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Fraxinus mandshurica (Oleaceae) is used as a traditional medicinal plant for the treatment of red eyes, menstrual disorders, excessive leucorrhea, chronic bronchitis and psoriasis. To perform chemical characterization of the secondary metabolites of F. mandshurica roots, bark, stems and leaves, 32 samples were collected from eight provinces in this study. A total of 64 chemical components were detected from four different parts of F. mandshurica by ultra‐performance liquid chromatography–quadrupole time‐of‐flight mass spectrometry. Meanwhile, a total of nine secoiridoids were obtained by natural product chemical extraction, isolation and identification methods. Quantitative analysis by high‐performance liquid chromatography–diode array detection–mass spectrometry showed the highest total content of secoiridoids in the bark, which is also consistent with the traditional medicinal parts. The results of methodological validation showed that the correlation coefficient (R2) values were all >0.9993, indicating a good linear range of the standard curve, while the relative standard deviations of precision, reproducibility and stability were <3%, and the spiked recoveries ranged from 98.22 to 102.27%, indicating that the experimental method was reliable and stable. In addition, fingerprinting and a heatmap were established to demonstrate the content trends of F. mandshurica more visually from different origins. Multivariate analysis, including principal component analysis and partial least squares discriminant analysis, was performed to determine the chemical characteristics of different parts of F. mandshurica, and six characteristic secoiridoids that could be used to distinguish different origins were screened. Finally, the inhibition of tyrosinase, α‐glucosidase, acetylcholinesterase and pancreatic lipase activities by the nine characteristic compounds and extracts from different parts were investigated, and the results showed that they all exhibited different degrees of enzyme activity inhibition and thus have potential applications in whitening and blemish removal, hypoglycemia, anti‐Alzheimer's disease and anti‐obesity as a new source of natural enzyme activity inhibitors. This study establishes an identification and evaluation method applicable to phytochemistry of different origins, which is a guideline for quality control, origin evaluation and clinical application of traditional medicinal plants. This is also an unprecedented study on the identification of the chemical composition of different parts of F. mandshurica, characteristic compounds and the inhibition of enzyme activity of extracts from different parts. [ABSTRACT FROM AUTHOR]

Electrochemical biosensors that combine high selectivity of biochemical affinity with precise electrochemical detection are one of the most necessary and powerful tools for assessing environmental pollution. This review addresses electrochemical biosensors that assess environmental pollutant toxicity. Electrochemical biosensors using enzyme activity inhibition, DNA, whole cells, and cytochrome P450 will be introduced, their advantages and applications will be discussed, and trends and challenges for designing reliable sensors for practical use will be addressed. [ABSTRACT FROM AUTHOR]

Neurodegenerative diseases, among which one of the more common is Alzheimer's disease, are the one of the biggest global public health challenges facing our generation because of the increasing elderly population in most countries. With the growing burden of these diseases, it is essential to discover and develop new treatment options capable of preventing and treating them. Neurodegenerative diseases, among which one of the most common is Alzheimer's disease, are a multifactorial disease and therefore demand multiple therapeutic approaches. One of the most important therapeutic strategies is controlling the level of acetylcholine—a neurotransmitter in cholinergic synapses—by blocking the degradation of acetylcholine using acetylcholinesterase inhibitors such as tacrine, galantamine, donepezil and rivastigmine. However, these drugs can cause some adverse side effects, such as hepatotoxicity and gastrointestinal disorder. Thus, the search for new, more effective drugs is very important. In the last few years, different active constituents from plants have been tested as potential drugs in neurodegenerative disease therapy. The availability, lower price and less toxic effects of herbal medicines compared with synthetic agents make them a simple and excellent choice in the treatment of neurodegenerative diseases. The empirical approach to discovering new drugs from the systematic screening of plant extracts or plant-derived compounds is still an important strategy when it comes to finding new biologically active substances. The aim of this review is to identify new, safe and effective compounds that are potential candidates for further in vivo and clinical tests from which more effective drugs for the treatment of Alzheimer's disease could be selected. We reviewed the methods used to determine anti-Alzheimer's disease activity. Here, we have discussed the relevance of plant-derived compounds with in vitro activity. Various plants and phytochemical compounds have shown different activity that could be beneficial in the treatment of Alzheimer's disorders. Most often, medicinal plants and their active components have been investigated as acetylcholinesterase and/or butyrylcholinesterase activity inhibitors, modifiers of β-amyloid processing and antioxidant agents. This study also aims to highlight species with assessed efficacy, usable plant parts and the most active plant components in order to identify species and compounds of interest for further study. Future research directions are suggested and recommendations made to expand the use of medicinal plants, their formulations and plant-derived active compounds to prevent, mitigate and treat Alzheimer's disease. [ABSTRACT FROM AUTHOR]

The bark of Fraxinus mandshurica is a traditional folk herb used to clear heat and dry dampness. To investigate the differences in coumarins content in the bark of F. mandshurica , 24 batches of samples from four origins were collected and analyzed. Eight coumarins were obtained by traditional natural product extraction, isolation and identification techniques and quantified by high performance liquid chromatography-photodiode array (HPLC-DAD). The quantitative results showed that the overall content of compound 30 (Fraxinol) was higher at 100.23 mg/g, while the overall content of compound 23 (Cichoriin) was lower, which may be related to environmental factors in different regions. The method validation showed that the linear range of the eight standards was between 10 and 2500 μg/mL with correlation coefficient (R 2) values >0.9991; the relative standard deviation (RSD, %) values of intra-day precision were between 0.35 and 1.38, while the RSD values of inter-day precision were between 0. 29–1.78; the RSD (%) values for the reproducibility experiments ranged from 0.29 to 1.87, while the RSD (%) values for the stability experiments ranged from 0.22 to 2.33; the spiked recovery of the samples ranged from 98.65 to 101.34%, and the RSD (%) values ranged from 0.22 to 1.96. The method validation results showed that the instrument used for the analysis had good precision, the reproducibility and stability of the samples were good, and the accuracy of the experimental method was high. In addition, a total of 54 chemical components were identified from F. mandshurica bark by ultra performance liquid chromatography-electrospray quadrupole time-of-flight mass spectrometry (UPLC-ESI-Q-TOF-MS). Based on this, fingerprinting, heatmap and multivariate analysis, including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), were established for 24 batches of samples, and four marker compounds that could be used to distinguish different origins of F. mandshurica were screened. To further investigate the bioactivities of the eight coumarins, in vitro enzyme activity inhibition studies were performed, and the results showed that they all exhibited different degrees of inhibition of acetylcholinesterase, tyrosinase and α-glucosidase, thus having potential applications in the treatment of Alzheimer's disease, blemish whitening and anti-diabetes, and becoming a new source of natural enzyme activity inhibitors. This study established an identification and evaluation method applicable to plants of different origins, which provides a strong reference for quality control, origin evaluation and clinical application of traditional medicinal plants. [Display omitted] • Fifty-four chemical constituents were identified from the bark of F. mandshurica using UPLC-ESI-Q-TOF-MS technique. • Eight coumarins were selectively isolated from the bark of F. mandshurica. • Fingerprinting, heatmap and multivariate analysis were established for the eight coumarins, and four marker compounds were screened out. • The inhibitory effects of these eight coumarins on the activities of three enzymes were evaluated. [ABSTRACT FROM AUTHOR]

Neurodegenerative diseases, among which one of the more common is Alzheimer’s disease, are the one of the biggest global public health challenges facing our generation because of the increasing elderly population in most countries. With the growing burden of these diseases, it is essential to discover and develop new treatment options capable of preventing and treating them. Neurodegenerative diseases, among which one of the most common is Alzheimer’s disease, are a multifactorial disease and therefore demand multiple therapeutic approaches. One of the most important therapeutic strategies is controlling the level of acetylcholine—a neurotransmitter in cholinergic synapses—by blocking the degradation of acetylcholine using acetylcholinesterase inhibitors such as tacrine, galantamine, donepezil and rivastigmine. However, these drugs can cause some adverse side effects, such as hepatotoxicity and gastrointestinal disorder. Thus, the search for new, more effective drugs is very important. In the last few years, different active constituents from plants have been tested as potential drugs in neurodegenerative disease therapy. The availability, lower price and less toxic effects of herbal medicines compared with synthetic agents make them a simple and excellent choice in the treatment of neurodegenerative diseases. The empirical approach to discovering new drugs from the systematic screening of plant extracts or plant-derived compounds is still an important strategy when it comes to finding new biologically active substances. The aim of this review is to identify new, safe and effective compounds that are potential candidates for further in vivo and clinical tests from which more effective drugs for the treatment of Alzheimer’s disease could be selected. We reviewed the methods used to determine anti-Alzheimer’s disease activity. Here, we have discussed the relevance of plant-derived compounds with in vitro activity. Various plants and phytochemical compounds have shown different activity that could be beneficial in the treatment of Alzheimer’s disorders. Most often, medicinal plants and their active components have been investigated as acetylcholinesterase and/or butyrylcholinesterase activity inhibitors, modifiers of β-amyloid processing and antioxidant agents. This study also aims to highlight species with assessed efficacy, usable plant parts and the most active plant components in order to identify species and compounds of interest for further study. Future research directions are suggested and recommendations made to expand the use of medicinal plants, their formulations and plant-derived active compounds to prevent, mitigate and treat Alzheimer’s disease.

Olive waste was used as a sustainable resource because it contained a variety of valuable compounds. The polyphenols active fraction from enrichment by microporous resin and extraction with ethyl acetate were analysed by different chromatographic methods. A total of 14 polyphenolic compounds were isolated and identified by structure elucidation. Based on the above obtained compounds, tyrosol was selected as a characteristic polyphenol and participated in transesterification reaction to synthesise β-ketoester using Yb(OTf)3. Then the Biginelli reaction with benzaldehyde, urea and ketoester (1:1.2:1.2) was performed at 90 °C for 3.0 h under the acidic condition. In addition, the β-ketoester prepared using tyrosol with benzyl had a greater inhibitory effect on α-glucosidase and α-amylase, and the inhibition of enzyme activity for 3, 4-dihydropyrimidinone derivatives prepared using abovementioned β-ketoester was improved significantly. Meanwhile, fluorine-containing dihydropyrimidinone derivatives were considerable inhibitors for both enzymes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Expression and purification conditions were optimized to improve yield of PfPlmV. • Conformational characterisation was done using CD and activity was evaluated by enzyme kinetics studies at pH 6.5. • Quinolines 4-AQ and 8-OHQ interact with PfPlmV at the active site via H-bonding and hydrophobic interaction. • 4-AQ and 8-OHQ inhibit the PEXEL cleavage activity of PfPlmV. • Quinolines can serve as an antimalarial targeting to non-food vacuole aspartic protease. Plasmodium falciparum plasmepsin V (PfPlmV) is an aspartic protease present in the malarial parasite and has emerged as potent anti-malarial target. In this work, we have optimized the bacterial recombinant expression conditions to increase the yield of PfPlmV in soluble fraction. The pH dependent enzyme activity assay was performed to determine the optimum pH for PfPlmV activity. The effects of two quinolines 4-amino quinoline (4-AQ) and 8-hydroxy quinoline (8-OHQ) on the activity of PfPlmV was studied in aqueous medium using various biophysical methods. The fluorescence quenching and circular dichroism studies show that both 4-AQ and 8-OHQ bind with PfPlmV with moderate affinity and induce slight conformational changes. The molecular docking studies along with thermodynamic parameters obtained by isothermal titration calorimetric experiments suggest that 4-AQ/8-OHQ binds at the catalytic site of PfPlmV via H-bonding/ionic/electrostatic and hydrophobic interactions. The binding of 4-AQ with PfPlmV reduces the thermal stability of the protein more than that of the 8-OHQ. The enzyme activity inhibition studies for PfPlmV in presence of quinolines shows that 4-AQ/8-OHQ efficiently inhibits the activity of PfPlmV in aqueous medium. These findings contribute to a deeper understanding of the enzymatic processes involved in malaria and pave the way for potential antimalarial therapy. [ABSTRACT FROM AUTHOR]

The design and synthesis of new herbicidal active compounds based on a new target are of great significance for the development of new herbicides. Transketolase (TK) plays a key role in the Calvin cycle of plant photosynthesis and has been confirmed as a potential candidate target to develop and discover new herbicides. To obtain compounds with ultraefficient targeting of TK, a series of pyrazole amide derivatives were designed and synthesized through structural optimization for lead compound 4u based on TK as the new target. The bioassay results showed that compounds 6ba and 6bj displayed a highly inhibitory effect with the root inhibition of about 90% against Digitaria sanguinalis ( DS ) and 80% against Amaranthus retroflexus ( AR ) and Setaria viridis ( SV ) by the small cup method, which was better than the positive control mesotrione and nicosulfuron. Furthermore, compounds 6ba and 6bj exhibited an excellent inhibitory effect with the inhibition of about 80% (against DS ) and over 80% (against SV ) at the dosage of 150 g of active ingredient/ha by the foliar spray method. The TK enzyme activity inhibition test showed that the inhibition effect of target compounds against TK was consistent with the results of herbicidal activities. Also, molecular docking analysis showed that compounds 6ba and 6bj went deep into the active cavity of TK, bound to TK by a strong interaction, and might act on the enzyme TK. Above of all, compounds 6ba and 6bj are promising herbicide lead compounds targeting TK. Hence, they could be developed into more efficient herbicides by further structural optimization.

A thermostable and detergent-stable α-amylase from a newly isolated Anoxybacillus sp. AH1 was purifi ed and characterized. Maximum enzyme production (1874.8 U/mL) was obtained at 24 h of incubation. The amylase was purified by using Sephadex G-75 gel filtration, after which an 18-fold increase in specific activity and a yield of 9 % were achieved. The molecular mass of the purified enzyme was estimated at 85 kDa by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH and temperature values of the enzyme were 7.0 and 60 °C, respectively. The enzyme was highly stable in the presence of 30 % glycerol, retaining 85 % of its original activity at 60 °C within 120 min. Km and vmax values were 0.102 μmol and 0.929 μmol/min, espectively, using Lineweaver-Burk plot. The enzyme activity was increased by various detergents, but it was significantly inhibited in the presence of urea. Mg2+ and Ca2+ also significantly activated α-amylase, while Zn2+, Cu2+ and metal ion chelators ethylenediaminetetraacetic acid (EDTA) and 1,10-phenanthroline (phen) greatly inhibited the enzyme activity. α-Amylase activity was enhanced by β-mercaptoethanol (β-ME) and dithiothreitol (DTT) to a great extent, but inhibited by p-chloromercuribenzoic acid (PCMB). Iodoacetamide (IAA) and N-ethylmaleimide (NEM) had a slight, whereas phenylmethylsulfonyl fluoride (PMSF) had a strong inhibitory effect on the amylase activity.

An enzymatic electrochemical biosensor was prepared based on glucose oxidase (GOD) immobilized on single-walled carbon nanotubes/Nile blue (Nb-SWCNTs) nanocomposite cross-linked with glutaraldehyde on graphite electrode. The function of glucose biosensor is based on the electrocatalytic reduction of H2O2 generated by the reaction of the enzyme with glucose molecules. The biosensor was characterized by Fourier transform infrared (FTIR) spectroscopy, emission scanning (FESEM), UV-Vis spectrometry, and voltammetric and amperometric methods. Parameters influencing the performance of the biosensor, namely pH and applied potential, were optimized. Inhibition was carried out for the detection of Hg2+ and Pb2+ species under optimized condition. Inhibition investigations showed that the type of inhibition for both the abov- mentioned heavy metal ions were reversible and competitive. [ABSTRACT FROM AUTHOR]

A thermostable and detergent-stable α-amylase from a newly isolated Anoxybacillus sp. AH1 was purified and characterized. Maximum enzyme production (1874.8 U/mL) was obtained at 24 h of incubation. The amylase was purified by using Sephadex G-75 gel filtration, after which an 18-fold increase in specific activity and a yield of 9 % were achieved. The molecular mass of the purified enzyme was estimated at 85 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH and temperature values of the enzyme were 7.0 and 60 °C, respectively. The enzyme was highly stable in the presence of 30 % glycerol, retaining 85 % of its original activity at 60 °C within 120 min. Km and vmax values were 0.102 μmol and 0.929 μmol/min, respectively, using Lineweaver-Burk plot. The enzyme activity was increased by various detergents, but it was significantly inhibited in the presence of urea. Mg2+ and Ca2+ also significantly activated α-amylase, while Zn2+, Cu2+ and metal ion chelators ethylenediaminetetraacetic acid (EDTA) and 1,10-phenanthroline (phen) greatly inhibited the enzyme activity. α-Amylase activity was enhanced by β-mercaptoethanol (β-ME) and dithiothreitol (DTT) to a great extent, but inhibited by p-chloromercuribenzoic acid (PCMB). Iodoacetamide (IAA) and N-ethylmaleimide (NEM) had a slight, whereas phenylmethylsulfonyl fluoride (PMSF) had a strong inhibitory effect on the amylase activity. [ABSTRACT FROM AUTHOR]

Legumes are affected by biotic factors such as insects, molds, bacteria, and viruses. These plants can produce many different molecules in response to the attack of phytopathogens. Protease inhibitors (PIs) are proteins produced by legumes that inhibit the protease activity of phytopathogens. PIs are known to reduce nutrient availability, which diminishes pathogen growth and can lead to the death of the pathogen. PIs are classified according to the specificity of the mechanistic activity of the proteolytic enzymes, with serine and cysteine protease inhibitors being studied the most. Previous investigations have reported the efficacy of these highly stable proteins against diverse biotic factors and the concomitant protective effects in crops, representing a possible replacement of toxic agrochemicals that harm the environment. [ABSTRACT FROM AUTHOR]