The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Tsutomu Nakayama - One of the best experts on this subject based on the ideXlab platform.
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efficient synthesis of theaflavin 3 Gallate by a tyrosinase catalyzed reaction with epicatechin and Epigallocatechin Gallate in a 1 octanol buffer biphasic system
Journal of Agricultural and Food Chemistry, 2018Co-Authors: Asako Naraikanayama, Yoshinori Uekusa, Fumiyuki Kiuchi, Tsutomu NakayamaAbstract:Theaflavins, the orange-red pigments contained in black tea, have attracted attention as a result of their health-promoting effects. However, their synthetic preparation, in which the enzymatic oxidation of catechol-type catechin is followed by the quinone-induced oxidative dimerization of selectively combined catechol- and pyrogallol-type catechins, provides only a low yield. In the present study, we found that a 1-octanol/buffer biphasic system improved the yield of theaflavin 3-Gallate in a tyrosinase-catalyzed synthetic reaction with (-)-epicatechin and (-)-Epigallocatechin Gallate. When the enzymatic reaction proceeded in a buffer solution, oxidized (-)-Epigallocatechin Gallate was preferentially used for self-dimerization. However, self-dimerization was suppressed in the octanol phase, allowing oxidized (-)-Epigallocatechin Gallate to participate in coupling with (-)-epicatechin quinone, leading to effective production of theaflavin 3-Gallate. Furthermore, the preferential localization of theaflavin 3-Gallate in the octanol phase prevented (-)-epicatechin-quinone-induced degradation.
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Efficient Synthesis of Theaflavin 3‑Gallate by a Tyrosinase-Catalyzed Reaction with (−)-Epicatechin and (−)-Epigallocatechin Gallate in a 1‑Octanol/Buffer Biphasic System
2018Co-Authors: Asako Narai-kanayama, Yoshinori Uekusa, Fumiyuki Kiuchi, Tsutomu NakayamaAbstract:Theaflavins, the orange–red pigments contained in black tea, have attracted attention as a result of their health-promoting effects. However, their synthetic preparation, in which the enzymatic oxidation of catechol-type catechin is followed by the quinone-induced oxidative dimerization of selectively combined catechol- and pyrogallol-type catechins, provides only a low yield. In the present study, we found that a 1-octanol/buffer biphasic system improved the yield of theaflavin 3-Gallate in a tyrosinase-catalyzed synthetic reaction with (−)-epicatechin and (−)-Epigallocatechin Gallate. When the enzymatic reaction proceeded in a buffer solution, oxidized (−)-Epigallocatechin Gallate was preferentially used for self-dimerization. However, self-dimerization was suppressed in the octanol phase, allowing oxidized (−)-Epigallocatechin Gallate to participate in coupling with (−)-epicatechin quinone, leading to effective production of theaflavin 3-Gallate. Furthermore, the preferential localization of theaflavin 3-Gallate in the octanol phase prevented (−)-epicatechin-quinone-induced degradation
Johannes Levin - One of the best experts on this subject based on the ideXlab platform.
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safety and efficacy of Epigallocatechin Gallate in multiple system atrophy promesa a randomised double blind placebo controlled trial
Lancet Neurology, 2019Co-Authors: Johannes Levin, Sylvia Maas, Madeleine Schuberth, Armin Giese, Claudia Trenkwalder, Wolfgang H Oertel, Gregor K WenningAbstract:Summary Background Multiple system atrophy is a rare neurodegenerative disease characterised by aggregation of α-synuclein in oligodendrocytes and neurons. The polyphenol Epigallocatechin Gallate inhibits α-synuclein aggregation and reduces associated toxicity. We aimed to establish if Epigallocatechin Gallate could safely slow disease progression in patients with multiple system atrophy. Methods We did a randomised, double-blind, parallel group, placebo-controlled clinical trial at 12 specialist centres in Germany. Eligible participants were older than 30 years; met consensus criteria for possible or probable multiple system atrophy and could ambulate independently (ie, were at Hoehn and Yahr stages 1–3); and were on stable anti-Parkinson's, anti-dysautonomia, anti-dementia, and anti-depressant regimens (if necessary) for at least 1 month. Participants were randomly assigned (1:1) to Epigallocatechin Gallate or placebo (mannitol) via a web-generated permuted blockwise randomisation list (block size=2) that was stratified by disease subtype (parkinsonism-predominant disease vs cerebellar-ataxia-predominant disease). All participants and study personnel were masked to treatment assignment. Participants were given one hard gelatin capsule (containing either 400 mg Epigallocatechin Gallate or mannitol) orally once daily for 4 weeks, then one capsule twice daily for 4 weeks, and then one capsule three times daily for 40 weeks. After 48 weeks, all patients underwent a 4-week wash-out period. The primary endpoint was change in motor examination score of the Unified Multiple System Atrophy Rating Scale (UMSARS) from baseline to 52 weeks. Efficacy analyses were done in all people who received at least one dose of study medication. Safety was analysed in all people who received at least one dose of the study medication to which they had been randomly assigned. This trial is registered with ClinicalTrials.gov ( NCT02008721 ) and EudraCT (2012-000928-18), and is completed. Findings Between April 23, 2014, and Sept 3, 2015, 127 participants were screened and 92 were randomly assigned—47 to Epigallocatechin Gallate and 45 to placebo. Of these, 67 completed treatment and 64 completed the study (altough one of these patients had a major protocol violation). There was no evidence of a difference in the mean change from baseline to week 52 in motor examination scores on UMSARS between the Epigallocatechin Gallate (5·66 [SE 1·01]) and placebo (6·60 [0·99]) groups (mean difference −0·94 [SE 1·41; 95% CI −3·71 to 1·83]; p=0·51). Four patients in the Epigallocatechin Gallate group and two in the placebo group died. Two patients in the Epigallocatechin Gallate group had to stop treatment because of hepatotoxicity. Interpretation 48 weeks of Epigallocatechin Gallate treatment did not modify disease progression in patients with multiple system atrophy. Epigallocatechin Gallate was overall well tolerated but was associated with hepatotoxic effects in some patients, and thus doses of more than 1200 mg should not be used. Funding ParkinsonFonds Deutschland, German Parkinson Society, German Neurology Foundation, Luneburg Foundation, Bischof Dr Karl Golser Foundation, and Dr Arthur Arnstein Foundation.
Gregor K Wenning - One of the best experts on this subject based on the ideXlab platform.
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safety and efficacy of Epigallocatechin Gallate in multiple system atrophy promesa a randomised double blind placebo controlled trial
Lancet Neurology, 2019Co-Authors: Johannes Levin, Sylvia Maas, Madeleine Schuberth, Armin Giese, Claudia Trenkwalder, Wolfgang H Oertel, Gregor K WenningAbstract:Summary Background Multiple system atrophy is a rare neurodegenerative disease characterised by aggregation of α-synuclein in oligodendrocytes and neurons. The polyphenol Epigallocatechin Gallate inhibits α-synuclein aggregation and reduces associated toxicity. We aimed to establish if Epigallocatechin Gallate could safely slow disease progression in patients with multiple system atrophy. Methods We did a randomised, double-blind, parallel group, placebo-controlled clinical trial at 12 specialist centres in Germany. Eligible participants were older than 30 years; met consensus criteria for possible or probable multiple system atrophy and could ambulate independently (ie, were at Hoehn and Yahr stages 1–3); and were on stable anti-Parkinson's, anti-dysautonomia, anti-dementia, and anti-depressant regimens (if necessary) for at least 1 month. Participants were randomly assigned (1:1) to Epigallocatechin Gallate or placebo (mannitol) via a web-generated permuted blockwise randomisation list (block size=2) that was stratified by disease subtype (parkinsonism-predominant disease vs cerebellar-ataxia-predominant disease). All participants and study personnel were masked to treatment assignment. Participants were given one hard gelatin capsule (containing either 400 mg Epigallocatechin Gallate or mannitol) orally once daily for 4 weeks, then one capsule twice daily for 4 weeks, and then one capsule three times daily for 40 weeks. After 48 weeks, all patients underwent a 4-week wash-out period. The primary endpoint was change in motor examination score of the Unified Multiple System Atrophy Rating Scale (UMSARS) from baseline to 52 weeks. Efficacy analyses were done in all people who received at least one dose of study medication. Safety was analysed in all people who received at least one dose of the study medication to which they had been randomly assigned. This trial is registered with ClinicalTrials.gov ( NCT02008721 ) and EudraCT (2012-000928-18), and is completed. Findings Between April 23, 2014, and Sept 3, 2015, 127 participants were screened and 92 were randomly assigned—47 to Epigallocatechin Gallate and 45 to placebo. Of these, 67 completed treatment and 64 completed the study (altough one of these patients had a major protocol violation). There was no evidence of a difference in the mean change from baseline to week 52 in motor examination scores on UMSARS between the Epigallocatechin Gallate (5·66 [SE 1·01]) and placebo (6·60 [0·99]) groups (mean difference −0·94 [SE 1·41; 95% CI −3·71 to 1·83]; p=0·51). Four patients in the Epigallocatechin Gallate group and two in the placebo group died. Two patients in the Epigallocatechin Gallate group had to stop treatment because of hepatotoxicity. Interpretation 48 weeks of Epigallocatechin Gallate treatment did not modify disease progression in patients with multiple system atrophy. Epigallocatechin Gallate was overall well tolerated but was associated with hepatotoxic effects in some patients, and thus doses of more than 1200 mg should not be used. Funding ParkinsonFonds Deutschland, German Parkinson Society, German Neurology Foundation, Luneburg Foundation, Bischof Dr Karl Golser Foundation, and Dr Arthur Arnstein Foundation.
Sylvia Maas - One of the best experts on this subject based on the ideXlab platform.
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safety and efficacy of Epigallocatechin Gallate in multiple system atrophy promesa a randomised double blind placebo controlled trial
Lancet Neurology, 2019Co-Authors: Johannes Levin, Sylvia Maas, Madeleine Schuberth, Armin Giese, Claudia Trenkwalder, Wolfgang H Oertel, Gregor K WenningAbstract:Summary Background Multiple system atrophy is a rare neurodegenerative disease characterised by aggregation of α-synuclein in oligodendrocytes and neurons. The polyphenol Epigallocatechin Gallate inhibits α-synuclein aggregation and reduces associated toxicity. We aimed to establish if Epigallocatechin Gallate could safely slow disease progression in patients with multiple system atrophy. Methods We did a randomised, double-blind, parallel group, placebo-controlled clinical trial at 12 specialist centres in Germany. Eligible participants were older than 30 years; met consensus criteria for possible or probable multiple system atrophy and could ambulate independently (ie, were at Hoehn and Yahr stages 1–3); and were on stable anti-Parkinson's, anti-dysautonomia, anti-dementia, and anti-depressant regimens (if necessary) for at least 1 month. Participants were randomly assigned (1:1) to Epigallocatechin Gallate or placebo (mannitol) via a web-generated permuted blockwise randomisation list (block size=2) that was stratified by disease subtype (parkinsonism-predominant disease vs cerebellar-ataxia-predominant disease). All participants and study personnel were masked to treatment assignment. Participants were given one hard gelatin capsule (containing either 400 mg Epigallocatechin Gallate or mannitol) orally once daily for 4 weeks, then one capsule twice daily for 4 weeks, and then one capsule three times daily for 40 weeks. After 48 weeks, all patients underwent a 4-week wash-out period. The primary endpoint was change in motor examination score of the Unified Multiple System Atrophy Rating Scale (UMSARS) from baseline to 52 weeks. Efficacy analyses were done in all people who received at least one dose of study medication. Safety was analysed in all people who received at least one dose of the study medication to which they had been randomly assigned. This trial is registered with ClinicalTrials.gov ( NCT02008721 ) and EudraCT (2012-000928-18), and is completed. Findings Between April 23, 2014, and Sept 3, 2015, 127 participants were screened and 92 were randomly assigned—47 to Epigallocatechin Gallate and 45 to placebo. Of these, 67 completed treatment and 64 completed the study (altough one of these patients had a major protocol violation). There was no evidence of a difference in the mean change from baseline to week 52 in motor examination scores on UMSARS between the Epigallocatechin Gallate (5·66 [SE 1·01]) and placebo (6·60 [0·99]) groups (mean difference −0·94 [SE 1·41; 95% CI −3·71 to 1·83]; p=0·51). Four patients in the Epigallocatechin Gallate group and two in the placebo group died. Two patients in the Epigallocatechin Gallate group had to stop treatment because of hepatotoxicity. Interpretation 48 weeks of Epigallocatechin Gallate treatment did not modify disease progression in patients with multiple system atrophy. Epigallocatechin Gallate was overall well tolerated but was associated with hepatotoxic effects in some patients, and thus doses of more than 1200 mg should not be used. Funding ParkinsonFonds Deutschland, German Parkinson Society, German Neurology Foundation, Luneburg Foundation, Bischof Dr Karl Golser Foundation, and Dr Arthur Arnstein Foundation.
Asako Naraikanayama - One of the best experts on this subject based on the ideXlab platform.
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efficient synthesis of theaflavin 3 Gallate by a tyrosinase catalyzed reaction with epicatechin and Epigallocatechin Gallate in a 1 octanol buffer biphasic system
Journal of Agricultural and Food Chemistry, 2018Co-Authors: Asako Naraikanayama, Yoshinori Uekusa, Fumiyuki Kiuchi, Tsutomu NakayamaAbstract:Theaflavins, the orange-red pigments contained in black tea, have attracted attention as a result of their health-promoting effects. However, their synthetic preparation, in which the enzymatic oxidation of catechol-type catechin is followed by the quinone-induced oxidative dimerization of selectively combined catechol- and pyrogallol-type catechins, provides only a low yield. In the present study, we found that a 1-octanol/buffer biphasic system improved the yield of theaflavin 3-Gallate in a tyrosinase-catalyzed synthetic reaction with (-)-epicatechin and (-)-Epigallocatechin Gallate. When the enzymatic reaction proceeded in a buffer solution, oxidized (-)-Epigallocatechin Gallate was preferentially used for self-dimerization. However, self-dimerization was suppressed in the octanol phase, allowing oxidized (-)-Epigallocatechin Gallate to participate in coupling with (-)-epicatechin quinone, leading to effective production of theaflavin 3-Gallate. Furthermore, the preferential localization of theaflavin 3-Gallate in the octanol phase prevented (-)-epicatechin-quinone-induced degradation.