Synthesis and biological evaluation of novel thiadiazole amides as potent Cdc25B and PTP1B inhibitors

A series of novel thiadiazole amide derivatives have been synthesized and evaluated for inhibitory activities against Cdc25B and PTP1B. Most of them showed inhibitory activities against Cdc25B (IC₅₀ = 1.18–8.01 μg/mL) and PTP1B (IC₅₀ = 0.85–8.75 μg/mL), respectively. Moreover, compounds 5b and 4l were most potent with IC₅₀ values of 1.18 and 0.85 μg/mL for Cdc25B and PTP1B, respectively, compared with reference drugs Na₃VO₄ (IC₅₀ = 0.93 μg/mL) and oleanolic acid (IC₅₀ = 0.85 μg/mL). The results of selectivity experiments showed that the target compounds were selective inhibitors against PTP1B and Cdc25B. Enzyme kinetic experiments demonstrated that compound 5k was a specific inhibitor with the typical characteristics of a mixed inhibitor.     

Novel thiophene derivatives as PTP1B inhibitors with selectivity and cellular activity

A series of novel thiophene derivatives was designed, synthesized and their activities as competitive inhibitors of protein tyrosine phosphatase (PTPs) 1B (PTP1B) inhibitors were evaluated. All the compounds showed inhibitory potencies, and 10 of these exhibited moderate inhibitory activities with IC₅₀ values less than 10 μM. The activity of the most potent compound P28 (IC₅₀ = 2.1 μM) was 15 times higher than that of the hit compound P01. Further, four representative compounds (P19, P22, P28, and P31) demonstrated remarkably high selectivities against other PTPs (e.g., PTPα, LAR, CD45, and TCPTP); P19 exhibited greater than sixfold selectivity over highly homologous TCPTP. More importantly, these compounds are permeable to cell membranes. The treatment of CHO-K1 cells with P28 (10 μM) resulted in increased phosphorylation of AKT, which suggested extensive cellular activity of this compound. The novel chemical entities reported in this study could be used for overcoming the poor selectivity and low cellular activity of PTP1B inhibitors and might represent a starting point for development of therapeutic PTP inhibitors.     

Synthesis and biological evaluation of novel bis-aromatic amides as novel PTP1B inhibitors

A series of bis-aromatic amides was designed, synthesized, and evaluated as a new class of inhibitors with IC₅₀ values in the micromolar range against protein tyrosine phosphatase 1B (PTP1B). Among them, compound 15 displayed an IC₅₀ value of 2.34 ± 0.08 μM with 5-fold preference over TCPTP. More importantly, the treatment of CHO/HIR cells with compound 15 resulted in increased phosphorylation of insulin receptor (IR), which suggested extensive cellular activity of compound 15. These results provided novel lead compounds for the design of inhibitors of PTP1B as well as other PTPs.     

Synthesis and biological evaluation of heterocyclic ring-substituted maslinic acid derivatives as novel inhibitors of protein tyrosine phosphatase 1B

A series of maslinic acid derivatives have been synthesized by introducing various fused heterocyclic rings at C-2 and C-3 positions. Their inhibitory effects on PTP1B, TCPTP and related PTPs are evaluated. Most of the compounds exhibited a dramatic increase in inhibitory potency and selectivity, the two most potent PTP1B inhibitors 20 (IC₅₀ = 0.61 μM) and 29 (IC₅₀ = 0.64 μM) showed about 10-fold more potent than lead compound maslinic acid. More importantly, 29 possesses the best selectivity of 6.9-fold for PTP1B over TCPTP.     

Protein tyrosine phosphatase 1B inhibitory effects of depsidone and pseudodepsidone metabolites from the Antarctic lichen Stereocaulon alpinum

Seven phenolic lichen metabolites (1–7) have been isolated from a methanol extract of the Antarctic lichen Stereocaulon alpinum by various chromatographic methods. The structures of these compounds were determined mainly by analysis of NMR spectroscopic data. A depsidone-type compound, lobaric acid (1) and two pseudodepsidone-type compounds, 2 and 3, exhibited potent inhibitory activity against protein tyrosine phosphatase 1B (PTP1B) with IC₅₀ values of 0.87 μM, 6.86 μM, and 2.48 μM, respectively. Kinetic analyses of PTP1B inhibition by compounds 1 and 2 suggested that these compounds inhibited PTP1B activity in a non-competitive manner.     

New prenylated isoflavonoids as protein tyrosine phosphatase 1B (PTP1B) inhibitors from Erythrina addisoniae

Bioassay-guided fractionation of the EtOAc extract of the root of Erythrina addisoniae (Leguminosae) resulted in the isolation of four new (1–4), along with 2 known prenylated isoflavonoids (5–6). The structures of the isolates were assigned on the basis of spectroscopic data analysis, focusing on interpretation of 1D and 2D NMR, and MS data. All the isolates were evaluated for their inhibitory effects on protein tyrosine phosphatase 1B (PTP1B), as well as their growth inhibition on MCF7, adriamycin-resistant MCF7 (MCF7/ADR), and MDA-MB-231 breast cancer cell lines. Compounds which exhibited PTP1B inhibitory activity (IC₅₀ values ranging from 4.6 ± 0.3 to 24.2 ± 2.1 μM) showed potential cytotoxic activity (IC₅₀ values ranging from 3.97 ± 0.17 to 11.4 ± 1.9 μM). Taken together, our data suggest that prenylated isoflavonoids, especially the isoflavone-type skeleton could be considered as new lead compounds against breast cancer via PTP1B inhibition.     

Dammaranes from Gynostemma pentaphyllum and synthesis of their derivatives as inhibitors of protein tyrosine phosphatase 1B

Protein tyrosine phosphatase 1B (PTP1B) is a key factor in the negative regulation of insulin pathway and a promising target for treatment of diabetes and obesity. Herein, the sapogenin 2b, prepared from the natural triterpene saponin 1b, was modified at 3-position to establish the dammarane derivatives library via esterification, oxidation and reductive amination reaction and evaluated as PTP1B inhibitors. 3-O-para-Carboxylphenyl substituted derivative 5b was found with the best in vitro inhibition activity to protein tyrosine phosphatase 1B (IC₅₀ = 0.27 μM), where 3-O-meta-carboxylphenyl substituted 5a exhibited the best selectivity (nearly fivefolds) between PTP1B and T-cell protein tyrosine phosphatase.     

Design,synthesis and insulin-sensitising effects of novel PTP1B inhibitors

Fifteen novel sulfathiazole-related compounds were designed as PTP1B inhibitors based on a previously reported allosteric inhibitor (1) of PTP1B. These compounds were synthesized and evaluated against human recombinant PTP1B. Six compounds (3, 4, 8 and 14–16) exhibited significant inhibitory activity against PTP1B. The most active compound (16) showed IC₅₀ value of 3.2 μM and kinetic analysis indicated that it is a non-competitive inhibitor of PTP1B. Furthermore, compound 16 demonstrated excellent selectivity to PTP1B over other PTPs. It also displayed in vivo insulin sensitizing effect in the insulin resistant mice.     

A tetramic acid derivative with protein tyrosine phosphatase 1B inhibitory activity and a new nortriterpene glycoside from the Indonesian marine sponge Petrosia sp.

During the search for protein tyrosine phosphatase 1B (PTP1B) inhibitors from marine organisms, the known tetramic acid derivative, melophlin C (1), was isolated as an active component together with the new nortriterpenoid saponin, sarasinoside S (2), and three homologues: sarasinosides A₁ (3), I₁ (4), and J (5), from the Indonesian marine sponge Petrosia sp. The structure of 2 was elucidated on the basis of its spectroscopic data. Compound 1 inhibited PTP1B activity with an IC₅₀ value of 14.6 μM, while compounds 2–5 were not active at 15.2–16.0 μM. This is the first study to report the inhibitory effects of a tetramic acid derivative on PTP1B activity.     

Novel non-peptide β-secretase inhibitors derived from structure-based virtual screening and bioassay

This Letter describes an efficient approach by integrating virtual screening with bioassay technology for finding small organic inhibitors targeting β-secretase (BACE-1). Fifteen hits with inhibitory potencies ranging from 2.8 to 118 μM (IC₅₀) against β-secretase were successfully identified. Compound 12 with IC₅₀ of 2.8 μM is the most potent hit against BACE-1. Docking simulation from gold 3.0 suggests putative binding mode of 12 in BACE-1 and potential key pharmacophore groups for further designing of non-peptide compounds as more powerful inhibitors against BACE-1.     

Two new diphenyl ethers from Acanthopanax senticosus (Rupr. & Maxim.) Harms with PTP1B inhibitory activity

Bioassay-guided fractionation of an EtOAc-soluble extract of Acanthopanax senticosus (Rupr. & Maxim.) Harms yielded two new diphenyl ethers, 3-[3′-methoxy-4′-(4″-formyl-2″,6″-dimethoxy-phenoxy)-phenyl]-propenal (1) and 3-[3′,5′-dihydroxy-4′-(4″-hydroxymethyl-3″,5″-dimethoxy-phenoxy)-phenyl]-propenal (2), along with eight other known compounds (3–10). The structures of these new ethers were elucidated with spectroscopic and physico-chemical analyses. All of the isolates were evaluated for their in vitro inhibitory activity against PTP1B, VHR and PP1. The new compounds (1 and 2) inhibited PTP1B with IC₅₀ values ranging from 9.2 ± 1.4 to 12.6 ± 1.2 μM.     

Design,synthesis and docking study of 5-(substituted benzylidene)thiazolidine-2,4-dione derivatives as inhibitors of protein tyrosine phosphatase 1B

A series of novel 5-(substituted benzylidene)thiazolidine-2,4-dione derivatives was designed, and synthesized based on our previous studies. Also their activities were evaluated as competitive inhibitors of protein tyrosine phosphatase 1B (PTP1B). Compounds 6d–6g, 7b, 7c, 7e, 7j, 7k, 7m, 14b and 14e–14f showed potent inhibitory effects against PTP1B, and compound 7e, the most potent among the series, had an IC₅₀ of 4.6 μM. Also a Surflex-Dock docking model of 7e was studied. Compound 7e showed a negative binding energy of −7.35 kcal/mol and a high affinity to PTP1B residues (Gly220, Ala217, Arg221, Asp181, Ser216, Cys215, Phe182, Gln262 and Ile219) in the active sites, indicating that it may stabilize the open form and generate tighter binding to the catalytic sites of PTP1B.     

PTP1B inhibitors from Selaginella tamariscina (Beauv.) Spring and their kinetic properties and molecular docking simulation

Diabetes is one of the most popular worldwide diseases, regulated by the defects in insulin secretion, insulin action, or both. The overexpression of protein tyrosine phosphatase 1B (PTP1B) was found to down-regulate the insulin-receptor activation. PTP1B has been known as a strategy for the treatment of diabetes via the regulation of insulin signal transduction pathway. Herein, we investigated the PTP1B inhibitors isolated from natural sources. The chemical investigation of Selaginella tamariscina (Beauv.) Spring revealed seven unsaturated alkynyl phenols 1–7, four new selaginellins T–W 1–4 together with three known compounds 5–7 isolated from the aerial parts. The structures of the isolates were determined by spectroscopic techniques (1D/2D-NMR, MS, and CD). The inhibitory effects of these isolates on the PTP1B enzyme activity were investigated. Among them, compounds 2–7 significantly exhibited the inhibitory effects with the IC₅₀ values ranging from 4.8 to 15.9 μM. Compound 1 moderately displayed the inhibitory activity with an IC₅₀ of 57.9 μM. Furthermore, active compounds were discovered from their kinetic and molecular docking analysis. The results revealed that compounds 2 and 4–7 were mixed-competitive inhibitors, whereas compound 3 was a non-competitive inhibitor. This data confirm that these compounds exhibited potential inhibitory effect on the PTP1B enzyme activity.     

Ellagitannin and flavonoid constituents from Agrimonia pilosa Ledeb. with their protein tyrosine phosphatase and acetylcholinesterase inhibitory activities

A new ellagitannin, agritannin (1), a new flavone glycoside, agriflavone (2), and another flavone glycoside with spectroscopic data reported for the first time, kaempferol-3-O-[(S)-3-hydroxy-3-methylglutaryl (1→6)]-β-d-glucoside (3), along with 16 known compounds were isolated from the aerial parts of Agrimonia pilosa Ledeb. These compounds were evaluated for PTP1B inhibitory activity. Among them, compounds 9 and 18 displayed potential inhibitory activity against PTP1B with IC₅₀ values of 7.14 ± 1.75 and 7.73 ± 0.24 μM, respectively. In addition, compound 1 showed significant inhibitory effect with an IC₅₀ value of 17.03 ± 0.09 μM. Furthermore, these compounds were tested in AChE inhibitory assays. Most of them were found to have moderate inhibitory effects, with IC₅₀ values ranging from 60.20 ± 1.09 to 92.85 ± 1.12 μM. Except compounds 3, 8, and 18 were inactive.     

Synthesis and biological evaluation of 4,4-dimethyl lithocholic acid derivatives as novel inhibitors of protein tyrosine phosphatase 1B

Protein tyrosine phosphatase 1B (PTP1B) is a major negative regulator of both insulin and leptin signals. For years, inhibiting of PTP1B has been considered to be a potential therapeutics for treating Type 2 diabetes and obesity. Recently, we recognized lithocholic acid (LCA) as a natural inhibitor against PTP1B (IC₅₀ = 12.74 μM) by a vertical screen for the first time. Further SAR research was carried out by synthesizing and evaluating a series of compounds bearing two methyls at C-4 position and a fused heterocycle to ring A. Among them, compound 14b achieved a PTP1B inhibitory activity about eightfold than LCA and a 14-fold selectivity over the homogenous enzyme TCPTP.     

Y-shaped bis-arylethenesulfonic acid esters: Potential potent and membrane permeable protein tyrosine phosphatase 1B inhibitors

Known PTP1B inhibitors with bis-anionic moieties exhibit potent inhibitory activity, good selectivity, however, they are incapable of penetrating cellular membranes. Based upon our finding of a new pharmacophoric group in inhibition of PTP1B and the structural characteristics of the binding pocket of PTP1B, a series of bis-arylethenesulfonic acid ester derivatives were designed and synthesized. These novel molecules, particularly Y-shaped bis-arylethenesulfonic acid ester derivatives, exhibited high PTP1B inhibitory activity, moderate selectivity, and great potential in penetrating cellular membranes (compound 7p, CLog P = 9.73, P_app = 9.6 × 10^-6 cm/s; IC₅₀ = 140, 1290 and 920 nM on PTP1B, TCPTP and SHP2, respectively). Docking simulations suggested that these Y-shaped inhibitors might interact with multiple secondary binding sites in addition to the catalytic site of PTP1B.     

Highly potent tyrosinase inhibitor,neorauflavane from Campylotropis hirtella and inhibitory mechanism with molecular docking

Tyrosinase inhibition may be a means to alleviate not only skin hyperpigmentation but also neurodegeneration associated with Parkinson’s disease. In the course of metabolite analysis from tyrosinase inhibitory methanol extract (80% inhibition at 20 μg/ml) of Campylotropis hirtella, we isolated fourteen phenolic compounds, among which neorauflavane 3 emerged as a lead structure for tyrosinase inhibition. Neorauflavane 3 inhibited tyrosinase monophenolase activity with an IC₅₀ of 30 nM. Thus this compound is 400-fold more active than kojic acid. It also inhibited diphenolase (IC₅₀ = 500 nM), significantly. Another potent inhibitor 1 (IC₅₀ = 2.9 μM) was found to be the most abundant metabolite in C. hirtella. In kinetic studies, compounds 3 showed competitive inhibitory behavior against both monophenolase and diphenolase. It manifested simple reversible slow-binding inhibition against monophenolase with the following kinetic parameters: K_i^app = 1.48 nM, k₃ = 0.0033 nM⁻¹ min⁻¹ and k₄ = 0.0049 min⁻¹. Neorauflavane 3 efficiently reduced melanin content in B16 melanoma cells with 12.95 μM of IC₅₀. To develop a pharmacophore model, we explored the binding mode of neuroflavane 3 in the active site of tyrosinase. Docking results show that resorcinol motif of B-ring and methoxy group in A-ring play crucial roles in the binding the enzyme.     

Design,synthesis and biological evaluation of new 2,3-diarylquinoline derivatives as selective cyclooxygenase-2 inhibitors

A new group of 2,3-diarylquinoline derivatives possessing a methylsulfonyl COX-2 pharmacophore at the para-position of the C-2 phenyl ring were synthesized and evaluated as selective COX-2 inhibitors. In vitro COX-1/COX-2 structure–activity relationships were determined by varying the substituents on the C-4 quinoline ring. Among the 2,3-diarylquinolines, 2-(4-(methylsulfonyl) phenyl)-3-phenylquinoline-4-carboxylic acid (8) exhibited the highest potency and selectivity for COX-2 inhibitory activity (COX-2 IC₅₀ = 0.07 μM; selectivity index = 687.1) that was more selective than the reference drug celecoxib (COX-2 IC₅₀ = 0.06 μM; selectivity index = 405). A molecular modeling study where 8 was docked in the binding site of COX-2 indicated that the p-MeSO₂ COX-2 pharmacophore group on the C-2 phenyl ring is oriented in the vicinity of the COX-2 secondary pocket (Arg⁵¹³, Phe⁵¹⁸ and Val⁵²³) and the carboxylic acid substituent can interact with Ser⁵³⁰. The structure activity data acquired indicate that the size and nature of the C-4 quinoline substituent are important for COX-2 inhibitory activity.     

A novel sesquiterpene quinone from Hainan sponge Dysidea villosa

A new sesquiterpene quinone, 21-dehydroxybolinaquinone (5), together with two known related analogues, bolinaquinone (6) and dysidine (7), had been isolated from the Hainan sponge Dysidea villosa. The structure of the new compound 5 was elucidated on the basis of detailed analysis of spectroscopic data and by comparison with related model compounds. Compounds 5–7 were evaluated for the inhibitory activity against hPTP1B, a potential drug target for treatment of type-II diabetes and obesity, and cytotoxic activity against Hela cell line. The results showed that dysidine (7) had the strongest hPTP1B inhibitory activity with an IC₅₀ value of 6.70 μM and 6 had significant cytotoxic activity against Hela cell line with an IC₅₀ value of 5.45 μM. New compound 5 showed moderate PTP1B inhibitory activity and cytotoxicity with IC₅₀ values of 39.50 and 19.45 μM, respectively.     

Tyrosinase inhibitory effects of 1,3-diphenylpropanes from Broussonetia kazinoki

Six 1,3-diphenylpropanes exhibiting inhibitory activities against both the monophenolase and diphenolase actions of tyrosinase were isolated from the methanol (95%) extract of Broussonetia kazinoki. These compounds, 1–6, were identified as kazinol C (1), D (2), F (3), broussonin C (4), kazinol S (5) and kazinol T (6). The latter two species (5 and 6) emerged to be new 1,3-diphenylpropanes which we fully spectroscopically characterized. The IC₅₀ values of compounds (1, 3–5) for monophenolase inhibition were determined to range between 0.43 and 17.9 μM. Compounds 1 and 3–5 also inhibited diphenolase significantly with IC₅₀ values of 22.8, 1.7, 0.57, and 26.9 μM, respectively. All four active tyrosinase inhibitors (1, 3–5) were competitive inhibitors. Interestigly they all mainfested simple reversible slow-binding inhibition against diphenolase. The most potent inhibitor, compound 4 diplayed the following kinetic parameters k₃ = 0.0993 μM^?1 min^?1, k₄ = 0.0048 min^-1, and K_i^app = 0.0485 μM.