This work includes the synthesis of 15 final compounds (6a-h and 7b-h) as prodrugs of 5-ASA in the form of the acid itself, esters and amides linked by an amide linkage through a spacer to the endocyclic ring N of nicotinamide. Also, 15 new intermediate compounds were prepared. The target compounds (6b, 6f, 7b, and 7e-h) revealed potent analgesic and anti-inflammatory activities in comparison to sulfasalazine and 5-ASA. In addition, ulcerogenicity, LD50, in vivo and in vitro metabolism of compound 7f were determined.

3-N-(4`-Hydroxy-3`-substituted phenyl)carbamoyl-1-methylpyridinium iodides (compds. 5b-j) and 3-carbamoyl-1-(N-(4`-hydroxy- 3`-substituted phenyl)carbamoyl) methyl pyridinium chlorides (compds. 7a-j) were synthesised and some of them were tested for their analgesic and antiinflammatory activities by hot plate test and carageenin-induced hind paw edema model, respectively. Compound 5b revealed the most potent analgesic and anti-inflammatory activities in comparison to sulfasalazine (SASP) and 5-ASA. In addition, ulcerogenicity, LD50, in-vivo and in vitro cleavage and pH stability of compound 5b were also determined.

Sialic acid-binding immunoglobulin-like lectins (Siglecs) are expressed in various immune cells and most of them carry signaling functions. High-affinity synthetic sialoside ligands have been developed for various Siglecs. Therapeutic potentials of the nanoparticles and compounds that contain multiple numbers of these sialosides and other reagents such as toxins and antigens have been demonstrated. However, whether immune responses can be regulated by monomeric sialoside ligands has not yet been known. CD22 (also known as Siglec-2) is an inhibitory molecule preferentially expressed in B lymphocytes (B cells) and is constitutively bound and functionally regulated by α2,6 sialic acids expressed on the same cell (cis-ligands). Here, we developed synthetic sialosides GSC718 and GSC839 that bind to CD22 with high affinity (IC₅₀ ~100 nM), and inhibit ligand binding of CD22. When B cells are activated by B cell antigen receptor (BCR) ligation, both GSC718 and GSC839 downregulate proliferation of B cells, and this regulation requires both CD22 and α2,6 sialic acids. This result suggests that these sialosides regulate BCR ligation-induced B cell activation by reversing endogenous ligand-mediated regulation of CD22. By contrast, GSC718 and GSC839 augment B cell proliferation induced by TLR ligands or CD40 ligation, and this augmentation requires CD22 but not α2,6 sialic acids. Thus, these sialosides appear to enhance B cell activation by directly suppressing the inhibitory function of CD22 independently of endogenous ligand-mediated regulation. Moreover, GSC839 augments B cell proliferation that depends on both BCR ligation and CD40 ligation as is the case for in vivo B cell responses to antigens, and enhanced antibody production to the extent comparable to CpG oligonuleotides or a small amount of alum. Although these known adjuvants induce production of the inflammatory cytokines or accumulation of inflammatory cells, CD22-binding sialosides do not. Thus, synthetic sialosides that bind to CD22 with high-affinity modulate B cell activation through endogenous ligand-dependent and independent pathways, and carry an adjuvant activity without inducing inflammation.

5-Acetyl-3-cyano-6-methyl-4-(2-phenylethenyl)pyridine-2(1H)-thione (2) was synthesized by interaction of cinnamylidene-2-cyanothioacetamide 1 and acetylacetone or via one-pot reaction of E-cinnamaldehyde, 2-cyanothioacetamide, and acetylacetone. Reaction of 2 with ethyl iodide (3a) or N-chloroacetyl derivative of aromatic amines 3b–e in boiling ethanol containing sodium ethoxide gave the corresponding thioether 4a and 5-acetyl-3-amino-2-(N-arylcarbamoyl)-6-methyl-4-(2-phenylethenyl)thieno[2,3-b]pyridines 5b–e, respectively. Compound 5e was reacted with 2,5-dimethoxytetrahydrofuran or triethyl orthoformate to furnish pyrrolylthienopyyridine 6 or pyrdiothienopyrimidinone 7, respectively. The photophysical properties of 5b, 5c, 5e, and 7 were fully studied and the obtained results included herein. The fluorescence data confirmed that compounds 5b, 5c, 5e, and 7 exhibit aggregation-induced emission behavior with high absolute quantum yields.

Reaction of 4,6-dimethyl-3-cyanopyridine-2(1H)-thione (IIIa) or 4,5,6-trisubstituted-3-cyanopyridine-2(1H)-thiones (IIIb–d) with 2-chloromethylquinazoline-4(3H)-one (IVa) furnished the corresponding 3-amino-2-(4-oxo-3,4-dihydroquinazolin-2-yl)thieno[2,3-b]pyridines (VIa–d). Reaction of aminothieno-pyridines (VIa, b, d) were reacted with triethyl orthoformate, acetic anhydride or nitrous acid to furnish pyridothienopyrimidoquinazolines (VIIIa, b, d), (IXa, b, d) or pyridothienotriazinoquinazolines (Xa, b, d). The new compound, 3-cyano-5-acetyl-6-methyl-4-styrylpyridine-2(1H)-thione (IIIe) was synthesized and reacted with 2-chloromethyl-1H-benzimadazole to give 5-acetyl-3-amino-2-(1H-benzimidazol-2-yl)-6-methyl-4-styryl-thieno[2,3-b]pyridine (XII) which was used as a key intermediate for synthesizing pyridothienopyrimidobenzimidazoles (XIII, XIV). All newly synthesized compounds were characterized on the basis of their elemental and spectral analyses. Also, most of the synthesized compounds were screened in vitro for their antifungal activity

Ethyl (3-cyano-5-ethoxycarbonyl-6-methyl-4-styryl-2-pyridylsulfanyl)acetate was prepared and reacted with hydrazine hydrate in ethanol to give a mixture of (3-cyano-5-ethoxycarbonyl-6-methyl-4-styryl-2-pyridylsulfanyl)acetohydrazide and diethyl 3-amino-6-methyl-4-styrylthieno[2,3-b]pyridine-2,5-dicarboxylate. The latter compound was reacted with 2,5-dimethoxytetrahydrofuran to give 3-(1H-pyrrol-1-yl)thieno[2,3-b]pyridine analogue which on treatment with hydrazine hydrate in ethanol furnished 5-ethoxycarbonyl-6-methyl-3-(1H-pyrrol-1-yl)-4-styrylthieno[2,3-b]pyridine-2-carbohydrazide. Both acetohydrazide and carbo-hydrazide were used as precursors for the title compounds.

3-Cyano-5-ethoxycarbonyl-6-methyl-4-styrylpyridine-2(1H)-thione (3) was prepared by reaction of 2-cyano-5-phenylpenta-2,4-dienethioamide (2) with ethyl acetoacetate or by multicomponent reaction of cinnamaldehyde (1), cyanothioacetamide and ethyl acetoacetate in a moderate yield. Reaction of compound 3 with some N-aryl-2-chloroacetamides, in the presence of sodium acetate, gave the corresponding 2-(N-arylcarbamoylmethylsulfanyl)-3-cyano-5-ethoxycarbonyl-6-methyl-4-styrylpyridines 4a-f. When compounds 4a-f were subjected to Thorpe-Ziegler reaction conditions, they converted into the corresponding 3-amino-5-ethoxycarbonyl-2-(N-arylcarbamoyl)-6-methyl-4-styrylthieno[2,3-b]pyridines 5a-f. Compounds 5a,e,f were reacted, in turn, with 2,5-dimethoxytetrahydrofuran to furnish the corresponding 3-(pyrrol-1-yl)thieno-pyridines 6a,e,f. Reactions of 5a-f with triethyl orthoformate or nitrous acid were also carried out and their products were identified. Structural formulas of all synthesized compounds was characterized and confirmed on the basis of their elemental and spectral analyses.