The Experts below are selected from a list of 1092 Experts worldwide ranked by ideXlab platform
Kirsten Benkendorff - One of the best experts on this subject based on the ideXlab platform.
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Extraction and Quantification of Bioactive Tyrian Purple Precursors: A Comparative and Validation Study from the Hypobranchial Gland of a Muricid Dicathais orbita
MDPI AG, 2016Co-Authors: Roselyn Valles-regino, David Rudd, Peter Mouatt, Lachlan H. Yee, Kirsten BenkendorffAbstract:Muricidae are marine molluscs known for the production of Tyrian purple and bioactive precursor compounds. A validation study for the extraction and analysis of secondary metabolites found in the hypobranchial gland of the muricid Dicathais orbita is reported, using high performance liquid chromatography–mass spectrometry (HPLC-MS) with diode array detector (DAD). Quantification of the dominant secondary metabolites from D. orbita is described, followed by a comparison of solvent extraction procedures and stability studies. The intra- and inter-day relative standard deviation (RSD) for tyrindoxyl sulphate was 0.46% and 0.17%, respectively. The quantification was linear for standards murexine, 6-bromoisatin, and tyrindoxyl sulphate. The limits of detection were 0.03, 0.004, and 0.07 mg/mL, respectively, and the limits of quantification were 0.09, 0.01, and 0.22 mg/mL, respectively. The results showed that alcoholic solvents were better for extracting Choline Ester and indoxyl sulphate ultimate precursors, while chloroform was more suitable for the extraction of the intermediate precursors. Multivariate analysis revealed significant differences in extract composition according to the solvent used. Stability testing showed an increase of the oxidative compounds 6-bromoisatin and putative tyrindoxyl S-oxide sulphate in the ethanol extracts while more degradation products were seen in the chloroform extracts after months of cold storage. The validated method was found to be simple, reproducible, precise, and suitable for quantification of the secondary metabolites of muricid molluscs for dye precursor and nutraceutical quality control, as well as applications in marine chemical ecology
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Mass spectrometry imaging reveals new biological roles for Choline Esters and Tyrian purple precursors in muricid molluscs
Scientific Reports, 2015Co-Authors: David Rudd, Maurizio Ronci, Martin R. Johnston, Taryn Guinan, Nicolas H. Voelcker, Kirsten BenkendorffAbstract:Despite significant advances in chemical ecology, the biodistribution, temporal changes and ecological function of most marine secondary metabolites remain unknown. One such example is the association between Choline Esters and Tyrian purple precursors in muricid molluscs. Mass spectrometry imaging (MSI) on nano-structured surfaces has emerged as a sophisticated platform for spatial analysis of low molecular mass metabolites in heterogeneous tissues, ideal for low abundant secondary metabolites. Here we applied desorption-ionisation on porous silicon (DIOS) to examine in situ changes in biodistribution over the reproductive cycle. DIOS-MSI showed muscle-relaxing Choline Ester murexine to co-localise with tyrindoxyl sulfate in the biosynthetic hypobranchial glands. But during egg-laying, murexine was transferred to the capsule gland and then to the egg capsules, where chemical ripening resulted in Tyrian purple formation. Murexine was found to tranquilise the larvae and may relax the reproductive tract. This study shows that DIOS-MSI is a powerful tool that can provide new insights into marine chemo-ecology.
Eliahu Heldman - One of the best experts on this subject based on the ideXlab platform.
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site directed decapsulation of bolaamphiphilic vesicles with enzymatic cleavable surface groups
Journal of Controlled Release, 2012Co-Authors: Mary Popov, Sarina Grinberg, Charles Linder, Richard J. Deckelbaum, Tal Waner, Bosmat Levihevroni, Eliahu HeldmanAbstract:Stable nano-sized vesicles with a monolayer encapsulating membrane were prepared from novel bolaamphiphiles with Choline Ester head groups. The head groups were covalently bound to the alkyl chain of the bolaamphiphiles either via the nitrogen atom of the Choline moiety, or via the Choline Ester's methyl group. Both types of bolaamphiphiles competed with acetylthioCholine for binding to acetylCholine Esterase (AChE), yet, only the Choline Ester head groups bound to the alkyl chain via the nitrogen atom of the Choline moiety were hydrolyzed by the enzyme. Likewise, only vesicles composed of bolaamphiphiles with head groups that were hydrolyzed by AChE released their encapsulated material upon exposure to the enzyme. Injection of carboxyfluorescein (CF)-loaded vesicles with cleavable Choline Ester head groups into mice resulted in the accumulation of CF in tissues that express high AChE activity, including the brain. By comparison, when vesicles with Choline Ester head groups that are not hydrolyzed by AChE were injected into mice, there was no accumulation of CF in tissues that highly express the enzyme. These results imply that bolaamphiphilic vesicles with surface groups that are substrates to enzymes which are highly expressed in target organs may potentially be used as a drug delivery system with controlled site-directed drug release.
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Synthesis of novel cationic bolaamphiphiles from vernonia oil and their aggregated structures.
Chemistry and physics of lipids, 2008Co-Authors: Sarina Grinberg, Charles Linder, Victoria Kolot, E. Shaubi, V. Kas’yanov, Richard J. Deckelbaum, Eliahu HeldmanAbstract:Abstract The present study describes the synthesis of a novel class of vesicle-forming bolaamphiphiles with Choline Ester head groups. These bolaamphiphiles were derived from vernonia oil, whose main constituent is vernolic acid, a fatty acid with a unique combination of epoxy, carboxy and unsaturated double bonds. A series of bolaamphiphiles containing amido or Ester groups within the hydrophobic domain were synthesized from N,N′-alkylenebis (vernolamides) and α,ω-alkylene divernolate Ester in a two-stage synthesis comprising opening of the epoxy ring with chloroacetic acid, followed by quaternization with N,N-dimethylaminoethyl acetate to form Choline Ester head groups. The products were characterized by FT-IR, 1H and 13C NMR, and ESI-MS. Vesicles prepared from these bolaamphiphiles have the potential to serve as a targeted drug delivery systems with selective decapsulation in the presence of the enzyme acetylCholine Esterase, resulting in site-specific release of the drug.
David Rudd - One of the best experts on this subject based on the ideXlab platform.
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Extraction and Quantification of Bioactive Tyrian Purple Precursors: A Comparative and Validation Study from the Hypobranchial Gland of a Muricid Dicathais orbita
MDPI AG, 2016Co-Authors: Roselyn Valles-regino, David Rudd, Peter Mouatt, Lachlan H. Yee, Kirsten BenkendorffAbstract:Muricidae are marine molluscs known for the production of Tyrian purple and bioactive precursor compounds. A validation study for the extraction and analysis of secondary metabolites found in the hypobranchial gland of the muricid Dicathais orbita is reported, using high performance liquid chromatography–mass spectrometry (HPLC-MS) with diode array detector (DAD). Quantification of the dominant secondary metabolites from D. orbita is described, followed by a comparison of solvent extraction procedures and stability studies. The intra- and inter-day relative standard deviation (RSD) for tyrindoxyl sulphate was 0.46% and 0.17%, respectively. The quantification was linear for standards murexine, 6-bromoisatin, and tyrindoxyl sulphate. The limits of detection were 0.03, 0.004, and 0.07 mg/mL, respectively, and the limits of quantification were 0.09, 0.01, and 0.22 mg/mL, respectively. The results showed that alcoholic solvents were better for extracting Choline Ester and indoxyl sulphate ultimate precursors, while chloroform was more suitable for the extraction of the intermediate precursors. Multivariate analysis revealed significant differences in extract composition according to the solvent used. Stability testing showed an increase of the oxidative compounds 6-bromoisatin and putative tyrindoxyl S-oxide sulphate in the ethanol extracts while more degradation products were seen in the chloroform extracts after months of cold storage. The validated method was found to be simple, reproducible, precise, and suitable for quantification of the secondary metabolites of muricid molluscs for dye precursor and nutraceutical quality control, as well as applications in marine chemical ecology
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Mass spectrometry imaging reveals new biological roles for Choline Esters and Tyrian purple precursors in muricid molluscs
Scientific Reports, 2015Co-Authors: David Rudd, Maurizio Ronci, Martin R. Johnston, Taryn Guinan, Nicolas H. Voelcker, Kirsten BenkendorffAbstract:Despite significant advances in chemical ecology, the biodistribution, temporal changes and ecological function of most marine secondary metabolites remain unknown. One such example is the association between Choline Esters and Tyrian purple precursors in muricid molluscs. Mass spectrometry imaging (MSI) on nano-structured surfaces has emerged as a sophisticated platform for spatial analysis of low molecular mass metabolites in heterogeneous tissues, ideal for low abundant secondary metabolites. Here we applied desorption-ionisation on porous silicon (DIOS) to examine in situ changes in biodistribution over the reproductive cycle. DIOS-MSI showed muscle-relaxing Choline Ester murexine to co-localise with tyrindoxyl sulfate in the biosynthetic hypobranchial glands. But during egg-laying, murexine was transferred to the capsule gland and then to the egg capsules, where chemical ripening resulted in Tyrian purple formation. Murexine was found to tranquilise the larvae and may relax the reproductive tract. This study shows that DIOS-MSI is a powerful tool that can provide new insights into marine chemo-ecology.
Sarina Grinberg - One of the best experts on this subject based on the ideXlab platform.
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site directed decapsulation of bolaamphiphilic vesicles with enzymatic cleavable surface groups
Journal of Controlled Release, 2012Co-Authors: Mary Popov, Sarina Grinberg, Charles Linder, Richard J. Deckelbaum, Tal Waner, Bosmat Levihevroni, Eliahu HeldmanAbstract:Stable nano-sized vesicles with a monolayer encapsulating membrane were prepared from novel bolaamphiphiles with Choline Ester head groups. The head groups were covalently bound to the alkyl chain of the bolaamphiphiles either via the nitrogen atom of the Choline moiety, or via the Choline Ester's methyl group. Both types of bolaamphiphiles competed with acetylthioCholine for binding to acetylCholine Esterase (AChE), yet, only the Choline Ester head groups bound to the alkyl chain via the nitrogen atom of the Choline moiety were hydrolyzed by the enzyme. Likewise, only vesicles composed of bolaamphiphiles with head groups that were hydrolyzed by AChE released their encapsulated material upon exposure to the enzyme. Injection of carboxyfluorescein (CF)-loaded vesicles with cleavable Choline Ester head groups into mice resulted in the accumulation of CF in tissues that express high AChE activity, including the brain. By comparison, when vesicles with Choline Ester head groups that are not hydrolyzed by AChE were injected into mice, there was no accumulation of CF in tissues that highly express the enzyme. These results imply that bolaamphiphilic vesicles with surface groups that are substrates to enzymes which are highly expressed in target organs may potentially be used as a drug delivery system with controlled site-directed drug release.
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Synthesis of novel cationic bolaamphiphiles from vernonia oil and their aggregated structures.
Chemistry and physics of lipids, 2008Co-Authors: Sarina Grinberg, Charles Linder, Victoria Kolot, E. Shaubi, V. Kas’yanov, Richard J. Deckelbaum, Eliahu HeldmanAbstract:Abstract The present study describes the synthesis of a novel class of vesicle-forming bolaamphiphiles with Choline Ester head groups. These bolaamphiphiles were derived from vernonia oil, whose main constituent is vernolic acid, a fatty acid with a unique combination of epoxy, carboxy and unsaturated double bonds. A series of bolaamphiphiles containing amido or Ester groups within the hydrophobic domain were synthesized from N,N′-alkylenebis (vernolamides) and α,ω-alkylene divernolate Ester in a two-stage synthesis comprising opening of the epoxy ring with chloroacetic acid, followed by quaternization with N,N-dimethylaminoethyl acetate to form Choline Ester head groups. The products were characterized by FT-IR, 1H and 13C NMR, and ESI-MS. Vesicles prepared from these bolaamphiphiles have the potential to serve as a targeted drug delivery systems with selective decapsulation in the presence of the enzyme acetylCholine Esterase, resulting in site-specific release of the drug.
Richard J. Deckelbaum - One of the best experts on this subject based on the ideXlab platform.
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site directed decapsulation of bolaamphiphilic vesicles with enzymatic cleavable surface groups
Journal of Controlled Release, 2012Co-Authors: Mary Popov, Sarina Grinberg, Charles Linder, Richard J. Deckelbaum, Tal Waner, Bosmat Levihevroni, Eliahu HeldmanAbstract:Stable nano-sized vesicles with a monolayer encapsulating membrane were prepared from novel bolaamphiphiles with Choline Ester head groups. The head groups were covalently bound to the alkyl chain of the bolaamphiphiles either via the nitrogen atom of the Choline moiety, or via the Choline Ester's methyl group. Both types of bolaamphiphiles competed with acetylthioCholine for binding to acetylCholine Esterase (AChE), yet, only the Choline Ester head groups bound to the alkyl chain via the nitrogen atom of the Choline moiety were hydrolyzed by the enzyme. Likewise, only vesicles composed of bolaamphiphiles with head groups that were hydrolyzed by AChE released their encapsulated material upon exposure to the enzyme. Injection of carboxyfluorescein (CF)-loaded vesicles with cleavable Choline Ester head groups into mice resulted in the accumulation of CF in tissues that express high AChE activity, including the brain. By comparison, when vesicles with Choline Ester head groups that are not hydrolyzed by AChE were injected into mice, there was no accumulation of CF in tissues that highly express the enzyme. These results imply that bolaamphiphilic vesicles with surface groups that are substrates to enzymes which are highly expressed in target organs may potentially be used as a drug delivery system with controlled site-directed drug release.
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Synthesis of novel cationic bolaamphiphiles from vernonia oil and their aggregated structures.
Chemistry and physics of lipids, 2008Co-Authors: Sarina Grinberg, Charles Linder, Victoria Kolot, E. Shaubi, V. Kas’yanov, Richard J. Deckelbaum, Eliahu HeldmanAbstract:Abstract The present study describes the synthesis of a novel class of vesicle-forming bolaamphiphiles with Choline Ester head groups. These bolaamphiphiles were derived from vernonia oil, whose main constituent is vernolic acid, a fatty acid with a unique combination of epoxy, carboxy and unsaturated double bonds. A series of bolaamphiphiles containing amido or Ester groups within the hydrophobic domain were synthesized from N,N′-alkylenebis (vernolamides) and α,ω-alkylene divernolate Ester in a two-stage synthesis comprising opening of the epoxy ring with chloroacetic acid, followed by quaternization with N,N-dimethylaminoethyl acetate to form Choline Ester head groups. The products were characterized by FT-IR, 1H and 13C NMR, and ESI-MS. Vesicles prepared from these bolaamphiphiles have the potential to serve as a targeted drug delivery systems with selective decapsulation in the presence of the enzyme acetylCholine Esterase, resulting in site-specific release of the drug.