Applications of solid-phase micro-extraction with mass spectrometry in pesticide analysis.

Pesticides, widely applied in agriculture, can produce a variety of transformation products and their continuous use causes deleterious effects to ecosystem. Efficient and sensitive analytical techniques for enrichment and analysis of pesticides samples are highly required. Compared with other extraction methods, solid-phase micro extraction is a solvent free, cost effective, robust, versatile, and high throughput sample preparation technique, especially for the analysis of pesticides from complicated matrices. Coupling of solid-phase micro extraction with gas chromatography and mass spectrometry and liquid chromatography-mass spectrometry has been extensively applied in pesticide analysis. On the other hand, in recent years, combination of fast separation using solid-phase micro extraction and rapid detection using ambient mass spectrometry is providing highly efficient pesticide screening. This article summarizes the applications of solid-phase micro extraction coupled to mass spectrometry for pesticides analysis.

Development of a fast CE method for high throughput screening of ecto-5'-nucleotidase inhibitors.

Overexpression of ecto-5'-nucleotidase is found to be linked to cancer progression and other diseases which makes screening of its inhibitors on demand. Unfortunately, there is scarcity of reported ecto-5'-nucleotidase inhibitors because of unavailability of simple, fast and efficient methods to study its inhibition. In this study, we have developed a very fast, reverse polarity capillary electrophoresis based method for screening of ecto-5'-nucleotidase inhibitors. Both EOF and electrophoretic mobility were maintained in same direction by dynamically coating lining of capillary and applying negative voltage, resulting in appearance of both adenosine monophosphate (AMP) and adenosine peaks in less than 2 min. Separations were performed in reverse polarity using -20 kV. Hexadimethrine bromide (HDB) was used as a buffer additive (0.025% in 40 mM borate buffer). An online sample stacking was attained by a special sweeping effect which enabled a long (65 s) injection time without compromise in peak shape. Using this newly developed method, both AMP and adenosine peaks were obtained with a baseline resolution, in less than two minutes. Method was validated by measuring km , and Vmax values of human ecto-5'-nucleotidas and Ki value of standard inhibitor quercitin against this enzyme. Method is simple and fast and can be conveniently optimized for high throughput screening of ecto-5'-nucleotidase inhibitors.

Identification of sulfonic acids as efficient ecto-5'-nucleotidase inhibitors.

Ecto-5'-nucleotidase (CD73) is well known for its implication in cancer. Inhibition of ecto-5'-nucleotidases is thought to provide an attractive approach to cancer therapy. This study identifies sulfonic acid compounds as efficient inhibitors of ecto-5'-nucleotidases. The compounds were tested against recombinant human and rat ecto-5'-nucleotidases. The most potent new sulfonic acid inhibitor 6-amino-4-hydroxynaphthalene-2-sulfonic acid (1) of ecto-5'-nucleotidase had an IC50 of 1.32 ± 0.09 µM for the human and 10.4 ± 3.3 µM for the rat enzyme. Generally, all compounds were more active against the human enzyme. Plausible binding mode models were developed for this new class of inhibitors. Furthermore, several sulfonic acid inhibitors were efficient cytotoxic agents when tested on H157 cancer cell lines. Hence, new ecto-5'-nucleotidases inhibitors displayed significant potential for further development as compounds for anti-cancer therapy.

Identification of novel chromone based sulfonamides as highly potent and selective inhibitors of alkaline phosphatases.

A new series of structurally diverse chromone containing sulfonamides has been developed. Crystal structures of three representative compounds (2a, 3a and 4a) in the series are reported. All compounds were screened for their inhibitory potential against alkaline phosphatases (ALPs). Two main classes of ALP isozymes were selected for this study, the tissue non-specific alkaline phosphatase (TNALP) from bovine and porcine source and the tissue-specific intestinal alkaline phosphatases (IALPs) from bovine source. All sulfonamide compounds had a marked preference for IALP (K(i), up to 0.01 ± 0.001 µM) over TNALPs. Kinetics studies of the compounds showed competitive mode of inhibition. Molecular docking studies were carried out in order to characterize the selective inhibition of the compounds. An additional interesting aspect of these chromone sulfonamides is their inhibitory activity against ecto-5'-nucleotidase enzyme.

Polyoxometalates as potent and selective inhibitors of alkaline phosphatases with profound anticancer and amoebicidal activities.

The biological significance of polyoxometalates is well renowned owing to their anticancer, antiviral and antibiotic properties. Here another therapeutic aspect of polyoxometalates has been explored as alkaline phosphatase inhibitors along with the remarked anticancer and amoebicidal properties. Synthesis and inhibitory studies of a set of seven polyoxotungstates against two major isozymes of alkaline phosphatase i.e. tissue specific and tissue non-specific alkaline phosphatase revealed their promising activity as alkaline phosphatase inhibitors. All compounds exhibited alkaline phosphatase inhibitory potency in nanomolar ranges. For tissue specific alkaline phosphatase, Na(10)[H(2)W(12)O(42)]·27H(2)O (A6) was found to be the most potent inhibitor (K(i) value 313 ± 7 nM), while for tissue non-specific alkaline phosphatase Na(33)[H(7)P(8)W(48)O(184)]·92H(2)O (A3) showed the highest inhibition potency (K(i) values 135 ± 10 nM). Moreover cytotoxicity evaluation of these compounds against lung carcinoma cells and immortalized human corneal epithelial cells demonstrated their anticancer potential with no cytotoxic effects on normal human cell lines. All anticancer drugs result in an impaired immune system and such immunocompromised persons become vulnerable to opportunistic infections specially Acanthamoeba which causes granulomatous amoebic encephalitis (GAE) which almost always results in death. The exclusive property of our tested polyoxotungstates is their strong amoebicidal activity against Acanthamoeba. Hence the study reveals a new window towards cancer therapy with the combined control of elevated levels of alkaline phosphatase and granulomatous amoebic encephalitis in cancer patients.

Identification of small molecule sulfonic acids as ecto-5'-Nucleotidase inhibitors.

Ecto-5'-Nucleotidase inhibitors have great potential as anti-tumor agents. We have investigated biochemical properties of human and rat ecto-5'-Nucleotidases and characterized 19 small molecule sulfonic acid derivatives as potential inhibitors of ecto-5'-Nucleotidases. We identified 11 potent inhibitors of human and rat ecto-5'-Nucleotidases and checked their selectivity. Compound 10 (Sodium 2,4-dinitrobenzenesulfonate) with K(i) value of 0.66 µM and 19 (N-(4-sulfamoylphenylcarbamothioyl) pivalamide) with K(i) value of 0.78 µM were identified as the most potent inhibitors for human and rat ecto-5'-Nucleotidase, respectively. The present compounds have low molecular weights, water solubility and equal potency as compared to the reported inhibitors.

Synthesis and biological evaluation of 3-thiazolocoumarinyl Schiff-base derivatives as cholinesterase inhibitors.

On the basis of the observed biological activity of the coumarins, a new set of 3-thiazolocoumarinyl Schiff-base derivatives with chlorine, hydroxy and methoxy functional group substitutions were designed and synthesized. These compounds were tested against acetylcholinesterase from Electrophorus electricus and butyrylcholinesterase from horse serum and their structure-activity relationship was established. Studies revealed them as the potential inhibitors of cholinesterase (acetylcholinesterase and butyrylcholinesterase). The 3f was found to be most potent against acetylcholinesterase with K(i) value of 1.05 ± 0.3 µM and 3l showed excellent inhibitory action against butyrylcholinesterase with K(i) value of 0.041 ± 0.002 µM. The synthesized compounds were also docked into the active sites of the homology models of acetylcholinesterase and butyrylcholinesterase to predict the binding modes of these compounds. It was predicted that most of the compounds have similar binding modes with reasonable binding affinities. Our docking studies have also shown that these synthesized compounds have better interaction patterns with butyrylcholinesterase over acetylcholinesterase. The main objective of the study was to develop new potent and selective compounds, which might be further optimized to prevent the progression of the Alzheimer's disease and could provide symptomatic treatment.