Identification and characterization of small molecule inhibitors of the LINE-1 retrotransposon endonuclease.

The long interspersed nuclear element-1 (LINE-1 or L1) retrotransposon is the only active autonomously replicating retrotransposon in the human genome. L1 harms the cell by inserting new copies, generating DNA damage, and triggering inflammation. Therefore, L1 inhibition could be used to treat many diseases associated with these processes. Previous research has focused on inhibition of the L1 reverse transcriptase due to the prevalence of well-characterized inhibitors of related viral enzymes. Here we present the L1 endonuclease as another target for reducing L1 activity. We characterize structurally diverse small molecule endonuclease inhibitors using computational, biochemical, and biophysical methods. We also show that these inhibitors reduce L1 retrotransposition, L1-induced DNA damage, and inflammation reinforced by L1 in senescent cells. These inhibitors could be used for further pharmacological development and as tools to better understand the life cycle of this element and its impact on disease processes.

Py-CoMFA, docking, and molecular dynamics simulations of Leishmania (L.) amazonensis arginase inhibitors.

Leishmaniasis is a disease caused by a protozoan of the genus Leishmania, affecting millions of people, mainly in tropical countries, due to poor social conditions and low economic development. First-line chemotherapeutic agents involve highly toxic pentavalent antimonials, while treatment failure is mainly due to the emergence of drug-resistant strains. Leishmania arginase (ARG) enzyme is vital in pathogenicity and contributes to a higher infection rate, thus representing a potential drug target. This study helps in designing ARG inhibitors for the treatment of leishmaniasis. Py-CoMFA (3D-QSAR) models were constructed using 34 inhibitors from different chemical classes against ARG from L. (L.) amazonensis (LaARG). The 3D-QSAR predictions showed an excellent correlation between experimental and calculated pIC50 values. The molecular docking study identified the favorable hydrophobicity contribution of phenyl and cyclohexyl groups as substituents in the enzyme allosteric site. Molecular dynamics simulations of selected protein-ligand complexes were conducted to understand derivatives' interaction modes and affinity in both active and allosteric sites. Two cinnamide compounds, 7g and 7k, were identified, with similar structures to the reference 4h allosteric site inhibitor. These compounds can guide the development of more effective arginase inhibitors as potential antileishmanial drugs.

Analysis of the interaction of antimalarial agents with Plasmodium falciparum glutathione reductase through molecular mechanical calculations.

CONTEXT: Malaria remains a significant global health challenge with emerging resistance to current treatments. Plasmodium falciparum glutathione reductase (PfGR) plays a critical role in the defense mechanisms of malaria parasites against oxidative stress. In this study, we investigate the potential of targeting PfGR with conventional antimalarials and dual drugs combining aminoquinoline derivatives with GR inhibitors, which reveal promising interactions between PfGR and studied drugs. The naphthoquinone Atovaquone demonstrated particularly high affinity and potential dual-mode binding with the enzyme active site and cavity. Furthermore, dual drugs exhibit enhanced binding affinity, suggesting their efficacy in inhibiting PfGR, where the aliphatic ester bond (linker) is essential for effective binding with the enzyme's active site. Overall, this research provides important insights into the interactions between antimalarial agents and PfGR and encourages further exploration of its role in the mechanisms of action of antimalarials, including dual drugs, to enhance antiparasitic efficacy. METHODS: The drugs were tested as PfGR potential inhibitors via molecular docking on AutoDock 4, which was performed based on the preoptimized structures in HF/3-21G-PCM level of theory on ORCA 5. Drug-receptor systems with the most promising binding affinities were then studied with a molecular dynamic's simulation on AMBER 16. The molecular dynamics simulations were performed with a 100 ns NPT ensemble employing GAFF2 forcefield in the temperature of 310 K, integration time step of 2 fs, and non-bond cutoff distance of 6.0 Å.

Elucidating the structural basis of vitamin B12 derivatives as novel potent inhibitors of PTP1B: Insights from inhibitory mechanisms using Gaussian accelerated molecular dynamics (GaMD) and in vitro study.

Vitamin B12 is a group of biologically active cobalamin compounds. In this study, we investigated the inhibitory effects of methylcobalamin (MeCbl) and hydroxocobalamin acetate (OHCbl Acetate) on protein tyrosine phosphatase 1B (PTP1B). MeCbl and OHCbl Acetate exhibited an IC50 of approximately 58.390 ± 2.811 µM and 8.998 ± 0.587 µM, respectively. The Ki values of MeCbl and OHCbl Acetate were 25.01 µM and 4.04 µM respectively. To elucidate the inhibition mechanism, we conducted a 500 ns Gaussian accelerated molecular dynamics (GaMD) simulation. Utilizing PCA and tICA, we constructed Markov state models (MSM) to examine secondary structure changes during motion. Our findings revealed that the α-helix at residues 37-42 remained the most stable in the PTP1B-OHCbl Acetate system. Furthermore, upon binding of OHCbl Acetate or MeCbl, the WPD loop of PTP1B moved inward to the active pocket, forming a closed conformation and potentially obstructs substrate entry. Protein-ligand interaction analysis and MM-PBSA showed that OHCbl Acetate exhibited lower binding free energy and engaged in more residue interactions with PTP1B. In summary, our study confirmed the substantial inhibitory activity of OHCbl Acetate against PTP1B, with its inhibitory potency notably surpassing that of MeCbl. We demonstrated potential molecular mechanisms of OHCbl Acetate inhibiting PTP1B.

Synthesis of obovatol and related neolignan analogues as α-glucosidase and α-amylase inhibitors.

Diabetes mellitus is a metabolic disease characterized by hyperglycemia, which can be counteracted by the inhibition of α-glucosidase (α-Glu) and α-amylase (α-Amy), enzymes responsible for the hydrolysis of carbohydrates. In recent decades, many natural compounds and their bioinspired analogues have been studied as α-Glu and α-Amy inhibitors. However, no studies have been devoted to the evaluation of α-Glu and α-Amy inhibition by the neolignan obovatol (1). In this work, we report the synthesis of 1 and a library of new analogues. The synthesis of these compounds was achieved by implementing methodologies based on: phenol allylation, Claisen/Cope rearrangements, methylation, Ullmann coupling, demethylation, phenol oxidation and Michael-type addition. Obovatol (1) and ten analogues were evaluated for their in vitro inhibitory activity towards α-Glu and α-Amy. Our investigation highlighted that the naturally occurring 1 and four neolignan analogues (11, 22, 26 and 27) were more effective inhibitors than the hypoglycemic drug acarbose (α-Amy: 34.6 µM; α-Glu: 248.3 µM) with IC5O value of 6.2-23.6 µM toward α-Amy and 39.8-124.6 µM toward α-Glu. Docking investigations validated the inhibition outcomes, highlighting optimal compatibility between synthesized neolignans and both the enzymes. Concurrently circular dichroism spectroscopy detected the conformational changes in α-Glu induced by its interaction with the studied neolignans. Detailed studies through fluorescence measurements and kinetics of α-Glu and α-Amy inhibition also indicated that 1, 11, 22, 26 and 27 have the greatest affinity for α-Glu and 1, 11 and 27 for α-Amy. Surface plasmon resonance imaging (SPRI) measurements confirmed that among the compounds studied, the neolignan 27 has the greater affinity for both enzymes, thus corroborating the results obtained by kinetics and fluorescence quenching. Finally, in vitro cytotoxicity of the investigated compounds was tested on human colon cancer cell line (HCT-116). All these results demonstrate that these obovatol-based neolignan analogues constitute promising candidates in the pursuit of developing novel hypoglycemic drugs.

Utilizing a structure-based virtual screening approach to discover potential LSD1 inhibitors.

BACKGROUND: Lysine-specific demethylase 1 (LSD1) is highly expressed in a variety of malignant tumors, rendering it a crucial epigenetic target for anti-tumor therapy. Therefore, the inhibition of LSD1 activity has emerged as a promising innovative therapeutic approach for targeted cancer treatment. METHODS: In our study, we employed innovative structure-based drug design methods to meticulously select compounds from the ZINC15 database. Utilizing virtual docking, we evaluated docking scores and binding modes to identify potential inhibitors. To further validate our findings, we harnessed molecular dynamic simulations and conducted meticulous biochemical experiments to deeply analyze the binding interactions between the protein and compounds. RESULTS: Our results showcased that ZINC10039815 exhibits an exquisite binding mode with LSD1, fitting perfectly into the active pocket and forming robust interactions with multiple critical residues of the protein. CONCLUSIONS: With its significant inhibitory effect on LSD1 activity, ZINC10039815 emerges as a highly promising candidate for the development of novel LSD1 inhibitors.

Exploring the Key Amino Acid Residues Surrounding the Active Center of Lactate Dehydrogenase A for the Development of Ideal Inhibitors.

Lactate dehydrogenase A (LDHA) primarily catalyzes the conversion between lactic acid and pyruvate, serving as a key enzyme in the aerobic glycolysis pathway of sugar in tumor cells. LDHA plays a crucial role in the occurrence, development, progression, invasion, metastasis, angiogenesis, and immune escape of tumors. Consequently, LDHA not only serves as a biomarker for tumor diagnosis and prognosis but also represents an ideal target for tumor therapy. Although LDHA inhibitors show great therapeutic potential, their development has proven to be challenging. In the development of LDHA inhibitors, the key active sites of LDHA are emphasized. Nevertheless, there is a relative lack of research on the amino acid residues around the active center of LDHA. Therefore, in this study, we investigated the amino acid residues around the active center of LDHA. Through structure comparison analysis, five key amino acid residues (Ala30, Met41, Lys131, Gln233, and Ala259) were identified. Subsequently, the effects of these five residues on the enzymatic properties of LDHA were investigated using site-directed mutagenesis. The results revealed that the catalytic activities of the five mutants varied to different degrees in both the reaction from lactic acid to pyruvate and pyruvate to lactic acid. Notably, the catalytic activities of LDHAM41G and LDHAK131I were improved, particularly in the case of LDHAK131I. The results of the molecular dynamics analysis of LDHAK131I explained the reasons for this phenomenon. Additionally, the optimum temperature of LDHAM41G and LDHAQ233M increased from 35 °C to 40 °C, whereas in the reverse reaction, the optimum temperature of LDHAM41G and LDHAK131I decreased from 70 °C to 60 °C. These findings indicate that Ala30, Met41, Lys131, Gln233, and Ala259 exert diverse effects on the catalytic activity and optimum temperature of LHDA. Therefore, these amino acid residues, in addition to the key catalytic site of the active center, play a crucial role. Considering these residues in the design and screening of LDHA inhibitors may lead to the development of more effective inhibitors.

Structure-Based Design of Novel Thiazolone[3,2-a]pyrimidine Derivatives as Potent RNase H Inhibitors for HIV Therapy.

Ribonuclease H (RNase H) was identified as an important target for HIV therapy. Currently, no RNase H inhibitors have reached clinical status. Herein, a series of novel thiazolone[3,2-a]pyrimidine-containing RNase H inhibitors were developed, based on the hit compound 10i, identified from screening our in-house compound library. Some of these derivatives exhibited low micromolar inhibitory activity. Among them, compound 12b was identified as the most potent inhibitor of RNase H (IC50 = 2.98 µM). The experiment of magnesium ion coordination was performed to verify that this ligand could coordinate with magnesium ions, indicating its binding ability to the catalytic site of RNase H. Docking studies revealed the main interactions of this ligand with RNase H. A quantitative structure activity relationship (QSAR) was also conducted to disclose several predictive mathematic models. A molecular dynamics simulation was also conducted to determine the stability of the complex. Taken together, thiazolone[3,2-a]pyrimidine can be regarded as a potential scaffold for the further development of RNase H inhibitors.

Targeting the cysteine biosynthesis pathway in microorganisms: Mechanism, structure, and drug discovery.

Owing to the global health crisis of resistant pathogenic infections, researchers are emphasizing the importance of novel prevention and control strategies. Existing antimicrobial drugs predominantly target a few pathways, and their widespread use has pervasively increased drug resistance. Therefore, it is imperative to develop new antimicrobial drugs with novel targets and chemical structures. The de novo cysteine biosynthesis pathway, one of the microbial metabolic pathways, plays a crucial role in pathogenicity and drug resistance. This pathway notably differs from that in humans, thereby representing an unexplored target for developing antimicrobial drugs. Herein, we have presented an overview of cysteine biosynthesis pathways and their roles in the pathogenicity of various microorganisms. Additionally, we have investigated the structure and function of enzymes involved in these pathways as well as have discussed drug design strategies and structure-activity relationships of the enzyme inhibitors. This review provides valuable insights for developing novel antimicrobials and offers new avenues to combat drug resistance.

Perspectives and challenges in developing small molecules targeting purine nucleoside phosphorylase.

As a cytosolic enzyme involved in the purine salvage pathway metabolism, purine nucleoside phosphorylase (PNP) plays an important role in a variety of cellular functions but also in immune system, including cell growth, apoptosis and cancer development and progression. Based on its T-cell targeting profile, PNP is a potential target for the treatment of some malignant T-cell proliferative cancers including lymphoma and leukemia, and some specific immunological diseases. Numerous small-molecule PNP inhibitors have been developed so far. However, only Peldesine, Forodesine and Ulodesine have entered clinical trials and exhibited some potential for the treatment of T-cell leukemia and gout. The most recent direction in PNP inhibitor development has been focused on PNP small-molecule inhibitors with better potency, selectivity, and pharmacokinetic property. In this perspective, considering the structure, biological functions, and disease relevance of PNP, we highlight the recent research progress in PNP small-molecule inhibitor development and discuss prospective strategies for designing additional PNP therapeutic agents.

Bioassay-Guided and DeepSAT-Driven Precise Mining of Monoterpenoid Coumarin Derivatives with Antifeedant Effects from the Leaves of Ailanthus altissima.

Demand for the exploration of botanical pesticides continues to increase due to the detrimental effects of synthetic chemicals on human health and the environment and the development of resistance by pests. Under the guidance of a bioactivity-guided approach and HSQC-based DeepSAT, 16 coumarin derivatives were discovered from the leaves of Ailanthus altissima (Mill.) Swingle, including seven undescribed monoterpenoid coumarins, three undescribed monoterpenoid phenylpropanoids, and two new coumarin derivatives. The structure and configurations of these compounds were established and validated via extensive spectroscopic analysis, acetonide analysis, and quantum chemical calculations. Biologically, 5 exhibited significant antifeedant activity toward the Plutella xylostella. Moreover, tyrosinase being closely related to the growth and development of larva, the inhibitory potentials of 5 against tyrosinase was evaluated in vitro and in silico. The bioactivity evaluation results highlight the prospect of 5 as a novel category of botanical insecticide.

Design, Synthesis, and Biological Evaluation of Pyridazinone-Containing Derivatives As Novel Protoporphyrinogen IX Oxidase Inhibitor.

Protoporphyrinogen IX oxidase (PPO, E.C. 1.3.3.4) plays a pivotal role in chlorophyll biosynthesis in plants, making it a prime target for herbicide development. In this study, we conducted an investigation aimed at discovering PPO-inhibiting herbicides. Through this endeavor, we successfully identified a series of novel compounds based on the pyridazinone scaffold. Following structural optimization and biological assessment, compound 10ae, known as ethyl 3-((6-fluoro-5-(6-oxo-4-(trifluoromethyl)pyridazin-1(6H)-yl)benzo[d]thiazol-2-yl)thio)propanoate, emerged as a standout performer. It exhibited robust activity against Nicotiana tabacum PPO (NtPPO) with an inhibition constant (Ki) value of 0.0338 µM. Concurrently, we employed molecular simulations to obtain further insight into the binding mechanism with NtPPO. Additionally, another compound, namely, ethyl 2-((6-fluoro-5-(5-methyl-6-oxo-4-(trifluoromethyl)pyridazin-1(6H)-yl)benzo[d]thiazol-2-yl)thio)propanoate (10bh), demonstrated broad-spectrum and highly effective herbicidal properties against all six tested weeds (Leaf mustard, Chickweed, Chenopodium serotinum, Alopecurus aequalis, Poa annua, and Polypogon fugax) at the dosage of 150 g a.i./ha through postemergence application in a greenhouse. This work identified a novel lead compound (10bh) that showed good activity in vitro and excellent herbicidal activity in vivo and had promising prospects as a new PPO-inhibiting herbicide lead.

Design of Inhibitors Targeting Chitin-Degrading Enzymes by Bioisostere Substitutions and Scaffold Hopping for Selective Control of Ostrinia furnacalis.

Chitin-degrading enzymes are critical components in regulating the molting process of the Asian corn borer and serve as potential targets for controlling this destructive pest of maize. Here, we used a scaffold-hopping strategy to design a series of efficient naphthylimide insecticides. Among them, compound 8c exhibited potent inhibition of chitinase from OfChi-h and OfChtI at low nanomolar concentrations (IC50 = 1.51 and 9.21 nM, respectively). Molecular docking simulations suggested that 8c binds to chitinase by mimicking the interaction of chitin oligosaccharide substrates with chitinase. At low ppm concentrations, compound 8c performed comparably to commercial insecticides in controlling the highly destructive plant pest, the Asian corn borer. Tests on a wide range of nontarget organisms indicate that compound 8c has very low toxicity. In addition, the effect of inhibitor treatment on the expression of genes associated with the Asian corn borer chitin-degrading enzymes was further investigated by quantitative real-time polymerase chain reaction. In conclusion, our study highlights the potential of 8c as a novel chitinase-targeting insecticide for effective control of the Asian corn borer, providing a promising solution in the quest for sustainable pest management.

Isolation, Characterization, Genome Annotation, and Evaluation of Hyaluronidase Inhibitory Activity in Secondary Metabolites of Brevibacillus sp. JNUCC 41: A Comprehensive Analysis through Molecular Docking and Molecular Dynamics Simulation.

Brevibacillus sp. JNUCC 41, characterized as a plant-growth-promoting rhizobacterium (PGPR), actively participates in lipid metabolism and biocontrol based on gene analysis. This study aimed to investigate the crucial secondary metabolites in biological metabolism; fermentation, extraction, and isolation were performed, revealing that methyl indole-3-acetate showed the best hyaluronidase (HAase) inhibitory activity (IC50: 343.9 µM). Molecular docking results further revealed that the compound forms hydrogen bonds with the residues Tyr-75 and Tyr-247 of HAase (binding energy: -6.4 kcal/mol). Molecular dynamics (MD) simulations demonstrated that the compound predominantly binds to HAase via hydrogen bonding (MM-PBSA binding energy: -24.9 kcal/mol) and exhibits good stability. The residues Tyr-247 and Tyr-202, pivotal for binding in docking, were also confirmed via MD simulations. This study suggests that methyl indole-3-acetate holds potential applications in anti-inflammatory and anti-aging treatments.

Competitive Inhibition of Okanin against Plasmodium falciparum Tyrosyl-tRNA Synthetase.

Malaria is a severe disease that presents a significant threat to human health. As resistance to current drugs continues to increase, there is an urgent need for new antimalarial medications. Aminoacyl-tRNA synthetases (aaRSs) represent promising targets for drug development. In this study, we identified Plasmodium falciparum tyrosyl-tRNA synthetase (PfTyrRS) as a potential target for antimalarial drug development through a comparative analysis of the amino acid sequences and three-dimensional structures of human and plasmodium TyrRS, with particular emphasis on differences in key amino acids at the aminoacylation site. A total of 2141 bioactive compounds were screened using a high-throughput thermal shift assay (TSA). Okanin, known as an inhibitor of LPS-induced TLR4 expression, exhibited potent inhibitory activity against PfTyrRS, while showing limited inhibition of human TyrRS. Furthermore, bio-layer interferometry (BLI) confirmed the high affinity of okanin for PfTyrRS. Molecular dynamics (MD) simulations highlighted the stable conformation of okanin within PfTyrRS and its sustained binding to the enzyme. A molecular docking analysis revealed that okanin binds to both the tyrosine and partial ATP binding sites of the enzyme, preventing substrate binding. In addition, the compound inhibited the production of Plasmodium falciparum in the blood stage and had little cytotoxicity. Thus, okanin is a promising lead compound for the treatment of malaria caused by P. falciparum.

Design, synthesis, and biological evaluation of 5-(1H-indol-5-yl)isoxazole-3-carboxylic acids as novel xanthine oxidase inhibitors.

Xanthine oxidase (XO) is a key enzyme for the production of uric acid in the human body. XO inhibitors (XOIs) are clinically used for the treatment of hyperuricemia and gout, as they can effectively inhibit the production of uric acid. Previous studies indicated that both indole and isoxazole derivatives have good inhibitory effects against XO. Here, we designed and synthesized a novel series of N-5-(1H-indol-5-yl)isoxazole-3-carboxylic acids according to bioisosteric replacement and hybridization strategies. Among the obtained target compounds, compound 6c showed the best inhibitory activity against XO with an IC50 value of 0.13 µM, which was 22-fold higher than that of the classical antigout drug allopurinol (IC50 = 2.93 µM). Structure-activity relationship analysis indicated that the hydrophobic group on the nitrogen atom of the indole ring is essential for the inhibitory potencies of target compounds against XO. Enzyme kinetic studies proved that compound 6c acted as a mixed-type XOI. Molecular docking studies showed that the target compound 6c could not only retain the key interactions similar to febuxostat at the XO binding site but also generate some new interactions, such as two hydrogen bonds between the oxygen atom of the isoxazole ring and the amino acid residues Ser876 and Thr1010. These results indicated that 5-(1H-indol-5-yl)isoxazole-3-carboxylic acid might be an efficacious scaffold for designing novel XOIs and compound 6c has the potential to be used as a lead for further the development of novel anti-gout candidates.

Design, Synthesis, and Biological Activity of Novel Triketone-Containing Phenoxy Nicotinyl Inhibitors of HPPD.

4-Hydroxyphenylpyruvate dioxygenase (HPPD) is a crucial target enzyme in albino herbicides. The inhibition of HPPD activity interferes with the synthesis of carotenoids, blocking photosynthesis and resulting in bleaching and necrosis. To develop herbicides with excellent activity, a series of 3-hydroxy-2-(6-substituted phenoxynicotinoyl)-2-cyclohexen-1-one derivatives were designed via active substructure combination. The title compounds were characterized via infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopies, and high-resolution mass spectrometry. The structure of compound III-17 was confirmed via single-crystal X-ray diffraction. Preliminary tests demonstrated that some compounds had good herbicidal activity. Crop safety tests revealed that compound III-29 was safer than the commercial herbicide mesotrione in wheat and peanuts. Moreover, the compound exhibited the highest inhibitory activity against Arabidopsis thaliana HPPD (AtHPPD), with a half-maximal inhibitory concentration of 0.19 µM, demonstrating superior activity compared with mesotrione (0.28 µM) in vitro. A three-dimensional quantitative structure-activity relationship study revealed that the introduction of smaller groups to the 5-position of cyclohexanedione and negative charges to the 3-position of the benzene ring enhanced the herbicidal activity. A molecular structure comparison demonstrated that compound III-29 was beneficial to plant absorption and conduction. Molecular docking and molecular dynamics simulations further verified the stability of the complex formed by compound III-29 and AtHPPD. Thus, this study may provide insights into the development of green and efficient herbicides.

Inhibitory effect of extracts from edible parts of nuts on α-amylase activity: a systematic review.

Elevated blood glucose concentration is a risk factor for developing metabolic dysfunction and insulin resistance, leading to type 2 diabetes and cardiovascular diseases. Nuts have the potential to inhibit α-amylase activity, and so lower postprandial glucose, due to their content of polyphenols and other bioactive compounds. We conducted a systematic literature review to assess the ability of extracts from commonly consumed edible parts of nuts to inhibit α-amylase. Among the 31 included papers, only four utilised human α-amylases. These papers indicated that polyphenol-rich chestnut skin extracts exhibited strong inhibition of both human salivary and pancreatic α-amylases, and that a polyphenol-rich almond skin extract was a potent inhibitor of human salivary α-amylase. The majority of the reviewed studies utilised porcine pancreatic α-amylase, which has ∼86% sequence homology with the corresponding human enzyme but with some key amino acid variations located within the active site. Polyphenol-rich extracts from chestnut, almond, kola nut, pecan and walnut, and peptides isolated from cashew, inhibited porcine pancreatic α-amylase. Some studies used α-amylases sourced from fungi or bacteria, outcomes from which are entirely irrelevant to human health, as they have no sequence homology with the human enzyme. Given the limited research involving human α-amylases, and the differences in inhibition compared to porcine enzymes and especially enzymes from microorganisms, it is recommended that future in vitro experiments place greater emphasis on utilising enzymes sourced from humans to facilitate a reliable prediction of effects in intervention studies.

Design, Synthesis, Antifungal Activity, and Action Mechanism of Pyrazole-4-carboxamide Derivatives Containing Oxime Ether Active Fragment As Succinate Dehydrogenase Inhibitors.

The dearomatization at the hydrophobic tail of the boscalid was carried out to construct a series of novel pyrazole-4-carboxamide derivatives containing an oxime ether fragment. By using fungicide-likeness analyses and virtual screening, 24 target compounds with theoretical strong inhibitory effects against fungal succinate dehydrogenase (SDH) were designed and synthesized. Antifungal bioassays showed that the target compound E1 could selectively inhibit the in vitro growth of R. solani, with the EC50 value of 1.1 µg/mL that was superior to that of the agricultural fungicide boscalid (2.2 µg/mL). The observations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that E1 could reduce mycelial density and significantly increase the mitochondrial number in mycelia cytoplasm, which was similar to the phenomenon treated with boscalid. Enzyme activity assay showed that the E1 had the significant inhibitory effect against the SDH from R. solani, with the IC50 value of 3.3 µM that was superior to that of boscalid (7.9 µM). The mode of action of the target compound E1 with SDH was further analyzed by molecular docking and molecular dynamics simulation studies. Among them, the number of hydrogen bonds was significantly more in the SDH-E1 complex than that in the SDH-boscalid complex. This research on the dearomatization strategy of the benzene ring for constructing pyrazole-4-carboxamides containing an oxime ether fragment provides a unique thought to design new antifungal drugs targeting SDH.

Phytochemical analysis, antioxidant, acetylcholinesterase, and α-amylase inhibitors from extract.

OBJECTIVE: To investigate the effects of Hippeastrum hybridum (HH) as a free radical scavenger, and an inhibitor of the two enzymes i-e Alpha-amylase (α-amylase) and acetylcholinesterase (AChE). METHODS: In this study, HH plant was preliminary analyzed for phytochemical screening and then tested for its antioxidant, anti-α-amylase, and anti-AChE efficiency via standard procedures. RESULTS: Phytochemical analysis shows the existence of different compounds; while Coumarins and quinones were absent. The total phenolic, flavonoid, and tannins content were found to be (78.52 ± 0.69) mg GAE/g, (2.01 ± 0.04) mg RUE/g, and (58.12 ± 0.23) mg TAE/g of plant extract respectively. 28.02% ± 0.02% alkaloid and 2.02% ± 0.05% saponins were present in the HH extract. The HH extract showed the anti-oxidant property with IC50 (50% inhibition) of (151.01 ± 0.13) (HH), (79.01 ± 0.04) (Ascorbic acid) for ferric reducing, (91.48 ± 0.13) (HH), (48.02 ± 0.11) (Ascorbic acid) against Ammonium molybdenum, (156.02 ± 0.31) (HH), (52.38 ± 0.21) (Ascorbic acid) against DPPH, 136.01 ± 0.21 (HH), 52.02± 0.31 (Ascorbic acid) against H2O2, and 154.12 ± 0.03 (HH), (40.05 ± 0.15) (Ascorbic acid) µg/mL against ABTS respectively. Statistical analysis indicated that HH caused a competitive type of inhibition of α-amylase (Vmax remained constant and Km increases from 10.65 to 84.37%) while Glucophage caused the un-competitive type of inhibition i-e both Km and Vmax decreased from 40.49 to 69.15% and 38.86 to 69.61% respectively. The Ki, (inhibition constant); KI, (dissociation constant), Km, (Michaelis-Menten constant), and IC50 were found to be 62, 364, 68.1, and 38.08 ± 0.22 for HH and 12, 101.05, 195, 34.01 ± 0.21 for Glucophage. Similarly, HH causes an anon-competitive type of inhibition of AChE i-e Km remains constant while Vmax decreases from 60.5% to 74.1%. The calculated Ki, KI, Km, and IC50 were found to be 32, 36.2, 0.05, and 18.117 ± 0.018. CONCLUSION: From the current results, it is concluded that HH extract contains bioactive compounds, and could be a good alternative to controlling oxidants, Alzheimer's and Type-II diabetic diseases.