The Experts below are selected from a list of 66 Experts worldwide ranked by ideXlab platform
Katherine Frato - One of the best experts on this subject based on the ideXlab platform.
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Identification of Hydroxypyrazine O-Methyltransferase Genes in Coffea arabica: A Potential Source of Methoxypyrazines That Cause Potato Taste Defect.
Journal of agricultural and food chemistry, 2018Co-Authors: Katherine FratoAbstract:The goal of this study is to identify Coffea arabica O-methyltransferase (OMT) genes involved in the biosynthesis of methoxypyrazines. High levels of 2-isopropyl-3-methoxypyrazine (IPMP) and 2-isobutyl-3-methoxypyrazine (IBMP) in coffee beans are associated with the potato taste defect (PTD). Among the 34 putative O-methyltransferase genes identified in the published genome of C. canephora, three genes are highly homologous to known Hydroxypyrazine OMT genes. Genes of interest were amplified and sequenced from genomic DNA of single C. arabica beans grown in eight different locations, including regions with endemic PTD. Although C. arabica OMT target sequences were almost identical regardless of source location, individual beans shared numerous polymorphisms in each of the target genes. Two of the predicted C. arabica OMT enzymes were successfully expressed in Escherichia coli and purified, and one enzyme shows slow yet measurable turnover of both 3-isobutyl-2-Hydroxypyrazine (IBHP) and 3-isopropyl-2- Hydroxypyrazine (IPHP), supporting a possible role of the coffee plant in PTD.
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Identification of Hydroxypyrazine O‑Methyltransferase Genes in Coffea arabica: A Potential Source of Methoxypyrazines That Cause Potato Taste Defect
2018Co-Authors: Katherine FratoAbstract:The goal of this study is to identify Coffea arabica O-methyltransferase (OMT) genes involved in the biosynthesis of methoxypyrazines. High levels of 2-isopropyl-3-methoxypyrazine (IPMP) and 2-isobutyl-3-methoxypyrazine (IBMP) in coffee beans are associated with the potato taste defect (PTD). Among the 34 putative O-methyltransferase genes identified in the published genome of C. canephora, three genes are highly homologous to known Hydroxypyrazine OMT genes. Genes of interest were amplified and sequenced from genomic DNA of single C. arabica beans grown in eight different locations, including regions with endemic PTD. Although C. arabica OMT target sequences were almost identical regardless of source location, individual beans shared numerous polymorphisms in each of the target genes. Two of the predicted C. arabica OMT enzymes were successfully expressed in Escherichia coli and purified, and one enzyme shows slow yet measurable turnover of both 3-isobutyl-2-Hydroxypyrazine (IBHP) and 3-isopropyl-2- Hydroxypyrazine (IPHP), supporting a possible role of the coffee plant in PTD
Gavin L. Sacks - One of the best experts on this subject based on the ideXlab platform.
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behavior of 3 isobutyl 2 Hydroxypyrazine ibhp a key intermediate in 3 isobutyl 2 methoxypyrazine ibmp metabolism in ripening wine grapes
Journal of Agricultural and Food Chemistry, 2012Co-Authors: Sarah A Harris, Imelda Ryona, Gavin L. SacksAbstract:3-Isobutyl-2-Hydroxypyrazine (IBHP) is thought to be a key intermediate in both the biosynthesis and degradation of the herbaceous smelling 3-isobutyl-2-methoxypyrazine (IBMP), but its behavior during the growing season is not well understood. First, an improved method for IBHP quantification was developed. A deuterated IBHP standard was added to samples prior to isolation by mixed-mode cation exchange solid phase extraction. Extracts were silylated prior to quantification by GC-MS. A limit of detection of ca. 20 ng/L could be achieved for a 100 mL juice sample. This method was used to quantify IBHP during the 2010 growing season in berries of two clones of Cabernet franc in the Finger Lakes region of New York and of Merlot grown in the California Central Valley. For all three sources, IBHP was detectable at the earliest sampling point, and its concentration per berry increased to a maximum around veraison, 208–477 pg/berry. On a per berry basis, IBHP peaked and began to decline 1–2 weeks after IBMP, indi...
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Correlation of 3-isobutyl-2-methoxypyrazine to 3-isobutyl-2-Hydroxypyrazine during maturation of bell pepper (Capsicum annuum) and wine grapes (Vitis vinifera).
Journal of agricultural and food chemistry, 2010Co-Authors: Imelda Ryona, Sophie Leclerc, Gavin L. SacksAbstract:Environmental factors affecting degradation of 3-isobutyl-2-methoxypyrazine (IBMP, “green pepper aroma”) in wine grapes (V. vinifera) are widely studied, but the degradation pathway is not defined. We hypothesized that IBMP is demethylated to 3-isobutyl-2-Hydroxypyrazine (IBHP) during fruit maturation effectively reversing the final putative step of IBMP biosynthesis. A quantification method for IBHP was developed using solid-phase extraction coupled to one- or two-dimensional gas chromatography−mass spectrometry with a recovery of ca. 80%. IBMP and IBHP in bell peppers (Capsicum annuum) and V. vinifera (cv. ‘Cabernet Franc’, ‘Riesling’, ‘Pinot noir’) were then measured at different maturities. IBMP and IBHP were inversely correlated in both bell peppers (R2 = 0.958) and Cabernet Franc grapes (R2 = 0.998) over a range of maturities. In bell peppers, we observed a significant decline in IBMP (125 to 15 ng/mL) and increase in IBHP (undetectable to 42 ng/mL) during ripening. In grapes, all cultivars had comp...
Rolf E Swenso - One of the best experts on this subject based on the ideXlab platform.
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synthesis of 18 f favipiravir and biodistribution in c3h hen mice as assessed by positron emission tomography
Scientific Reports, 2019Co-Authors: Toscano Montes De Oca J, Falguni Asuli, Robe G Stafford, Alle J Duplantie, Xiang Zhang, Rolf E SwensoAbstract:Favipiravir (T705; 6-fluoro-3-Hydroxypyrazine-2-carboxamide) is a pyrazine analog that has demonstrated potent antiviral activity against a broad spectrum of viruses in multiple in vivo disease models. To better understand the compounds anti-viral activity, assessment of the drug’s biodistribution and kinetics in vivo may lend insight into how best to evaluate the compound efficacy preclinically and to contribute to the design of clinical studies to take into account the compound’s pharmacokinetic distribution and kinetics. In the current study, a method for synthesis of [18F]favipiravir was developed and the biodistribution in mice naive to and pre-dosed with favipiravir was assessed by PET and gamma counting of tissue samples. Fluorine-18 labeling of favipiravir was achieved in a one-pot, two-step synthesis using a commercially available precursor, methyl-5-chloroisoxazolo[4,5-b]pyrazine-3-carboxylate, with an overall radiochemical yield of 15–24%, a molar activity of 37–74 GBq/µmol in a 70 minute synthesis time. [18F]favipiravir tissue uptake and distribution was similar in naive and pre-dosed mice; however, in the pre-dosed animals plasma clearance was more rapid and tissue clearance appeared to be prolonged. In conclusion, application of PET to the evaluation of favipiravir has demonstrated the importance of dosing regimen on the distribution and tissue uptake and clearance of the molecule. Favipiravir is cleared through the kidney as previously reported but the liver and intestinal excretion may also play an important role in compound elimination. Measurement of the tissue uptake of favipiravir as determined by PET may be a more important indicator of a compound’s potential efficacy than purely monitoring plasma parameters such as viremia and drug levels.
Toscano Montes De Oca J - One of the best experts on this subject based on the ideXlab platform.
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synthesis of 18 f favipiravir and biodistribution in c3h hen mice as assessed by positron emission tomography
Scientific Reports, 2019Co-Authors: Toscano Montes De Oca J, Falguni Asuli, Robe G Stafford, Alle J Duplantie, Xiang Zhang, Rolf E SwensoAbstract:Favipiravir (T705; 6-fluoro-3-Hydroxypyrazine-2-carboxamide) is a pyrazine analog that has demonstrated potent antiviral activity against a broad spectrum of viruses in multiple in vivo disease models. To better understand the compounds anti-viral activity, assessment of the drug’s biodistribution and kinetics in vivo may lend insight into how best to evaluate the compound efficacy preclinically and to contribute to the design of clinical studies to take into account the compound’s pharmacokinetic distribution and kinetics. In the current study, a method for synthesis of [18F]favipiravir was developed and the biodistribution in mice naive to and pre-dosed with favipiravir was assessed by PET and gamma counting of tissue samples. Fluorine-18 labeling of favipiravir was achieved in a one-pot, two-step synthesis using a commercially available precursor, methyl-5-chloroisoxazolo[4,5-b]pyrazine-3-carboxylate, with an overall radiochemical yield of 15–24%, a molar activity of 37–74 GBq/µmol in a 70 minute synthesis time. [18F]favipiravir tissue uptake and distribution was similar in naive and pre-dosed mice; however, in the pre-dosed animals plasma clearance was more rapid and tissue clearance appeared to be prolonged. In conclusion, application of PET to the evaluation of favipiravir has demonstrated the importance of dosing regimen on the distribution and tissue uptake and clearance of the molecule. Favipiravir is cleared through the kidney as previously reported but the liver and intestinal excretion may also play an important role in compound elimination. Measurement of the tissue uptake of favipiravir as determined by PET may be a more important indicator of a compound’s potential efficacy than purely monitoring plasma parameters such as viremia and drug levels.
Imelda Ryona - One of the best experts on this subject based on the ideXlab platform.
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behavior of 3 isobutyl 2 Hydroxypyrazine ibhp a key intermediate in 3 isobutyl 2 methoxypyrazine ibmp metabolism in ripening wine grapes
Journal of Agricultural and Food Chemistry, 2012Co-Authors: Sarah A Harris, Imelda Ryona, Gavin L. SacksAbstract:3-Isobutyl-2-Hydroxypyrazine (IBHP) is thought to be a key intermediate in both the biosynthesis and degradation of the herbaceous smelling 3-isobutyl-2-methoxypyrazine (IBMP), but its behavior during the growing season is not well understood. First, an improved method for IBHP quantification was developed. A deuterated IBHP standard was added to samples prior to isolation by mixed-mode cation exchange solid phase extraction. Extracts were silylated prior to quantification by GC-MS. A limit of detection of ca. 20 ng/L could be achieved for a 100 mL juice sample. This method was used to quantify IBHP during the 2010 growing season in berries of two clones of Cabernet franc in the Finger Lakes region of New York and of Merlot grown in the California Central Valley. For all three sources, IBHP was detectable at the earliest sampling point, and its concentration per berry increased to a maximum around veraison, 208–477 pg/berry. On a per berry basis, IBHP peaked and began to decline 1–2 weeks after IBMP, indi...
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Correlation of 3-isobutyl-2-methoxypyrazine to 3-isobutyl-2-Hydroxypyrazine during maturation of bell pepper (Capsicum annuum) and wine grapes (Vitis vinifera).
Journal of agricultural and food chemistry, 2010Co-Authors: Imelda Ryona, Sophie Leclerc, Gavin L. SacksAbstract:Environmental factors affecting degradation of 3-isobutyl-2-methoxypyrazine (IBMP, “green pepper aroma”) in wine grapes (V. vinifera) are widely studied, but the degradation pathway is not defined. We hypothesized that IBMP is demethylated to 3-isobutyl-2-Hydroxypyrazine (IBHP) during fruit maturation effectively reversing the final putative step of IBMP biosynthesis. A quantification method for IBHP was developed using solid-phase extraction coupled to one- or two-dimensional gas chromatography−mass spectrometry with a recovery of ca. 80%. IBMP and IBHP in bell peppers (Capsicum annuum) and V. vinifera (cv. ‘Cabernet Franc’, ‘Riesling’, ‘Pinot noir’) were then measured at different maturities. IBMP and IBHP were inversely correlated in both bell peppers (R2 = 0.958) and Cabernet Franc grapes (R2 = 0.998) over a range of maturities. In bell peppers, we observed a significant decline in IBMP (125 to 15 ng/mL) and increase in IBHP (undetectable to 42 ng/mL) during ripening. In grapes, all cultivars had comp...
