Aldose reductase and protein tyrosine phosphatase 1B inhibitory active compounds from Syzygium cumini seeds

Can Polyherbal Medicine be used for the Treatment of Diabetes? - A Review of Historical Classics, Research Evidence and Current Prevention Programs

Diabetes mellitus (DM), a chronic medical condition, has attained a global pandemic status over the last few decades affecting millions of people. Despite a variety of synthetic drugs available in the market, the use of herbal medicines for managing diabetes is gaining importance because of being comparatively safer. This article reviews the result of a substantial literature search on polyherbal formulations (PHFs) developed and evaluated with potential for DM. The accumulated data in the literature allowed us to enlist 76PHFs consisting of different parts of 147 plant species belonging to 58 botanical families. The documented plant species are laden with bioactive components with anti-diabetic properties and thus draw attention. The most favoured ingredient for PHFs was leaves of Gymnema sylvestre and seeds of Trigonella foenum-graecum used in 27 and 22 formulations, respectively. Apart from herbs, shilajit (exudates from high mountain rocks) formed an important component of 9 PHFs, whereas calcined Mytilus margaritiferus and goat pancreas were used in Dolabi, the most commonly used tablet form of PHF in Indian markets. The healing properties of PHFs against diabetes have been examined in both pre-clinical studies and clinical trials. However, the mechanism(s) of action of PHFs are still unclear and considered the pitfalls inherent in understanding the benefits of PHFs. From the information available based on experimental systems, it could be concluded that plant-derived medicines will have a considerable role to play in the control of diabetes provided the challenges related to their bioavailability, bioefficacy, optimal dose, lack of characterization, ambiguous mechanism of action, and clinical efficiency are addressed.

Exploring the underutilized novel foods and starches for formulation of low glycemic therapeutic foods: a review

Rising incidences of life-style disorders like obesity, diabetes and cardiovascular diseases are a matter of concern coupled with escalated consumption of highly refined and high energy foods with low nutrient density. Food choices of consumers have witnessed significant changes globally with rising preference to highly processed palatable foods. Thus, it calls food scientists, researchers and nutritionists' attention towards developing and promoting pleasant-tasting yet healthy foods with added nutritional benefits. This review highlights selected underutilized and novel ingredients from different food sources and their by-products that are gaining popularity because of their nutrient density, that can be employed to improve the nutritional quality of conventionally available empty-calorie foods. It also emphasizes on the therapeutic benefits of foods developed from these understudied grains, nuts, processing by-products of grains, fruits- and vegetable-byproducts and nutraceutical starches. This review aims to draw attention of food scientists and industrialists towards popularizing the utilization of these unconventional, yet nutrient rich foods sources in improving the nutritional profile of the conventional foods lacking in nutrient density.

Fishing the Targets of Bioactive Compounds from Psidium guajava L. Leaves in the Context of Diabetes

Psidium guajava L. (guava) leaves have demonstrated their in vitro and in vivo effect against diabetes mellitus (DM). However, there is a lack of literature concerning the effect of the individual phenolic compounds present in the leaves in DM disease. The aim of the present work was to identify the individual compounds in Spanish guava leaves and their potential contribution to the observed anti-diabetic effect. Seventy-three phenolic compounds were identified from an 80% ethanol extract of guava leaves by high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry. The potential anti-diabetic activity of each compound was evaluated with the DIA-DB web server that uses a docking and molecular shape similarity approach. The DIA-DB web server revealed that aldose reductase was the target protein with heterogeneous affinity for compounds naringenin, avicularin, guaijaverin, quercetin, ellagic acid, morin, catechin and guavinoside C. Naringenin exhibited the highest number of interactions with target proteins dipeptidyl peptidase-4, hydroxysteroid 11-beta dehydrogenase 1, aldose reductase and peroxisome proliferator-activated receptor. Compounds catechin, quercetin and naringenin displayed similarities with the known antidiabetic drug tolrestat. In conclusion, the computational workflow showed that guava leaves contain several compounds acting in the DM mechanism by interacting with specific DM protein targets.

Major Bioactive Compounds from Java Plum Seeds: An Investigation of Its Extraction Procedures and Clinical Effects

Java plum is widely recognized as a plant with valuable medicinal properties, originating from Indonesia and India and distributed globally in the tropic and sub-tropic regions of the world. The plant is rich in alkaloids, flavonoids, phenyl propanoids, terpenes, tannins, and lipids. The phytoconstituents of the plant seeds possess various vital pharmacological activities and clinical effects including their antidiabetic potential. The bioactive phytoconstituents of Java plum seeds include jambosine, gallic acid, quercetin, β-sitosterol, ferulic acid, guaiacol, resorcinol, p-coumaric acid, corilagin, ellagic acid, catechin, epicatechin, tannic acid, 4,6 hexahydroxydiphenoyl glucose, 3,6-hexahydroxy diphenoylglucose, 1-galloylglucose, and 3-galloylglucose. Considering all the potential beneficial effects of the major bioactive compounds present in the Jamun seeds, in the current investigation, the specific clinical effects and the mechanism of action for the major bioactive compounds along with the extraction procedures are discussed.

Potential Therapeutic Target Protein Tyrosine Phosphatase-1B for Modulation of Insulin Resistance with Polyphenols and Its Quantitative Structure–Activity Relationship

The increase in the number of cases of type 2 diabetes mellitus (T2DM) and the complications associated with the side effects of chemical/synthetic drugs have raised concerns about the safety of the drugs. Hence, there is an urgent need to explore and identify natural bioactive compounds as alternative drugs. Protein tyrosine phosphatase 1B (PTP1B) functions as a negative regulator and is therefore considered as one of the key protein targets modulating insulin signaling and insulin resistance. This article deals with the screening of a database of polyphenols against PTP1B activity for the identification of a potential inhibitor. The research plan had two clear objectives. Under first objective, we conducted a quantitative structure–activity relationship analysis of flavonoids with PTP1B that revealed the strongest correlation (R² = 93.25%) between the number of aromatic bonds (naro) and inhibitory concentrations (IC₅₀) of PTP1B. The second objective emphasized the binding potential of the selected polyphenols against the activity of PTP1B using molecular docking, molecular dynamic (MD) simulation and free energy estimation. Among all the polyphenols, silydianin, a flavonolignan, was identified as a lead compound that possesses drug-likeness properties, has a higher negative binding energy of −7.235 kcal/mol and a pKd value of 5.2. The free energy-based binding affinity (ΔG) was estimated to be −7.02 kcal/mol. MD simulation revealed the stability of interacting residues (Gly183, Arg221, Thr263 and Asp265). The results demonstrated that the identified polyphenol, silydianin, could act as a promising natural PTP1B inhibitor that can modulate the insulin resistance.

Approaches to Decrease Hyperglycemia by Targeting Impaired Hepatic Glucose Homeostasis Using Medicinal Plants

Liver plays a pivotal role in maintaining blood glucose levels through complex processes which involve the disposal, storage, and endogenous production of this carbohydrate. Insulin is the hormone responsible for regulating hepatic glucose production and glucose storage as glycogen, thus abnormalities in its function lead to hyperglycemia in obese or diabetic patients because of higher production rates and lower capacity to store glucose. In this context, two different but complementary therapeutic approaches can be highlighted to avoid the hyperglycemia generated by the hepatic insulin resistance: 1) enhancing insulin function by inhibiting the protein tyrosine phosphatase 1B, one of the main enzymes that disrupt the insulin signal, and 2) direct regulation of key enzymes involved in hepatic glucose production and glycogen synthesis/breakdown. It is recognized that medicinal plants are a valuable source of molecules with special properties and a wide range of scaffolds that can improve hepatic glucose metabolism. Some molecules, especially phenolic compounds and terpenoids, exhibit a powerful inhibitory capacity on protein tyrosine phosphatase 1B and decrease the expression or activity of the key enzymes involved in the gluconeogenic pathway, such as phosphoenolpyruvate carboxykinase or glucose 6-phosphatase. This review shed light on the progress made in the past 7 years in medicinal plants capable of improving hepatic glucose homeostasis through the two proposed approaches. We suggest that Coreopsis tinctoria, Lithocarpus polystachyus, and Panax ginseng can be good candidates for developing herbal medicines or phytomedicines that target inhibition of hepatic glucose output as they can modulate the activity of PTP-1B, the expression of gluconeogenic enzymes, and the glycogen content.

Pharmacological potentials and Nutritional values of Tropical and Sub-tropical Fruits of India: Emphasis on their anticancer bioactive components

BACKGROUND

Fruits are an important dietary component, which supply vitamins, minerals, as well as dietary fiber. In addition, they are rich sources of various biological and pharmacologically active compounds. Among these, temperate fruits are well studied for their pharmacological potentials, whereas tropical/subtropical fruits are less explored for their health impacts. In India, most of the consumed fruits are either tropical or subtropical.

OBJECTIVES

The present review aims to provide a health impact of major tropical and sub-tropical fruits of India, emphasizing their anticancer efficacy. In addition, the identified bioactive components from these fruits exhibiting anticancer efficacy are also discussed along with the patent literature published.

METHODS

The literature was collected from various repositories, including NCBI, ScienceDirect, Eurekaselect, and Web of Science; literature from predatory journals was omitted during the process. Patent literature was collected from google patents and similar patent databases.

RESULTS

Tropical fruits are rich sources of various nutrients and bioactive components including polyphenols, flavonoids, anthocyanin, etc. By virtue of these biomolecules, tropical fruits have been shown to interfere with various steps in carcinogenesis, metastasis, and drug resistance. Their mode of action is either by activation of apoptosis, regulation of cell cycle, inhibition of cell survival and proliferation pathways, increased lipid trafficking or inhibiting inflammatory pathways. Several molecules and combinations have been patented for their anticancer and chemoprotective properties.

CONCLUSION

Overall, the present concludes that Indian tropical/ subtropical fruits are nutritionally and pharmacologically active and may serve as a source of novel anticancer agents in the future.

Natural Compounds as Source of Aldose Reductase (AR) Inhibitors for the Treatment of Diabetic Complications: A Mini Review

BACKGROUND

Aldol reductase (AR) is the polyol pathway's main enzyme that portrays a crucial part in developing 'complications of diabetes' involving cataract, retinopathy, nephropathy, and neuropathy. These diabetic abnormalities are triggered tremendously via aggregation of sorbitol formation (catalyzed by AR) in the polyol pathway. Consequently, it represents an admirable therapeutic target and vast research was done for the discovery of novel molecules as potential AR inhibitors for diabetic complications.

OBJECTIVE

This review article has been planned to discuss an outline of diabetic complications, AR and its role in diabetic complications, natural compounds reported as AR inhibitors, and benefits of natural/plant derived AR inhibitors for the management of diabetic abnormalities.

RESULTS

The goal of AR inhibition remedy is to stabilize the increased flux of blood glucose and sorbitol via the 'polyol pathway' in the affected tissues. A variety of synthetic inhibitors of AR have been established such as tolrestat and sorbinil, but both of these face limitations including low permeability and health problems. Pharmaceutical industries and other scientists were also undertaking work to develop newer, active, and 'safe' AR inhibitors from natural sources. Therefore, several naturally found molecules were documented to possess a potent inhibitory action on AR activity.

CONCLUSION

Natural inhibitors of AR appeared as harmless pharmacological agents for controlling diabetic complications. The detailed literature throughout this article shows the significance of herbal extracts and phytochemicals as prospective useful AR inhibitors in treating diabetic complications.

Pharmacological reflection of plants traditionally used to manage diabetes mellitus in Tanzania

ETHNOPHARMACOLOGICAL RELEVANCE

The increasing national prevalence of diabetes mellitus (DM) and its complications have overstretched the health care system in Tanzania and influenced patients to use herbal medicines as alternative therapeutic strategies. Therefore, an urgent need exists to validate the safety and efficacy of plants used locally.

AIM OF THE STUDY

To identify plants used for the management of DM in Tanzania and analyses their pharmacological, phytochemistry, and safety evidence with a special focus on the mechanism of action.

METHODS

Researchers searched Medline, web of science, and Scopus for published articles. Also, specialized herbarium documents of Muhimbili Institute of traditional medicine were reviewed. Articles were assessed for relevance, quality, and taxonomical accuracy before being critically reviewed.

RESULTS

We identified 62 plant species used locally for DM management. Moringa oleifera Lam. and Cymbopogon citratus (D.C) stapf were the most mentioned. Fifty-four phytochemicals from 13 species had DM activities. These were mainly; polyphenolics, phytosterols, and triterpenoids. Extracts, fractions, and pure compounds from 18 species had in vitro antidiabetic activities of which 14 had α-glucosidase and α-amylase inhibition effects. The most studied -Momordica charantia L. increased; glucose uptake and adiponectin release in 3T3-L1 adipocytes, insulin secretion, insulin receptor substrate-1 (IRS-1), GLUT-4 translocation, and GLP-1 secretion; and inhibited protein tyrosine phosphatase 1 B (PTP1B). Preclinical studies reported 30 species that lower plasma glucose with molecular targets in the liver, skeletal muscles, adipose tissues, pancreases, and stomach. While three species; Aspilia mossambiscensis (Oliv.) Willd, Caesalpinia bonduc (L.) Roxb, and Phyllanthus amarus Schumach. & Thonn. had mild toxicity in animals, 33 had no report of their efficacy in DM management or toxicity.

CONCLUSION

Local communities in Tanzania use herbal medicine for the management of DM. However, only a fraction of such species has scientific evidence. A. mossambiscensis, C. bonduc., and P. amarus had mild toxicity in animals. Together, our findings call for future researches to focus on in vitro, in vivo, and phytochemical investigation of plant species for which their use in DM among the local communities in Tanzania have not been validated.

Flower Infusions FromCornus masandCornus kousaInhibit Aldose Reductase Enzyme, Without Any Effects on Lipotoxicity

Aldose reductase inhibitors are considered to be potential therapeutic agents for chronic diabetic complications. Diabetes mellitus can be accompanied by elevated blood levels of free fatty acids, which can cause lipotoxicity. Herbal extracts and their constituents are promising agents which have the potential for alleviating these complications. Our study was focused on the influence on these effects by flower infusions from Cornus mas L. and Cornus kousa F.Buerger ex Hance. Initially, phenolic compounds were quantified in the dried flowers. Next, we studied the ability of flower infusions from both plants to inhibit aldose reductase in vitro, the protective role in the cell model of lipotoxicity, and the cytotoxic action on fibroblast cell line NIH-3T3 by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2 H-tetrazolium bromide assay. Both species are rich in phenolics; C. kousa flowers contain slightly higher amounts of phenolic acids (20.8%) and flavonoids (56.1%) than C. mas (20.2%) and (47.4%), respectively. Both extracts showed effective inhibition, expressed as half-maximal inhibitory concentration (IC50) (the concentration of inhibitor required to exhibit 50% inhibition of the enzyme reaction), of aldose reductase in non-toxic low concentrations (IC50= 3.06 μg/mL for C. mas and IC50= 2.49 μg/mL for C. kousa, respectively). In contrast, these concentrations of both extracts had almost no effects in the lipotoxicity cell model. To our knowledge, this study is the first report on C. mas and C. kousa flowers’ aldose reductase inhibitory activity and influence upon lipotoxicity.

Cataract Preventive Role of Isolated Phytoconstituents: Findings from a Decade of Research

Cataract is an eye disease with clouding of the eye lens leading to disrupted vision, which often develops slowly and causes blurriness of the eyesight. Although the restoration of the vision in people with cataract is conducted through surgery, the costs and risks remain an issue. Botanical drugs have been evaluated for their potential efficacies in reducing cataract formation decades ago and major active phytoconstituents were isolated from the plant extracts. The aim of this review is to find effective phytoconstituents in cataract treatments in vitro, ex vivo, and in vivo. A literature search was synthesized from the databases of Pubmed, Science Direct, Google Scholar, Web of Science, and Scopus using different combinations of keywords. Selection of all manuscripts were based on inclusion and exclusion criteria together with analysis of publication year, plant species, isolated phytoconstituents, and evaluated cataract activities. Scientists have focused their attention not only for anti-cataract activity in vitro, but also in ex vivo and in vivo from the review of active phytoconstituents in medicinal plants. In our present review, we identified 58 active phytoconstituents with strong anti-cataract effects at in vitro and ex vivo with lack of in vivo studies. Considering the benefits of anti-cataract activities require critical evaluation, more in vivo and clinical trials need to be conducted to increase our understanding on the possible mechanisms of action and the therapeutic effects.

Assessment of traditional knowledge of the antidiabetic plants of Darjeeling and Sikkim Himalayas in the context of recent phytochemical and pharmacological advances

Darjeeling and Sikkim Himalayas, a part of Eastern Himalayan Hotspot, is characterized by its richness of plant diversity. Herbal medicine has been one of the most popular and reliable healing practices among the different ethnic groups of this region for ages. However, the lack of documentation practice by the traditional healers has led to obscurity regarding the efficacy of herbal medicine among the present generation, though they have to depend on the same quite often. Meanwhile, several reviews have attempted to document the plants used for the treatment of diabetes from this region, but interestingly, very few research works can be obtained regarding the characterization of antidiabetic properties of the plants of this region. Therefore, it demands a better understanding of the potentiality of these plants in the purview of scientific evidence. This review article reports 55 such plant species which have been reported to be frequently used in the treatment of hyperglycemia and our objective was to validate the potentiality of the plants in the light of recent phytochemical and pharmacological researches being carried out locally or elsewhere.

Protein tyrosine phosphatase 1B inhibitors from natural sources

Since PTP1B enzyme was discovered in 1988, it has captured the research community's attention. This landmark discovery has stimulated numerous research studies on a variety of human diseases, including cancer, inflammation, and diabetes. Tremendous progress has been made in finding PTP1B inhibitors and exploring PTP1B regulatory mechanisms. This review investigates for the natural PTP1B inhibitors, and focuses on the common characteristics of the discovered structures and structure-activity relationships. To facilitate understanding, all the natural compounds are here divided into five different classes (fatty acids, phenolics, terpenoids, steroids, and alkaloids), according to their skeletons. These PTP1B inhibitors of scaffold structures could serve as a theoretical basis for new concept drug discovery and design.

High-Resolution Inhibition Profiling Combined with HPLC-HRMS-SPE-NMR for Identification of PTP1B Inhibitors from Vietnamese Plants

Protein tyrosine phosphatase 1B (PTP1B) plays a key role as a negative regulator in insulin signal transduction by deactivating the insulin receptor. Thus, PTP1B inhibition has emerged as a potential therapeutic strategy for curing insulin resistance. In this study, 40 extracts from 18 different plant species were investigated for PTP1B inhibitory activity in vitro. The most promising one, the EtOAc extract of Ficus racemosa, was investigated by high-resolution PTP1B inhibition profiling combined with HPLC-HRMS-SPE-NMR analysis. This led to the identification of isoderrone (1), derrone (2), alpinumisoflavone (3) and mucusisoflavone B (4) as PTP1B inhibitors. IC₅₀ of these compounds were 22.7 ± 1.7, 12.6 ± 1.6, 21.2 ± 3.8 and 2.5 ± 0.2 µM, respectively. Kinetics analysis revealed that these compounds inhibited PTP1B non-competitively with K_i values of 21.3 ± 2.8, 7.9 ± 1.9, 14.3 ± 2.0, and 3.0 ± 0.5 µM, respectively. These findings support the important role of F. racemosa as a novel source of new drugs and/or as a herbal remedy for treatment of type 2 diabetes.

Phloroglucinol Derivatives with Protein Tyrosine Phosphatase 1B Inhibitory Activities from Eugenia jambolana Seeds

Fifteen new phloroglucinol derivatives, jamunones A-O (1-8 and 10-16, respectively), along with one known analogue spiralisone C (9), were isolated from Eugenia jambolana seeds. Their structures were elucidated by detailed nuclear magnetic resonance and mass spectrometry spectroscopic data interpretation. Compounds 1-9, 11, 12, and 14-16 inhibited protein tyrosine phosphatase 1B activity with IC₅₀ values ranging from 0.42 to 3.2 μM.