Computer-Aided and AILDE Approaches to Design Novel 4-Hydroxyphenylpyruvate Dioxygenase Inhibitors.

4-Hydroxyphenylpyruvate dioxygenase (HPPD) is a pivotal enzyme in tocopherol and plastoquinone synthesis and a potential target for novel herbicides. Thirty-five pyridine derivatives were selected to establish a Topomer comparative molecular field analysis (Topomer CoMFA) model to obtain correlation information between HPPD inhibitory activity and the molecular structure. A credible and predictive Topomer CoMFA model was established by "split in two R-groups" cutting methods and fragment combinations (q2 = 0.703, r2 = 0.957, ONC = 6). The established model was used to screen out more active compounds and was optimized through the auto in silico ligand directing evolution (AILDE) platform to obtain potential HPPD inhibitors. Twenty-two new compounds with theoretically good HPPD inhibition were obtained by combining the high-activity contribution substituents in the existing molecules with the R-group search via Topomer search. Molecular docking results revealed that most of the 22 fresh compounds could form stable π-π interactions. The absorption, distribution, metabolism, excretion and toxicity (ADMET) prediction and drug-like properties made 9 compounds potential HPPD inhibitors. Molecular dynamics simulation indicated that Compounds Y12 and Y14 showed good root mean square deviation (RMSD) and root mean square fluctuation (RMSF) values and stability. According to the AILDE online verification, 5 new compounds with potential HPPD inhibition were discovered as HPPD inhibitor candidates. This study provides beneficial insights for subsequent HPPD inhibitor design.

Virtual screening based on pharmacophore model for developing novel HPPD inhibitors.

4-Hydroxyphenylpyruvate dioxygenase (HPPD) is an important target for herbicide design. A multilayered virtual screening workflow was constructed by combining two pharmacophore models based on ligand and crystal complexes, molecular docking, molecular dynamics (MD), and biological activity determination to identify novel small-molecule inhibitors of HPPD. About 110, 000 compounds of Bailingwei and traditional Chinese medicine databases were screened. Of these, 333 were analyzed through docking experiments. Five compounds were selected by analyzing the binding pattern of inhibitors with amino acid residues in the active pocket. All five compounds could produce stable coordination with cobalt ion, and form favorable π-π interactions. MD simulation demonstrated that Phe381 and Phe424 made large contributions to the strength of binding. The enzyme activity experiment verified that compound-139 displayed excellent potency against AtHPPD (IC50 = 0.742 µM), however, compound-5222 had inhibitory effect on human HPPD (IC50 = 6 nM). Compound-139 exhibited herbicidal activity to some extent on different gramineous weeds. This work provided a strong insight into the design and development of novel HPPD inhibitor using in silico techniques.

NPA-Cu2+ Complex as a Fluorescent Sensing Platform for the Selective and Sensitive Detection of Glyphosate.

Glyphosate is a highly effective, low-toxicity, broad-spectrum herbicide, which is extensively used in global agriculture to control weeds and vegetation. However, glyphosate has become a potential threat to human and ecosystem because of its excessive usage and its bio-concentration in soil and water. Herein, a novel turn-on fluorescent probe, N-n-butyl-4-(3-pyridin)ylmethylidenehydrazine-1,8-naphthalimide (NPA), is proposed. It efficiently detected Cu2+ within the limit of detection (LOD) of 0.21 µM and displayed a dramatic turn-off fluorescence response in CH3CN. NPA-Cu2+ complex was employed to selectively and sensitively monitor glyphosate concentrations in real samples accompanied by a fluorescence turn-on mode. A good linear relationship between NPA and Cu2+ of glyphosate was found in the range of 10-100 µM with an LOD of 1.87 µM. Glyphosate exhibited a stronger chelation with Cu2+ than NPA and the system released free NPA through competitive coordination. The proposed method demonstrates great potential in quantitatively detecting glyphosate in tap water, local water from Songhua River, soil, rice, millet, maize, soybean, mung bean, and milk with mild conditions, and is a simple procedure with obvious consequences and no need for large instruments or pretreatment.

Expression characteristics of hypoxia inducible factor-1a and its clinical values in hepatocellular carcinoma / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the dynamic expression of hypoxia inducible factor-1alpha (HIF-1alpha) and its clinical values in hepatocellular carcinoma (HCC).</p><p><b>METHODS</b>The dynamic changes of liver pathology, HIF-1alpha transcription and expression were observed through the hepatoma model. The self-control specimens from 35 human HCC patients were collected and the expression, cellular distribution, and clinicopathological features of HIF-1alpha and its gene was analyzed by immunohistochemistry, western blotting and nested- PCR, respectively.</p><p><b>RESULTS</b>Both levels of hepatic HIF-1alpha and HIF-1alpha mRNA expression increased during the HCC development course. The incidence of HIF-1alpha and the ratio of HIF-1alpha to beta-actin was 0% and 0.16+/-0.02 in the control rats, 77.8% and 0.29+/-0.04 in the denatured rats, 88.9% and 0.52+/-0.03 in the precancerous rats, and 100% and 0.84+/-0.02 in the cancerous rats respectively, with significant difference between the control group and any of the experimental groups (P = 0.000). The positive HIF-1alpha was brown and granule-like and mainly presented in cytoplasm and few in nucleus. The incidence of HIF-1alpha was 80% (28/35) in HCC and 100% (35/35) in its surrounding tissues. The clinical pathological features indicated HIF-1alpha expression associated with tumor size and differentiation degree the of HCC. No correlation was found between HIF-1alpha and tumor numbers or positive-HBsAg.</p><p><b>CONCLUSIONS</b>HIF-1alpha expression is associated with occurrence and development of HCC, and is perhaps a target molecule for HCC therapy.</p>

Dynamic expression and quantitative analysis of hepatic nuclear factor-kappa B and its gene during the development of hepatocellular carcinoma / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the kinetic expression and alteration of nuclear transcription factor-kappa B (NF-kappaB) and its gene in hepatocellular carcinoma (HCC) development.</p><p><b>METHODS</b>A hepatoma model was established with N-(2-fluorenyl) acetamide (2-FAA) using male SD rats. Morphological changes and dynamic alterations of NF-kappaB and NF-kappaB mRNA of the rat livers at different stages of HCC development were observed by pathological examinations. The liver specimens from HCC patients were collected by self-control method. The expression of NF-kappaB was quantitatively analyzed by ELISA.</p><p><b>RESULTS</b>Hepatocytes showed vacuole-like denaturation, atypical hyperplasia, and transformation into highly differentiated cancerous hepatocytes with increasing tendencies of liver NF-kappaB and NF-kappaB mRNA expressions. The NF-kappaB positive material was granule-like and stained brown, with dot-nest-like staining localized in the nuclei and cytoplasm of HCC cells, but only in the cytoplasm of the cells of park cancer tissues. Its expression in HCC cells was stronger than that in their surrounding tissues (chi2 = 13.1, P less than 0.01). No positive relationship was found between NF-kappaB expression and histological grades, the number of tumors, or size of the tumors.</p><p><b>CONCLUSION</b>The expression of NF-kappaB and its gene are associated with the development of HCC. To inhibit the expression may be useful to HCC therapy.</p>