Synthesis and Structure-Activity Relationships of Pyridoxal-6-arylazo-5'-phosphate and Phosphonate Derivatives as P2 Receptor Antagonists.

Novel analogs of the P2 receptor antagonist pyridoxal-5'-phosphate-6-phenylazo-2',4'-disulfonate (PPADS) were synthesized. Modifications were made through functional group substitution on the sulfophenyl ring and at the phosphate moiety through the inclusion of phosphonates, demonstrating that a phosphate linkage is not required for P2 receptor antagonism. Substituted 6-phenylazo and 6-naphthylazo derivatives were also evaluated. Among the 6-phenylazo derivatives, 5'-methyl, ethyl, propyl, vinyl, and allyl phosphonates were included. The compounds were tested as antagonists at turkey erythrocyte and guinea-pig taenia coli P2Y(1) receptors, in guinea-pig vas deferens and bladder P2X(1) receptors, and in ion flux experiments by using recombinant rat P2X(2) receptors expressed in Xenopus oocytes. Competitive binding assay at human P2X(1) receptors in differentiated HL-60 cell membranes was carried out by using [(35)S]ATP-?-S. A 2'-chloro-5'-sulfo analog of PPADS (C(14)H(12)O(9)N(3)ClPSNa), a vinyl phosphonate derivative (C(15)H(12)O(11)N(3)PS(2)Na(3)), and a naphthylazo derivative (C(18)H(14)O(12)N(3)PS(2)Na(2)), were particularly potent in binding to human P2X(1) receptors. The potencies of phosphate derivatives at P2Y(1) receptors were generally similar to PPADS itself, except for the p-carboxyphenylazo phosphate derivative C(15)H(13)O(8)N(3)PNa and its m-chloro analog C(15)H(12)O(8)N(3)ClPNa, which were selective for P2X vs. P2Y(1) receptors. C(15)H(12)O(8)N(3)ClPNa was very potent at rat P2X(2) receptors with an IC(50) value of 0.82 ?M. Among the phosphonate derivatives, [4-formyl-3-hydroxy-2-methyl-6-(2-chloro-5-sulfonylphenylazo)-pyrid-5-yl]methylphosphonic acid (C(14)H(12)-O(8)N(3)ClPSNa) showed high potency at P2Y(1) receptors with an IC(50) of 7.23 ?M. The corresponding 2,5-disulfonylphenyl derivative was nearly inactive at turkey erythrocyte P2Y(1) receptors, whereas at recombinant P2X(2) receptors had an IC(50) value of 1.1 ?M. An ethyl phosphonate derivative (C(15)H(15)O(11)N(3)PS(2)Na(3)), whereas inactive at turkey erythrocyte P2Y(1) receptors, was particularly potent at recombinant P2X(2) receptors

BF₃·Et₂O-Promoted Decomposition of Cyclic α-Diazo-β-Hydroxy Ketones: Novel Insights into Mechanistic Aspects

We report novel insights into the cascade rearrangement of destabilized vinyl cations deriving from the BF3·Et2O-induced decomposition of cyclic α-diazo-β-hydroxy ketones in turn prepared by aldol-type condensation of cycloalkanones with diazoacetone. Complexation of the hydroxy group of the α-diazo-β-hydroxy compound with the Lewis acid is the first event, followed by the generation of the cycloalkanylidenediazonium salt that, after nitrogen loss, produces the highly reactive vinyl cation. The subsequent ring expansion results in the formation of a cycloalkenyl vinyl cation that affords the allylic cation by 1,2-methylene shift and ring contraction. The cation can then trap the solvent, the fluoride or the hydroxide released from the [BF3OH]− to afford different reaction products. The effect of both solvent and substrate ring size on products types and ratios were analyzed and discussed from a mechanistic point of view

Multi-Gram Scale Synthesis and Characterization of Mometasone Furoate EP Impurity C

Mometasone furoate is a synthetic corticosteroid used in the treatment of skin inflammatory conditions, hay fever and asthma. The industrial manufacturing routes to mometasone furoate are generally accompanied by the formation of numerous process impurities that need to be detected and quantified, as requested by regulatory authorities. The ready availability of such impurities in the required quantity and purity is therefore essential for toxicological studies, analytical method development and process validation. Herein, we report the multi-gram scale preparation of 21′-chloro-(16′α-methyl-3′,11′,20′-trioxo-pregna-1′,4′-dien-17′-yl)-furan-2-carboxylate (mometasone furoate EP impurity C), one of the known impurities of mometasone furoate. This study also includes the systematic investigation of the final acylation step, as well as the characterization of the difuroate enol ether intermediate and its conversion to the target impurity C

A Green Nanostructured Pesticide to Control Tomato Bacterial Speck Disease

Bacterial speck disease, caused by Pseudomonas syringae pv. tomato (Pst), is one of the most pervasive biological adversities in tomato cultivation, in both industrial and in table varieties. In this work synthesis, biochemical and antibacterial properties of a novel organic nanostructured pesticide composed of chitosan hydrochloride (CH) as active ingredient, cellulose nanocrystals (CNC) as nanocarriers and starch as excipient were evaluated. In order to study the possibility of delivering CH, the effects of two different types of starches, extracted from a high amylose bread wheat (high amylose starch—HA Starch) and from a control genotype (standard starch—St Starch), were investigated. Nanostructured microparticles (NMP) were obtained through the spray-drying technique, revealing a CH loading capacity proximal to 50%, with a CH release of 30% for CH-CNC-St Starch NMP and 50% for CH-CNC-HA Starch NMP after 24 h. Both NMP were able to inhibit bacterial growth in vitro when used at 1% w/v. Moreover, no negative effects on vegetative growth were recorded when NMP were foliar applied on tomato plants. Proposed nanostructured pesticides showed the capability of diminishing Pst epiphytical survival during time, decreasing disease incidence and severity (from 45% to 49%), with results comparable to one of the most used cupric salt (hydroxide), pointing out the potential use of CH-CNC-Starch NMP as a sustainable and innovative ally in Pst control strategies

Competitive and selective antagonism of P2Y(1) receptors by N(6)-methyl 2′-deoxyadenosine 3′,5′-bisphosphate

The antagonist activity of N(6)-methyl 2′-deoxyadenosine 3′,5′-bisphosphate (N6MABP) has been examined at the phospholipase C-coupled P2Y(1) receptor of turkey erythrocyte membranes. N6MABP antagonized 2MeSATP-stimulated inositol phosphate hydrolysis with a potency approximately 20 fold greater than the previously studied parent molecule, adenosine 3′,5′-bisphosphate. The P2Y(1) receptor antagonism observed with N6MABP was competitive as revealed by Schild analysis (pK(B)=6.99±0.13). Whereas N6MABP was an antagonist at the human P2Y(1) receptor, no antagonist effect of N6MABP was observed at the human P2Y(2), human P2Y(4) or rat P2Y(6) receptors