Piperine analogs as potent Staphylococcus aureus NorA efflux pump inhibitors

Based on our recent findings that piperine is a potent Staphylococcus aureus NorA efflux pump inhibitor (EPI), 38 piperine analogs were synthesized and bioevaluated for their EPI activity. Twenty-five of them were found active with potentiating activity equivalent or more than known EPIs like reserpine, carsonic acid and verapamil. The inhibitory mechanism of the compounds was confirmed by efflux inhibition assay using ethidium bromide as NorA substrate. The present communication describes the synthesis, bioevaluation and structure related activity of these efflux pump inhibitors.     

Carboxy derivatized glucosamine is a potent inhibitor of matrix metalloproteinase-9 in HT1080 cells

Experimental evidences have confirmed that matrix metalloproteinases (MMPs) play a fundamental role in a wide variety of pathologic conditions and recent advances in medicinal chemistry approach to the design of MMP inhibitors with desired structural and functional properties. Among MMPs, MMP-9 has demonstrated to play a major role in the establishment of metastases and it is substantially increased in the majority of malignant tumors. Inhibition of MMP-9 is thought to have a therapeutic benefit to cancer. Results of this study present a novel synthetic MMP-9 inhibitor that downregulates MMP-9 expression level in HT1080, human fibrosarcoma cells.     

Strong electronic charge as an important factor for anticancer activity of chitooligosaccharides (COS)

Even though several studies report the importance of chitosan derivatives for their anticancer activity, no clear information is available to describe the relationship between their charge properties and observed activities. In this research, differently charged chitooligosaccharide (COS) derivatives were synthesized and their anticancer activities were studied using three cancer cell lines, HeLa, Hep3B and SW480. Neutral red and MTT cell viability studies revealed that, highly charged COS derivatives could significantly reduce cancer cell viability, regardless to the positive or negative charge. Further, fluorescence microscopic observations and DNA fragmentation studies confirmed that the anticancer effect of these highly charged COS derivatives were due to necrosis. However, the exact molecular mechanism for anticancer activity of strongly charged COS compared to their poorly charged counterparts is not clear.     

Phlorotannins in Ecklonia cava extract inhibit matrix metalloproteinase activity

Matrix metalloproteinase (MMP) inhibitors have been identified as potential therapeutic candidates for metastasis, arthritis, chronic inflammation and wrinkle formation. For the first time here we report a detailed study on the inhibitory effects of phlorotannins in brown algae, Ecklonia cava (EC) on MMP activities in cultured human cell lines. A novel gelatin digestion assay could visualize complete inhibition of bacterial collagenase-1 activity at 20 microg/ml of EC extract during preliminary screening studies. Sensitive fluorometric assay revealed that EC extract can specifically inhibit both MMP-2 and MMP-9 activities significantly (P < 0.001) at 10 microg/ml. In addition, artificially induced activities of MMP-2 and MMP-9 in human dermal fibroblasts and HT1080 cells were inhibited by EC extract in a more or less similar manner to the positive control doxycycline. Even though the expression levels of MMPs differ from one cell type to the other, gelatin zymography clearly revealed that both MMP expression and activity in cells can be inhibited by EC extract. More interestingly, EC extract did not exert any cytotoxic effect even at 100 microg/ml anticipating its potential use as a safe MMP inhibitor.     

Synthesis of the 2′-,3′-Didehydro-2′-,3′-dideoxy and 2′-,3′-Dideoxy Derivatives of 6-Azauridine and a New Route to 2′-,3′-Didehydro-2′-,3′-dideoxy-5-chlorouridine

Abstract

The 5′-O-(4,4′-dimethoxytrityl) and 5′-O-(tert-butyldimethylsilyl) derivatives of 2′-,3′-O-thiocarbonyl-6-azauridine and 2′,3′-O-thiocarbonyl-5-chlorouridine were synthesized from the parent nucleosides by reaction with 4, 4′-dimethoxytrityl chloride and tert-butyldimethylsilyl chloride, respectively, followed by treatment with 1,1′-thiocarbonyldiimidazole. Introduction of a 2′-,3′-double bond into the sugar ring by reaction of the 5′-protected 2′-,3′-O-thionocarbonates with 1, 3-dimethyl-2-phenyl-1, 3, 2-diazaphospholidiine was unsuccessful, but could be accomplished satisfactorily with trimethyl phosphite. Reactions were generally more successful with the 5′-silylated than with the 5′-tritylated nucleosides. Formation of 2′-,3′-O-thiocarbonyl derivatives proceeded in higher yield with 5′-protected 6-azauridines than with the corresponding 5-chlorouridines because of the propensity of the latter to form 2,2′-anhydro derivatives. In the reaction of 5′-O-(tert-butyldimethylsilyl)-2′-,3′-O-thiocarbonyl-6-azauridine with trimethyl phosphite, introduction of the double bond was accompanied by N³-methylation. However this side reaction was not a problem with 5′-O-(tert-butyldimethylsilyl)-2′-, 3′-O-thioarbonyl-5-chlorouridine. Treatment of 5′-O-(tert-butyldimethylsilyl)-2′-, 3′-didehydro-2′-,3′-dideoxy-6-azauridine with tetrabutylammonium fluoride followed by hydrogenation afforded 2′-,3′-dideoxy-6-azauridine. Deprotection of 5′-O-(tert-butyldimethylsilyl)-2′-, 3′-didehydro-2′-,3′-dideoxy-5-chlorouridine yielded 2′-,3′-didehydro-2′-,3′-dide-oxy-5-chlorouridine.     

Marker-free transgenic (MFT) near-isogenic introgression lines (NIILs) of 'golden' indica rice (cv. IR64) with accumulation of provitamin A in the endosperm tissue

We have developed near-isogenic introgression lines (NIILs) of an elite indica rice cultivar (IR64) with the genes for β-carotene biosynthesis from dihaploid (DH) derivatives of golden japonica rice (cv. T309). A careful analysis of the DH lines indicated the integration of the genes of interest [phytoene synthase ( psy ) and phytoene desaturase ( crtI )] and the selectable marker gene (hygromycin phosphotransferase, hph ) in two unlinked loci. During subsequent crossing, progenies could be obtained carrying only the locus with psy and crtI , which was segregated independently from the locus containing the hph gene during meiotic segregation. The NIILs (BC₂F₂) showed maximum similarity with the recurrent parent cultivar IR64. Further, progenies of two NIILs were devoid of any fragments beyond the left or right border, including the chloramphenicol acetyltransferase ( cat ) antibiotic resistance gene of the transformation vector. Spectrophotometric readings showed the accumulation of up to 1.06 µg total carotenoids, including β-carotene, in 1 g of the endosperm. The accumulation of β-carotene was also evident from the clearly visible yellow colour of the polished seeds.     

Simultaneous storage of medical images in the spatial and frequency domain: A comparative study

Background  

Digital watermarking is a technique of hiding specific identification data for copyright authentication. This technique is adapted here for interleaving patient information with medical images, to reduce storage and transmission overheads.