, polydispersity index, and zeta potential of the aforementioned nanoliposomes ranged from 179-494 nm, 0.362-0.483, and (-22) to (-17) mV, respectively. The atomic force microscopy (AFM) imaging reflected that the nanoparticles have desired morphological characteristics and Fourier-transform infrared (FTIR) spectroscopy analysis revealed successful encapsulation of plant extracts into nanoparticles. However, only the S. auriculata aqueous extract encapsulated nanoliposome, despite the slow release (9% by 30 hours), showed significant (p < 0.05) in vitro α-glucosidase inhibitory activity and in vivo glucose-lowering activity compared to free extract, proving worthy for future investigations.

Ayurveda and in silico Approach: A Challenging Proficient Confluence for Better Development of Effective Traditional Medicine Spotlighting Network Pharmacology

Coalescence of traditional medicine Ayurveda and in silico technology is a rigor for supplementary development of future-ready effective traditional medicine. Ayurveda is a popular traditional medicine in South Asia, emanating worldwide for the treatment of metabolic disorders and chronic illness. Techniques of in silico biology are not much explored for the investigation of a variety of bioactive phytochemicals of Ayurvedic herbs. Drug repurposing, reverse pharmacology, and polypharmacology in Ayurveda are areas in silico explorations that are needed to understand the rich repertoire of herbs, minerals, herbo-minerals, and assorted Ayurvedic formulations. This review emphasizes exploring the concept of Ayurveda with in silico approaches and the need for Ayurinformatics studies. It also provides an overview of in silico studies done on phytoconstituents of some important Ayurvedic plants, the utility of in silico studies in Ayurvedic phytoconstituents/formulations, limitations/challenges, and prospects of in silico studies in Ayurveda. This article discusses the convergence of in silico work, especially in the least explored field of Ayurveda. The focused coalesce of these two domains could present a predictive combinatorial platform to enhance translational research magnitude. In nutshell, it could provide new insight into an Ayurvedic drug discovery involving an in silico approach that could not only alleviate the process of traditional medicine research but also enhance its effectiveness in addressing health care.

Ethnopharmacological, Phytochemical, Pharmacological, and Toxicological Review on Senna auriculata (L.) Roxb.: A Special Insight to Antidiabetic Property

Avartaki (Senna auriculata (L.) Roxb. syn. Cassia auriculata L.; Family- Fabaceae ) is a traditional medicinal plant, widely used for the treatment of various ailments in Ayurveda and Siddha system of medicine in India. Almost all the parts of the plant, such as flowers, leaves, seeds, barks, and roots have been reported for their medicinal uses. Traditionally, it has been used in the treatment of diabetes, asthma, rheumatism, dysentery, skin disease, and metabolic disorders. The principle phytochemicals in Senna auriculata (L.) Roxb. are alkaloids, anthraquinone, flavone glycosides, sugar, saponins, phenols, terpenoids, flavonoids, tannins, steroids, palmitic acid, linoleic acid, benzoic acid 2-hydroxyl methyl ester, 1-methyl butyl ester, resorcinol, α-tocopherol-β-D-mannosidase, epicatechin, ferulic acid, quercetin-3-O-rutinoside, quercetin, proanthocyanidin B1. The extracts from its different parts and their isolated compounds possess a wide range of pharmacological activities such as antidiabetic, antioxidant, anti-inflammatory, antihyperlipidemic, hepatoprotective, nephroprotective, cardioprotective, anti-atherosclerotic, anticancer, antimutagenic, antimicrobial, antiulcer, antipyretic, anthelmintic, immunomodulatory, antifertility, anti-venom, and anti-melanogenesis. The toxicological findings from preclinical studies ensured the safety of the plant, but comprehensive clinical studies are required for the safety and efficacy of the plant in humans. The current review article aimed to provide up-to-date information about Senna auriculata (L.) Roxb. covering its ethnomedicinal, phytochemical, pharmacological, and toxicological aspects with special emphasis on its clinical implications in diabetes.

Monoamine Oxidase Inhibition by Major Tanshinones from Salvia miltiorrhiza and Selective Muscarinic Acetylcholine M4 Receptor Antagonism by Tanshinone I

Monoamine oxidases (MAOs) and muscarinic acetylcholine receptors (mAChRs) are considered important therapeutic targets for Parkinson's disease (PD). Lipophilic tanshinones are major phytoconstituents in the dried roots of Salvia miltiorrhiza that have demonstrated neuroprotective effects against dopaminergic neurotoxins and the inhibition of MAO-A. Since MAO-B inhibition is considered an effective therapeutic strategy for PD, we tested the inhibitory activities of three abundant tanshinone congeners against recombinant human MAO (hMAO) isoenzymes through in vitro experiments. In our study, tanshinone I (1) exhibited the highest potency against hMAO-A, followed by tanshinone IIA and cryptotanshinone, with an IC50 less than 10 µM. They also suppressed hMAO-B activity, with an IC50 below 25 µM. Although tanshinones are known to inhibit hMAO-A, their enzyme inhibition mechanism and binding sites have yet to be investigated. Enzyme kinetics and molecular docking studies have revealed the mode of inhibition and interactions of tanshinones during enzyme inhibition. Proteochemometric modeling predicted mAChRs as possible pharmacological targets of 1, and in vitro functional assays confirmed the selective M4 antagonist nature of 1 (56.1% ± 2.40% inhibition of control agonist response at 100 µM). These findings indicate that 1 is a potential therapeutic molecule for managing the motor dysfunction and depression associated with PD.

In Vitro and In Silico Characterization of G-Protein Coupled Receptor (GPCR) Targets of Phlorofucofuroeckol-A and Dieckol

Phlorotannins are polyphenolic compounds in marine alga, especially the brown algae. Among numerous phlorotannins, dieckol and phlorofucofuroeckol-A (PFF-A) are the major ones and despite a wider biological activity profile, knowledge of the G protein-coupled receptor (GPCR) targets of these phlorotannins is lacking. This study explores prime GPCR targets of the two phlorotannins. In silico proteocheminformatics modeling predicted twenty major protein targets and in vitro functional assays showed a good agonist effect at the α2C adrenergic receptor (α2CAR) and an antagonist effect at the adenosine 2A receptor (A2AR), δ-opioid receptor (δ-OPR), glucagon-like peptide-1 receptor (GLP-1R), and 5-hydroxytryptamine 1A receptor (5-TH1AR) of both phlorotannins. Besides, dieckol showed an antagonist effect at the vasopressin 1A receptor (V1AR) and PFF-A showed a promising agonist effect at the cannabinoid 1 receptor and an antagonist effect at V1AR. In silico molecular docking simulation enabled us to investigate and identify distinct binding features of these phlorotannins to the target proteins. The docking results suggested that dieckol and PFF-A bind to the crystal structures of the proteins with good affinity involving key interacting amino acid residues comparable to reference ligands. Overall, the present study suggests α2CAR, A2AR, δ-OPR, GLP-1R, 5-TH1AR, CB1R, and V1AR as prime receptor targets of dieckol and PFF-A.

Alterations of Glucose Uptake and Protein Expression Related to the Insulin Signaling Pathway in the Brain of Phenobarbital-Addictive Rats by 18F-FDG PET/CT and Proteomic Analysis

Drug addiction is a chronic relapsing brain disease. Alterations of glucose uptake and metabolism are found in the brain of drug addicts. Insulin mediates brain glucose metabolism and its abnormality could induce brain injury and cognitive impairment. Here, we established a rat model of phenobarbital addiction by 90 days of dose escalation and evaluated addiction-related symptoms. We also performed ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) to detect glucose uptake in the brain and proteomic analysis of the function of the differentially expressed (DE) proteins via bioinformatics in brain tissues by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) on days 60 and 90 of phenobarbital or 0.5% carboxymethyl cellulose sodium (CMC-Na) (vehicle) administration. The results showed that phenobarbital-addictive rats developed severe withdrawal symptoms after abstinence and glucose uptake was significantly increased in the brain. Proteomics analysis showed that numerous DE proteins were enriched after phenobarbital administration, among which CALM1, ARAF, and Cbl proteins (related to the insulin signaling pathway) were significantly downregulated on day 60 but not day 90. However, SLC27A3 and NF-κB1 proteins (related to insulin resistance) were significantly upregulated on day 90 (data are available via ProteomeXchange with identifier PXD021101). Our data indicate that the insulin signaling pathway and insulin resistance may play a role in the development of phenobarbital addiction and brain injury, so the findings may have important clinical implications.

Luteolin, a Potent Human Monoamine Oxidase-A Inhibitor and Dopamine D4 and Vasopressin V1A Receptor Antagonist

Luteolin, a flavonoid widely distributed in the plant kingdom, contains two benzene rings and hydroxyl groups, and this structural specificity contributes to its diverse biological activities. However, no previous studies have simultaneously investigated the therapeutic potency of luteolin isolated from a plant as an antipsychotic and antidepressant. Here, luteolin exhibited selective inhibition of hMAO-A (IC₅₀ = 8.57 ± 0.47 μM) over hMAO-B (IC₅₀ > 100 μM). In silico proteochemometric modeling predicted promising targets of luteolin, and verification via cell-based G protein-coupled receptor functional assays showed that luteolin is a selective antagonist of the vasopressin receptor V_1AR (IC₅₀ = 19.49 ± 6.32 μM) and the dopamine D₄ receptor (IC₅₀ = 39.59 ± 1.46 μM). Molecular docking showed the tight binding of luteolin with a low binding score and the high stability of the luteolin-receptor complex, corroborating its functional effect. Thus, hMAO-A, hD₄R, and hV_1AR are prime targets of luteolin and potential alternatives for the management of neurodegenerative diseases.

A novel metformin derivative showed improvement of lipid metabolism in obese rats with type 2 diabetes

In this study, we investigated the lipid metabolism regulatory activity of a novel metformin derivative (MD568) and its potential mechanism of action in obese rats with type 2 diabetes mellitus (T₂ DM). Previous gene chip analysis of 3T3-L1 cells have shown that MD568 regulates the transcription of genes involved in the peroxisome proliferator-activated receptor (PPAR) signalling pathway, fatty acid metabolism, and glycerolipid metabolism. In this study, obese T₂ DM rats were treated with MD568 (200 mg/kg) for 8 weeks. Results showed that MD568 significantly reduced the body weight gain, plasma glucose, insulin, total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels. MD568 treatment also improved the insulin resistance of obese T₂ DM model rats. In particular, in white adipose tissue, MD568 inhibited the excessive volume increment of adipose cells by down-regulating the protein levels of CCAAT/enhancer-binding protein-α (C/EBP-α) and PPAR-γ, as well as the transcription of their target lipid metabolism-related genes. In the liver, MD568 inhibited hepatic fatty lesions and interfered with hepatic gluconeogenesis by regulating the expression of lipid metabolism-related genes and glycogen-related kinases. In conclusion, our results suggest that the newly synthesized MD568 affects the maintenance of lipid homeostasis in obese type 2 diabetic rats.

Establishing GPCR Targets of hMAO Active Anthraquinones from Cassia obtusifolia Linn Seeds Using In Silico and In Vitro Methods

The present study examines the effect of human monoamine oxidase active anthraquinones emodin, alaternin (=7-hydroxyemodin), aloe-emodin, and questin from Cassia obtusifolia Linn seeds in modulating human dopamine (hD₁R, hD₃R, and hD₄R), serotonin (h5-HT_1AR), and vasopressin (hV_1AR) receptors that were predicted as prime targets from proteocheminformatics modeling via in vitro cell-based functional assays, and explores the possible mechanisms of action via in silico modeling. Emodin and alaternin showed a concentration-dependent agonist effect on hD₃R with EC₅₀ values of 21.85 ± 2.66 and 56.85 ± 4.59 μM, respectively. On hV_1AR, emodin and alaternin showed an antagonist effect with IC₅₀ values of 10.25 ± 1.97 and 11.51 ± 1.08 μM, respectively. Interestingly, questin and aloe-emodin did not have any observable effect on hV_1AR. Only alaternin was effective in antagonizing h5-HT_1AR (IC₅₀: 84.23 ± 4.12 μM). In silico studies revealed that a hydroxyl group at C1, C3, and C8 and a methyl group at C6 of anthraquinone structure are essential for hD₃R agonist and hV_1AR antagonist effects, as well as for the H-bond interaction of 1-OH group with Ser192 at a proximity of 2.0 Å. Thus, based on in silico and in vitro results, hV_1AR, hD₃R, and h5-HT_1AR appear to be prime targets of the tested anthraquinones.

A novel berberine-metformin hybrid compound exerts therapeutic effects on obese type 2 diabetic rats

In this study, we investigated the biological activities of a novel berberine-metformin hybrid compound (BMH473) as an anti-diabetic agent. BMH473 exhibited significant anti-hyperglycaemic and anti-hyperlipidaemic effects on T2DM rats. In white adipose tissue, BMH473 reduced the perirenal and epididymal adipose tissue mass and modulated the lesions in perirenal adipose tissue, by inhibiting the protein expressions of PPAR-Ɣ, C/EBP-α and SREBP-1c as well as the mRNA expressions of lipogenic genes. Moreover, BMH473 downregulated the levels of pro-inflammatory cytokines in perirenal adipose tissue through the suppression of p-NF-κB. In liver, BMH473 reduced liver ectopic fat accumulation, by regulating the protein expression levels of SREBP-1c and PPAR-α as well as the mRNA expression levels of lipogenic genes. In addition, BMH473 inhibited hepatic gluconeogenesis by promoting the phosphorylation levels of AMPK α and ACC, and down-regulating the mRNA expression levels of FBPase, G6Pase and PEPCK. Furthermore, BMH473 exhibited significant inhibitory effects on lipogenesis and lipid accumulation in 3T3-L1 adipocytes by modulating the protein expression levels of PPAR-Ɣ, C/EBP-α and SREBP-1 c as well as the mRNA expression levels of lipogenic genes. In conclusion, our results suggest that the newly synthesized BMH473 is beneficial for maintaining glucose and lipid homeostasis in type 2 diabetic rats, and exhibits better anti-hyperlipidaemic effects compared to metformin and berberine.

Progress in the discovery of naturally occurring anti-diabetic drugs and in the identification of their molecular targets

Diabetes mellitus (DM), a chronic metabolic disease, severely affects patients' life and intensively increases risks of developing other diseases. It is estimated that 0.4 billion individuals worldwide are subjected to diabetes, especially type 2 diabetes mellitus. At present, although various synthetic drugs for diabetes such as Alogliptin and Rosiglitazone, etc. have been used to manage diabetes, some of them showed severe side effects. Given that the pathogenesis of type 2 diabetes mellitus, natural occurring drugs are beneficial alternatives for diabetes therapy with low adverse effects or toxicity. Recently, more and more plant-derived extracts or compounds were evaluated to have anti-diabetic activities. Their anti-diabetic mechanisms involve certain key targets like α-glucosidase, α-amylase, DPP-4, PPAR γ, PTP1B, and GLUT4, etc. Here, we summarize the newly found anti-diabetic (type 2 diabetes mellitus) natural compounds and extracts from 2011-2017, and give the identification of their molecular targets. This review could provide references for the research of natural agents curing type 2 diabetes mellitus (T2DM).

Improvement of high-glucose and insulin resistance of chromium malate in 3T3-L1 adipocytes by glucose uptake and insulin sensitivity signaling pathways and its mechanism

Previous study has revealed that chromium malate could improve insulin resistance and the regulation of fasting blood glucose in type 2 diabetic rats. This study was designed to investigate the effect of chromium malate on hypoglycemic and improve insulin resistance activities in 3T3-L1 adipocytes with insulin resistance and investigate the acting mechanism. The result indicated that chromium malate exhibited direct hypoglycemic activity in vitro. Compared with the model group, chromium malate could significantly promote the expression levels of GLUT-4, Akt, Irs-1, PPARγ, PI3K and p38-MAPK and their mRNA, increase p-AKT/AKT level, AKT and AMPKβ1 phosphorylation and reduce Irs-1 phosphorylation and p-Irs-1/Irs-1 level in 3T3-L1 adipocytes (p < 0.05). Chromium malate is more effective in regulating the proteins and mRNA expressions than those of chromium trichloride and chromium picolinate. Compared to the model group, pretreatment with the specific p38-MAPK inhibitor completely inhibited the GLUT-4 and Irs-1 proteins and mRNA expressions induced by the chromium malate. In conclusion, chromium malate had a beneficial influence on improvement of controlling glucose levels and insulin resistance in 3T3-L1 adipocytes with insulin resistance by regulating proteins productions and genes expressions in glucose uptake and insulin sensitivity signaling pathways.

Chromium malate could increase the related protein and mRNA levels in 3T3-L1 adipocytes with insulin resistant. Pretreatment with the inhibitor completely/partially inhibited the GLUT-4 and Irs-1 proteins and mRNA expression compared to model group.

Dendrobium nobile Lindl. alkaloids regulate metabolism gene expression in livers of mice

Objectives

In our previous studies, Dendrobium nobile Lindl. alkaloids (DNLA) has been shown to have glucose-lowering and antihyperlipidaemia effects in diabetic rats, in rats fed with high-fat diets, and in mice challenged with adrenaline. This study aimed to examine the effects of DNLA on the expression of glucose and lipid metabolism genes in livers of mice.

Methods

Mice were given DNLA at doses of 10–80 mg/kg, po for 8 days, and livers were removed for total RNA and protein isolation to perform real-time RT-PCR and Western blot analysis.

Key findings

Dendrobium nobile Lindl. alkaloids increased PGC1α at mRNA and protein levels and increased glucose metabolism gene Glut2 and FoxO1 expression. DNLA also increased the expression of fatty acid β-oxidation genes Acox1 and Cpt1a. The lipid synthesis regulator Srebp1 (sterol regulatory element-binding protein-1) was decreased, while the lipolysis gene ATGL was increased. Interestingly, DNLA increased the expression of antioxidant gene metallothionein-1 and NADPH quinone oxidoreductase-1 (Nqo1) in livers of mice. Western blot on selected proteins confirmed these changes including the increased expression of GLUT4 and PPARα.

Conclusions

DNLA has beneficial effects on liver glucose and lipid metabolism gene expressions, and enhances the Nrf2-antioxidant pathway gene expressions, which could play integrated roles in regulating metabolic disorders.