Protein tyrosine phosphatase 1B (PTP1B) inhibitory activity and glucosidase inhibitory activity of compounds isolated from Agrimonia pilosa

Flavonoids as dual-target inhibitors against α-glucosidase and α-amylase: a systematic review of in vitro studies

Diabetes mellitus remains a major global health issue, and great attention is directed at natural therapeutics. This systematic review aimed to assess the potential of flavonoids as antidiabetic agents by investigating their inhibitory effects on α-glucosidase and α-amylase, two key enzymes involved in starch digestion. Six scientific databases (PubMed, Virtual Health Library, EMBASE, SCOPUS, Web of Science, and WHO Global Index Medicus) were searched until August 21, 2022, for in vitro studies reporting IC50 values of purified flavonoids on α-amylase and α-glucosidase, along with corresponding data for acarbose as a positive control. A total of 339 eligible articles were analyzed, resulting in the retrieval of 1643 flavonoid structures. These structures were rigorously standardized and curated, yielding 974 unique compounds, among which 177 flavonoids exhibited inhibition of both α-glucosidase and α-amylase are presented. Quality assessment utilizing a modified CONSORT checklist and structure-activity relationship (SAR) analysis were performed, revealing crucial features for the simultaneous inhibition of flavonoids against both enzymes. Moreover, the review also addressed several limitations in the current research landscape and proposed potential solutions. The curated datasets are available online at https://github.com/MedChemUMP/FDIGA .

Anti-Inflammatory Flavonoids from Agrimonia pilosa Ledeb: Focusing on Activity-Guided Isolation

To elucidate the anti-inflammatory properties and constituents of Agrimonia pilosa Ledeb. (A. pilosa), a comprehensive investigation was conducted employing activity-guided isolation. The anti-inflammatory effects were evaluated through an in vitro nitric oxide (NO) assay on lipopolysaccharide (LPS)-treated RAW 264.7 macrophage cells. Seven bio-active compounds with anti-inflammatory properties were successfully isolated from the butanol fraction and identified as follows: quercetin-7-O-β-d-rhamnoside (1), apigenin-7-O-β-d-glucopyranoside (2), kaempferol-7-O-β-d-glucopyranoside (3), quercetin (4), kaempferol (5), apigenin (6), and apigenin-7-O-β-d-glucuronide-6″-butylester (7). All isolated compounds showed strong NO inhibitory activity with IC50 values ranging from 1.4 to 31 µM. Compound 6 demonstrated the most potent NO inhibition. Compound 7, a rare flavonoid, was discerned as a novel anti-inflammatory agent, ascertained through its inaugural demonstration of nitric oxide inhibition. Subsequently, a comprehensive structure-activity relationship (SAR) analysis was conducted employing eight flavonoids derived from A. pilosa. The outcomes elucidated that flavones exhibit superior NO inhibitory effects compared to flavonols, and the aglycone form manifests greater potency in NO inhibition than the glycone counterpart. These results highlight A. pilosa as a promising source of effective anti-inflammatory agents and indicate its potential as a health-beneficial dietary supplement and therapeutic material.

Enzyme immobilized on magnetic fluorescent bifunctional nanoparticles for α-glucosidase inhibitors virtual screening from Agrimonia pilosa Ledeb extracts accompanied with molecular modeling

Agrimonia pilosa Ledeb (APL) is a significant source of inhibitors for α-glucosidase, which is an essential target enzyme for the treatment of type 2 diabetes, cancer and acquired immune deficiency syndrome. Ligand fishing is a suitable approach for the highly selective screening of bioactive substances in complex mixtures. Yet it is unable to conduct biomedical imaging screening, which is crucial for real-time identification. In this case, a bioanalytical platform combining magnetic fluorescent ligand fishing and in-situ imaging technique was established for the screening and identification of α-glucosidase inhibitors (AGIs) from APL crude extract, utilizing α-glucosidase coated CuInS2/ZnS-Fe3O4@SiO2 (AG-CIZSFS) nanocomposites as extracting material and fluorescent tracer. The AG-CIZSFS nanocomposites prepared through solvothermal and crosslinking methods displayed fast magnetic separation, excellent fluorescence performance and high enzyme activity. The tolerance of immobilized enzyme to temperature and pH was stronger than that of free enzyme. Prior to proof-of-concept with APL crude extract, a number essential parameters (glutaraldehyde concentration, immobilized time, enzyme amount, reaction solution pH, incubation temperature, incubation time, percentage of methanol in eluen, elution times and eluent volume) were optimized using an artificial test mixture. The fished ligands were identified by UPLC-MS/MS and their biological activities were preliminarily evaluated by real-time cellular morphological imaging of human colon carcinoma (HCT-116) cells based on confocal laser scanning microscope (CLSM). Their α-glucosidase inhibitory activities were further verified and studied by classical pNPG method and molecular docking. The isolated compounds exhibited significant α-glucosidase inhibitory activities with a IC50 value of 11.57 µg·mL-1. Six potential AGIs including tribuloside, ivorengenin A, tormentic acid, 1β, 2β, 3β, 19α-Tetra hydroxyurs-12-en-28-oic acid, corosolic acid and pomolic acid were ultimately screened out and identified from APL crude extracts. The proposed approach, which combined highly specific screening with in-situ visual imaging, provided a powerful platform for discovering bioactive components from multi-component and multi-target traditional Chinese medicine (TCM).

Discovery of inhibitors of protein tyrosine phosphatase 1B contained in a natural products library from Mexican medicinal plants and fungi using a combination of enzymatic and in silico methods*

This work aimed to discover protein tyrosine phosphatase 1B (PTP1B) inhibitors from a small molecule library of natural products (NPs) derived from selected Mexican medicinal plants and fungi to find new hits for developing antidiabetic drugs. The products showing similar IC50 values to ursolic acid (UA) (positive control, IC50 = 26.5) were considered hits. These compounds were canophyllol (1), 5-O-(β-D-glucopyranosyl)-7-methoxy-3',4'-dihydroxy-4-phenylcoumarin (2), 3,4-dimethoxy-2,5-phenanthrenediol (3), masticadienonic acid (4), 4',5,6-trihydroxy-3',7-dimethoxyflavone (5), E/Z vermelhotin (6), tajixanthone hydrate (7), quercetin-3-O-(6″-benzoyl)-β-D-galactoside (8), lichexanthone (9), melianodiol (10), and confusarin (11). According to the double-reciprocal plots, 1 was a non-competitive inhibitor, 3 a mixed-type, and 6 competitive. The chemical space analysis of the hits (IC50 < 100 μM) and compounds possessing activity (IC50 in the range of 100-1,000 μM) with the BIOFACQUIM library indicated that the active molecules are chemically diverse, covering most of the known Mexican NPs' chemical space. Finally, a structure-activity similarity (SAS) map was built using the Tanimoto similarity index and PTP1B absolute inhibitory activity, which allows the identification of seven scaffold hops, namely, compounds 3, 5, 6, 7, 8, 9, and 11. Canophyllol (1), on the other hand, is a true analog of UA since it is an SAR continuous zone of the SAS map.

New Halogenated Flavonoids from Adenosma bracteosum and Vitex negundo and Their α-Glucosidase Inhibition

Adenosma bracteosum and Vitex negundo are natural sources of methoxylated flavonoids. Little is known about the α-glucosidase inhibition of multi-methoxylated flavonoid derivatives. Eighteen natural flavonoids were isolated from A. bracteosum and V. negundo. Seven halogenated derivatives were synthesized. Their chemical structures were elucidated by extensive NMR analysis and high-resolution mass spectroscopy as well as comparisons in literature. All compounds were evaluated for their α-glucosidase inhibition. Most compounds showed good activity with IC50 values ranging from 16.7 to 421.8 μM. 6,8-Dibromocatechin was the most active compound with an IC50 value of 16.7 μM. A molecular docking study was conducted, indicating that those compounds are potent α-glucosidase inhibitors.

Phytochemical and Pharmacological Research in Agrimonia eupatoria L. Herb Extract with Anti-Inflammatory and Hepatoprotective Properties

The most promising plant from the genus Agrimony (Agrimonia L.) of the Rosaceae family for use in medical practice is Agrimonia eupatoria L. Phytochemical and pharmacological research in Agrimonia eupatoria L. herb extract, obtained with using 40% ethanol solution as an extractant were carried out. A total of 11 free and 17 bound monosaccharides, 17 amino acids were found in the studied extract, 9 of which are essential. Gallic and ellagic acids, gallocatechin, epigallocatechin, catechin, epicatechin, and epicatechin gallate were identified in the extract of A. eupatoria by the HPLC method; as well as hydroxycinnamic acids: hydroxyphenylacetate, caffeic, syringic, p-coumaric, ferulic, sinapic, cinnamic and quinic acid; flavonoids: quercetin-3-D-glucoside (isoquercitrin), neohesperidin, naringenin, luteolin were found, and their quantitative content was determined, as well by spectrophotometric methods. The herb extract of A. eupatoria belongs to practically non-toxic substances and has pronounced anti-inflammatory (at a dose of 10.0 mg/kg anti-exudative activity reached a maximum in 5 h (88.17%)) and hepatoprotective activity (at a dose of 25 mg/kg it reduce AlAt level by 1.1 and 1.2 times, respectively; AsAt by 1.2 and 1.1 times, respectively), reduces the level of lipid peroxidation and stabilizes the membrane structures of liver cells. Thus, the herb extract of A. eupatoria is a promising substance for the creation of phytomedicines with anti-inflammatory and hepatoprotective activity.

Agrimonia Pilosa Ledeb.: A review of its traditional uses, botany, phytochemistry, pharmacology, and toxicology

Ethnopharmacological relevance

Agrimonia pilosa Ledeb. is the dried above-ground part of dragon's tooth grass, a plant of the Rosaceae family, which is widely distributed in China, Korea, and Japan. Agrimonia pilosa Ledeb. is a herbal medicine with great scope for development and use. It is astringent and hemostatic, and it is used for treating malaria, preventing dysentery, detoxification, and as a tonic for deficiency.

Aim of the review

We summarize the traditional uses, botanical and chemical composition, extraction methods, and pharmacological and toxicological progress of Agrimonia pilosa Ledeb. and discuss the future research trends and development prospects of this plant.

Materials and methods

Information on Agrimonia pilosa Ledeb. was gathered via the Internet (China National Knowledge Infrastructure, Google Scholar, PubMed, Web of Science, SpringerLink, Wiley, Wanfang Data, and Baidu Academic). Additional information was obtained from books (Ben Cao Tu Jing, A Textual Research on the Name and Reality of Plants, Modern Practical Chinese Medicine, Zhen Nan Ben Cao) and PhD and MS dissertations.

Results

Phytochemical studies have identified more than 252 compounds from Agrimonia pilosa Ledeb., including flavonoids, volatile oils, tannins, phenols, m-benzotrienols, pentacyclic triterpenoids, isocoumarins, lignans, organic acids, and other chemical constituents. The compounds and extracts isolated from Agrimonia pilosa Ledeb. show various pharmacological activities, including anti-inflammatory, anticancer, antitumor effects, antioxidant, analgesic effects, and other pharmacological effects.

Conclusion

This review highlights the botany, phytochemistry, pharmacology, toxicology, and traditional uses of Agrimonia pilosa Ledeb., providing a basis for future research and clinical applications. Agrimonia pilosa Ledeb. has shown remarkable effectiveness in the treatment of various diseases, especially enteritis, gastric ulcers, and gastrointestinal bleeding. Most prescriptions for Agrimonia pilosa Ledeb. are empirical and lack rigorous clinical observation. For these reasons, the toxicology, standardized clinical studies, nature of active ingredients, pharmacokinetics, mechanism, and metabolism of Agrimonia pilosa Ledeb. should be deepened, especially through clinical trials, to ensure the clinical safety of its use for further research.

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.

The triterpenoids and sesquiterpenoids from the plant of Agrimonia pilosa

A phytochemistry of the whole plant of Agrimonia pilosa led to the discovery of two new nortriterpenoids, agrimonorterpenes A and B (1 and 2), together with one known triterpenoid fupenzic acid (3) and seven known sesquiterpenoids (4-10). The new structures were determined as 19α-hydroxy-2-oxo-nor-A (3)-urs-11,12-dien-28-oic acid (1) and 2, 19β-dihydroxy-3-oxo-23-noroleana-1, 4, 12-trien-28-oic acid (2) by the spectroscopic data of UV, IR, HR-ESI-MS, and NMR. Notably, the structure of 1 possessed a rare five-membered A ring. And this is the first time to discover the sesquiterpenoids (4-10) from A. pilosa. Compound 3 displayed the selective cytotoxicity against HCT116, BGC823, and HepG2 cell lines with the IC₅₀ values of 16.31 μM, 21.94 μM, and 23.40 μM, respectively.

Natural α-Glucosidase and Protein Tyrosine Phosphatase 1B Inhibitors: A Source of Scaffold Molecules for Synthesis of New Multitarget Antidiabetic Drugs

Diabetes mellitus (DM) represents a group of metabolic disorders that leads to acute and long-term serious complications and is considered a worldwide sanitary emergence. Type 2 diabetes (T2D) represents about 90% of all cases of diabetes, and even if several drugs are actually available for its treatment, in the long term, they show limited effectiveness. Most traditional drugs are designed to act on a specific biological target, but the complexity of the current pathologies has demonstrated that molecules hitting more than one target may be safer and more effective. The purpose of this review is to shed light on the natural compounds known as α-glucosidase and Protein Tyrosine Phosphatase 1B (PTP1B) dual-inhibitors that could be used as lead compounds to generate new multitarget antidiabetic drugs for treatment of T2D.

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.

Gas Chromatography-Mass Spectrometry Coupled with Multivariate Statistical Analysis to Identify the Alpha Glucosidase Inhibitors from Flesh of Salacca zalacca Fruits and Their Molecular Docking Studies

Fruit of salak (Salaaca zalacca) is traditionally used and commercialized as an antidiabetic agent. However, scientific evidence to prove this folk claim is quite lacking. Therefore, this research was aimed to evaluate the α-glucosidase inhibition activity of S. zalacca fruit and identify the bioactive compounds. The fruits were extracted by different ratios of ethanol and water (0, 20, 40, 60, 80, 100%, v/v) to get E0 (100% water), E20 (20% ethanol), E40 (40% ethanol), E60 (60% ethanol), E80 (80% ethanol), and E100 (100% ethanol) extracts. The extracts obtained were subjected to the α-glucosidase inhibitory assay. Gas chromatography-mass spectrometry- (GC-MS-) based metabolomics approach was used in profiling the bioactive metabolites present in the extracts. Orthogonal partial least square (OPLS) was used to correlate GC-MS data and α-glucosidase assay results to identify the possible chemical markers. All active compounds identified were subjected to molecular docking. The extracts from the S. zalacca fruit showed potent inhibition activity against α-glucosidase. The IC50 values from the α-glucosidase inhibitory assay ranged between 16 and 275 µg/ml. Overall, E60 displayed significantly higher α-glucosidase inhibition activity, while E0 showed the lowest α-glucosidase inhibition activity. Major compounds detected in S. zalacca fruits were sugars, fatty acids, and sterols, including myo-inositol, palmitic acid, stearic acid, and β-sitosterol. Moreover, the results obtained from molecular docking indicated that palmitic acid and β-sitosterol were close to the active side of the enzyme. Some of the residues that interacted include HID295, ASN259, LEU313, LYS125, PHE159, VAL216, PHE178, TYR72, TYR158, HIE315, ARG315, and PHE303. The bioassay result strongly suggests that E60 extract from S. zalacca fruits has potential α-glucosidase inhibitory activity. The hydrophobic compounds, including palmitic acid and β-sitosterol, were found to induce the α-glucosidase inhibition activity.

Effects of Hydroxyl Group on the Interaction of Carboxylated Flavonoid Derivatives with S. Cerevisiae α-Glucosidase

Introduction

Carboxyalkyl flavonoids derivatives are considered as effective inhibitors in reducing post-prandial hyperglycaemia.

Methods

Combined with Density Functional Theory (DFT) and the theory of Atoms in Molecules (AIM), molecular docking and charge density analysis are carried out to understand the molecular flexibility, charge density distribution and the electrostatic properties of these carboxyalkyl derivatives.

Results

Results show that the electron density of the chemical bond C14-O17 on B ring of molecule II increases while O17-H18 decreases at the active site, suggesting the existence of weak non-covalent interactions, most prominent of which are H-bonding and electrostatic interaction. When hydroxyl groups are introduced, the highest positive electrostatic potentials are distributed near the B ring hydroxyl hydrogen atom and the carboxyl hydrogen atom on the A ring. It was reported that quercetin has a considerably inhibitory activity to S. cerevisiae α-glucosidase, from the binding affinities, it is suggested that the position and number of hydroxyl groups on the B and C rings are also pivotal to the hypoglycemic activity when the long carboxyalkyl group is introduced into the A ring.

Conclusion

It is concluded that the presence of three well-defined zones in the structure, both hydrophobicity alkyl, hydrophilicity carboxyl and hydroxyl groups are necessary.

Phenolome of Asian Agrimony Tea (Agrimonia asiatica Juz., Rosaceae): LC-MS Profile, α-Glucosidase Inhibitory Potential and Stability

Functional beverages constitute the rapidly increasing part of the functional food section and represent an area with a wide range of products including herbal-based beverages. We carried out screening investigations of the extracts of 85 Rosaceous tea plants. Among the extracts analyzed Agrimonia asiatica herb extract demonstrated the highest inhibitory activity against the enzyme α-glucosidase (20.29 µg/mL). As a result of chromato-mass-spectrometric profiling of A. asiatica herb with high-performance liquid chromatography with photodiode array and electrospray triple quadrupole mass-spectrometric detection (HPLC-PDA-ESI-tQ-MS) 60 compounds were identified, including catechins, ellagitannins, flavones, flavonols, gallotannins, hydroxycinnamates, procyanidins, most for the very first time. The analysis of the seasonal variation of metabolites in A. asiatica herb demonstrated that the phenolic content was highest in summer samples and lower in spring and autumn. HPLC activity-based profiling was utilized to identify compounds of A. asiatica herb with the maximal α-glucosidase inhibitory activity. The most pronounced inhibition of α-glucosidase was observed for agrimoniin, while less significant results of inhibition were revealed for ellagic acid and isoquercitrin. The evaluation of phenolic content in A. asiatica herbal teas with the subsequent determination of α-glucosidase inhibiting potential was discovered. Maximum inhibition of α-glucosidase was observed for hot infusion (75.33 µg/mL) and the minimum for 30 min decoction (159.14 µg/mL). Our study demonstrated that A. asiatica herbal tea is a prospective functional beverage in which dietary intake may help to reduce blood glucose.

Synthesis, Antimicrobial Study, and Molecular Docking Simulation of 3,4-Dimethoxy-β-Nitrostyrene Derivatives as Candidate PTP1B Inhibitor

A derivative series of 3,4-dimethoxy-β-nitrostyrene was synthesized through nitroaldol reaction, including a new compound of 3,4-ethylenedioxy-β-bromo-β-nitrostyrene. The antimicrobial activity effect of 3,4-alkyloxy modification of β-nitrostyrene was investigated. A molecular docking study was also performed to obtain information about their interactions with protein tyrosine phosphatase 1B (PTP1B). The active residues of cysteine-215 and arginine-221 of PTP1B play a key role in signaling pathways that regulate various microorganism cell functions. It also acts as a negative regulator in signaling pathways of insulin that are involved in type 2 diabetes and other metabolic diseases. These derivatives exhibited potential antifungal activity. The studied compounds were also had potential as fragments to be PTP1B inhibitors by interacting with serine-216 and arginine-221 residues, according to their molecular docking. 3,4-Ethylenedioxy-β-methyl-β-nitrostyrene was the most successful potential candidate as a PTP1B inhibitor. However, further research is needed to investigate their potential for medicinal use.

A comparative study to elucidate the biological activities of crude extracts from rice bran and wheat bran in cell line models

The present study investigated the nutritional composition of bran from rice (RB) and wheat (WB) and compared the natural virtues of crude extracts based on phenolic composition, antidiabetic and anticancer activities. The profiling of phenolic-rich ethyl acetate extracts (RBE and WBE) confirms that RBE is rich in catechol (0.122 mg/g dw), p-coumaric acid (0.159 mg/g dw), kaempferol (0.374 mg/g dw) and apigenin (0.399 mg/g dw); and WBE is affluent with catechol (0.144 mg/g dw), ferulic acid (0.160 mg/g dw), caffeic acid (0.083 mg/g dw) and ellagic acid (0.074 mg/g dw). RBE exhibited better antioxidant activity, inhibited the activity of α-amylase (IC50-353.41 µg/mL) and α-glucosidase (IC50-314.22 µg/mL), hindered glycation process (IC50-451.11 µg/mL), and enhanced glucose uptake in L6 muscle cells (20.4%) indicating its potential in diabetic management. RBE was toxic to HT29 colon cancer cells and decreased cell membrane integrity. RBE and WBE arrested cell-cycle transition in HT29 cells from G0 to G1 and G2 to M phase respectively and induced apoptosis (27.15% and 5.9%, respectively for RBE and WBE) suggesting anticancer activities of the extract. The study indicates that bran from rice and wheat are a potential source of dietary fibre and phytochemicals with antidiabetic and anticancer properties for developing value-added products with nutraceutical benefits.

Antioxidant and Anti-Inflammatory Activities of Agrimonia pilosa Ledeb. Extract

The purpose of this study is to investigate the effect of Agrimonia pilosa Ledeb. extract (APLE) on lipopolysaccharide- (LPS-) induced cell damage in hepatocytes with a focus on antioxidant and anti-inflammatory activities. Total antioxidant and anti-inflammatory activities of APLE itself were analyzed and phytochemical analysis was performed. Moreover, inhibitory effects of APLE on LPS-induced oxidative stress and inflammation were assessed in human HepG2 hepatocytes. APLE was found to exert α,α-diphenyl-β-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), and nitrite scavenging activities and reducing power in a dose-dependent manner. The total phenolic and flavonoid contents of APLE were 44.30 ± 1.61 mg GAE/g and 29.65 ± 1.81 mg QE/g, respectively. HPLC analysis revealed that gallic acid is the major phenolic compound in APLE, followed by rutin, genistein, taxifolin, quercetin, luteolin, and apigenin, in descending order. Treatment of 100 and 200 μg/mL APLE significantly reduced LPS-stimulated intracellular reactive oxygen species production to the basal level without any cytotoxicity. Oppositely, APLE reversed LPS-suppressed expression of glutathione peroxidase gene and protein. Consistent with this result, APLE suppressed LPS-triggered expression of proinflammatory cytokine genes in a dose-dependent manner. These results reinforce the fact that the antioxidant and anti-inflammatory activity of APLE helps protect hepatocytes from LPS. Thus, APLE may be utilized as a bioactive ingredient in functional foods.

Isolation of Isocoumarins and Flavonoids as α-Glucosidase Inhibitors from Agrimonia pilosa L

Agrimonia pilosa L. (AP) showed potent α-glucosidase inhibitory (AGI) activity, but it is uncertain what phytochemicals play a key factor. The phytochemical study of AP based on AGI activity led to the isolation of four isocoumarins; agrimonolide (1), agrimonolide-6-O-β-d-glucopyranoside (2), desmethylagrimonolide (3), desmethylagrimonolide-6-O-β-d-glucopyranoside (4), and four flavonoids; luteolin (5), quercetin (6), vitexin (7), and isovitexin (8). The four isocoumarins were isolated as α-glucosidase inhibitors for the first time. Isocoumarins, compound 1 (agrimonolide) and 3 (desmethylagrimonolide) showed strong α-glucosidase inhibitory activities with IC₅₀ values of 24.2 and 37.4 µM, respectively. Meanwhile, isocoumarin and flavonoid glycosides showed weak AGI activity. In the kinetic analysis, isocoumarins, compounds 1 and 3 showed non-competitive inhibition, whereas flavonoid, compound 6 showed competitive inhibition.

PTP1B-Inhibiting Branched-Chain Fatty Acid Dimers from Eremophila oppositifolia subsp. angustifolia Identified by High-Resolution PTP1B Inhibition Profiling and HPLC-PDA-HRMS-SPE-NMR Analysis

Ten new branched-chain fatty acid (BCFA) dimers with a substituted cyclohexene structure, five new monomers, and two known monomers, (2E,4Z,6E)-5-(acetoxymethyl)tetradeca-2,4,6-trienoic acid and its 5-hydroxymethyl analogue, were identified in the leaf extract of Eremophila oppositifolia subsp. angustifolia using a combination of HPLC-PDA-HRMS-SPE-NMR analysis and semipreparative-scale HPLC. The dimers could be classified as three types of Diels-Alder reaction products formed between monomers at two different sites of unsaturation of the dienophile. Two of the monomers represent potential biosynthetic intermediates of branched-chain fatty acids. Several compounds were found by high-resolution bioactivity profiling to inhibit PTP1B and were purified subsequently by semipreparative-scale HPLC. The dimers were generally more potent than the monomers with IC₅₀ values ranging from 2 to 66 μM, compared to 38-484 μM for the monomers. The ten fatty acid dimers represent both a novel class of compounds and a novel class of PTP1B inhibitors.

Chemistry, Biological Activities and In Silico Bioprospection of Sterols and Triterpenes from Mexican Columnar Cactaceae

The Cactaceae family is an important source of triterpenes and sterols. The wide uses of those plants include food, gathering, medicinal, and live fences. Several studies have led to the isolation and characterization of many bioactive compounds. This review is focused on the chemistry and biological properties of sterols and triterpenes isolated mainly from some species with columnar and arborescent growth forms of Mexican Cactaceae. Regarding the biological properties of those compounds, apart from a few cases, their molecular mechanisms displayed are not still fully understand. To contribute to the above, computational chemistry tools have given a boost to traditional methods used in natural products research, allowing a more comprehensive exploration of chemistry and biological activities of isolated compounds and extracts. From this information an in silico bioprospection was carried out. The results suggest that sterols and triterpenoids present in Cactaceae have interesting substitution patterns that allow them to interact with some bio targets related to inflammation, metabolic diseases, and neurodegenerative processes. Thus, they should be considered as attractive leads for the development of drugs for the management of chronic degenerative diseases.

Protein Tyrosine Phosphatase (PTP1B): A promising Drug Target Against Life-threatening Ailments

Background:

Protein tyrosine phosphatases are enzymes which help in the signal transduction in diabetes, obesity, cancer, liver diseases and neurodegenerative diseases. PTP1B is the main member of this enzyme from the protein extract of human placenta. In phosphate inhibitors development, significant progress has been made over the last 10 years. In early-stage clinical trials, few compounds have reached whereas in the later stage trials or registration, yet none have progressed. Many researchers investigate different ways to improve the pharmacological properties of PTP1B inhibitors.

Objective:

In the present review, authors have summarized various aspects related to the involvement of PTP1B in various types of signal transduction mechanisms and its prominent role in various diseases like cancer, liver diseases and diabetes mellitus.

Conclusion:

There are still certain challenges for the selection of PTP1B as a drug target. Therefore, continuous future efforts are required to explore this target for the development of PTP inhibitors to treat the prevailing diseases associated with it.

Multidirectional insights into the biochemical and toxicological properties of Bougainvillea glabra (Choisy.) aerial parts: A functional approach for bioactive compounds

The current research work was conducted in order to probe into the biochemical and toxicological characterisation of methanol and dichloromethane (DCM) extracts of Bougainvillea glabra (Choisy.) aerial parts. Biological fingerprints were assessed for in vitro antioxidant, key enzyme inhibitory and cytotoxicity potential. Total bioactive contents were determined spectrophotometrically and the secondary metabolite components of methanol extract was assessed by UHPLC mass spectrometric analysis. The antioxidant capabilities were evaluated via six different in vitro antioxidant assays namely DPPH, ABTS (free radical scavenging), FRAP, CUPRAC (reducing antioxidant power), phosphomolybdenum (total antioxidant capacity) and ferrous chelating activity. Inhibition potential against key enzymes urease, α-glucosidase and cholinesterases were also determined. Methanol extract exhibited higher phenolic (24.01 mg GAE/g extract) as well as flavonoid (41.51 mg QE/g extract) contents. Phytochemical profiling of methanol extract identified a total of twenty secondary metabolites and the major compounds belonged to flavonoids, phenolics and alkaloid derivatives. The findings of antioxidant assays revealed the methanol extract to exhibit stronger antioxidant (except phosphomolybdenum) activities. Similarly, the methanol extract showed highest butyrylcholinesterase and urease inhibition. The DCM extract was most active for phosphomolybdenum and α-glucosidase inhibition assays. Moreover, both extracts exhibited significant cytotoxic potential against five (MCF-7, MDA-MB-231, CaSki, DU-145, and SW-480) human carcinoma cell lines with half maximal inhibitory concentration values of 22.09 to 257.2 μg/mL. Results from the present study highlighted the potential of B. glabra aerial extracts to be further explored in an endeavour to discover novel phytotherapeutics as well as functional ingredients.

A New Tannin from Fruits of Torreya Nucifera with Protein Tyrosine Phosphatase 1B Inhibitory Activity

A new compound 1, 3, 6-tri -O-galloyl-2- O-(4 - carboxylgalloyl)-β-D-glucopyranose (1), together with six known compounds (2-7) were isolated from EtOAc-soluble extract of fruits of Torreya nucifera. Their structures were elucidated on the basis of detailed spectroscopic and physico-chemical analyses. All the isolates were evaluated for in vitro inhibitory activity against PTP1B, VHR and PP1. Among them, new compound 1 was found to exhibit selective inhibitory activity on PTP1B with IC50 value 8.9 ± 1.4 μM.

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.

α-Glucosidase inhibition by flavonoids: an in vitro and in silico structure-activity relationship study

α-Glucosidase inhibitors are described as the most effective in reducing post-prandial hyperglycaemia (PPHG) from all available anti-diabetic drugs used in the management of type 2 diabetes mellitus. As flavonoids are promising modulators of this enzyme’s activity, a panel of 44 flavonoids, organised in five groups, was screened for their inhibitory activity of α-glucosidase, based on in vitro structure–activity relationship studies. Inhibitory kinetic analysis and molecular docking calculations were also applied for selected compounds. A flavonoid with two catechol groups in A- and B-rings, together with a 3-OH group at C-ring, was the most active, presenting an IC₅₀ much lower than the one found for the most widely prescribed α-glucosidase inhibitor, acarbose. The present work suggests that several of the studied flavonoids have the potential to be used as alternatives for the regulation of PPHG.

Probing the influence of carboxyalkyl groups on the molecular flexibility and the charge density of apigenin derivatives

Apigenin is an important flavonoids due to its antidiabetic bioactivity. It was reported experimentally that the 7-substituent derivative of apigenin has higher biological activity than 4'- and 5-substituted derivatives while introducing sole carboxyalkyl group -(CH₂)₇COOH into the parent structure. Molecular docking studies indicated that the other two derivatives have lower binding affinities than the 7-substituent derivative (-7.52 kcal mol^-1), which is considered to be a better inhibitor than the parent molecule. Almost all of the carbon atoms and oxygen atoms are coplaner for all three molecules in solution phase, however, all carboxyalkyl groups bend inside into the parent molecules in the active site, and the jagged geometries of the carbon chains are destroyed correspondingly. In addition, most of the electron densities of the chemical bonds for all molecules are decreased, especially the 7-substituent derivative. In contrast, most of the Laplacian values for three molecules are increased in the active site, which suggests that the charge densities at the bond critical point (bcp) are much more depleted than the solution phase. Dipole moments of derivatives are all increased in the active site, suggesting strong intermolecular interactions. After interacting with the S. cerevisiae α-glucosidase, only the 7-substituent derivative has the lowest energy gap ΔE _HOMO-LUMO, which indicates the lowest stability and the highest inhibition activity. Graphical abstract Probing the influence of carboxyalkyl groups on the molecular flexibility and the charge density of apigenin derivatives.