Synthesis,in vitro evaluation,and molecular docking studies of benzofuran based hydrazone a new inhibitors of urease

This work has described the synthesis of novel class (1–25) of benzofuran based hydrazone. The hybrid scaffolds (1–25) of benzofuran based hydrazone were evaluated in vitro, for their urease inhibition. All the newly synthesized analogues (1–25) were found to illustrate moderate to good urease inhibitory profile ranging from 0.20 ± 0.01 to 36.20 ± 0.70 µM. Among the series, compounds 22 (IC₅₀ = 0.20 ± 0.01 µM), 5 (IC₅₀ = 0.90 ± 0.01 µM), 23 (IC₅₀ = 1.10 ± 0.01 µM) and 25 (IC₅₀ = 1.60 ± 0.01 µM) were found to be the many folds more potent than thiourea as standard inhibitor (IC₅₀ = 21.86 ± 0.40 µM). The elevated inhibitory profile of these analogues might be due to presence of dihydroxy and flouro groups at different position of phenyl ring B attached to hydrazone skeleton. These dihydroxy and fluoro groups bearing compounds have shown many folds better inhibitory profile through involvement of oxygen of dihydroxy groups in hydrogen bonding with active site of enzymes. Various types of spectroscopic techniques such as ¹H-, ¹³C- NMR and HREI-MS spectroscopy were used to confirm the structure of all the newly developed compounds. To find SAR, molecular docking studies were performed to understand, the binding mode of potent inhibitors with active site of enzymes and results supported the experimental data.     

Synthesis of new 1,2-disubstituted benzimidazole analogs as potent inhibitors of β-Glucuronidase and in silico study

New benzimidazole analogues (1–18) were synthesized and characterized through different spectroscopic techniques such as ¹H NMR, ¹³C NMR and HREI-MS. All analogues were screened for β-glucuronidase inhibitory potential. All analogues showed varied degree of inhibitory potentials with IC₅₀ values ranging between 1.10 ± 0.10 to 39.60 ± 0.70 μM when compared with standard _D-saccharic acid-1,4- lactone having IC₅₀ value 48.30 μM. Analogues 17, 11, 9, 6, 1 and 13 having IC₅₀ values 1.10 ± 0.10, 1.70 ± 0.10, 2.30 ± 0.10, 5.30 ± 0.20, 6.20 ± 0.20 and 8.10 ± 0.20 μM respectively, showed excellent β-glucuronidase inhibitory potential many folds better than the standard. All other analogues also showed good inhibitory potential better as compared to standard. Structure activity relationships (SAR) has been established for all compounds. The results from molecular docking studies supports the established SAR and developed a strong correlation with the results from in to vitro assay. The molecular docking results clearly highlighted how substituents like nitro and chloro affect the binding position of the active compounds in the active site. The docking results were also used to properly establish the effect of bulky substituents of least active compounds on reduced β-glucuronidase inhibitory activity. Compounds 1–18 were found non-toxic.     

Identification of novel oxadiazole-based benzothiazole derivatives as potent inhibitors of α-glucosidase and urease: Synthesis,in vitro bio-evaluation and their in silico molecular docking study

This research work represents a synthetic approach for the development of hybrids derivatives of oxadiazole-based benzothiazole (1–17) and diversity in derivatives was achieved using variety of aryl ring of S-substituted benzothiazole to see the effect on the biological activities. All the synthesized derivatives were evaluated for their in vitro α-glucosidase and urease inhibitory potential. The α-glucosidase and urease inhibition profile of the new derivatives represents moderate to good inhibitory potential with IC₅₀ values ranging from 4.60 ± 1.20 µM to 48.40 ± 7.70 µM (α-glucosidase) and 8.90 ± 2.80 to 57.30 ± 7.70 µM (urease) respectively. The results were compared to standard acarbose (38.60 ± 4.50 µM) and thiourea (58.70 ± 6.80 µM) drugs respectively. Among the synthesized series, the analogs 1 having IC₅₀ values of and 4.60 ± 1.20 (α-glucosidase), 8.90 ± 2.80 (urease) and 2 with IC₅₀ values of 5.60 ± 1.60 (α-glucosidase) and 10.90 ± 2.10(urease) were found to be significantly active against targeted α-glucosidase and urease enzymes. The structure of all the newly synthetics scaffolds were confirmed by using different types of spectroscopic techniques such as HREI-MS, ¹H- and ¹³C- NMR spectroscopy. The molecular docking studies of the synthesized derivatives showed good correlations with the experimental findings. The binding modes of active compounds and their interactions with active site residues revealed them as possible anti-diabetics and anti-urease leads. The degree of activity and docking studies displayed by the novel innovative structural hybrids of oxadiazole-based benzothiazole moieties make these compounds new active leads and promising candidates for the development of anti-diabetics and anti-urease agents.     

Biology-oriented drug synthesis of nitrofurazone derivatives: Their α-glucosidase inhibitory activity and molecular docking studies

In the present study, twenty (20) structural variants of nitrofurazone were synthesized based on BIODS (Biology-oriented drug synthesis) approach. The structure elucidation of the synthetic molecules (1–20) was carried out using different spectroscopic techniques, and their α-glucosidase inhibitory activity was also determined. The synthetic molecules 1–20 exhibited good α-glucosidase inhibition than the parent, nitrofurazone. Four compounds 2, 4, 6, and 7 showed potential inhibition against α-glucosidase with IC₅₀ values ranging between 0.63 ± 0.25–1.29 ± 0.46 µM as compared to the standard acarbose (IC₅₀ = 2.05 ± 0.41 µM). Nevertheless, compounds 15 (IC₅₀ = 0.74 ± 0.12 µM), and 19 (IC₅₀ = 0.54 ± 0.3 µM) also displayed good α-glucosidase inhibition and compound 19 was the most active compound of the series. Kinetic study of the active compounds 7 and 19 was also carried out to confirm the mode of inhibition. The binding interactions of the most active compounds within the active site of enzyme were determined by molecular docking. Moreover, molecular dynamic simulation of compound 19 was also performed in order to determine the stability of the overall complex (α-glucosidase + c19) in an explicit watery environment. The synthetic molecules were predicted as non-cytotoxic, however, seven compounds 1, 3, 4, 9, 10, 11, and 12 were predicted as carcinogenic.     

New benzoxazole-based sulphonamide hybrids analogs as potent inhibitors of α-amylase and α-glucosidase: Synthesis and in vitro evaluation along with in silico study

The development of drugs resistance in diabetes mellitus is a growing clinical problem, creates many challenges for patient. To overcome these problems, there is a serious deficiency of anti-diabetic agents, may be synthesized that inhibit alpha amylase and alpha glucosidase activity. Here, we have design and synthesized benzoxazole based sulphonamide derivatives and evaluated for their anti-diabetic activity. Twenty-two benzoxazole based sulphonamide derivatives were synthesized by reacting 2-aminophenol with carbon disulphide in the presence of base (Et3N) to obtained 2-marcapto benzoxazole which was further dissolved in ethanol by slow addition of different substituted phenacyl bromide in the presence of triethylamine, afforded varied S-substituted benzoxazole products. These products were dissolved in ethanol and hydrazine hydrate was added an excess in the presence of acetic acid to gives Schiff base. This Schiff base products were further dissolved in THF along with different substituted benzene sulphonyl chloride followed by addition of few drops of Et3N, yielded benzoxazole based sulphonamide derivatives (1–22). Moreover, SAR was established for the synthesized compounds and molecular docking studies were conducted for the potent moieties in order to explore the binding modalities of analogs. Among the tested series few analogues were found few folds better potential than standard drug but analog 1 (IC₅₀ = 1.10 ± 0.20 µM, 1.20 ± 0.30 µM), showed promising anti-diabetic activity against α-amylase and α-glucosidase (11.12 ± 0.15 µM and 11.29 ± 0.07 µM respectively).     

In vitro evaluation of novel mefenamic acid derivatives as potential α-glucosidase and urease inhibitors: Design,synthesis, in silico and cytotoxic studies

This study aim to synthesize new 1,3,4-oxadiazole derivatives incorporating mefenamic acid as promising α-glucosidase and urease inhibitors, potentially leading to the treatment of postprandial hyperglycemia as well as H. pylori related disorders. In this regards, we have designed a series of Mefenamic acid derivatives. The synthetic compounds were structurally elucidated through ¹H NMR, ¹³C NMR and HR-EIMS analysis. The biological evaluation of these derivatives against α-glucosidase and urease enzyme depicted some novel derivatives with potent inhibition against the said enzymes. All the derivatives exhibited potent inhibition against α-glucosidase enzymes with IC₅₀ ranging from 25.81 ± 1.63–113.61 ± 1.31 µM against standard drug acarbose (IC₅₀ = 375.82 ± 1.76 µM) while with respect to urease these derivatives possessed inhibitory potential varied between IC₅₀ = 8.04 ± 1.01–58.18 ± 1.03 µM against the standard thiourea (IC₅₀ = 21.0 ± 1.76 µM). The cell viability results revealed that all of the derivatives were found least cytotoxic. Furthermore, molecular docking studies of the most potent derivatives identify number of key features involved in binding interactions between potential inhibitors and the enzyme's active site.     

Antitubercular and antioxidant activities of hydroxy and chloro substituted chalcone analogues: Synthesis,biological and computational studies

A series of chalcone analogues (1–15) were synthesized by Claisen-Schmidt condensation in good yields (70–95%) and characterized by FT-IR, ¹H NMR and mass spectral methods. Additionally, compounds 3 and 7 were characterized by ¹³C NMR. Antitubercular and antioxidant activities of the chalcones were evaluated by MABA and DPPH free radical assays. In MABA assay analogues 3 (MIC = 14 ± 0.11 µM) and 11 (MIC = 14 ± 0.17 µM) bearing fluorine and methoxy groups at para and meta positions were 1.8-times more active than the standard pyrazinamide (MIC = 25.34 ± 0.22 µM). The chalcone analogues such as compound 7 (IC₅₀ = 4 ± 1 µg/mL) containing electron releasing groups such as OH at ortho position had slightly more antioxidant activity than Gallic acid (IC₅₀ = 5 ± 1 µg/mL). The potential compounds 3, 7, 9 and 11 were less selective and toxic against human live cell lines-LO2. Further, molecular docking results of chalcones against anti-tubercular drug target isocitrate lyase (PDB ID: 1F8M) revealed that compound 3 and 11 shown least binding energies as ?7.6, and ?7.5 kcal/mol are in line with in vitro MABA assay, suggesting that these compounds 3 and 11 are strong inhibitor of isocitrate lyase. SwissADME programme estimated the drug likeliness properties of compounds 3, 7, 9 and 11. The lead molecules arisen through this study helps to develop new antitubercular and antioxidant agents.     

Optimization of pyrazolo[1,5-a]pyrimidine based compounds with pyridine scaffold: Synthesis,biological evaluation and molecular modeling study

BackgroundPyrazolopyrimidine heterocycle and its isosteres represent the main scaffold for many pharmacologically active drugs including anti-inflammatory agents. The COX-2 inhibitors are the principal gate for the design of new safe and potent anti-inflammatory agents.MethodsNovel derivatives of pyrazolo[1,5-a] pyrimidines were synthesized and screened in vivo and in vitro for their anti-inflammatory potential.ResultsWithin the constructed compounds, compound 11 was the most active compound on IL-6 and TNF-α (percentage inhibition = 80 and 89%, respectively). In addition, compound 12 displayed the most inhibitory effect towards COX-2 (IC₅₀ = 1.11 µM), whereas compound 11 recorded the highest COX-2 selectivity (S.I = 8.97). The target derivatives 11–14 displayed good edema inhibitory potential (46–68%) and compound 11 was the most potent candidate (ED₅₀ = 35 mg/kg). Additionally, the most potent sPLA2-V inhibitors were compounds 11 and 13 (IC₅₀ = 1 and 1.7 µM respectively). Regarding activity towards 15-LOX, derivative 12 was the most active compound with IC₅₀ = 5.6 µM revealing higher inhibitory activity than nor-dihydroguaiaretic acid (IC₅₀ = 8.5 µM). To confirm the anti-inflammatory potential of the target derivatives, molecular modeling was performed inside COX-2 and 15-LOX active sites.ConclusionDisplay discoveries increment the plausibility that these pyrazolo[1,5-a]pyrimidines might act as a beginning point for the improvement of anti-inflammatory agents.     

Potential enzyme inhibitor triazoles from aliphatic esters: Synthesis,enzyme inhibition and docking studies

Enzyme inhibitors are vital aspects for studying enzymes and are employed as drugs to treat certain disorders, thus implying pivotal role in drug discovery. In the current study, a series of triazole compounds 4(a-o) were synthesised to explore their inhibitory potential against α-glucosidase and urease enzymes. These derivatives with dichlorophenyl substituents were prepared by cyclization of thiosemicarbazides and their structures were confirmed through spectroanalytical techniques. The in vitro biological screening revealed that the compounds 4a, 4b, 4k, 4l, 4m, 4o having IC₅₀ values of 121.09 ± 1.25, 137.22 ± 0.22, 110.4 ± 2.4, 114.79 ± 1.1, 146.72 ± 1.29, 94.21 ± 0.15 [µM] respectively, exhibited good potential α-glucosidase inhibition, in comparison to Acarbose: IC₅₀ 51.23 µM, while the compounds 4a, 4b, 4c, 4k, 4l, having IC₅₀ values of 48.52 ± 0.39, 52.22 ± 1.37, 60.98 ± 0.34, 37.06 ± 0.51, 38.66 ± 1.7 [µM] respectively exhibited good potential for urease inhibition near to standard(Thiourea: IC₅₀ 24.14 [µM]). These in vitro findings were accompanied further by molecular docking simulations, which revealed significant binding interactions of the synthesized derivatives within the active sites of the enzymes.     

Design,synthesis and docking studies of new hydrazinyl-thiazole derivatives as anticancer and antimicrobial agents

Increase in the number of infections caused by pathogenic microbes in cancer patients has prompted the searcher to invest in the development of agents having dual anticancer and antimicrobial properties. The present study is concerned with synthesis and screening for anticancer and antimicrobial activity of a series of 5-hydrazinyl-2-(2-(1-(thien-2-yl)ethylidene)hydrazinyl)thiazole derivatives. The structure elucidation of the synthesized hydrazinyl thiazole derivatives was illustrated by spectroscopic and elemental analysis. All the newly synthesized compounds 5a-p were evaluated for in-vitro cytotoxic activity against breast carcinoma (MCF-7 cell line), hepatocellular carcinoma (HePG-2) and colorectal cancer (HCT-116) cell lines using MTT assay method. Compounds 5 g, 5h showed broad spectrum activity against three cancer cell lines with IC₅₀ ranged from 3.81 to 11.34 µM in compared to the reference drug Roscovitine (IC₅₀ = 9.32 to 13.82 µM), while compounds 5 l and 5 m were found to be more selective against HePG-2 and HCT-116 cell line (IC₅₀ = 9.29 and 8.93 µM respectively) and compound 5j was more selective against HePG-2 and MCF-7 cell lines (IC₅₀ = 6.73 and 10.87 µM respectively). The inhibitory activity of the most promising compounds was tested against the EGFR and ARO enzymes and were further tested for apoptosis and Annexin V/PI staining. The results of enzyme-based tests revealed that the tested compound 5j has a dual inhibitory effect on the EGFR and ARO enzymes with IC₅₀ = 82.8 and 98.6 nM respectively in compared to the reference drugs Erlotinib and Letrozole (IC₅₀ = 62.4 and 79 nM respectively). Furthermore, the majority of the tested hydrazinyl thiazole derivatives exhibited significant antimicrobial activity against the used pathogenic microbes species. Compounds 4b, 5h, 5j and 5 m exerted a good antibacterial and antifungal activity against all tested pathogenic microbes. Therefore, it was concluded that compounds 5 h, 5j and 5 m proved to possess dual anticancer and antimicrobial agent and may serves as a useful lead compounds in search for further modification or derivatization to give more potent and selective agents.     

Identification of novel diclofenac acid and naproxen bearing hydrazones as 15-LOX inhibitors: Design,synthesis, in vitro evaluation,cytotoxicity, and in silico studies

Inflammation is the immune system's adaptive response to tissue dysfunction or homeostatic imbalance, inducing fever, pain, physiological and biochemical changes via the cyclooxygenase (COX) and lipoxygenase (LOX) pathways. NSAIDs (non-steroidal anti-inflammatory drugs), such as diclofenac acid and naproxen, are the most common inhibitors of the COX pathway. These drugs, however, are currently being studied as LOX inhibitors as well. Therefore, in the present study, a novel series of diclofenac acid and naproxen-bearing hydrazones 7(a-r) were designed, synthesized, and characterized by different spectroscopic methods like ¹H NMR, ¹³C NMR, IR and HRMS (EI) analysis. All these synthesized compounds were evaluated for their in vitro inhibitory potential against the Soybean 15-lipoxygenase (15-LOX) enzyme. These compounds exhibited varying degrees of inhibitory potential ranging from IC₅₀ 4.61 ± 3.21 μM to 193.62 ± 4.68 μM in comparison to standard inhibitors quercetin (IC₅₀ 4.84 ± 6.43 μM) and baicalein (IC₅₀ 22.46 ± 1.32 μM). The most potent compounds in the series were compounds 7c (IC₅₀ 4.61 ± 3.21 μM), and 7f (IC₅₀ 6.64 ± 4.31 μM). These compounds were found least cytotoxic and showed 96.42 ± 1.3 % and 94.87 ± 1.6 % viability to cells at 0.25 mM concentration respectively. ADME and in silico studies supported the drug-likeness and binding studies of the molecules with the target enzyme.     

Exploring facile synthesis and cholinesterase inhibiting potential of heteroaryl substituted imidazole derivatives for the treatment of Alzheimer’s disease

Alzheimer’s disease (AD) is a neurodegenerative disorder and cholinesterase (ChE) enzymes are considered as crucial targets for the treatment of AD. Herein, a series of heteroaryl substituted imidazole derivatives (5a-5x) was prepared using amino acid catalyzed, one-pot facile synthetic approach. In this context, the catalytic potentials of different amino acids were investigated and 15 mol% of glutamic acid was identified as the most suitable catalyst to obtain the target products in good yields up to 90 %. These structurally exciting heterocyclic hybrids were screened against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. This series displayed moderate to excellent inhibitory potential against AChE with IC₅₀ values > 25 µM and the most active compound was 3-(4-(1-(3,5-dimethylphenyl)-4,5-diphenyl-1H-imidazol-2-yl)-1-phenyl-1H-pyrazol-3-yl)–2H-chromen-2-one (5x) with IC₅₀ value of 25.83 ± 0.25 µM.This inhibitory potential was attributed to hydrophobicity as the major contributory factor. The most potent compound against BChE was 1,3-diphenyl-4-(1,4,5-triphenyl-1H-imidazol-2-yl)-1H-pyrazole (5a) with IC₅₀ value of 0.35 ± 0.02 µM followed by other potent compounds 5p, 5 m, 5x, 5b, 5c, 5e and 5f with IC₅₀ values < 10 µM. SAR studies further revealed that coumarinyl moiety at R¹ position in the imidazolylpyrazole skeleton significantly improved the overall cholinesterase inhibitory potential. However, a simple phenyl ring attached at this R¹ site was highly effective and selective for BChE inhibition (5a) over AChE. Docking data also demonstrated the interaction of 5x and AChE with a docking score of 7564 and atomic contact energy (ACE) value of –291.90 kcal/mol whereas docking score for 5a against BChE was 7096 with ACE value of –332.95 kcal/mol. The results altogether suggest further investigations of the heteroaryl substituted imidazole core skeleton in search of potential leads towards designing of new anti-cholinesterase drugs for the treatment of AD.     

Aryl-oxadiazole Schiff bases: Synthesis, α-glucosidase in vitro inhibitory activity and their in silico studies

α-Glucosidase enzyme is a therapeutic target for diabetes mellitus and its inhibitors play a vital role in the treatment of this disease. A new series of aryl-oxadiazole Schiff bases (1–18) were synthesized and evaluated for α-glucosidase inhibitory potential. Fifteen compounds 1–8, 11–13, and 15–18 showed excellent inhibition with IC₅₀ values ranging from 0.30 ± 0.2 to 35.1 ± 0.80 µM as compared to the standard inhibitor acarbose (IC₅₀ = 38.45 ± 0.80 µM), nonetheless, the remaining compounds were found to have moderate activity. Among the series, compounds 7 (IC₅₀ = 0.30 ± 0.2 μM) with hydroxy groups at phenyl rings on either side of the oxadiazole ring was identified as the most potent inhibitor of α-glucosidase. The molecular docking studies were conducted to understand the binding mode of active inhibitors with the active site of enzyme and results supported the experimental data.     

Synthesis characterization and evaluation of novel triazole based analogs as a acetylcholinesterase and α-glucosidase inhibitors

A series of novel triazole analogs (10a-k) bearing piperidine were synthesized in an aprotic solvent on the most effective pharmacophore with acetylcholinesterase (AChE) and α-glucosidase inhibitory activity. Triazole analogs (10a-k) were obtained in excellent yields (75–90 %) and characterized by EI-MS, IR, ¹³C NMR and ¹H NMR. The newly synthesized triazole analogs (10a-k) showed potent AChE inhibitory activity in the range of K_i = 0.0155 ± 1.25 µM to 0.557 ± 0.50 µM, IC₅₀ = 0.031 ± 0.85 to 0.537 ± 0.76 µM than Eserine (0.04 ± 0.001 µM) having strong electron-withdrawing fluorine group on the pyridine ring was recorded as a most potent inhibitor of AChE while (%) inhibition against α-glucosidase was ranging between 52.36 ± 1.67 to 85.35 ± 1.39. The kinetic study predicted that triazole analogs (10a-k) followed the un-competitive and mixed type of inhibition against AChE. In silico molecular docking was performed at the active site of the AChE co-crystal structure (PDB ID:1NEN). The results of molecular docking corelate will with the experimental findings.     

One-pot multicomponent synthesis of novel 3, 4-dihydro-3-methyl-2(1H)-quinazolinone derivatives and their biological evaluation as potential antioxidants,enzyme inhibitors,antimicrobials, cytotoxic and anti-inflammatory agents

A series of novel 3, 4-dihydro-3-methyl-2(1H)-quinazolinone derivatives with substituted amine moieties (1–13) and substituted aldehyde (S) were designed and synthesized by a reflux condensation reaction in the presence of an acid catalyst to get N-Mannich bases. Mannich bases were evaluated pharmacologically for their antioxidant, α-amylase enzyme inhibition, antimicrobial, cell cytotoxicity and anti-inflammatory activities. Most of the compounds exhibited potent activities against these bioassays. Among them, SH1 and SH13 showed potent antioxidant activity against DPPH free radical at IC₅₀ of 9.94 ± 0.16 µg/mL and 11.68 ± 0.32 µg/mL, respectively. SH7, SH10 and SH13 showed significant results in TAC and TRP antioxidant assays, comparable to that of ascorbic acid. SH2 and SH3 showed potent activity in inhibiting α-amylase enzyme at IC₅₀ of 10.17 ± 0.23 µg/mL and 9.48 ± 0.17 µg/mL, respectively, when compared with acarbose (13.52 ± 0.19 µg/mL). SH7 was the most active against gram-positive and gram-negative bacterial strains, SH13 being the most potent against P. aeruginosa by inhibiting its growth up to 80% (MIC = 11.11 µg/mL). SH4, SH5 and SH6 exhibited significant activity against some fungal strains. Among the thirteen synthesized compounds (SH1-SH13), four were screened out based on the results of brine shrimp lethality assay (LD₅₀) and cell cytotoxicity assay (IC₅₀), to determine their anti-cancer potential against Hep-G2 cells. The study was conducted for 24, 48, and 72 h. SH12 showed potent results at IC₅₀ of 6.48 µM at 72 h when compared with cisplatin (2.56 µM). An in vitro nitric oxide (NO) assay was performed to shortlist compounds for in vivo anti-inflammatory assay. Among shortlisted compounds, SH13 exhibited potent anti-inflammatory activity by decreasing the paw thickness to the maximum compared to the standard, acetylsalicylic acid (ASA).     

Phenolic composition,antioxidant and enzyme inhibitory activities of Parkia biglobosa (Jacq.) Benth., Tithonia diversifolia (Hemsl) A. Gray,and Crossopteryx febrifuga (Afzel.) Benth

Medicinal plants from Chad grow under special climatic conditions in between the equatorial forest of Central Africa and the desert of North Africa and are understudied. Three medicinal plants from Chad (T. diversifolia, P. Biglobosa and C. Febrifuga) were evaluated for their phenolic composition, antioxidant and enzyme inhibition activities. The total phenolic composition varied from 203.19 ± 0.58 mg GAE/g DW in the ethyl acetate extract of P. biglobosa, to 56.41 ± 0.89 mg GAE/g DW in the methanol extract of C. febrifuga while the total flavonoid content varied from 51.85 ± 0.91 mg QE/g DW in the methanol extract of P. biglobosa to 08.56 ± 0.25 mg QE/g DW in the methanol extract of C. febrifuga. HPLC-DAD revealed that rutin, gallic acid and protocatechuic acid were the most abundant phenolics in T. diversifolia, P. Biglobosa and C. Febrifuga respectively. The antioxidant activity assayed by five different methods revealed very good activity especially in the DPPH^?, ABTS^?+ and CUPRAC assays where the extracts were more active than the standard compounds used. Good inhibition was exhibited against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with methanol (IC₅₀: 15.63 ± 0.72 µg/mL), ethyl acetate (IC₅₀: 16.20 ± 0.67 µg/mL) extracts of P. biglobosa, and methanol (IC₅₀: 21.53 ± 0.65 µg/mL) and ethyl acetate (IC₅₀: 30.81 ± 0.48 µg/mL) extracts of T. diversifolia showing higher inhibition than galantamine (IC₅₀: 42.20 ± 0.44 µg/mL) against BChE. Equally, good inhibition was shown on α-amylase and α-glucosidase. On the α-glucosidase, the ethyl acetate (IC₅₀ = 12.47 ± 0.61 µg/mL) and methanol extracts (IC₅₀ = 16.51 ± 0.18 µg/mL) of P. biglobosa showed higher activity compared to the standard acarbose (IC₅₀ = 17.35 ± 0.71 µg/mL) and on α-amylase, the ethyl acetate (IC₅₀ = 13.50 ± 0.90 µg/mL) and methanol (IC₅₀ = 18.12 ± 0.33 µg/mL) extracts of P. biglobosa showed higher activity compared to acarbose (IC₅₀ = 23.84 ± 0.25 µg/mL). The results indicate that these plants are good sources of antioxidant phenolics and can be used to manage oxidative stress linked illnesses such as Alzheimer’s disease and diabetes.     

Design,synthesis of new novel quinoxalin-2(1H)-one derivatives incorporating hydrazone,hydrazine, and pyrazole moieties as antimicrobial potential with in-silico ADME and molecular docking simulation

A series of 6-(morpholinosulfonyl)quinoxalin-2(1H)-one based hydrazone, hydrazine, and pyrazole moieties were designed, synthesized, and evaluated for their in vitro antimicrobial activity. All the synthesized quinoxaline derivatives were characterized by IR, NMR (¹H /¹³C), and EI MS. The results displayed good to moderate antimicrobial potential against six bacterial, and two fungal standard strains. Among the tested derivatives, six quinoxalin-2(1H)-one derivatives 4a, 7, 8a, 11b, 13, and 16 exhibited a significant antibacterial activity with MIC values (0.97–62.5 µg/mL), and MBC values (1.94–88.8 µg/mL) compared with Tetracycline (MICs = 15.62–62.5 µg/mL, and MBCs = 18.74–93.75 µg/mL), and Amphotericin B (MICs = 12.49–88.8 µg/mL, and MFC = 34.62–65.62 µg/mL). In addition, according to CLSI standards, the most active quinoxalin-2(1H)-one derivatives demonstrated bactericidal and fungicidal behavior. Moreover, the most active quinoxaline derivatives showed a considerable antibacterial activity with bactericidal potential against multi-drug resistance bacteria (MDRB) strains with MIC values ranged between (1.95–15.62 µg/mL), and MBC values (3.31–31.25 µg/mL) near to standard Norfloxacin (MIC = 0.78–3.13 µg/mL, and MBC = 1.4–5.32 µg/mL. Further, in vitro S. aureus DNA gyrase inhibition activity were evaluated for the promising derivatives and displayed potency with IC₅₀ values (10.93 ± 1.81–26.18 ± 1.22 µM) compared with Ciprofloxacin (26.31 ± 1.64 µM). Interestingly, these derivatives revealed as good immunomodulatory agents by a percentage ranging between 82.8 ± 0.37 and 142.4 ± 0.98 %. Finally, some in silico ADME, toxicity prediction, and molecular docking simulation were performed and showed a promising safety profile with good binding mode.     

Synthesis and anti-α-glucosidase activity evaluation of betulinic acid derivatives

In this article, a series of betulinic acid derivatives (3a ～ 3u, 4a ～ 4e) were synthesized through a stepwise structure optimization and evaluated for their anti-α-glucosidase activities. All synthesized derivatives exhibited stronger anti-α-glucosidase activities (IC₅₀: 0.56 ± 0.05 ～ 3.99 ± 0.23 μM) than betulinic acid (IC₅₀: 7.21 ± 0.58 μM) and acarbose (IC₅₀: 611.45 ± 15.51 μM). Compound 3q presented the outstanding inhibitory activity (IC₅₀: 0.56 ± 0.05 μM), which was ～ 1100 time stronger than that of acarbose. Compound 3q was revealed as a reversible and noncompetitive α-glucosidase inhibitor by inhibitory mechanism assay. Fluorescence spectra, 3D fluorescence and CD spectra results showed that the interaction of compound 3q with α-glucosidase caused the conformational and secondary structure content change of α-glucosidase. Finally, the molecular docking simulated the interaction between compound 3q with α-glucosidase and the physicochemical parameter was assessed using SwissADME software.     

Synthesis, α-glucosidase inhibition and molecular docking studies of natural product 2-(2-phenyethyl)chromone analogues

A series of natural product (2-phenyethyl)chromone analogues (3–34) were designed, synthesized, and screened for their α-glucosidase inhibitory activity. The results indicated that some of the synthesized derivatives displayed inhibitory activities against α-glucosidase with IC₅₀ values ranging from 11.72 ± 0.08 to 85.58 ± 2.30 μM when compared to the standard drug acarbose (IC₅₀ = 832.22 ± 2.00 μM). Among them, compound 4 with a hydroxyl group at the 7-position of chromone and a chloro group at the 4-position of the benzene ring, displayed the most significant inhibitory activity with the IC₅₀ value of 11.72 ± 0.08 μM. The inhibitory mechanism of compound 4 against α-glucosidase was studied by enzyme kinetic, circular dichroism spectra, fluorescence quenching, and molecular docking. Sucrose loading test in vivo further demonstrated that it could decrease blood glucose levels after sucrose administration in normal Kunming mice. In vitro cytotoxicity showed that 4 exhibited low cytotoxicity against normal human cell lines. The ADME study suggested that all compounds are likely to be orally active as they obeyed Lipinski’s rule of five. In summary, our studies showed that these derivatives are a new class of α-glucosidase inhibitors.     

The design of fluoroquinolone-based cholinesterase inhibitors: Synthesis,biological evaluation and in silico docking studies

An enhanced acetylcholinesterase (AChE) activity is a hallmark in early stages of Alzheimer's ailment that results in decreased acetylcholine (ACh) levels, which in turn leads to cholinergic dysfunction and neurodegeneration. Consequently, inhibition of both AChE and butyrylcholinesterase (BChE) is important to prolong ACh activity in synapses for the enhanced cholinergic neurotransmission. In this study, a series of new fluoroquinolone derivatives (7a-m) have synthesized and evaluated for AChE and BChE inhibitory activities. The screening results suggested that 7 g bearing ortho fluorophenyl was the most active inhibitor against both AChE and BChE, exhibiting IC₅₀ values of 0.70 ± 0.10 µM and 2.20 ± 0.10 µM, respectively. The structure–activity relationship (SAR) revealed that compounds containing electronegative functions (F, Cl, OMe, N and O) at the ortho position of the phenyl group exhibited higher activities as compared to their meta- and/or para substituted counterparts. Molecular docking studies of synthesized compounds 7a, 7g, 7j and 7l docked into the active site of AChE and 7a-f docked into the active site of BChE revealed that these compounds exhibited conventional H-bonding along with π-π interaction with the active residues of AChE through their electronegative functions and phenyl ring, respectively. All the synthesized compounds are characterized by spectroscopic methods including FT-IR, ¹H- and ¹³C NMR as well as elemental analysis. This is the first example of fluoroquinolone-based cholinesterase inhibitors.