Design, synthesis, biological evaluation and docking study of some new aryl and heteroaryl thiomannosides as FimH antagonists.

FimH is a mannose-recognizing lectin that is expressed by Escherichia coli guiding its ability to adhere and infect cells. It is involved in pathogenesis of urinary tract infections and Chron's disease. Several X-ray structure-guided ligand design studies were extensively utilized in the discovery and optimization of small molecule aryl mannoside FimH antagonists. These antagonists retain key specific interactions of the mannose scaffolds with the FimH carbohydrate recognition domains. Thiomannosides are attractive and stable scaffolds, and this work reports the synthesis of some of their new aryl and heteroaryl derivatives as FimH antagonists. FimH-competitive binding assays as well as biofilm inhibition of the new compounds (24-32) were determined in comparison with the reference n-heptyl α-d-mannopyranoside (HM). The affinity among these compounds was found to be governed by the structure of the aryl and heteroarylf aglycones. Two compounds 31 and 32 revealed higher activity than HM. Molecular docking and total hydrophobic to topological polar surface area ratio calculations attributed to explain the obtained biological results. Finally, the SAR study suggested that introducing an aryl or heteroaryl aglycone of sufficient hydrophobicity and of proper orientation within the tyrosine binding site considerably enhance binding affinity. The potent and synthetically feasible FimH antagonists described herein hold potential as leads for the development of sensors for detection of E. coli and treatment of its diseases.

Design, synthesis and mechanistic anticancer activity of new acetylated 5-aminosalicylate-thiazolinone hybrid derivatives.

The development of hybrid compounds has been widely considered as a promising strategy to circumvent the difficulties that emerge in cancer treatment. The well-established strategy of adding acetyl groups to certain drugs has been demonstrated to enhance their therapeutic efficacy. Based on our previous work, an approach of accommodating two chemical entities into a single structure was implemented to synthesize new acetylated hybrids (HH32 and HH33) from 5-aminosalicylic acid and 4-thiazolinone derivatives. These acetylated hybrids showed potential anticancer activities and distinct metabolomic profile with antiproliferative properties. The in-silico molecular docking predicts a strong binding of HH32 and HH33 to cell cycle regulators, and transcriptomic analysis revealed DNA repair and cell cycle as the main targets of HH33 compounds. These findings were validated using in vitro models. In conclusion, the pleiotropic biological effects of HH32 and HH33 compounds on cancer cells demonstrated a new avenue to develop more potent cancer therapies.

New nitazoxanide derivatives: design, synthesis, biological evaluation, and molecular docking studies as antibacterial and antimycobacterial agents.

A new series inspired by combining fragments from nitazoxanide (NTZ) and 4-aminosalicylic acid (4-ASA) was synthesized and screened for in vitro antibacterial and antimycobacterial activities. The majority showed higher antibacterial potency than NTZ against all the screened strains, notably, 5f, 5j, 5n and 5o with MICs of 0.87-9.00 µM. Compounds 5c, 5n and 5o revealed higher potency than ciprofloxacin against K. pneumoniae, while 5i was equipotent. For E. faecalis, 3b, 5j, and 5k showed higher potency than ciprofloxacin. 5j was more potent against P. aeruginosa than ciprofloxacin, while 5n was more potent against S. aureus with an MIC of 0.87 µM. 5f showed equipotency to ciprofloxacin against H. pylori with an MIC of 1.74 µM. Compounds 3a and 3b (4-azidoNTZ, MIC 4.47 µM) are 2 and 5-fold more potent against Mycobacterium tuberculosis (Mtb H37Rv) than NTZ (MIC 20.23 µM) and safer. 4-Azidation and/or acetylation of NTZ improve both activities, while introducing 1,2,3-triazoles improves the antibacterial activity. Molecular docking studies within pyruvate ferredoxin oxidoreductase (PFOR), glucosamine-6-phosphate synthase (G6PS) and dihydrofolate reductase (DHFR) active sites were performed to explore the possible molecular mechanisms of actions. Acceptable drug-likeness properties were found. This study may shed light on further rational design of substituted NTZ as broad-spectrum more potent antimicrobial candidates.

The design, synthesis, biological evaluation, and molecular docking of new 5-aminosalicylamide-4-thiazolinone hybrids as anticancer agents.

New 5-aminosalicylamide-4-thiazolinone hybrids (27) were efficiently synthesized, characterized, and evaluated to explore their structure-activity relationship as anticancer agents. The antiproliferative activities of the new hybrids were evaluated against eight cancer cell lines using the sulforhodamine B assay. The most potent compound (24b) possessed high selectivity on the tested cell lines in the low micromolar range, with much lower effects on normal fibroblast cells (IC50 > 50 µM). The cell lines derived from leukemia (Jurkat), cervix (HeLa), and colon (HCT116) cancers appeared to be the most sensitive, with IC50 of 2 µM. 24b is the N-ethylamide derivative with p-dimethylaminobenzylidene at position 5 of the 4-thiazolinone moiety. Other N-substituents or arylidene derivatives showed lower activity. Hybrids with salicylamides showed lower activity than with methyl salicylate. The results clearly show that the modifications of the carboxy group and arylidene moiety greatly affect the activity. Investigating the possible molecular mechanisms of these hybrids revealed that they act through cell-cycle arrest and induction of apoptosis and epidermal growth factor receptor (EGFR) inhibition. Molecular docking studies rationalize the molecular interactions of 24b with EGFR. This work expands our knowledge of the structural requirements to improve the anticancer activity of 5-aminosalicylic-thiazolinone hybrids and pave the way toward multitarget anticancer salicylates.

Synthesis, biological evaluation and molecular docking study of some new 4-aminosalicylic acid derivatives as anti-inflammatory and antimycobacterial agents.

In this study, new derivatives of the antitubercular and anti-inflammatory drug, 4-aminosaliclic acids (4-ASA) were synthesized, characterized, and evaluated for these activities. In vivo and in viro evaluation of anti-inflammatory activity revealed that compounds 10, 19 and 20 are the most active with potent cyclooxygenase-2 (COX-2) and 5-lipooxgenase (5-LOX) inhibition and without causing gasric lesions. The minimum inhibitory concentrations (MIC) of the newly synthesized compound were, also, measured against Mycobacterium tuberculosis H37RV. Among the tested compounds 17, 19 and 20 exhibited significant activities against the growth of M. tuberculosis. 20 is the most potent with (MIC 1.04 µM) 2.5 folds more potent than the parent drug 4-ASA. 20 displayed low cytotoxicity against normal cell providing a high therapeutic index. Important structure features were analyzed by docking and structure-activity relationship analysis to give better insights into the structural determinants for predicting the anti-inflammatory and anti-TB activities. Our results indicated that compounds 19 and 20 are potential lead compounds for the discovery of dual anti-inflammatory and anti-TB drug candidates.

Ionic liquid of ketoprofen-piperine modulates the pharmaceutical and therapeutic characters of ketoprofen.

Efficiency of drug delivery is product of drug properties and formulation design. Modulating drug's unfavorable properties such as poor solubility or permeation is the first step towards optimum delivery. By combining a drug with a selected bulky counter ion, it can be transformed into a low-melting point salt, i.e., an ionic liquid (IL), with favorable physicochemical properties. In this study, we prepared a novel IL of anti-inflammatory drug, ketoprofen (KP), to enable its transdermal administration. KP was paired with piperine (PI) forming equimolar KP-PI IL, via solvent evaporation. KP-PI IL showed extended stability. Thermal analysis and X-ray diffractometry proved that KP was transformed into a low-melting point amorphous form, while spectroscopic analysis and computational studies demonstrated that KP-PI interaction was mediated by hydrogen bonding. In the IL form, KP's solubility increased due to IL formation by 71 to 83%, while 218% more KP was permeated through rat skin in the IL form, than in a KP/PI mixture. Importantly, upon transdermal administration to rats with induced paw edema; KP-PI IL resulted in a 68% less paw swelling than KP/PI mixture. These findings demonstrate the utility of IL as an economic, simple and efficient strategy for improving the therapeutic application of drugs/drug combinations.

The inhibitory coreceptor CD22 restores B cell signaling by developmentally regulating Cd45-/- immunodeficient B cells.

The protein tyrosine phosphatase CD45 plays a crucial role in B cell antigen receptor (BCR) signaling by activating Src family kinases. Cd45-/- mice show altered B cell development and a phenotype likely due to reduced steady-state signaling; however, Cd45-/- B cells show relatively normal BCR ligation-induced signaling. In our investigation of how BCR signaling was restored in Cd45-/- cells, we found that the coreceptor CD22 switched from an inhibitory to a stimulatory function in these cells. We disrupted the ability of CD22 to interact with its ligands in Cd45-/- B cells by generating Cd45-/-St6galI-/- mice, which cannot synthesize the glycan ligand of CD22, or by treating Cd45-/- B cells in vitro with the sialoside GSC718, which inhibits ligand binding to CD22. BCR ligation-induced signaling was reduced by ST6GalI deficiency, but not by GSC718 treatment, suggesting that CD22 restored BCR ligation-induced signaling in Cd45-/- mature B cells by altering cellular phenotypes during development. CD22 was required for the increase in the surface amount of IgM-BCR on Cd45-/- B cells, which augmented signaling. Because B cell survival depends on steady-state BCR signaling, IgM-BCR abundance was likely increased by the selective survival of IgM-BCRhi Cd45-/- B cells because of CD22-mediated signaling under conditions of substantially reduced steady-state signaling. Because the amount of surface IgM-BCR is increased on B cells from patients with other BCR signaling deficiencies, including X-linked agammaglobulinemia, our findings suggest that CD22 may contribute to the partial restoration of B cell function in these patients.

Crystal structure and Hirshfeld surface analysis of 5-acetyl-3-amino-6-methyl-N-phenyl-4-[(E)-2-phenyl-ethen-yl]thieno[2,3-b]pyridine-2-carbox-amide.

The asymmetric unit of the title compound, C25H21N3O2S, comprises four mol-ecules. Their conformations differ primarily in the orientations of the styryl and the N-phenyl-carboxamido groups. In the crystal, inter-molecular N-H⋯N, C-H⋯O and C-H⋯S hydrogen-bonding contacts as well a C-H⋯π(ring) inter-actions lead to the formation of a layer structure parallel to (010). Hirshfeld surface analysis revealed that H⋯H inter-actions represent the main contributions to the crystal packing.

The Protein Tyrosine Phosphatase SHP-1 (PTPN6) but Not CD45 (PTPRC) Is Essential for the Ligand-Mediated Regulation of CD22 in BCR-Ligated B Cells.

CD22 is an inhibitory B cell coreceptor that regulates B cell development and activation by downregulating BCR signaling through activation of SH2-containing protein tyrosine phosphatase-1 (SHP-1). CD22 recognizes α2,6 sialic acid as a specific ligand and interacts with α2,6 sialic acid-containing membrane molecules, such as CD45, IgM, and CD22, expressed on the same cell. Functional regulation of CD22 by these endogenous ligands enhances BCR ligation-induced signaling and is essential for normal B cell responses to Ags. In this study, we demonstrate that CD45 plays a crucial role in CD22-mediated inhibition of BCR ligation-induced signaling. However, disruption of ligand binding of CD22 enhances CD22 phosphorylation, a process required for CD22-mediated signal inhibition, upon BCR ligation in CD45-/- as well as wild-type mouse B cells but not in mouse B cells expressing a loss-of-function mutant of SHP-1. This result indicates that SHP-1 but not CD45 is required for ligand-mediated regulation of CD22. We further demonstrate that CD22 is a substrate of SHP-1, suggesting that SHP-1 recruited to CD22 dephosphorylates nearby CD22 as well as other substrates. CD22 dephosphorylation by SHP-1 appears to be augmented by homotypic CD22 clustering mediated by recognition of CD22 as a ligand of CD22 because CD22 clustering increases the number of nearby CD22. Our results suggest that CD22 but not CD45 is an endogenous ligand of CD22 that enhances BCR ligation-induced signaling through SHP-1-mediated dephosphorylation of CD22 in CD22 clusters.

Design and synthesis of novel 2,3-dihydropyrazino[1,2-a]indole-1,4-dione derivatives as antiproliferative EGFR and BRAFV600E dual inhibitors.

Recent studies have shown additive and synergistic effects associated with the combination of kinase inhibitors. BRAFV600E and EGFR are attractive targets for many diseases treatments and have been studied extensively. In keeping with our interest in developing anticancer targeting EGFR and BRAFV600E, a novel series of 2,3-dihydropyrazino[1,2-a]indole-1,4-dione has been rationally designed, synthesized and evaluated for their antiproliferative activity against a panel of four human cancer cell lines. Compounds 20-23, 28-31, and 33 showed promising antiproliferative activities. These compounds were further tested for their inhibitory potencies against EGFR and BRAFV600E kinases with erlotinib as a reference drug. Compounds 23 and 33 exhibited equipotency to doxorubicin against the four cell lines and efficiently inhibited both EGFR (IC50 = 0.08 and 0.09 µM, respectively) and BRAFV600E (IC50 = 0.1 and 0.29 µM, respectively). In cell cycle study of MCF-7 cell line, compounds 23 and 33 induced apoptosis and exhibited cell cycle arrest in both Pre-G1 and G2/M phases. Molecular docking analyses revealed that the new compounds can fit snugly into the active sites of EGFR, and BRAFV600E kinases. Compound 23, 31 and 33 adopted similar binding orientations and interactions to those of erlotinib and vemurafenib.

Design, synthesis and molecular docking study of α-triazolylsialosides as non-hydrolyzable and potent CD22 ligands.

Ligand 1 was the first reported example of monomeric high-affinity synthetic CD22 ligand that regulated B cell activation in vitro, augmented antibody production and regulated immune responses in mice. Replacing O-glycoside linkage of 1 by nitrogen of triazole by click reaction afforded compounds which are as potent as the parent compound. The synthesis of the new compounds is straightforward with fewer synthetic steps and higher yield. Such a strategy provided stable ligand that can bind avidly and can be conjugated to drugs for B-cell targeting or multimeric formation. The new compounds were screened for their affinity to CD22, using surface plasmon resonance (SPR). Compound 12 was obtained as a bioisosteric analogue and an anomerically stable imitation of 1. It was, also, screened for MAG to test for selectivity and analyzed by molecular docking and dynamic simulation to explore the potential binding modes and source of selectivity within CD22. Our results could enable the development of small molecule drug capable of modulating the activity of CD22 in autoimmune diseases and malignancies derived from B-cells.

Induction of DNA damage, apoptosis and cell cycle perturbation mediate cytotoxic activity of new 5-aminosalicylate-4-thiazolinone hybrid derivatives.

Modulation of several targets in cancer cells enhances the effect of anti-cancer drugs. This can be achieved by using combinations of anti-cancer drugs or by designing new drugs with novel pharmacophore structures that target different molecules within cancer cells. We developed a panel of such compounds by accommodating two chemical entities (5-Aminoslicylic acid and thiazolin-4-one) known to have anti-cancer activities into a single framework structure. Using a panel of 7 cancer cell lines, two compounds (HH3 and HH13) showed efficient cytotoxic effects on some types of cancer comparable to the standard anti-cancer drug doxorubicin with tumor specificity and minimal effects on normal fibroblasts. Investigating the molecular mechanisms of the two compounds revealed (i) induction of DNA damage, (ii) cell cycle arrest in G2/M phase and (iii) induction of apoptosis as indicated by annexin-V staining and activation of caspases. These effects were more prominent in HH compounds-sensitive cells (with IC50 < 0.5µM) than -resistant or normal cells (with IC50 > 1µM). Moreover, both compounds modulate the expression and activity of several factors in the DNA damage response pathway (γ-H2AX, ATM, ATR, CHK1, CHK2), cyclins/cyclin dependent kinases and CDC25 phosphatase. Altogether, our results show that both HH3 and HH13 compounds are good candidates as anti-cancer drug leads for certain types of cancer and worth further detailed investigations of their safety and effectiveness on animal/xenograft models.

Further insight into the dual COX-2 and 15-LOX anti-inflammatory activity of 1,3,4-thiadiazole-thiazolidinone hybrids: The contribution of the substituents at 5th positions is size dependent.

Herin we report the design, synthesis, full characterization and biological investigation of new 15-LOX/COX dual inhibitors based on 1,3-thiazolidin-4-one (15-lipoxygenase pharmacophore) and 1,3,4-thiadiazole (COX pharmacophore) scaffolds. This series of molecular modifications is an extension of a previously reported series to further explore the structural activity relationship. Compounds 3a, 4e, 4n, 4q, 7 and 8 capable of inhibiting 15-LOX at (2.74, 4.2, 3.41, 10.21, 3.71 and 3.36 µM, respectively) and COX-2 at (0.32, 0.28, 0.28, 0.1, 0.28 and 0.27 µM, respectively). The results revealed that binding to 15-LOX and COX is sensitive to the bulkiness of the substituents at the 5 positions. 15-LOX bind better with small substituents, while COXs bind better with bulky substituents. Compounds 3a, 4r and 4q showed comparable in vivo anti-inflammatory activity to the reference drug (celecoxib). The ulcer liability test showed no sign of ulceration which ensures the safe gastric profile. Docking study was performed to explore the possible mode of interaction of the new compounds with the active site of human 15-LOX and COX-2. This study discloses some structural features for binding to 15-LOX and COX, thus pave the way to design anti-inflammatory agents with balanced dual inhibition of these enzymes.

Click chemistry synthesis, biological evaluation and docking study of some novel 2'-hydroxychalcone-triazole hybrids as potent anti-inflammatory agents.

A hybrid pharmacophore approach is used to design and synthesize two novel series of 2'-hydroxychalcone-triazole hybrid molecules 6a-j and 8a-j. These compounds were fully characterized by spectral and elemental analyses. They were evaluated in vitro and in vivo for anti-inflammatory activity. Most of compounds were selective inhibitors for COX-2. Among them, compounds 6d, 6f, 6i, 8c, 8e and 8h demonstrated highly potent dual inhibition of COX-2 (IC50 = 0.037-0.041 µM) and 15-LOX (IC50 = 1.41-1.80 µM). Compounds 6i, 8c and 8h showed 116%, 113% and 109% of the in vivo anti-inflammatory activity of celecoxib. Therefore, compounds 6d, 6f, 6i, 8c, 8e and 8h-j are potent dual inhibitors of COX-2 and 15-LOX. Docking study over COX-2 and 15-LOX active sites ensures the binding affinity and selectivity. These compounds are promising candidates for further development as anti-inflammatory drugs.

Conjugation of 4-aminosalicylate with thiazolinones afforded non-cytotoxic potent in vitro and in vivo anti-inflammatory hybrids.

Eicosanoids like leukotrienes and prostaglandins that produced within the arachidonic acid cascade are involved in the pathogenesis of pain, acute and chronic inflammatory diseases. A promising approach for an effective anti-inflammatory therapy is the development of inhibitors targeting more than one enzyme of this cascade. Aiming to develop balanced COX/LOX inhibitors; 4-aminosalicylate based thiazolinones having different substituents at the 5th position of the 4-thiazolinone ring (2-22) were designed, synthesized, characterized and evaluated in vitro and in vivo for their anti-inflammatory activity. Most of the investigated compounds showed high COX-2 inhibitory potencies (IC50 39-200 nM) with selectivity indexes (30-84). Two compounds, 19 and 21, (IC50 = 41 and 44 nM), are equipotent to celecoxib (IC50 = 49 nM), while compound 22 (IC50 = 39 nM) was the most potent. For 15-LOX, compounds 5, 11, 19, 21 and 22 revealed higher potency (IC50 1.5-2.2 µM) than zileuton (IC50 15 µM). Thus, compounds 5, 11, 19, 21 and 22 are potent dual inhibitors of COX-2 and 15-LOX. In vivo anti-inflammatory testing of these compounds revealed that, compounds 5 and 21 had an anti-inflammatory activity similar to indomethacin and celecoxib (% inhibition of oedema = 60 ±â€¯9) and higher than diclofenac potassium (% inhibition = 52 ±â€¯29), while compound 22 (% inhibition = 63 ±â€¯5) was more active than the reference drugs. The results showed that the activity is controlled by the bulkiness and lipophilicity of the substituent at the 5th position. The cytotoxicity results revealed that all compounds are not cytotoxic, additionally, in an experimental model of ulcerogenic effect, the most active compounds 21 and 22 showed better safety profile than indomethacin. Further, at the active sites of the COX-1, COX-2 and 15-LOX co-crystal, 19, 21, and 22 showed high binding forces in free binding energy study, which is consistent with in vitro and in vivo results. In conclusion, these compounds are good candidates for further biological investigation as potential anti-inflammatory drugs with dual balanced inhibition of COX and 15-LOX and good safety profile.

Synthesis, biological evaluation and docking study of 1,3,4-thiadiazole-thiazolidinone hybrids as anti-inflammatory agents with dual inhibition of COX-2 and 15-LOX.

Selective inhibition of both cyclooxygenase-2 (COX-2) and 15-lipooxygenase (15-LOX) may provide good strategy for alleviation of inflammatory disorders while minimizing side effects associated with current anti-inflammatory drugs. The present study describes the synthesis, full characterization and biological evaluation of a series of thiadiazole-thiazolidinone hybrids bearing 5-alk/arylidene as dual inhibitors of these enzymes. Our design was based on merging pharmacophores that exhibit portent anti-inflammatory activities in one molecular frame. 5-(4-hydroxyphenyl)-1,3,4-thiadiazol-2-amine (3) was efficiently synthesized, chloroacetylated and cyclized to give the key 4-thiazolidinone (5). Knovenagel condensation of 5 with different aldehydes afforded the final compounds 6a-m, 7, 8 and 9. These compounds were subjected to in vitro COX-1/COX-2, 15-LOX inhibition assays. Compounds (6a, 6f, 6i, 6l, 6m and 9) with promising potency (IC50 = 70-100 nM) and selectivity index (SI = 220-55) were further tested for in vivo anti-inflammatory activity and effect on gastric mucosa. The most promising compound (6l) inhibits COX-2 enzyme at a nanomolar concentration (IC50 = 70 nM, SI = 220) with simultaneous inhibition of 15-LOX (IC50 = 11 µM). These results are comparable to the potency and selectivity of the standard drugs of both enzymes; celecoxib (COX-2 IC50 = 49 nM, SI = 308) and zileuton (15-LOX IC50 = 15 µM) in one construct. Interestingly three compounds (6a, 6l and 9) exhibited equivalent to or even higher than that of celecoxib in vivo anti-inflammatory activity at 3 h interval with good GIT safety profile. Molecular docking study conferred binding sites of these compounds on COX-2 and 15-LOX. Such type of compounds would represent valuable leads for further investigation and derivatization.

Novel N-substituted 5-aminosalicylamides as dual inhibitors of cyclooxygenase and 5-lipoxygenase enzymes: Synthesis, biological evaluation and docking study.

Three new series of 5-aminosalicylic acid derivatives; series I (14, 16-18), series II (19-30) and series III (31-41) were synthesized as potential dual COX-2/5-LOX inhibitors. Their chemical structures were confirmed using spectroscopic tools including IR, 1H NMR, 13C NMR, mass spectroscopy and elemental analyses. The anti-inflammatory activity for all target compounds was evaluated in vivo using carrageenan-induced paw edema. Compound 36 showed the highest anti-inflammatory activity (114.12%) relative to reference drug indomethacin at 4 h interval. Selected derivatives were evaluated in vitro to inhibit ovine COX-1, human recombinant COX-2 and 5-LOX enzymes. Compounds 34 &35 exhibited significant COX-2 inhibition (IC50 = 0.10 µM) with significant COX-2 selectivity indices (SI = 135 & 145 respectively) approximate to celecoxib (IC50 = 0.049 µM, SI = 308.16) and exceeding indomethacin (IC50 = 0.51 µM, SI = 0.08). Interestingly, all compounds showed superior 5-LOX inhibitory activity about 2-5 times relative to zileuton. Compound 16 was the superlative 5-LOX inhibitor that revealed (IC50 = 3.41 µM) relative to zileuton (IC50 = 15.6 µM). Compounds 34, 35, 36 and 41 showed significant dual COX-2/5-LOX inhibitions. The gastric ulcerogenic effect of compound 36 was examined on gastric mucosa of albino rats and they showed superior GI safety profile compared with indomethacin. Molecular docking studies of the compounds into the binding sites of COX-1, COX-2 and 5-LOX allowed us to shed light on the binding mode of these novels dual COX and 5-LOX inhibitors.

Proximity labeling of cis-ligands of CD22/Siglec-2 reveals stepwise α2,6 sialic acid-dependent and -independent interactions.

Lectins expressed on the cell surface are often bound and regulated by the membrane molecules containing the glycan ligands on the same cell (cis-ligands). However, molecular nature and function of cis-ligands are generally poorly understood partly because of weak interaction between lectins and glycan ligands. Cis-ligands are most extensively studied in CD22 (also known as Siglec-2), an inhibitory B lymphocyte receptor specifically recognizing α2,6 sialic acids. CD22, CD45 and IgM are suggested to be ligands of CD22. Here we labeled molecules in the proximity of CD22 in situ on B cell surface using biotin-tyramide. Molecules including CD22, CD45 and IgM were labeled in wild-type but not ST6GalI-/- B cells that lack α2,6 sialic acids, indicating that these molecules associate with CD22 by lectin-glycan interaction, and are therefore cis-ligands. In ST6GalI-/- B cells, these cis-ligands are located in a slightly more distance from CD22. Thus, the lectin-glycan interaction recruits cis-ligands already located in the relative proximity of CD22 through non-lectin-glycan interaction to the close proximity. Moreover, cis-ligands are labeled in Cmah-/- B cells that lack Neu5Gc preferred by mouse CD22 as efficiently as in wild-type B cells, indicating that very low affinity lectin-glycan interaction is sufficient for recruiting cis-ligands, and can be detected by proximity labeling. Thus, proximity labeling with tyramide appears to be a useful method to identify cis-ligands and to analyze their interaction with the lectins.

Synthesis and anti-mycobacterial activity of 4-(4-phenyl-1H-1,2,3-triazol-1-yl)salicylhydrazones: revitalizing an old drug.

The antitubercular drug; para-aminosalicylic acid (PAS) was used as the core scaffold for the design of a series of 1H-1,2,3-triazolylsalicylhydrazones upon coupling with triazole and arylhydrazone moietis to furnish a single molecular architecture. The obtained derivatives were screened against Mycobacterium tuberculosis H37Rv revealing good to high activity for the active compounds (MIC values of 0.39-1.5 µg/mL) compared to the marketed drugs isoniazid, rifampicin and ethambutol. Moreover, the most active analogue N-(1-(4-chlorobenzyl)-2-oxoindolin-3-ylidene)-2-hydroxy-4-(4-phenyl-1H-1,2,3-triazol-1-yl)-benzohydrazide (20) was found to be ten-fold more potent than PAS and equipotent to rifampicin (MIC 0.39 µg/mL), while exhibiting low cytotoxicity with a selectivity index of >128. In addition, this compound was shown to be active against persistent forms of mycobacteria comparable to standard drugs in nutrient starvation model. Accordingly, we introduce compound 20 as a valuable lead for further development. A 3D-QSAR study was also conducted to help in explaining the observed activity and to serve as a tool for further development.

Nature-inspired design of tetraindoles: Optimization of the core structure and evaluation of structure-activity relationship.

Building on the initial successful optimization of a novel series of tetraindoles, a second generation of the compounds with changes in the core phenyl ring was synthesized to improve anticancer properties. 17 new compounds with different rigidity, planarity, symmetry and degree of conjugation of their core structures to 5-hydroxyindole units were synthesized. All the compounds were fully characterized and tested against breast cancer cell line (MDA-MB-231). The results revealed that the core structure is required for activity and it should be aromatic, rigid, planar, symmetrical and conjugated for optimal activity. Compound 29, which has strong anticancer activity against various tumor-derived cell lines, including Mahlavu (hepatocellular), SK-HEP-1 (hepatic), HCT116 (colon), MIA PaCa-2 (pancreatic), H441 (lung papillary), A549 (lung), H460 (non-small cell lung) and CL1-5 (lung carcinoma) with IC50 values ranging from 0.19 to 3.50µM, was generated after series of successive optimizations. It was found to induce cell cycle arrest and apoptosis in vitro and inhibit tumor growth in the non-obese diabetic-severe combined immunodeficiency (NOD/SCID) mice bearing xenografted MIA PaCa-2 human pancreatic cancer.