Angel Resendez | University of California, Santa Cruz (original) (raw)

Papers by Angel Resendez

Research paper thumbnail of Multi-Well Assay for the Analysis of Sugar Gut Permeability Markers: Discrimination of Sugar Alcohols With a Fluorescent Probe Array Based on Boronic Acid Appended Viologens

Analytical chemistry, Jan 26, 2016

With the aim of discerning between different sugar and sugar alcohols of biomedical relevance, su... more With the aim of discerning between different sugar and sugar alcohols of biomedical relevance, such as gut permeability, arrays of 2-component probes were assembled with up to six boronic acid¬¬-appended viologens (BBVs): 4,4'-o-BBV, 3,3'-o-BBV, 3,4'-o-BBV, 4,4'-o,m-BBV, 4,7'-o-PBBV and pBoB, each coupled to the fluorophore 8-hydroxypyrene, 1,3,6-trisulfonic acid trisodium salt (HPTS). These probes were screened for their ability to discriminate between lactulose, L-rhamnose, 3-O-methyl-D-glucose, and xylose. Binding studies of sugar alcohols mannitol, sorbitol, erythritol, adonitol, arabitol, galactitol, xylitol revealed that diols containing threo-1,2-diol units have higher affinity for BBVs relative diols containing erythro-1,2 units. Those containing both threo-1,2- and 1,3-syn diol motifs showed high affinity for boronic acid binding. Fluorescence from the arrays were examined by principle component analysis (PCA) and linear discriminant analysis (LDA). Arra...

Research paper thumbnail of CHAPTER 5. Boronic Acid Functionalized Viologens as Saccharide Sensors

Monographs in Supramolecular Chemistry, 2015

Research paper thumbnail of ChemInform Abstract: Reaction of InCl 3 with Various Reducing Agents: InCl 3 -NaBH 4 -Mediated Reduction of Aromatic and Aliphatic Nitriles to Primary Amines

ChemInform, 2012

Primary Amines. -Nitriles containing halide moieties undergo tandem reduction giving dehalogenate... more Primary Amines. -Nitriles containing halide moieties undergo tandem reduction giving dehalogenated amines such as (IV). Selective dehalogenation without nitrile reduction can be performed in the presence of InCl3/LiBH3(NMe2) or with InCl3/NaBH4 in MeCN. -(SAAVEDRA, J. Z.; RESENDEZ, A.; ROVIRA, A.; EAGON, S.; HADDENHAM, D.; SINGARAM*, B.; J. Org. Chem. 77 (2012) 1, 221-228, http://dx.

Research paper thumbnail of ChemInform Abstract: Synthesis of Dichloroindium Hydride and Exploration of Its Reactivity with Organic Functional Groups. Tandem, Selective and Partial Reductions of Halo-nitriles

Research paper thumbnail of Indium

Encyclopedia of Reagents for Organic Synthesis, 2001

Research paper thumbnail of Reaction of InCl3 with various reducing agents: InCl3-NaBH4-mediated reduction of aromatic and aliphatic nitriles to primary amines

The Journal of organic chemistry, Jan 6, 2012

While alternative methods of preparing dichloroindium hydride (HInCl(2)) via the in situ reductio... more While alternative methods of preparing dichloroindium hydride (HInCl(2)) via the in situ reduction of InCl(3) using lithium amino borohydride (LAB) were explored, generation of HInCl(2) from the reduction of InCl(3) by sodium borohydride (NaBH(4)) was also re-evaluated for comparison. The reductive capability of the InCl(3)/NaBH(4) system was found to be highly dependent on the solvent used. Investigation by (11)B NMR spectroscopic analyses indicated that the reaction of InCl(3) with NaBH(4) in THF generates HInCl(2) along with borane-tetrahydrofuran (BH(3)·THF) in situ. Nitriles underwent reduction to primary amines under optimized conditions at 25 °C using 1 equiv of anhydrous InCl(3) with 3 equiv of NaBH(4) in THF. A variety of aromatic, heteroaromatic, and aliphatic nitriles were reduced to their corresponding primary amine in 70-99% isolated yields. Alkyl halide and nitrile functional groups were reduced in tandem by utilizing the reductive capabilities of both HInCl(2) and BH(...

Research paper thumbnail of Construction of a Biomimetic Peroxynitrite-Generating Platform: A Two-Component System to Synthesize Peroxynitrite in Situ under the Control of Light

ChemBioChem, 2013

Surge protector: a two-component peroxynitrite-generating platform has been engineered to release... more Surge protector: a two-component peroxynitrite-generating platform has been engineered to release peroxynitrite (PN) in situ under the control of light. The system, which is constructed by layering sol-gel matrices containing xanthine oxidase (bottom layer) and a metal nitrosyl (top layer), allows studies of PN chemistry at varying fluxes of its precursors.

Research paper thumbnail of Rapid small intestinal permeability assay based on riboflavin and lactulose detected by bis-boronic acid appended benzyl viologens

Background: Although organoboronic acids are efficient high-throughput sugar sensors, they have n... more Background: Although organoboronic acids are efficient high-throughput sugar sensors, they have not been pursued for gut permeability studies. A modification of the lactulose/mannitol assay is described by which small intestinal permeability is assessed at the time of urine collection using a lactulose/riboflavin ratio. Methods: Volunteers ingested 50 mg riboflavin and either 5 g mannitol or 10 g lactulose. Urine was collected for 6 hrs. Riboflavin was assayed by autofluorescence. Riboflavin was removed by C18 solid phase extraction. Lactulose and mannitol were then assayed using 1,1'-bis(2-boronobenzyl)-4,4'-bipyridinium (4,4'oBBV) coupled to the fluorophore HPTS. Results: The temporal profile over 6 hrs for riboflavin paralleled mannitol. Riboflavin recovery in urine was 11.1 ± 1.9 % (mean ± SEM, n = 7), similar to mannitol. There was selective binding of 4,4'oBBV to lactulose, likely involving cooperativity between the fructose and galactose moieties. Lower limits of detection and quan-tification were 90 and 364 μM. The lactulose assay was insensitive to other permeability probes (e.g., sucrose, sucralose) while tolerating glucose or lactose. This assay can be adapted to automated systems. Stability of 4,4'oBBV exceeds 4 years. Conclusions: Riboflavin measured by autofluorescence combined with lactulose measured with 4,4'oBBV represents a useful new chemistry for rapid measurement of intestinal permeability with excellent stability, cost and throughput benefits.

Research paper thumbnail of Rapid small intestinal permeability assay based on riboflavin and lactulose detected by bis-boronic acid appended benzyl viologens.

background: Although organoboronic acids are efficient high-throughput sugar sensors, they have n... more background: Although organoboronic acids are efficient high-throughput sugar sensors, they have not been pursued for gut permeability studies. A modification of the lactulose/mannitol assay is described by which small intestinal permeability is assessed at the time of urine collection using a lactulose/riboflavin ratio.
METHODS:
Volunteers ingested 50mg riboflavin and either 5g mannitol or 10g lactulose. Urine was collected for 6hrs. Riboflavin was assayed by autofluorescence. Riboflavin was removed by C18 solid phase extraction. Lactulose and mannitol were then assayed using 1,1'-bis(2-boronobenzyl)-4,4'-bipyridinium (4,4'oBBV) coupled to the fluorophore HPTS.
RESULTS:
The temporal profile over 6hrs for riboflavin paralleled mannitol. Riboflavin recovery in urine was 11.1±1.9 % (mean±SEM, n=7), similar to mannitol. There was selective binding of 4,4'oBBV to lactulose, likely involving cooperativity between the fructose and galactose moieties. Lower limits of detection and quantification were 90 and 364μM. The lactulose assay was insensitive to other permeability probes (e.g., sucrose, sucralose) while tolerating glucose or lactose. This assay can be adapted to automated systems. Stability of 4,4'oBBV exceeds 4years.
CONCLUSIONS:
Riboflavin measured by autofluorescence combined with lactulose measured with 4,4'oBBV represents a useful new chemistry for rapid measurement of intestinal permeability with excellent stability, cost and throughput benefits.

Research paper thumbnail of Multi-Well Assay for the Analysis of Sugar Gut Permeability Markers: Discrimination of Sugar Alcohols With a Fluorescent Probe Array Based on Boronic Acid Appended Viologens

Analytical chemistry, Jan 26, 2016

With the aim of discerning between different sugar and sugar alcohols of biomedical relevance, su... more With the aim of discerning between different sugar and sugar alcohols of biomedical relevance, such as gut permeability, arrays of 2-component probes were assembled with up to six boronic acid¬¬-appended viologens (BBVs): 4,4'-o-BBV, 3,3'-o-BBV, 3,4'-o-BBV, 4,4'-o,m-BBV, 4,7'-o-PBBV and pBoB, each coupled to the fluorophore 8-hydroxypyrene, 1,3,6-trisulfonic acid trisodium salt (HPTS). These probes were screened for their ability to discriminate between lactulose, L-rhamnose, 3-O-methyl-D-glucose, and xylose. Binding studies of sugar alcohols mannitol, sorbitol, erythritol, adonitol, arabitol, galactitol, xylitol revealed that diols containing threo-1,2-diol units have higher affinity for BBVs relative diols containing erythro-1,2 units. Those containing both threo-1,2- and 1,3-syn diol motifs showed high affinity for boronic acid binding. Fluorescence from the arrays were examined by principle component analysis (PCA) and linear discriminant analysis (LDA). Arra...

Research paper thumbnail of CHAPTER 5. Boronic Acid Functionalized Viologens as Saccharide Sensors

Monographs in Supramolecular Chemistry, 2015

Research paper thumbnail of ChemInform Abstract: Reaction of InCl 3 with Various Reducing Agents: InCl 3 -NaBH 4 -Mediated Reduction of Aromatic and Aliphatic Nitriles to Primary Amines

ChemInform, 2012

Primary Amines. -Nitriles containing halide moieties undergo tandem reduction giving dehalogenate... more Primary Amines. -Nitriles containing halide moieties undergo tandem reduction giving dehalogenated amines such as (IV). Selective dehalogenation without nitrile reduction can be performed in the presence of InCl3/LiBH3(NMe2) or with InCl3/NaBH4 in MeCN. -(SAAVEDRA, J. Z.; RESENDEZ, A.; ROVIRA, A.; EAGON, S.; HADDENHAM, D.; SINGARAM*, B.; J. Org. Chem. 77 (2012) 1, 221-228, http://dx.

Research paper thumbnail of ChemInform Abstract: Synthesis of Dichloroindium Hydride and Exploration of Its Reactivity with Organic Functional Groups. Tandem, Selective and Partial Reductions of Halo-nitriles

Research paper thumbnail of Indium

Encyclopedia of Reagents for Organic Synthesis, 2001

Research paper thumbnail of Reaction of InCl3 with various reducing agents: InCl3-NaBH4-mediated reduction of aromatic and aliphatic nitriles to primary amines

The Journal of organic chemistry, Jan 6, 2012

While alternative methods of preparing dichloroindium hydride (HInCl(2)) via the in situ reductio... more While alternative methods of preparing dichloroindium hydride (HInCl(2)) via the in situ reduction of InCl(3) using lithium amino borohydride (LAB) were explored, generation of HInCl(2) from the reduction of InCl(3) by sodium borohydride (NaBH(4)) was also re-evaluated for comparison. The reductive capability of the InCl(3)/NaBH(4) system was found to be highly dependent on the solvent used. Investigation by (11)B NMR spectroscopic analyses indicated that the reaction of InCl(3) with NaBH(4) in THF generates HInCl(2) along with borane-tetrahydrofuran (BH(3)·THF) in situ. Nitriles underwent reduction to primary amines under optimized conditions at 25 °C using 1 equiv of anhydrous InCl(3) with 3 equiv of NaBH(4) in THF. A variety of aromatic, heteroaromatic, and aliphatic nitriles were reduced to their corresponding primary amine in 70-99% isolated yields. Alkyl halide and nitrile functional groups were reduced in tandem by utilizing the reductive capabilities of both HInCl(2) and BH(...

Research paper thumbnail of Construction of a Biomimetic Peroxynitrite-Generating Platform: A Two-Component System to Synthesize Peroxynitrite in Situ under the Control of Light

ChemBioChem, 2013

Surge protector: a two-component peroxynitrite-generating platform has been engineered to release... more Surge protector: a two-component peroxynitrite-generating platform has been engineered to release peroxynitrite (PN) in situ under the control of light. The system, which is constructed by layering sol-gel matrices containing xanthine oxidase (bottom layer) and a metal nitrosyl (top layer), allows studies of PN chemistry at varying fluxes of its precursors.

Research paper thumbnail of Rapid small intestinal permeability assay based on riboflavin and lactulose detected by bis-boronic acid appended benzyl viologens

Background: Although organoboronic acids are efficient high-throughput sugar sensors, they have n... more Background: Although organoboronic acids are efficient high-throughput sugar sensors, they have not been pursued for gut permeability studies. A modification of the lactulose/mannitol assay is described by which small intestinal permeability is assessed at the time of urine collection using a lactulose/riboflavin ratio. Methods: Volunteers ingested 50 mg riboflavin and either 5 g mannitol or 10 g lactulose. Urine was collected for 6 hrs. Riboflavin was assayed by autofluorescence. Riboflavin was removed by C18 solid phase extraction. Lactulose and mannitol were then assayed using 1,1'-bis(2-boronobenzyl)-4,4'-bipyridinium (4,4'oBBV) coupled to the fluorophore HPTS. Results: The temporal profile over 6 hrs for riboflavin paralleled mannitol. Riboflavin recovery in urine was 11.1 ± 1.9 % (mean ± SEM, n = 7), similar to mannitol. There was selective binding of 4,4'oBBV to lactulose, likely involving cooperativity between the fructose and galactose moieties. Lower limits of detection and quan-tification were 90 and 364 μM. The lactulose assay was insensitive to other permeability probes (e.g., sucrose, sucralose) while tolerating glucose or lactose. This assay can be adapted to automated systems. Stability of 4,4'oBBV exceeds 4 years. Conclusions: Riboflavin measured by autofluorescence combined with lactulose measured with 4,4'oBBV represents a useful new chemistry for rapid measurement of intestinal permeability with excellent stability, cost and throughput benefits.

Research paper thumbnail of Rapid small intestinal permeability assay based on riboflavin and lactulose detected by bis-boronic acid appended benzyl viologens.

background: Although organoboronic acids are efficient high-throughput sugar sensors, they have n... more background: Although organoboronic acids are efficient high-throughput sugar sensors, they have not been pursued for gut permeability studies. A modification of the lactulose/mannitol assay is described by which small intestinal permeability is assessed at the time of urine collection using a lactulose/riboflavin ratio.
METHODS:
Volunteers ingested 50mg riboflavin and either 5g mannitol or 10g lactulose. Urine was collected for 6hrs. Riboflavin was assayed by autofluorescence. Riboflavin was removed by C18 solid phase extraction. Lactulose and mannitol were then assayed using 1,1'-bis(2-boronobenzyl)-4,4'-bipyridinium (4,4'oBBV) coupled to the fluorophore HPTS.
RESULTS:
The temporal profile over 6hrs for riboflavin paralleled mannitol. Riboflavin recovery in urine was 11.1±1.9 % (mean±SEM, n=7), similar to mannitol. There was selective binding of 4,4'oBBV to lactulose, likely involving cooperativity between the fructose and galactose moieties. Lower limits of detection and quantification were 90 and 364μM. The lactulose assay was insensitive to other permeability probes (e.g., sucrose, sucralose) while tolerating glucose or lactose. This assay can be adapted to automated systems. Stability of 4,4'oBBV exceeds 4years.
CONCLUSIONS:
Riboflavin measured by autofluorescence combined with lactulose measured with 4,4'oBBV represents a useful new chemistry for rapid measurement of intestinal permeability with excellent stability, cost and throughput benefits.