Hussain Raza

Hybrid Pharmacophoric Approach in the Design and Synthesis of Coumarin Linked Pyrazolinyl as Urease Inhibitors, Kinetic Mechanism and Molecular Docking

The current research article reports the synthesis of coumarinyl pyrazolinyl thioamide derivatives and their biological activity as inhibitors of jack bean urease. The coumarinyl pyrazolinyl thioamides were synthesized by reacting thiosemicarbazide with newly synthesized chalcones to afford the products in good yields and the synthesized compounds were purified by recrystallization. Coumarinyl pyrazolinyl thioamide derivatives 5a – 5q showed significant activity against Urease enzyme and also exhibited good antioxidant potential. The compound 3‐(2‐oxo‐2H‐chromen‐3‐yl)‐5‐phenyl‐4,5‐dihydro‐1H‐pyrazole‐1‐carbothioamide (5n) was found to be superior agent in the series with an IC50 = 0.358 ± 0.017 μm compared to standard thiourea with an IC50 = 4720 ± 174 μm. To undermine the binding mode of inhibition kinetic studies were performed for most potent derivative and it was found that compound 5n inhibits urease enzyme by non‐competitive mode of inhibition. Molecular docking studies were carried out to delineate the binding affinity of the synthesized derivatives.

Isolation, characterization, and in silico, in vitro and in vivo antiulcer studies of isoimperatorin crystallized from Ostericum koreanum

Abstract Context: Ostericum koreanum (Maxim.) Kitagawa (Apiaceae) roots are traditionally used as an analgesic and antiulcer agent. However, the antiulcer potential of isoimperatorin isolated from O. koreanum has not yet been explored. Aim: To evaluate the antiulcer activity of isoimperatorin isolated from the roots of O. koreanum. Materials and methods: Isoimperatorin was isolated as cubic crystals by repeated column chromatography of the ethyl acetate fraction and structure was verified with 1H NMR, 13C NMR and high-resolution mass spectrometry (HRMS-FAB). The crystals obtained were analyzed with the single crystal X-ray method. The MTT assay was used to determine its cytotoxicity against chondrocytes at different concentrations (0.0–737.74 μM, 24 h). The in vivo antiulcer activity of isoimperatorin (40 mg/kg) was determined against ethanol-, indomethacin- and pyloric ligation-induced ulcers in Sprague-Dawley rats. Furthermore, the effect of isoimperatorin (0.0–737.74 μM, 24 h) on the expression of type II collagen in chondrocytes was determined using western blot method. The in vitro urease inhibitory activity of isoimperatorin (0–80 μM) and molecular docking was also performed against urease. Results and discussion: Isoimperatorin demonstrated significant inhibitory activity (IC50 36.43 μM) against urease as compared to the standard drug thiourea (IC50 33.57 μM) without cytotoxic effects. It provided 70.9%, 67.65% and 54.25% protection in ulcer models induced by ethanol, indomethacin and pyloric ligation, respectively. Isoimperatorin showed the highest expression level of type II collagen at 368.87 μM. The docking results confirmed strong binding affinity with the target protein. Conclusion: Isoimperatorin may be used to develop antiulcer drugs with decreased side effects.

Sulfonamide-Linked Ciprofloxacin, Sulfadiazine and Amantadine Derivatives as a Novel Class of Inhibitors of Jack Bean Urease; Synthesis, Kinetic Mechanism and Molecular Docking

Sulfonamide derivatives serve as an important building blocks in the drug design discovery and development (4D) process. Ciprofloxacin-, sulfadiazine- and amantadine-based sulfonamides were synthesized as potent inhibitors of jack bean urease and free radical scavengers. Molecular diversity was explored and electronic factors were also examined. All 24 synthesized compounds exhibited excellent potential against urease enzyme. Compound 3e (IC50 = 0.081 ± 0.003 µM), 6a (IC50 = 0.0022 ± 0.0002 µM), 9e (IC50 = 0.0250 ± 0.0007 µM) and 12d (IC50 = 0.0266 ± 0.0021 µM) were found to be the lead compounds compared to standard (thiourea, IC50 = 17.814 ± 0.096 µM). Molecular docking studies were performed to delineate the binding affinity of the molecules and a kinetic mechanism of enzyme inhibition was propounded. Compounds 3e, 6a and 12d exhibited a mixed type of inhibition, while derivative 9e revealed a non-competitive mode of inhibition. Compounds 12a, 12b, 12d, 12e and 12f showed excellent radical scavenging potency in comparison to the reference drug vitamin C.

Jack Bean Urease Inhibitors, and Antioxidant Activity Based on Palmitic acid Derived 1-acyl-3- Arylthioureas: Synthesis, Kinetic Mechanism and Molecular Docking Studies

A series of acylthioureas was synthesized and their inhibitory effects on the DPPH and jack bean urease were evaluated. The results showed that all of the synthesized compounds exhibited significant jack bean urease inhibitory activities. Especially, 1-(4-chlorophenyl)-3 palmitoylthiourea 5a bearing 4-chloro substituted phenyl ring exhibited the most potent tyrosinase inhibitory activity with an IC50 value 0.0170 μM compared to the IC50 value of 4.720 μM of thiourea used as standard. The inhibition mechanism analyzed by Lineweaver-Burk plots revealed that the type of inhibition of compound 5a on tyrosinase was noncompetitive. The docking study against jack bean urease enzyme was also performed to determine the binding affinity of the compounds. The compounds 4c and 4e showed the highest binding affinity with the active binding site of tyrosinase. The initial structure activity relationships (SARs) analysis suggested that further development of such compounds might be of interest. The statistics of our results endorses that all compounds and particularly 5a may serve as a structural template for the design and development of novel urease inhibitors Graphical Abstract.

Synthesis, molecular docking studies of coumarinyl-pyrazolinyl substituted thiazoles as non-competitive inhibitors of mushroom tyrosinase

A series of coumarinyl-pyrazolinyl substituted thiazoles derivatives were synthesized and their inhibitory effects on the DPPH and mushroom tyrosinase were evaluated. The results showed that all of the synthesized compounds exhibited significant mushroom tyrosinase inhibitory activities. In particular, 3-(5-(4-(benzyloxy)-3-methoxyphenyl)-1-(4-(4-bromophenyl)thiazol-2-yl)-4,5-dihydro-1H-pyrazol-3-yl)-2H-chromen-2-one (7j) exhibited the most potent tyrosinase inhibitory activity with IC50 value 0.00458±0.00022μM compared with the IC50 value of kojic acid is 16.84±0.052μM. The inhibition mechanism analyzed by Lineweaver-Burk plots revealed that the type of inhibition of compound 7j on tyrosinase was noncompetitive. The docking study against tyrosinase enzyme was also performed to determine the binding affinity of the compounds. The compound 7a showed the highest binding affinity (-10.20kcal/mol) with active binding site of tyrosinase. The initial structure activity relationships (SARs) analysis suggested that further development of such compounds might be of interest. The statistics of our results endorses that compound 7j may serve asa structural template for the design and development of novel tyrosinase inhibitors.

Synthesis and Molecular Docking Studies of (E)-4-(Substituted-benzylideneamino)-2H-Chromen-2-one Derivatives: Entry to New Carbonic Anhydrase Class Of Inhibitors

The present article illustrated the synthesis and characterization of a novel series of (E)-4-(substituted-benzylideneamino)-2H-chromen-2-one derivatives 4A-4J: in good to excellent yields. The target compounds were synthesized by refluxing 4-aminocoumarin with aromatic aldehydes in ethanol. The structural confirmation was achieved by spectroscopic techniques such as (1H, 13C-NMR and FT-IR) and elemental analysis. The synthesized compounds were evaluated for carbonic anhydrase II (CA-II) inhibition and free radical scavenging activity. All the compounds showed CA-II inhibition in the micro molar range. The compound 4C: exhibited higher potential in the series with IC50=0.0928±0.00545 µM (standard Acetazolamide IC50=0.997±0.0586 µM). Pharmacological investigations showed that the synthesized compounds 4A-4J: obey Lipinsks rule. Compound 4C: elicited drug likeness and showed drug score value of 0.05. Molecular docking analysis showed that compound 4C: interacts with Asn66 and Gln91 amino acid residues. Graphical Abstract.

Acetazolamide inhibits the level of tyrosinase and melanin: An enzyme kinetic, in vitro, in vivo and in silico studies

Melanin is the major factor that determines skin color and protects from ultraviolet radiation. In present study we evaluated the anti‐melanogenesis effect of acetazolamide (ACZ) using four different approaches: enzyme kinetic, in vitro, in vivo and in silico. ACZ demonstrated significant inhibitory activity (IC50 7.895 ± 0.24 μm) against tyrosinase as compared to the standard drug kojic acid (IC50 16.84 ± 0.64 μm) and kinetic analyses showed that ACZ is a non‐competitive inhibitor without cytotoxic effect. In in vitro experiments, A375 human melanoma cells were treated with 20 or 40 μm of ACZ with or without 50 μm of l‐DOPA. Western blot results showed that ACZ significantly (P < 0.05) decreased the expression level of tyrosinase at 40 μm. Zebrafish embryos were treated with 10, 20 or 40 μm of ACZ and of positive control kojic acid. At 72 h of treatment with ACZ and kojic acid, ACZ significantly (P < 0.001) decreased the embryos pigmentation to 40.8% of untreated embryos at the dose of 40 μm of ACZ while kojic acid decreased only 25.0% of pigmentation at the same dose of kojic acid. In silico docking were performed against tyrosinase using PyRx tool. Docking studies suggested that His244, Asn260 and His85 are the major interacting residues in the binding site of the protein. In conclusion, our results suggest that ACZ is a good candidate for the inhibition of melanin and it could be used as a lead for developing the drugs for hyperpigmentary disorders and skin whitening.

In Vitro, In Silico Elucidation of Antiurease Activity, Kinetic Mechanism and COX-2 Inhibitory Efficacy of Coagulansin A of Withania coagulans

Urease enzyme plays a crucial role in the survival of Helicobacter pylori that contributes to different diseases, including peptic ulcer (gastric and duodenal ulcers). Coagulansin A is the steroidal lactone (withanolide) found in plants of solanaceae family such Withania coagulans. The current study was carried out to examine the in vitro urease, COX‐2 inhibitory activity and effect on type II collagen expression of coagulansin A. Moreover, we investigated cytotoxic effects on rabbit articular chondrocytes through MTT assay. COX‐2 and type II collagen expressions were determined through a Western blot method. Molecular docking and simulation studies of urease (PDBID 4H9M) and COX‐2 (PDBID 5F1A) proteins were also performed as an in silico approach. Results showed that COX‐2 expression was decreased dose dependably, significantly higher expression of type II collagen was observed at higher doses. In the current study, coagulansin A was found as non‐toxic, and showed notable urease inhibitory activity in non‐competitive manner with IC50 23.14 μm in comparison to reference drug thiourea 17.81 μm. Significant decrease in COX‐2 expression (40%) and increase in type II collagen (20%) were observed as compared to control. In silico results unveiled the strong binding affinities of coagulansin A with both of these urease and COX‐2 proteins. Therefore, herein we proposed the significant antiurease potential of this compound that could be used in treating different diseases such as ulcers. Moreover, detailed in vivo studies and molecular mechanism based studies are suggested.

Extending the scope of amantadine drug by incorporation of phenolic azo Schiff bases as potent selective inhibitors of carbonic anhydrase II, drug-likeness and binding analysis

A series of Amantadine‐based azo Schiff base dyes 6a–6e have been synthesized and characterized by 1H NMR and 13C NMR and evaluated for their in vitro carbonic anhydrase II inhibition activity and antioxidant activity. All of the synthesized showed excellent carbonic inhibition. Compound 6b was found to be the most potent derivative in the series, and the IC50 of 6b was found to be 0.0849 ± 0.00245 μm (standard Acetazolamide IC50 = 0.9975 ± 0.049 μm). The binding interactions of the most active analogs were confirmed through molecular docking studies. Docking studies showed 6b is interacting by making two hydrogen bonds w at His93 and Ser1 residues, respectively. All compounds showed a good drug score and followed Lipinskis rule. In summary, our studies have shown that these amantadine‐derived phenolic azo Schiff base derivatives are a new class of carbonic anhydrase II inhibitors.

Synthesis, in vitro and in silico studies of novel potent urease inhibitors: N -[4-({5-[(3-Un/substituted-anilino-3-oxopropyl)sulfanyl]-1,3,4-oxadiazol-2-yl}methyl)-1,3-thiazol-2-yl]benzamides

The present article describes the synthesis, in vitro urease inhibition and in silico molecular docking studies of a novel series of bi-heterocyclic bi-amides. The synthesis of title compounds was initiated by benzoylation, with benzoyl chloride (1), of the key starter ethyl 2-(2-amino-1,3-thiazol-4-yl)acetate (2) in weak basic aqueous medium followed by hydrazide formation, 4, and cyclization with CS2 to reach the parent bi-heterocyclic nucleophile, N-{4-[(5-sulfanyl-1,3,4-oxadiazol-2-yl)methyl]-1,3-thiazol-2-yl}benzamide (5). Various electrophiles, 8a-l, were synthesized by a two-step process and these were finally coupled with 5 to yield the targeted bi-heterocyclic bi-amide molecules, 9a-l. The structures of the newly synthesized products were corroborated by IR, 1H NMR, 13C NMR, EI-MS and elemental analysis. The in vitro screening of these molecules against urease explored that most of the compounds exhibit potent inhibitory potential against this enzyme. The compound 9j, with IC50 value of 2.58 ± 0.02 µM, exhibited most promising inhibitory activity among the series, relative to standard thiourea having IC50 value of 21.11 ± 0.12 µM. In silico studies fully augmented the experimental enzyme inhibition results. Chemo-informatics analysis showed that synthesized compounds (9a-l) mostly obeyed the Lipinskis rule. Molecular docking study suggested that ligand 9j exhibited good binding energy value (-7.10 kcal/mol) and binds within the active region of target protein. So, on the basis of present investigation, it was inferred that 9j may serve as a novel scaffold for designing more potent urease inhibitors.