Chemical profile and inhibition of α-glycosidase and protein tyrosine phosphatase 1B (PTP1B) activities by flavonoids from licorice (Glycyrrhiza uralensis Fisch)

Real-time monitoring of dephosphorylation process of phosphopeptide and rapid assay of PTP1B activity based on a 100 MHz QCM biosensing platform

The misregulation of protein phosphatases is a key factor in the development of many human diseases, notably cancers. Here, based on a 100 MHz quartz crystal microbalance (QCM) biosensing platform, the dephosphorylation process of phosphopeptide (P-peptide) caused by protein tyrosine phosphatase 1B (PTP1B) was monitored in real time for the first time and PTP1B activity was assayed rapidly and sensitively. The QCM chip, coated with a gold (Au) film, was used to immobilized thiol-labeled single-stranded 5'-phosphate-DNAs (P-DNA) through Au-S bond. The P-peptide, specific to PTP1B, was then connected to the P-DNA via chelation between Zr4+ and phosphate groups. When PTP1B was injected into the QCM flow cell where the P-peptide/Zr4+/MCH/P-DNA/Au chip was placed, the P-peptide was dephosphorylated and released from the Au chip surface, resulting in an increase in the frequency of the QCM Au chip. This allowed the real-time monitoring of the P-peptide dephosphorylation process and sensitive detection of PTP1B activity within 6 min with a linear detection range of 0.01-100 pM and a detection limit of 0.008 pM. In addition, the maximum inhibitory ratios of inhibitors were evaluated using this proposed 100 MHz QCM biosensor. The developed 100 MHz QCM biosensing platform shows immense potential for early diagnosis of diseases related to protein phosphatases and the development of drugs targeting protein phosphatases.

Green Synthesis of Gold Nanoparticles Using Liquiritin and Other Phenolics from Glycyrrhiza glabra and Their Anti-Inflammatory Activity

Phenolic compounds are the main phytochemical constituents of many higher plants. They play an important role in synthesizing metal nanoparticles using green technology due to their ability to reduce metal salts and stabilize them through physical interaction/conjugation to the metal surface. Six pure phenolic compounds were isolated from licorice (Glycyrrhiza glabra) and employed in synthesizing gold nanoparticles (AuNPs). The isolated compounds were identified as liquiritin (1), isoliquiritin (2), neoisoliquiritin (3), isoliquiritin apioside (4), liquiritin apioside (5), and glabridin (6). The synthesized AuNPs were characterized using UV, zeta sizer, HRTEM, and IR and tested for their stability in different biological media. The phenolic isolates and their corresponding synthesized NP conjugates were tested for their potential in vitro cytotoxicity. The anti-inflammatory effects were investigated in both normal and inflammation-induced settings, where inflammatory biomarkers were stimulated using lipopolysaccharides (LPSs) in the RAW 264.7 macrophage cell line. LPS, functioning as a mitogen, promotes cell growth by reducing apoptosis, potentially contributing to observed outcomes. Results indicated that all six pure phenolic isolates inhibited cell proliferation. The AuNP conjugates of all the phenolic isolates, except liquiritin apioside (5), inhibited cell viability. LPS initiates inflammatory markers by binding to cell receptors and setting off a cascade of events leading to inflammation. All the pure phenolic isolates, except isoliquiritin, neoisoliquiritin, and isoliquiritin apioside inhibited the inflammatory activity of RAW cells in vitro.

Bipartite graph search optimization for type II diabetes mellitus Jamu formulation using branch and bound algorithm

Jamu is an Indonesian traditional herbal medicine that has been practiced for generations. Jamu is made from various medicinal plants. Each plant has several compounds directly related to the target protein that are directly associated with a disease. A pharmacological graph can form relationships between plants, compounds, and target proteins. Research related to the prediction of Jamu formulas for some diseases has been carried out, but there are problems in finding combinations or compositions of Jamu formulas because of the increase in search space size. Some studies adopted the drug–target interaction (DTI) implemented using machine learning or deep learning to predict the DTI for discovering the Jamu formula. However, this approach raises important issues, such as imbalanced and high-dimensional dataset, overfitting, and the need for more procedures to trace compounds to their plants. This study proposes an alternative approach by implementing bipartite graph search optimization using the branch and bound algorithm to discover the combination or composition of Jamu formulas by optimizing the search on a plant–protein bipartite graph. The branch and bound technique is implemented using the search strategy of breadth first search (BrFS), Depth First Search, and Best First Search. To show the performance of the proposed method, we compared our method with a complete search algorithm, searching all nodes in the tree without pruning. In this study, we specialize in applying the proposed method to search for the Jamu formula for type II diabetes mellitus (T2DM). The result shows that the bipartite graph search with the branch and bound algorithm reduces computation time up to 40 times faster than the complete search strategy to search for a composition of plants. The binary branching strategy is the best choice, whereas the BrFS strategy is the best option in this research. In addition, the the proposed method can suggest the composition of one to four plants for the T2DM Jamu formula. For a combination of four plants, we obtain Angelica Sinensis, Citrus aurantium, Glycyrrhiza uralensis, and Mangifera indica. This approach is expected to be an alternative way to discover the Jamu formula more accurately.

Black soybean (Glycine max (L.) Merr.): paving the way toward new nutraceutical

Black soybean (BS) is a nutritious legume that is high in proteins, essential amino acids, dietary fiber, vitamins, minerals, anthocyanins, phenolic acids, isoflavones, and flavones. Traditional approaches for extracting BS bioactive compounds are commonly employed because they are simple and inexpensive, but they use toxic solvents and have lower yields. As a result, new extraction techniques have been developed, such as microwave, ultrasound, and enzyme-assisted extraction. Modern approaches are less harmful to the environment, are faster, and produce higher yields. The major anthocyanin in the BS seed coat was discovered as cyanidin-3-O-glucoside, accounting for nearly 75% of the total anthocyanins. BS and its seed coat also contains phenolic acids (p-hydroxybenzoic, gallic, vanillin, syringic acid), isoflavones (daidzein, glycitein and genistein), flavones, flavonols, flavanones, and flavanols. Bioactive compounds present in BS exhibit antioxidant, anti-cancerous, anti-diabetic, anti-obesity, anti-inflammatory, cardio and neuroprotective activities. The characterization and biological activity investigation of these bioactive compounds has provided researchers and food manufacturers with valuable information for developing functional food products and nutraceutical ingredients. In this review, the nutritional makeup of BS is reviewed, and the paper seeks to provide an insight of bioactive compound extraction methods as well as bioactive compounds identified by various researchers. The biological activities of BS extracts and their potential applications in food products (noodles), biodegradable films (pH sensitive film), and therapeutic applications (wound healing and anti-inflammation) are also discussed in the study. Therefore, BS have enormous potential for use in developing functional foods and nutraceutical components. This is the first review of its sort to describe and explain various extraction methodologies and characterization of bioactives, as well as their biological activity recorded in diverse works of literature, making it possible for food manufacturers and scientists to get a quick overview.

Genus Lonicera: New drug discovery from traditional usage to modern chemical and pharmacological research

BACKGROUND

Lonicera Linn. belonging to the family Caprifoliaceae, the largest genus in the plant family, includes about more than 200 species, which are mainly distributed in northern Africa, North America, Europe and Asia. Some species of this genus have been usually used in traditional Chinese medicine as well as functional foods, cosmetics and other applications, such as L. japonica Thunb. Bioactive components and pharmacological activities of the genus Lonicera plants have received an increasing interest from the scientific community. Thus, a comprehensive and systematic review on their traditional usage in China, chemical components, and their pharmacological properties of their whole plants, bioactive extracts, and bioactive isolates including partial structure-activity relationships from the genus is indispensable.

METHODS

Information on genus Lonicera of this systematic electronic literature search was gathered via the published articles, patents, clinical trials website (https://clinicaltrials.gov/) and several online bibliographic databases (PubMed, Sci Finder, Research Gate, Science Direct, CNKI, Web of Science and Google Scholar). The following keywords were used for the online search: Lonicera, phytochemical composition, Lonicerae japonica, Lonicera review articles, bioactivities of Lonicera, anti-inflammatory, antiviral, antimicrobial, anticancer, hepatoprotective, antioxidant, neuroprotective, anti-diabetic, and clinical trials. This review paper consists of a total of 225 papers covering the Lonicera genus from 1800 to 2021, including research articles, reviews, patents, and book chapters.

RESULTS

In this review (1800s-2021), about 420 components from the genus of Lonicera Linn. including 87 flavonoids, 222 terpenoids, 51 organic acids, and other compounds, together with their pharmacological activities including anti-inflammatory, antiviral, antimicrobial, anticancer, hepatoprotective, antioxidant, neuroprotective, antidiabetic, anti-allergic, immunomodulatory effects, and toxicity were summarized.

CONCLUSION

The relationship is discussed among their traditional usage, their pharmacological properties, and their chemical components, which indicate the genus Lonicera have a large prospect in terms of new drug exploitation, especially in COVID-19 treatment.

Pharmacological Effects and Underlying Mechanisms of Licorice-Derived Flavonoids

Glycyrrhizae Radix et Rhizoma is the most frequently prescribed natural medicine in China and has been used for more than 2,000 years. The flavonoids of licorice have garnered considerable attention in recent decades due to their structural diversity and myriad pharmacological effects, especially as novel therapeutic agents against inflammation and cancer. Although many articles have been published to summarize different pharmacological activities of licorice in recent years, the systematic summary for flavonoid components is not comprehensive. Therefore, in this review, we summarized the pharmacological and mechanistic data from recent researches on licorice flavonoids and their bioactive components.

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.

Novel Antioxidants and α-Glycosidase and Protein Tyrosine Phosphatase 1B Inhibitors from an Endophytic Fungus Penicillium brefeldianum F4a

Oxidative stress plays a very important role in the progression of diabetes and its complications. A therapeutic agent that is both antidiabetic and antioxidant would be the preferred choice for the treatment of diabetes. The crude extract of the endophytic fungus Penicillium brefeldianum F4a has significant antioxidant and α-glycosidase and protein tyrosine phosphatase 1B (PTP1B) inhibition activities. Chemical investigation of P. brefeldianum F4a using an activity-guided isolation led to the discovery of three new compounds called peniorcinols A-C (1-3) along with six known compounds: penialidins A (4), penialidin F (5), myxotrichin C (6), riboflavin (7), indole-3-acetic acid (8), and 2-(4-hydroxy-2-methoxy-6-methylphenyl) acetic acid (9). Their chemical structures were established by their NMR and HRESIMS. The absolute configurations of 1 and 3 were determined by experimental and calculated electronic circular dichroism (ECD). Their antioxidant activities were evaluated by DPPH• and ABTS•+ scavenging assays. Compounds 1-6 and 8-9 showed moderate to strong free radical scavenging activities. Significantly, 4-6 exhibited more potent ABTS•+ scavenging activity than that of the positive control. Their α-glycosidase and PTP1B inhibition activities were tested. Among them, compound 3 showed α-glucosidase inhibition activity, and compounds 7 and 8 showed PTP1B inhibitory activity for the first time. It is worth noting that 3 and 8 displayed both antioxidant and α-glycosidase or PTP1B inhibition activities. These finding suggest that compounds 3 and 8 could be used as lead compounds to generate new potent drugs for the treatment of oxidative stress-related diabetes.

A Review on Antidiabetic Activity of Centaurea spp.: A New Approach for Developing Herbal Remedies

Objective

Diabetes mellitus (DM) is a long-life metabolic disorder, characterized by high blood glucose levels. The hyperglycemic condition generally leads to irreversible nerve injury and vascular damage. Among different types of diabetes, type 2 is more common and has spread all over the world. Although various therapeutic approaches have been developed to control type 2 DM, regulating blood glucose levels has still remained a controversial challenge for patients. Also, most prescription drugs cause different side effects, such as gastrointestinal disorders. Thus, developing novel and efficient antidiabetic agents possessing fewer adverse effects is in high demand.

Method

The literature was comprehensively surveyed via search engines such as Google Scholar, PubMed, and Scopus using appropriate keywords.

Results

Medicinal plants, both extracts and isolated active components, have played a significant role in controlling the blood glucose levels. Good-to-excellent results documented in the literature have made them a precious origin for developing and designing drugs and supplements against DM. Centaurea spp. have been traditionally used for controlling high blood glucose levels. Also, the antidiabetic properties of different species of Centaurea have been confirmed in recent studies through in vitro assays as well as in vivo experiments.

Conclusion

Potent results encouraged us to review their efficacy to open a new horizon for development of herbal antidiabetic agents.

Hypoglycemic Effects of Licochalcone A on the Streptozotocin-Induced Diabetic Mice and Its Mechanism Study

Type 2 diabetes mellitus (T2DM) is a type of metabolic illness based on relatively insufficient insulin secretion and insulin resistance (IR) as pathophysiological bases. Currently, it is the main type of diabetes. Hypoglycemic and hypolipidemic effects of licochalcone A (LicA) on high-fat diet and streptozocin-caused T2DM were studied. LicA can remarkably decline the IR index and blood glucose and serum lipid levels. Also, the treatment of LicA can improve the "three more and one less" phenomenon in T2DM mice, such as excessive drinking, eating, urine, and weight loss. In addition, LicA can improve oral glucose tolerance, pancreatic injury, and liver enlargement in T2DM mice. Network pharmacology analysis demonstrated that the observed pharmacological effects were mediated by regulating the insulin signal transduction pathway. Therefore, the PI3K/Akt-signaling pathway was selected for verification; it was demonstrated that LicA could improve the insulin-signaling pathway, protect islet cells, improve IR, reduce blood glucose levels, and alleviate lipid metabolism disorder. Its mechanism of influence may be closely related to LicA up-regulating the liver and pancreas IRS-2/PI3K/AKT-signaling pathway. Among them, the high-dose group of LicA had the best effect, which provided an idea for the use of LicA as a nutritional agent in the cure of T2DM.

A comprehensive review on the antidiabetic activity of flavonoids targeting PTP1B and DPP-4: a structure-activity relationship analysis

Type 2 diabetes (T2D) is an expanding global health problem, resulting from defects in insulin secretion and/or insulin resistance. In the past few years, both protein tyrosine phosphatase 1B (PTP1B) and dipeptidyl peptidase-4 (DPP-4), as well as their role in T2D, have attracted the attention of the scientific community. PTP1B plays an important role in insulin resistance and is currently one of the most promising targets for the treatment of T2D, since no available PTP1B inhibitors were still approved. DPP-4 inhibitors are among the most recent agents used in the treatment of T2D (although its use has been associated with possible cardiovascular adverse events). The antidiabetic properties of flavonoids are well-recognized, and include inhibitory effects on the above enzymes, although hitherto not therapeutically explored. In the present study, a comprehensive review of the literature of both synthetic and natural isolated flavonoids as inhibitors of PTP1B and DPP-4 activities is made, including their type of inhibition and experimental conditions, and structure-activity relationship, covering a total of 351 compounds. We intend to provide the most favorable chemical features of flavonoids for the inhibition of PTP1B and DPP-4, gathering information for the future development of compounds with improved potential as T2D therapeutic agents.

Flavonoids as potential agents in the management of type 2 diabetes through the modulation of α-amylase and α-glucosidase activity: a review

Type 2 diabetes (T2D) is one of the most prevalent metabolic diseases worldwide and is characterized by increased postprandial hyperglycemia (PPHG). α-Amylase and α-glucosidase inhibitors have been shown to slow the release of glucose from starch and oligosaccharides, resulting in a delay of glucose absorption and a reduction in postprandial blood glucose levels. Since current α-glucosidase inhibitors used in the management of T2D, such as acarbose, have been associated to strong gastrointestinal side effects, the search for novel and safer drugs is considered a hot topic of research. Flavonoids are phenolic compounds widely distributed in the Plant Kingdom and important components of the human diet. These compounds have shown promising antidiabetic activities, including the inhibition of α-amylase and α-glucosidase. The aim of this review is to provide an overview on the scientific literature concerning the structure-activity relationship of flavonoids in inhibiting α-amylase and α-glucosidase, including their type of inhibition and experimental procedures applied. For this purpose, a total of 500 compounds is covered in this review. Available data may be considered of high value for the design and development of novel flavonoid derivatives with effective and potent inhibitory activity against those carbohydrate-hydrolyzing enzymes, to be possibly used as safer alternatives for the regulation of PPHG in T2D.

Aldose reductase and protein tyrosine phosphatase 1B inhibitors as a promising therapeutic approach for diabetes mellitus

Diabetes mellitus is a metabolic disease characterized by high blood glucose levels and usually associated with several chronic pathologies. Aldose reductase and protein tyrosine phosphatase 1B enzymes have identified as two novel molecular targets associated with the onset and progression of type II diabetes and related comorbidities. Although many inhibitors against these enzymes have already found in the field of diabetic mellitus, the research for discovering more effective and selective agents with optimal pharmacokinetic properties continues. In addition, dual inhibition of these target proteins has proved as a promising therapeutic approach. A variety of diverse scaffolds are presented in this review for the future design of potent and selective inhibitors of aldose reductase and protein tyrosine phosphatase 1B based on the most important structural features of both enzymes. The discovery of novel dual aldose reductase and protein tyrosine phosphatase 1B inhibitors could be effective therapeutic molecules for the treatment of insulin-resistant type II diabetes mellitus. The methods used comprise a literature survey and X-ray crystal structures derived from Protein Databank (PDB). Despite the available therapeutic options for type II diabetes mellitus, the inhibitors of aldose reductase and protein tyrosine phosphatase 1B could be two promising approaches for the effective treatment of hyperglycemia and diabetes-associated pathologies. Due to the poor pharmacokinetic profile and low in vivo efficacy of existing inhibitors of both targets, the research turned to more selective and cell-permeable agents as well as multi-target molecules.

Synthesis of triterpenoid derivatives and their anti-tumor and anti-hepatic fibrosis activities

Oleanolic acid (1), ursolic acid (2), hederagenin (3), betulinol (4), betulinic acid (5), and glycyrrhetinic acid (6) are obtained from acorn/licorice industrial wastes with common triterpenoid structure as a model set for esterification. Eight 3,4,5-methoxybenzoyl triterpenoid derivatives (1a-6a), including four new derivatives (1a, 3a-1, 3a-2, and 3a-3), are synthesized by classical procedures. Their antitumor and anti-hepatic fibrosis activities are evaluated on four human tumor cell lines and t-HSC/Cl-6 cells. Derivative 1a shows maximum antiproliferative effects against all cell lines, especially against tumor cells with IC50 values in the range of 5.32-15.23 μM, but does not affect the viability of normal cells. The anti-tumor mechanisms of 1a are also investigated by western blot and docking studies. The 3,4,5-methoxybenzoyl triterpenoids offers an intriguing solution for naturally derived antitumor drugs and may be invaluable for further development of cancer therapy.

Lonicerae japonicae flos and Lonicerae flos: a systematic review of ethnopharmacology, phytochemistry and pharmacology

Lonicerae japonicae flos (called Jinyinhua, JYH in Chinese), flowers or flower buds of Lonicera japonica Thunberg, is an extremely used traditional edible-medicinal herb. Pharmacological studies have already proved JYH ideal clinical therapeutic effects on inflammation and infectious diseases and prominent effects on multiple targets in vitro and in vivo, such as pro-inflammatory protein inducible nitric oxide synthase, toll-like receptor 4, interleukin-1 receptor. JYH and Lonicerae flos [called Shanyinhua, SYH in Chinese, flowers or flower buds of Lonicera hypoglauca Miquel, Lonicera confusa De Candolle or Lonicera macrantha (D.Don) Spreng] which belongs to the same family of JYH were once recorded as same herb in multiple versions of Chinese Pharmacopoeia (ChP). However, they were listed as two different herbs in 2005 Edition ChP, leading to endless controversy since they have close proximity on plant species, appearances and functions, together with traditional applications. In the past decades, there has no literature regarding to systematical comparison on the similarity concerning research achievements of the two herbs. This review comprehensively presents similarities and differences between JYH and SYH retrospectively, particularly proposing them the marked differences in botanies, phytochemistry and pharmacological activities which can be used as evidence of separate list of JYH and SYH. Furthermore, deficiencies on present studies have also been discussed so as to further research could use for reference.

The effects of naringin on different cyclophosphamide-induced organ toxicities in rats: investigation of changes in some metabolic enzyme activities

Cyclophosphamide (CYP) is a common anticancer drug used in the treatment of various malignancies. Naringin (NG) is a natural bioflavonoid that have been reported to have many medicinal and pharmacological properties. Acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carbonic anhydrase (CA), α-glycosidase (α-Gly), and aldose reductase (AR) enzymes are the essential biological molecules needed for metabolic processes in all living cells. In the present study, the aim was to investigate the effect of NG against CYP-induced liver, brain, kidney, heart, and testis toxicities on some metabolic enzyme activities such as AChE, BChE, CA, α-Gly, and AR. Thirty-five male Wistar rats were randomly divided into five groups with each group consisting of seven rats. The rats were subjected to oral treatment of NG (50 and 100 mg/kg body weight) for 7 days before administering a single dose of CYP (200 mg/kg body weight, i.p) on the seventh day. Treatment with NG in all tissues regulated these enzyme activities in CYP-induced rats. The results of this study showed that NG regulates abnormal increases and decreases in CYP-induced metabolic enzyme activities in all tissues.

The Chinese herbal formulae (Yitangkang) exerts an antidiabetic effect through the regulation of substance metabolism and energy metabolism in type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Type 2 diabetes mellitus (T2DM) regarded as a "hot" disease in traditional Chinese medicine (TCM). Accordingly, TCM uses a cold drug or formula such as the Chinese herbal formulae "Yitangkang" (YTK) as a treatment. YTK exhibited a good clinical antidiabetic effect in several experiments. The correlation between the properties of a TCM drug or formula and its ability to regulate the substance metabolism, the energy metabolism and the endocrine system has been proven.

AIM OF THE STUDY

The present study aiming to evaluate the mechanism of antidiabetic action of YTK from the above perspective.

MATERIALS AND METHODS

Three groups of streptozotocin (STZ)-diabetic rats have been treated with YTK at oral doses of 56 g/kg/d, 28 g/kg/d and 14 g/kg/d for 28 days using metformin as a reference drug. After treatment, several indices correlated with energy metabolism (superoxide dismutase, glutathione peroxidase, lactic dehydrogenase, adenotriphos, creatine phosphate kinase, AMPK, Na⁺-K⁺-ATPase and Respiratory Chain Complex I, II, III, IV), substance metabolism (hepatic glycogen, acetyl-coenzyme A, pyruvic acid, adipose triglyceride lipase, triglycerides, high-density lipoproteins, low-density lipoproteins, malonyldialdehyde), endocrine system (triiodothyronine, thyroxine, 17-hydroxycorticosteroid) and cyclic nucleotide system (cyclic adenosine monophosphate, cyclic guanosine monophosphate) have been determined. The specialty and tendency of YTK's effects were analyzed to elucidate its property and mechanism of action according to the theory of TCM.

RESULTS

Our findings showed that the formulae YTK could effectively regulate the levels of blood glucose, HbA1c, glucagon-like peptide-1, and significantly down-regulate the substance metabolism, energy metabolism and endocrine system indices of the diabetic rats.

CONCLUSION

These results were consistent with the TCM description of YTK as a "cold" treatment. It could provide an effective way to interpret the scientific connotation and comprehensive system of the Chinese herbal formulae.

Effects of phytochemicals against diabetes

Diabetes mellitus, a chronic metabolic disease, characterized by elevated levels of blood glucose and insufficiency in production and action of insulin is the seventh leading cause of death worldwide. Numerous studies have shown that diabetes mellitus is associated with increased formation of free radicals and decrease in antioxidant potential. In the patients with diabetes mellitus, the levels of antioxidant parameters are found to decrease, hence in many studies phytochemicals which can exert antioxidant and free radical scavenging activities, are suggested to improve the insulin sensitivity. Several phytoactive compounds such as flavonoids, lignans, prophenylphenols, are also found to combat the complications of diabetes. This chapter mainly focuses on the relationship between diabetes mellitus and preventive roles of various phytochemicals on diabetes via their antioxidant properties.

Enrichment of total flavones and licochalcone A from licorice residues and its hypoglycemic activity

Industrial processing of glycyrrhizic leads to a lot of residues which are usually threw away randomly or used as feed. Therefore, the purpose of this study was to study licorice residues as a source of bioactive compounds with potentially applications. In this study, the enrichment and purification of total flavones from the licorice residues was achieved by using macroporous resins. The performances and separation characteristics of four selected macroporous resins with different chemical and physical properties were investigated. HPD-100 resin was the most effective, the content of total flavones increased from 50.94% in the original extract to 82.98% in the 80% ethanol fraction (a 1.63-fold increase). Further purification treatment by polyamide resin, licochalcone A with a purity of 80.28% was obtained in a 45% ethanol fraction, and a higher purity (>85%) of licochalcone A can be obtained by single crystallization operation. And hypoglycemic effect of the total flavones from licorice residues on high fat diet and STZ induced diabetic c57 mice was preliminary investigated. The results showed: the fasting blood glucose of mice in the low and medium dose total flavones group decreased significantly. The proposed technique is uncomplicated, easily managed, cost-effective, and environmentally friendly and is proper for both large-scale licorice residues application and waste management.

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.

Inhibition of protein tyrosine phosphatase 1B by flavonoids: A structure - activity relationship study

The classical non-transmembrane protein tyrosine phosphatase 1B (PTP1B) has emerged as a key negative regulator of insulin signaling pathways that leads to insulin resistance, turning this enzyme a promising therapeutic target in the management of type 2 diabetes mellitus (T2DM). In the present work, the in vitro inhibitory activity of a panel of structurally related flavonoids, for recombinant human PTP1B was studied and the type of inhibition of the most active compounds further evaluated. The majority of the studied flavonoids was tested in this work for the first time, including flavonoid C13, which was the most potent inhibitor. It was observed that the ability to inhibit PTP1B depends on the nature, position and number of substituents in the flavonoid structure, as the presence of both 7- and 8-OBn groups in the A ring, together with the presence of both 3' and 4'-OMe groups in the B ring and the 3-OH group in the C ring; these substituents increase the flavonoids' ability to inhibit PTP1B. In conclusion, some of the tested flavonoids seem to be promising PTP1B inhibitors and potential effective agents in the management of T2DM, by increasing insulin sensitivity.

A simple and visible colorimetric method through Zr4+–phosphate coordination for the assay of protein tyrosine phosphatase 1B and screening of its inhibitors

Inhibitors of protein tyrosine phosphatase 1B (PTP1B) are promising agents for the treatment of type 2 diabetes and obesity, so a colorimetric method has been developed in this work for PTP1B assay and screening of its inhibitors.