Hongguang Du

BF061, a novel antiplatelet and antithrombotic agent targeting P2Y12 receptor and phosphodiesterase

The addition of phosphodiesterase (PDE) inhibitors has been reported to potentiate the antithrombotic effects of P2Y₁₂ antagonists without increasing bleeding risk. In this study, we report that a potent antiplatelet agent, 2-ethylthio-6-phenethylaminoadenosine (BF061), inhibits platelet activation and thrombosis via P2Y₁₂ antagonism and PDE inhibition. We explored the antiplatelet mechanism of BF061 by measuring cAMP, cGMP levels, PDE activity, and the interaction between ADP and P2Y₁₂ using atomic force microscopy. The antithrombotic effect of BF061 was evaluated in mice using intravital microscopy in FeCl₃₋induced mesenteric and laser-induced cremasteric arterial thrombosis models. BF061 robustly inhibited platelet aggregation and ATP release induced by multiple platelet agonists via P2Y₁₂ antagonism and PDE inhibition. Interestingly, despite being structurally similar to BF061, P2Y₁₂ receptor antagonist AR-C69931MX had no effect on human platelet PDE. In FeCl3-induced mesenteric arterial thrombosis model, BF061 effectively prevented thrombus formation similarly to clopidogrel; it also reduced thrombus volume in laser-injured cremaster arteriole model. In contrast, BF061 induced dramatically less bleeding at an antithrombotic dose compared to clopidogrel. In summary, we developed a novel antiplatelet and antithrombotic agent targeting both P2Y₁₂ and PDE. Given the prevalence of combined antiplatelet therapy in clinical practice, an antiplatelet agent bearing dual activities may have therapeutic advantage as a potential antithrombotic drug.

BF0801, a novel adenine derivative, inhibits platelet activation via phosphodiesterase inhibition and P2Y12 antagonism

Though antiplatelet drugs are proven beneficial to patients with coronary heart disease and stroke, more effective and safer antiplatelet drugs are still needed. In this study we report the antiplatelet effects and mechanism of BF0801, a novel adenine derivative. BF0801 dramatically inhibited platelet aggregation and ATP release induced by ADP, 2MeSADP, AYPGKF, SFLLRN or convulxin without affecting shape change in vitro . It also potentiated the inhibitory effects of adenosine-based P2Y12 antagonist AR-C69931MX or phosphodiesterase (PDE) inhibitor IBMX on platelet aggregation. The cAMP levels in both resting and forskolin-stimulated platelets were increased by BF0801 suggesting its PDE inhibitor activity, which is further confirmed by the concentration-dependent suppression of BF0801 on the native and recombinant PDE. Similar to AR-C69931MX, BF0801 drastically inhibited 2MeSADP- induced adenylyl cyclase inhibition in platelets indicating its P2Y12 antagonism activity, which is substantiated by the inhibition of BF0801 on the interaction between ADP and P2Y12 receptor expressed in CHO-K1 cells measured by atomic force microscopy. Moreover, we confirmed the antiplatelet effects of BF0801 using platelets from rats intravenously given BF0801. In summary, for the first time we developed a novel adenine derivative bearing dual activities of PDE inhibition and P2Y12 antagonism, which may have therapeutic advantage as a potential antithrombotic drug.

BF066, a Novel Dual Target Antiplatelet Agent without Significant Bleeding

In this study, we report BF066, a novel adenine derivative, inhibits platelet activation and thrombosis via the adenosine receptor (A2A) activation and phosphodiesterase (PDE) inhibition. BF066 inhibits platelet aggregation and ATP releasing induced by multiple platelet agonists in a dose-dependent manner. The inhibition of BF066 on ADP-induced aggregation is potentiated by adenosine and can be dramatically antagonized by the A2A antagonist SCH58261. BF066 also inhibits the PDE activity and platelet spreading on fibrinogen. In FeCl3-injured mouse mesenteric arterial thrombosis model, BF066 prevents thrombus formation effectively, similar to clopidogrel. Intriguingly, at dose achieving similar antithrombotic effect compared to clopidogrel, BF066 does not increase bleeding significantly. Taken together, these results suggest that BF066 may be an effective and safe antiplatelet agent targeting both PDE and A2A. Considering the successful use of combined antiplatelet therapy, BF066 may be further developed as a novel dual target antiplatelet agent.

Synthesis and Fungicidal Activity of Simple Structural 1,3-Thiazolidine-2-Thione Derivatives

GRAPHICAL ABSTRACT Abstract A series of simple structural 1,3-thiazolidine-2-thione derivatives with various substituents on the S-, N-, 4-, and 5-positions was synthesized with high yields from various vicinal amino alcohols via two steps and screened for their antifungal activity. Bioassay results reveal that some thiazolidine-2-thione derivatives show strong antifungal activities against P. capsici, G. zeae, S. sclerotiorum, A. alternata, B. cinerea, or R. solani. The SAR analysis indicates that N-acyl substituted and 4-alkyl substituents can enhance the antifungal activity. Notably, 4-isopropyl-N-propionylthiazoldine-2-thione shows excellent activity against B. cinerea and G. zeae with IC50 values at 3.7 μg/mL and 6.5 μg/mL, respectively, and 4-isobutyl-N-propionylthiazoldine-2-thione shows remarkable fungicidal activity against R. solani, S. sclerotiorum, and G. zeae with IC50 values at 1.0 μg/mL, 12.1 μg/mL, and 11.0 μg/mL, respectively.

Proton NMR investigations on 6‐alkylamino‐2‐alkylthioadenosine derivatives

Purine nucleosides have taken up an important role in living systems. Not only are purines the basic subunits of the nucleic acids, but they also interact with enzymes and other proteins as components of cofactors and signal molecules. Their modified nucleosides and nucleotides are very important classes of compounds used in the therapy of a wide variety of diseases, because they can act as antiviral, antitumor and antimicrobial agents. Purine nucleosides in which the alkylthio group at C-2 position and the alkylamine substituent at C-6 position typically excel in antiplatelet activities (Fig. 1). So the synthesis and characterization of the modified purine nucleosides have attracted the attention of our and other many scientific teams. The distribution of electrons around the purine skeleton affects not only its chemical properties and reactivity but also the nuclear magnetic resonance (NMR) parameters. The nature of the substituent is reflected in the NMR chemical shifts and nuclear spin–spin coupling constants, which makes NMR spectroscopy an excellent tool for investigating and interpreting the structure, reactivity and intermolecular interactions in terms of the electron distribution. The use of proton NMR spectroscopy could be a helpful tool to achieve it. Recently, we have published a complete analysis of proton NMR data for 6-alkylamino-2-alkylthioadenosine derivatives, andwe observed that two protons of SCH2 at C-2 of purine skeleton are split into one/two ‘dt’ or ‘dq’ coupling peaks, rather than canonical ‘t’ or ‘q’ peaks, but the reason is not clear. To reveal the general behaviors of the chemical shifts signals of SCH2 group depending on the configuration for SCH2-containing adenosine derivatives, two series of 6-alkyl(aryl)amino-2-alkyl(aryl) thioadenosines and 6-alkyl(aryl)amino-2-alkylthiopurines were synthesized, and their proton NMR spectroscopic properties were described.

Expeditious synthesis of 9-allenylpurines via cesium carbonate catalyzed isomerization of 9-alkynylpurines

GRAPHICAL ABSTRACT ABSTRACT An expeditious and convenient method to synthesize 9-allenylpurines via cesium carbonate catalyzed isomerization of 9-alkynylpurines has been successfully developed. The reactions proceeded rapidly under the base conditions and formed the desired products in good to excellent yields. The method was suitable with a broad substrate scope and proceeded well even on a multgram-scale. The obtained 9-allenylpurines were successfully applied to prepare various potential bioactive 9-acyclic nucleosides with high regioselectivity promoted by AgNO3.

Expedient synthesis of 2-alkylthio-N6-aryladenosines from guanosine

ABSTRACT A general approach for the synthesis of 2-alkylthio-N6-aryladenosine was developed from the commercially available guanosine through the acetyl protection, chlorination, diazotization-alkylthionation, aromatic nucleophilic substitution and deacetylation. Two approaches were designed for the transformation of 2-amino-6-chloroguanosine to 2-alkylthio-N6-aryladenosines but only the one with diazotization-alkylthionation first could afford the target molecules. Both electron-rich and deficient anilines can afford the desired products in moderate to good yield. Finally, under the optimized condition, 20 2-alkylthio-N6-aryladenosines were synthesized, 5 of which exhibit poor antiplatelet aggregation activities. GRAPHICAL ABSTRACT

New Approach to Synthesize Symmetrical and Unsymmetrical 6-(N-Alkyl(Aryl)Amino)- and 6-(N,N-Dialkyl(Aryl)Amino)-2,4-Bis(Alkyl(Aryl)Thio)Pyrimidines as anti-Platelet Agents

Abstract A new and straightforward procedure has been developed for the preparation of symmetrical and unsymmetrical 6-(N-alkyl(aryl)amino)- and 6-(N,N-bisalkyl(aryl)amino)-2,4-bis(alkyl(aryl)thio)pyrimidines. The two identical or different alkylthio groups were successfully introduced into the pyrimidine ring of 4-amino-6-hydroxy-2- mercaptopyrimidine via S-alkylation with alkyl halides, and via a nucleophilic displacement with sodium alkylmercaptides, affording the key intermediate symmetrical and unsymmetrical 2,4-bis(alkyl(aryl)thio)-6-aminopyrimidines. Subsequently, N-alkylation of the 2,4-bis(alkyl(aryl)thio)-6-aminopyrimidines with alkyl halides conveniently gave the desired products. The human anti-platelet activities of all the synthesized new compounds were also evaluated. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT