Hypoglycaemic and Hypolipidemic Activities of Rauwolfia serpentina in Alloxan-Induced Diabetic Rats

Insight to phytochemical investigation and anti-hyperlipidemic effects of Eucalyptus camaldulensis leaf extract using in vitro, in vivo and in silico approach

Hyperlipidemia is a key risk factor mainly for hypertension and cardiac abnormalities. Previously eucalyptus plant (river red gum) had been used for its medicinal value for the treatment of many ailments. This study focused on phytochemical examination, investigation of an in vitro potential and in vivo effects in mice fed with high cholesterol diet, GC-MS analysis of extracts of Eucalyptus camaldulensis leaves and further confirmation of anti-hyperlipidemic potential of different constituents of plant extracts by using in silico technique. For in vitro study screening of different extracts of Eucalyptus camaldulensis leaves was performed by using pancreatic lipase enzyme inhibition assay. Ethanolic extract presented the highest potential among all the extracts by inhibiting pancreatic lipase having IC50-11.88 µg/mL. For in vivo study mice were fed with high cholesterol diet for induction of Hyperlipidemia. Water extract showed great anti-hyperlipidemic potential by reducing the level of cholesterol, triglycerides, low density lipoproteins and increasing high density lipoproteins level significantly (p < 0.05). Moreover, molecular docking and prime MM-GBSA study were applied for screening of compounds having anti-hyperlipidemic potential which showed that Alpha-cadinol was the lead compound for inhibition of pancreatic lipase enzyme having docking score (-6.604). The ADMET properties and toxicity profile of the top docked compounds were also detailed for ensuring their safety aspects. In this way in silico analysis substantiate the experimental findings by showing anti-hyperlipidemic potential in constituents of eucalyptus plant. Thus, there is a need of advanced research for isolation of active constituents having said anti-hyperlipidemic potential in the Eucalyptus camaldulensis plant.Communicated by Ramaswamy H. Sarma.

Short-chain fatty acids, secondary bile acids and indoles: gut microbial metabolites with effects on enteroendocrine cell function and their potential as therapies for metabolic disease

The gastrointestinal tract hosts the largest ecosystem of microorganisms in the body. The metabolism of ingested nutrients by gut bacteria produces novel chemical mediators that can influence chemosensory cells lining the gastrointestinal tract. Specifically, hormone-releasing enteroendocrine cells which express a host of receptors activated by these bacterial metabolites. This review will focus on the activation mechanisms of glucagon-like peptide-1 releasing enteroendocrine cells by the three main bacterial metabolites produced in the gut: short-chain fatty acids, secondary bile acids and indoles. Given the importance of enteroendocrine cells in regulating glucose homeostasis and food intake, we will also discuss therapies based on these bacterial metabolites used in the treatment of metabolic diseases such as diabetes and obesity. Elucidating the mechanisms gut bacteria can influence cellular function in the host will advance our understanding of this fundamental symbiotic relationship and unlock the potential of harnessing these pathways to improve human health.

Antioxidant and anti-inflammatory activities of Centratherum anthelminticum (L.) Kuntze seed oil in diabetic nephropathy via modulation of Nrf-2/HO-1 and NF-κB pathway

Background

Type 2 diabetes mellitus (T2DM) approximately constitutes 90% of the reported cases. 30-40% of diabetics eventually develop diabetic nephropathy (DN); accounting for one of the major causes of morbidity and mortality. Increased glucose autoxidation and non-enzymatic glycation of proteins in diabetic kidneys lead to the excessive generation of reactive oxygen species (ROS) that results in lipid peroxidation and activation of inflammatory mediators which overwhelms the scavenging capacity of the antioxidant defense system (Nrf2/Keap1/HO-1). Centratherum anthelminticum commonly called as kali zeeri (bitter cumin) and its seeds are well known for culinary purposes in Asia (Pakistan). It has reported anti-inflammatory, antioxidant, and anti-diabetic activities. The present study has attempted to explore the in-vivo anti-inflammatory, antioxidant and antihyperglycemic potential of the C. anthelminticum seed’s fixed oil (FO) and its fractions in high fat-high fructose-streptozotocin (HF-HFr-STZ) induced T2DM rat model.

Methods

The T2DM rat model was developed by giving a high-fat and high-fructose diet followed by a single intraperitoneal injection of streptozotocin (STZ 60 mg/kg) on 28th day of the trial. After 72 hours of this injection, rats showing fasting blood glucose (FBG) levels≥230 mg/dL were recruited into six groups. These groups were orally administered distilled water (1 mL/kg), Gliclazide (200 mg/kg), Centratherum anthelminticum seed (FO) and its hexane (HF), chloroform (CF) and ethanol (EF) soluble fractions (200 mg/kg each), respectively for 4 weeks (i.e. 28 days). Blood, serum, and kidney tissue samples of euthanized animals were used for biochemical, pro-inflammatory, and antioxidant markers (ELISA, qRT-PCR, and spectrophotometric assays) and histology, respectively.

Results

C. anthelminticum FO and its fractions reduced the lipid peroxidation, and improved the antioxidant parameters: enzymatic (SOD, CAT, and GPx), non-enzymatic (GSH), and mRNA expression of anti-inflammatory markers (Nrf-2, keap1, and HO-1). mRNA expression of inflammatory and apoptotic markers (TNF-α, IL-1β, COX-1, NF-κB, Bax, and Bcl-2) were attenuated along with improved kidney architecture.

Conclusion

C. anthelminticum can mitigate inflammation and oxidative stress in early DN. The anti-nephropathic effect can be attributed to its ability to down-regulate NF-κB and by bringing the Nrf-2 expression levels to near normal.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03776-x.

Genus Rauvolfia: A review of its ethnopharmacology, phytochemistry, quality control/quality assurance, pharmacological activities and clinical evidence

ETHNOPHARMACOLOGICAL RELEVANCE

The plants are from the genus Rauvolfia Plum. ex L. (Apocynaceae), which is represented by 74 species with many synonyms, and distributed worldwide, especially in the Asian, and African continents. Traditionally, some of them are used for the treatment of various disorders related to the central nervous system (CNS), cardiovascular diseases (CVD), and as an antidote due to the presence of monoterpene indole alkaloids (MIAs) such as ajmaline (144), ajmalicine (164) serpentine (182), yohimbine (190) and reserpine (214).

AIM

The present review provides comprehensive summarization and critical analysis of the traditional to modern applications of Rauvolfia species, and the major focus was to include traditional uses, phytochemistry, quality control, pharmacological properties, as well as clinical evidence that may be useful in the drug discovery process.

MATERIALS AND METHODS

Information related to traditional uses, chemical constituents, separation techniques/analytical methods, and pharmacological properties of the genus Rauvolfia were obtained using electronic databases such as Web of Science, Scopus, SciFinder, PubMed, PubChem, ChemSpider, and Google Scholar between the years 1949-2021. The scientific name of the species and its synonyms were checked with the information of The Plant List.

RESULTS

A total of seventeen Rauvolfia species have been traditionally explored for various therapeutic applications, out of which the roots of R. serpentina and R. vomitoria are used most commonly for the treatment of many diseases. About 287 alkaloids, seven terpenoids, nine flavonoids, and four phenolic acids have been reported in different parts of the forty-three species. Quality control (QC)/quality assurance (QA) of extracts/herbal formulations of Rauvolfia species was analyzed by qualitative and quantitative methods based on the major MIAs such as compounds 144, 164, 182, 190, and 214 using HPTLC, HPLC, and HPLC-MS. The various extracts of different plant parts of thirteen Rauvolfia species are explored for their pharmacological properties such as antimicrobial, antioxidant, antiprotozoal, antitrypanosomal, antipsychotic, cardioprotective, cholinesterase inhibitory, and hepatoprotective. Of which, clinical trials of herbal formulations/extracts of R. serpentina and MIAs have been reported for CVD, CNS, antihypertensive therapy, antidiabetic effects, and psoriasis therapy, while the extracts and phytoconstituents of remaining Rauvolfia species are predominantly significant, owning them to be additional attention for further investigation under clinical trials and QC/QA.

CONCLUSION

The present communication has provided a comprehensive, systematic, and critically analyzed vision into the traditional uses, phytochemistry, and modern therapeutic applications of the genus Rauvolfia are validated by scientific evidence. In addition, different plant parts from this genus, especially raw and finished herbal products of the roots of R. serpentina have been demonstrated for the QC/QA.

Update of Indoles: Promising molecules for ameliorating metabolic diseases

Obesity and metabolic disorders have gradually become public health-threatening problems. The metabolic disorder is a cluster of complex metabolic abnormalities which are featured by dysfunction in glucose and lipid metabolism, and results from the increasing prevalence of visceral obesity. With the core driving factor of insulin resistance, metabolic disorder mainly includes type 2 diabetes mellitus (T2DM), micro and macro-vascular diseases, non-alcoholic fatty liver disease (NAFLD), dyslipidemia, and the dysfunction of gut microbiota. Strategies and therapeutic attention are demanded to decrease the high risk of metabolic diseases, from lifestyle changes to drug treatment, especially herbal medicines. Indole is a parent substance of numerous bioactive compounds, and itself can be produced by tryptophan catabolism to stimulate glucagon-like peptide-1 (GLP-1) secretion and inhibit the development of obesity. In addition, in heterocycles drug discovery, the indole scaffold is primarily found in natural compounds with versatile biological activity and plays a prominent role in drug molecules synthesis. In recent decades, plenty of natural or synthesized indole deriviatives have been investigated and elucidated to exert effects on regulating glucose hemeostasis and lipd metabolism. The aim of this review is to trace and emphasize the compounds containing indole scaffold that possess immense potency on preventing metabolic disorders, particularly T2DM, obesity and NAFLD, along with the underlying molecular mechanisms, therefore facilitate a better comprehension of their druggability and application in metabolic diseases.

Antihypertensive and Antihyperlipidemic Activity of Aqueous Methanolic Extract of Rauwolfia Serpentina in Albino Rats

Rauwolfia serpentina has a wide range of therapeutic effects so this study was planned to explore the antihypertensive and antihyperlipidemic therapeutic responses of R serpentina doses using albino rats by measuring the blood pressure, biochemical parameters, and histological architecture of liver and kidney tissues. Thirty albino rats were divided into 5 groups (n = 6) as G1 (normal Control) received normal diet, G2 (positive control) received only 8% NaCl added diet (high salt diet); G3 was given atenolol (standard drug control) 50 mg/kg body weight, G4 and G5 groups were given methanolic plant extract as low dose (100 mg/kg body weight) and high dose (200 mg/Kg body weight) daily along with high salt diet for 4 weeks, respectively. Rauwolfia serpentina significantly (P < .05) decreased the blood pressure in G4 and G5 groups as compared to G2 and G3. Significant (P < .05) impact was reported, on serum lipid profile and serum proteins as well as hepatoprotective and renoprotective potential on studying tissues sections under microscope, in animal groups given herbal extract as compared to control groups. It could be concluded that R serpentina has therapeutic effect to manage the hypertension and hypercholesterolemia most probably via protecting the liver and renal architectures.

Oral Supplementation Effect of Iron and its Complex Form With Quercetin on Oxidant Status and on Redistribution of Essential Metals in Organs of Streptozotocin Diabetic Rats

Background and aims: Quercetin, is a polyphenolic antioxidant compound. It is able to form complex with metal ions such as iron and exerts a broad range of biological activities like improving metabolic disorders. This research aims at investigating the effect of oral supplementation of iron (2.5mg Fe/Kg/day) and its complex form (molar ratio 1:5; 2.5mg/25mg/Kg/day) with quercetin (25mg/Kg/day) on lipid metabolism, oxidant status and trace elements contents in organs of Wistar diabetic rats (45 mg/kg/rat.ip of streptozotocin) during eight weeks of experimentation.

Material and method: To achieve this, liver and adipose tissue enzymes activities, NO • , O2 −• , TBARs, carbonyl protein levels in plasma were analysed. Metals (Cu, Fe, Mg, Zn) analysis of organs were determined by inductively coupled plasma atomic emission spectroscopy.

Results: Iron supplemented alone induced a noticeable disorder in lipid, lipoprotein, lipases and oxidant status. Yet, it caused an imbalance in the redistribution of metals in the organs of diabetic and non diabetic rats. Iron-quercetin complex was shown as less harmful and more beneficial than iron supplemented alone.

Conclusions: This complex could reverse oxidative stress and iron deficiency mostly caused by the diabetic disease but at the same time it induces an imbalance in redistribution of other essential metals.

Delftia tsuruhatensis WGR-UOM-BT1, a novel rhizobacterium with PGPR properties from Rauwolfia serpentina (L.) Benth. ex Kurz also suppresses fungal phytopathogens by producing a new antibiotic-AMTM

The bacterial strain designated as WGR-UOM-BT1 isolated from rhizosphere of Rauwolfia serpentina exhibited broad-spectrum antifungal activity and also improved early plant growth. Based on morphological, biochemical and 16S rRNA gene sequence analyses, the strain BT1 was identified as Delftia tsuruhatensis (KF727978). Under in vitro conditions, the strain BT1 suppressed the growth of wide range of fungal phytopathogens. Purified antimicrobial metabolite from the strain BT1 was identified as nitrogen-containing heterocyclic compound, 'amino(5-(4-methoxyphenyl)-2-methyl-2-(thiophen-2-yl)-2,3-dihydrofuran-3-yl)methanol' (AMTM), with molecular mass of 340•40 and molecular formula of C17 H19 NO3 S. The strain BT1 was positive for rhizosphere colonization (tomato), IAA production, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity and phosphate solubilization. Under laboratory and greenhouse conditions, the strain BT1 promoted plant growth and suppressed foliar and root fungal pathogens of tomato. Therefore, antimicrobial and disease protection properties of strain BT1 could serve as an effective biological control candidate against devastating fungal pathogens of vegetable plants. Besides, the production of IAA, P solubilization and ACC deaminase activity enhance its potential as a biofertilizer and may stabilize the plant performance under fluctuating environmental conditions.

SIGNIFICANCE AND IMPACT OF THE STUDY

In this study, we reported that Delftia tsuruhatensis WGR-UOM-BT1 strain has the plant growth promotion activities such as rhizosphere colonization (tomato), IAA production, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity and phosphate solubilization. This bacterial strain was found producing an antimicrobial nitrogen-containing heterocyclic compound identified as 'amino(5-(4-methoxyphenyl)-2-methyl-2-(thiophen-2-yl)-2,3-dihydrofuran-3-yl)methanol' [C17 H19 NO3 S] (AMTM), which is new to the bacterial world.

Phytochemica: a platform to explore phytochemicals of medicinal plants

Plant-derived molecules (PDMs) are known to be a rich source of diverse scaffolds that could serve as the basis for rational drug design. Structured compilation of phytochemicals from traditional medicinal plants can facilitate prospection for novel PDMs and their analogs as therapeutic agents. Atropa belladonna, Catharanthus roseus, Heliotropium indicum, Picrorhiza kurroa and Podophyllum hexandrum are important Himalayan medicinal plants, reported to have immense therapeutic properties against various diseases. We present Phytochemica, a structured compilation of 963 PDMs from these plants, inclusive of their plant part source, chemical classification, IUPAC names, SMILES notations, physicochemical properties and 3-dimensional structures with associated references. Phytochemica is an exhaustive resource of natural molecules facilitating prospection for therapeutic molecules from medicinally important plants. It also offers refined search option to explore the neighbourhood of chemical space against ZINC database to identify analogs of natural molecules at user-defined cut-off. Availability of phytochemical structured dataset may enable their direct use in in silico drug discovery which will hasten the process of lead identification from natural products under proposed hypothesis, and may overcome urgent need for phytomedicines. Compilation and accessibility of indigenous phytochemicals and their derivatives can be a source of considerable advantage to research institutes as well as industries.

Database URL: home.iitj.ac.in/∼bagler/webservers/Phytochemica

Structural and functional diversity of rhizobacteria associated with Rauwolfia spp. across the Western Ghat regions of Karnataka, India

The present study carried out with denaturing gradient gel electrophoresis of DNA extracted from rhizosphere soils of Rauwolfia spp. collected from Western Ghat (WG) regions of Karnataka indicated that Pseudomonas sp. was prevalently found followed by Methylobacterium sp., Bacillus sp. and uncultured bacteria. A total of 200 rhizobacteria were isolated from 58 rhizosphere soil samples comprising of 15 different bacterial genera. The Shannon Weaver diversity index (H') and Simpson's diversity index (D) were found to be 2.57 and 0.91 for cultivable bacteria, respectively. The total species richness of cultivable rhizobacteria was high in Coorg district comprising 15 bacterial genera while in Mysore district, four bacterial genera were recorded. Rarefaction curve analysis also indicated the presence of higher species richness in samples of Shimoga and Coorg. All the rhizobacteria were screened for their multiple plant growth promotion and disease suppression traits. The results revealed that 70% of the isolates colonized tomato roots, 42% produced indole acetic acid, 55% solubilized phosphorus, while 43, 22, 27, 19, 40, 15 and 44% produced siderophore, salicylic acid, hydrogen cyanide, chitinase, phytase, cellulase and protease, respectively. Rhizobacterial isolates showing antagonistic activity against Fusarium oxysporum and Aspergillus flavus were 53 and 33%, respectively. Plant growth promotion studies revealed that most of the isolates increased percent germination with significantly higher vigour index as compared to untreated control. Most predominant rhizobacteria found in the rhizospheres of Rauwolfia spp. of WG regions are potential PGPR which can serve as biofertilizers and biopesticides.

Prospecting for novel plant-derived molecules of Rauvolfia serpentina as inhibitors of Aldose Reductase, a potent drug target for diabetes and its complications

Aldose Reductase (AR) is implicated in the development of secondary complications of diabetes, providing an interesting target for therapeutic intervention. Extracts of Rauvolfia serpentina, a medicinal plant endemic to the Himalayan mountain range, have been known to be effective in alleviating diabetes and its complications. In this study, we aim to prospect for novel plant-derived inhibitors from R. serpentina and to understand structural basis of their interactions. An extensive library of R. serpentina molecules was compiled and computationally screened for inhibitory action against AR. The stability of complexes, with docked leads, was verified using molecular dynamics simulations. Two structurally distinct plant-derived leads were identified as inhibitors: indobine and indobinine. Further, using these two leads as templates, 16 more leads were identified through ligand-based screening of their structural analogs, from a small molecules database. Thus, we obtained plant-derived indole alkaloids, and their structural analogs, as potential AR inhibitors from a manually curated dataset of R. serpentina molecules. Indole alkaloids reported herein, as a novel structural class unreported hitherto, may provide better insights for designing potential AR inhibitors with improved efficacy and fewer side effects.

Methanolic Root Extract of Rauwolfia serpentina Benth Improves the Glycemic, Antiatherogenic, and Cardioprotective Indices in Alloxan-Induced Diabetic Mice

The aim of the study was to evaluate the phytochemistry and the effect of methanolic root extract (MREt) of Rauwolfia serpentina on alloxan-induced diabetic Wister male mice. Mice were divided in control (distilled water at 1 mL/kg) and alloxan-induced diabetic mice which subdivided into diabetic (distilled water at 1 mL/kg), negative (0.05% dimethyl sulfoxide at 1 mL/kg), positive (glibenclamide at 5 mg/kg) controls, and three test groups (MREt at 10, 30, and 60 mg/kg). All treatments were given orally for 14 days. Qualitatively MREt showed the presence of alkaloids, carbohydrates, flavonoids, glycosides, cardiac glycosides, phlobatannins, resins, saponins, steroids, tannins, and triterpenoids, while quantitatively extract was rich in total phenols. The flavonoids, saponins and alkaloids were also determined in root powder. MREt found effective in improving the body weights, glucose and insulin levels, insulin/glucose ratio, glycosylated and total hemoglobin in test groups as compared to diabetic control. Similarly, significantly decreased levels of total cholesterol, triglycerides, low-density lipoprotein (LDL-c), and very low-density lipoprotein (VLDL-c) cholesterols were found in test groups. Significant lipolysis with improved glycogenesis was also found in liver tissues of all test groups. ALT levels were found normal in all groups. Thus, MREt improves the glycemic, antiatherogenic, coronary risk, and cardioprotective indices in alloxan-induced diabetic mice.