Synthesis, structural characterization, and anti-ulcerogenic activity of schiff base ligands derived from tryptamine and 5-chloro, 5-nitro, 3,5-ditertiarybutyl salicylaldehyde and their nickel(II), copper(II), and zinc(II) complexes

A Novel Rhodamine Functionalized Schiff Base Type Ratiometric Fluorescent Chemosensor for the Sensing of Hg2+ Ions; Experimental and Theoretical Approach

A new Rhodamine functionalised Schiff Base sensor 3',6'-bis(diethylamino)-2-((4-hydroxybenzylidene)amino)spiro[isoindoline-1,9'-xanthen]-3-one (SBRB1) was designed and synthesized. The recognition ability of sensor SBRB1 towards Hg2+ was studied by using UV-Vis and fluorescence spectroscopy. The fluorescence results showed that the sensor SBRB1 has specific selectivity as well as sensitivity towards Hg2+ among other competitive metal ions as the fluorescence intensity at 479 nm quenched only in the presence of Hg2+. This sensitivity towards Hg2+ was due to the chelation between ligand and Hg2+. From the fluorescence titration the binding constant and detection limit of SBRB1:Hg2+ complex were calculated and found to be 5.114× 106 M-1 and 2.91× 10-5 M respectively. It showed The 1:1 complexation between SBRB1 and Hg2+ which was conformed from the DFT and TD-DFT study of SBRB1 in both solvent and gas phase.

In Vivo Gastroprotective Upshots of the Novel Schiff Base CdCl2 (C14H21N3O2) Compound by Bax/HSP-70 Signaling and Inflammatory Cytokines

BACKGROUND

Synthesis of the original Schiff base CdCl2 (C14H21N3O2) compound (Schiff base complex) displays an extensive range of bioactivities and was predictably utilized to treat several syndromes.

PURPOSE

The goal of the existing experiment is to evaluate the gastroprotective effects of a novel Schiff base CdCl₂ (C14H21N3O2) compound in alcohol-induced gastric ulcers in rats by examining its antioxidant activity, anti-inflammatory effects, and modulation of key molecular markers, including heat shock protein-70 (HSP-70) and Bcl-2-associated X protein (Bax) proteins.

METHODS

Five groups of rats were utilized in the current study. Control and model groups were orally administered 10% Tween 20. The treated groups were orally administered 20 mg/kg omeprazole or Schiff base compound (25 or 50 mg/kg). One hour later, only the control group received oral 10% Tween 20, and the treated groups received oral (5 ml/cage) absolute alcohol. During the second hour, all rats were sacrificed.

RESULTS

All treated rats presented considerable improvement in alcohol-induced gastric injury recognized by decreasing ulcer index and raising % of ulcer inhibition. Increased mucus and gastric pH content and decreased ulcerated portion, reduced or non-appearance of edema, and leucocytes penetrated the subcutaneous layer. In stomach epithelium homogenate, the Schiff base compound obtainable significant upsurge superoxide dismutase (SOD), catalase (CAT) activities, considerable declining malondialdehyde (MDA) quantity. Moreover, the Schiff base compound raised the intensity of periodic acid-Schiff (PAS) stains gastric epithelium. Furthermore, the Schiff base compound formed up-regulated HSP-70 and down-regulated Bax proteins gastric epithelium Schiff base compound, reduced the level of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and improved the quantity of IL-10. Administering a high dose of 500 mg/kg Schiff base compound revealed the nontoxic nature of the compound in rats.

CONCLUSION

Schiff base compound exhibited gastroprotective effects attributed to its antioxidant nature, its capability to enhance mucus excretion, SOD and CAT, reduce MDA amount, up-regulate HSP-70 protein, down-regulate Bax protein, and inflammatory cytokines.

Tryptamine-Derived Schiff Bases: Potent Antimicrobial Agents and Evaluation of Cytotoxicity, ADME and DNA Binding Properties

Inspired by the fact that the introduction of indole pharmacophore in organic scaffolds could enable interesting pharmacological properties, the series of novel tryptamine-derived Schiff bases was synthetized. Tryptamine was used as a source of indole pattern, as well as an example of biogenic amines which chemical transformations lead to the compounds with prominent biological activities. The obtained results for antimicrobial activity against a range of bacterial and fungal strains and cytotoxic activities have revealed that Schiff base TSB4 combining the tryptamine and p-nitro aryl patterns in the structure showed better antifungal activity at low concentrations than standard drug Fluconazole, while compound TSB6 with molecular scaffold composed from tryptamine and quinoline moieties showed certain cytotoxic effect on HCT-116 cell line with a strongly expressed selectivity about healthy fibroblast cells, MRC-5. For these two selected compounds, additional ADME analysis and DNA interactions were performed. to obtain better insight into their pharmacokinetics and determination of binding mode for DNA molecules. As results suggested, strong binding of examined compounds to CT-DNA was observed, while the ADME screening showed that selected compounds possess suitable physicochemical properties for oral bioavailability and druglikeness.

In vivo acute toxicity and anti-gastric evaluation of a novel dichloro Schiff base: Bax and HSP70 alteration

Chlorine is shown to possess anti-gastric ulcer activity, since it can inactivate Helicobacter pylori, which is regarded as one of the most common risk factors for causing gastric problems. In the current study, the gastroprotective property of a novel dichloro-substituted Schiff base complex, 2, 2'- [-1, 2-cyclohexanediylbis(nitriloethylidyne)] bis(4-chlorophenol) (CNCP), against alcohol-induced gastric lesion in SD rats was assessed. SD rats were divided into four groups, i.e. normal, ulcer control, testing, and reference groups. Ulcer area, gastric wall mucus, and also gastric acidity of the animal stomachs were measured. In addition, antioxidant activity of CNCP was evaluated and its safe dose was identified. Immunohistochemistry staining was also carried to evaluate two important proteins, i.e. Bcl2-associated X protein (Bax) and heat shock protein 70 (HSP70). Moreover, the activities of super oxide dismutase and catalase, as well as the levels of prostaglandin E2 (PGE2) and malondialdehyde (MDA) were also measured. Antioxidant activity of CNCP was approved via the aforementioned experiments. Histological evaluations showed that the compound possesses stomach epithelial defense activity. Additionally, periodic acid-Schiff staining exhibited over-expression of HSP70 and down-expression of Bax protein in the CNCP-treated rats. Moreover, CNCP caused deceased MDA level and elevated PGE2 level, and at the same time increased the activities of the two enzymes.

New transition metal complexes with a pendent indole ring: insights into the antifungal activity and mode of action

Development of new chemotherapeutic agents to treat multidrug-resistant fungal infections to augment the current treatment options is a must. In this direction, a series of mixed ligand complexes was synthesized from a Schiff base (L) obtained by the condensation of 2-hydroxynapthaldehyde and tryptamine, and 1,10-phenanthroline (1,10-phen) as a secondary ligand. Based on spectral characterization and physical measurements an octahedral geometry was assigned to [Co(phen)LClH₂O] (C2), [Ni(phen)LClH₂O](C3), and [Zn(phen)LClH₂O](C4) complexes while a distorted octahedral geometry was assigned to the [Cu(phen)LClH₂O](C1) complex. All the synthesized compounds were tested for antifungal activity against 11 Candida albicans isolates, including fluconazole (FLC) resistant isolates, by determining minimum inhibitory concentrations and studying growth curves. MIC results suggest that all the newly synthesized compounds have potent antifungal activity at varying levels. The rapid action of these compounds on fungal cells suggested a membrane-located target for their action.

Mixed ligand complexes containing a pendent indole showed significant proton pump ATPase targeted antifungal activity.

Schiff bases of tryptamine as potent inhibitors of nucleoside triphosphate diphosphohydrolases (NTPDases): Structure-activity relationship

Overexpression of NTPDases leads to a number of pathological situations such as thrombosis, and cancer. Thus, effective inhibitors are required to combat these pathological situations. Different classes of NTPDase inhibitors are reported so far including nucleotides and their derivatives, sulfonated dyes such as reactive blue 2, suramin and its derivatives, and polyoxomatalates (POMs). Suramin is a well-known and potent NTPDase inhibitor, nonetheless, a range of side effects are also associated with it. Reactive blue 2 also had non-specific side effects that become apparent at high concentrations. In addition, most of the NTPDase inhibitors are high molecular weight compounds, always required tedious chemical steps to synthesize. Hence, there is still need to explore novel, low molecular weight, easy to synthesize, and potent NTPDase inhibitors. Keeping in mind the known NTPDase inhibitors with imine functionality and nitrogen heterocycles, Schiff bases of tryptamine, 1-26, were synthesized and characterized by spectroscopic techniques such as EI-MS, HREI-MS, ¹H-, and ¹³C NMR. All the synthetic compounds were evaluated for the inhibitory avidity against activities of three major isoforms of NTPDases: NTPDase-1, NTPDase-3, and NTPDase-8. Cumulatively, eighteen compounds were found to show potent inhibition (Ki = 0.0200-0.350 μM) of NTPDase-1, twelve (Ki = 0.071-1.060 μM) of NTPDase-3, and fifteen compounds inhibited (Ki = 0.0700-4.03 μM) NTPDase-8 activity. As a comparison, the Kis of the standard inhibitor suramin were 1.260 ± 0.007, 6.39 ± 0.89 and 1.180 ± 0.002 μM, respectively. Kinetic studies were performed on lead compounds (6, 5, and 21) with human (h-) NTPDase-1, -3, and -8, and Lineweaver-Burk plot analysis showed that they were all competitive inhibitors. In silico study was conducted on compound 6 that showed the highest level of inhibition of NTPDase-1 to understand the binding mode in the active site of the enzyme.

Spectral Investigation andIn VitroAntibacterial Evaluation of NiIIand CuIIComplexes of Schiff Base Derived from Amoxicillin andα-Formylthiophene (αft)

Two new metal complexes of general formula M(Haαft)2[M =NiIIandCuII] of asymmetrical Schiff base ligand (HL = Haαft) derived from amoxicillin andα-formylthiophene have been prepared and characterized by various physicochemical and spectral techniques. Molar conductance measurement indicates nonelectrolytic nature of the metal complexes. FT-IR spectral study reveals the ligation of metal ions at two different nitrogen [NN] donor sites of Haαft. FT-IR and electronic absorption spectral evidences suggest distorted tetrahedral and square planar geometry forCuIIandNiIIcomplexes, respectively. The structure optimization by molecular mechanics (MM) force field calculation through ArgusLab 4.0.1 version software also supports the concerned geometry of the complexes. The cell dimensions as suggested by XRPD study,a(6.753 Å),b(13.904 Å),c(20.122 Å),α(142.76°),β(106.580°), andγ(72.4343°) forCuIIanda(24.2547 Å),b(6.6371 Å),c(5.5047 Å) (α=β=γ= 90°) forNiIIcomplexes, are in good agreement with their triclinic and orthorhombic crystal systems. Particle size calculation by Scherrer’s formula indicates nanocrystalline nature of the complexes. The antibacterial sensitivity study suggests promising activities of Haαft (Ligand) and M(Haαft)2complexes against four clinical pathogenic bacteria, namely,E. coli,P. vulgaris,P. aeruginosa, andS. aureus, though being less active than the standard drug amikacin.

Hadi AH, Mohd Ali H, Majid N, Abdulla MA. Acute toxicity and gastroprotection studies of a new schiff base derived copper (II) complex against ethanol-induced acute gastric lesions in rats

BACKGROUND

Copper is an essential element in various metabolisms. The investigation was carried out to evaluate acute gastroprotective effects of the Copper (II) complex against ethanol-induced superficial hemorrhagic mucosal lesions in rats.

METHODOLOGY/PRINCIPAL FINDINGS

Rats were divided into 7 groups. Groups 1 and 2 were orally administered with Tween 20 (10% v/v). Group 3 was orally administered with 20 mg/kg omeprazole (10% Tween 20). Groups 4-7 received 10, 20, 40, and 80 mg/kg of the complex (10% Tween 20), respectively. Tween 20 (10% v/v) was given orally to group 1 and absolute ethanol was given orally to groups 2-7, respectively. Rats were sacrificed after 1 h. Group 2 exhibited severe superficial hemorrhagic mucosal lesions. Gastric wall mucus was significantly preserved by the pre-treatment complex. The results showed a significant increase in glutathione (GSH), superoxide dismutase (SOD), nitric oxide (NO), and Prostaglandin E2 (PGE(2)) activities and a decrease in malondialdehyde (MDA) level. Histology showed marked reduction of hemorrhagic mucosal lesions in groups 4-7. Immunohistochemical staining showed up-regulation of Hsp70 and down-regulation of Bax proteins. PAS staining of groups 4-7 showed intense stain uptake of gastric mucosa. The acute toxicity revealed the non-toxic nature of the compound.

CONCLUSIONS/SIGNIFICANCE

The gastroprotective effect of the Copper (II) complex may possibly be due to preservation of gastric wall mucus; increase in PGE(2) synthesis; GSH, SOD, and NO up-regulation of Hsp70 protein; decrease in MDA level; and down-regulation of Bax protein.

Acute toxicity and gastroprotective effect of the Schiff base ligand ¹H-indole-3-ethylene-5-nitrosalicylaldimine and its nickel (II) complex on ethanol induced gastric lesions in rats

The present study was performed to evaluate the gastroprotective activity of Schiff base ligand derived from the condensation reaction of tryptamine (an indole derivative) and 5-nitrosalicylaldehyde (TNS) and its nickel (II) complex against ethanol-induced gastric ulcer in rats. The compounds were orally administered with low (30 mg/kg) and high (60 mg/kg) doses to ulcer-induced Sprague-Dawley rats. Macroscopically, the ulcer control group exhibited severe mucosal injury, whereas pre-treatment with either cimetidine or TNS and its nickel (II) complex each resulted in significant protection against gastric mucosal injury. Flattening of gastric mucosal folds was also observed in rats pretreated with TNS and its nickel complex. Histological studies of the gastric wall of ulcer control group revealed severe damage of gastric mucosa, along with edema and leucocytes infiltration of the submucosal layer compared to rats pre-treated with either cimetidine or TNS and its nickel (II) compound, where there was marked gastric protection along with reduction of edema and leucocytes infiltration of the submucosal layer. Acute toxicity study done on mice with a higher dose of 5 g/kg of TNS and its nickel (II) complex did not manifest any toxicological signs. Research finding suggest that TNS and its nickel (II) complex could be considered as effective gastroprotective compounds.

Bis{2-[(2-hy-droxy-2-methyl-prop-yl)imino-meth-yl]-4-nitro-phenolato}nickel(II) dimethyl-formamide monosolvate

In the title compound, [Ni(C₁₁H₁₃N₂O₄)₂]·C₃H₇NO, the Ni^II ion is octa­hedrally coordinated in an N₂O₄ environment by two identical Schiff base ligands. The Ni—O bond lengths range from 2.004 (2) to 2.106 (2) Å, while the Ni—N bond lengths are 2.038 (2) and 2.0465 (19) Å. The cis bond angles range from 78.64 (8) to 97.30 (8)°, with the former being due to the small bite of the amino­alcohol ligand, while the trans bond angles range from 167.86 (8) to 171.23 (8)°. One of the alcohol H atoms forms a hydrogen bond with the dimethyl­formamide (DMF) solvent mol­ecule, while the other links mol­ecules into chains along the b axis through inter­molecular O—H⋯O hydrogen bonds. There are bifurcated C—H⋯O inter­actions involving one of the nitro groups between parallel stacks of mol­ecules in the b-axis direction.

Synthesis and anti-bacterial activities of some novel Schiff bases derived from aminophenazone

A series of 1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one-containing Schiff bases were synthesized, characterized and screened for their antibacterial activities. The structures of the synthesized compounds were established by spectroscopic (FT-IR, ¹H-NMR, ¹³C-NMR, MS) and elemental analyses. The anti-bacterial activities (with MIC values) of compounds were evaluated. The anti-bacterial screening results reveal that among the six compounds screened, four compounds showed moderate to good anti-bacterial activity. Among the tested compounds, the most effective compounds against four bacterial strains, viz. Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and Streptococcus pyogenes, are [(2-Chlorobenzylidene)amino]-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one (4) and [(1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylimino)methyl]benzonitrile(5) with MIC values of 6.25 μg/mL.