906-33-2Relevant articles and documents
Efficient and versatile synthesis of 5-O-acylquinic acids with a direct esterification using a p-methoxybenzyl quinate as a key intermediate
Oyama, Kin-Ichi,Watanabe, Noriyuki,Yamada, Tomomi,Suzuki, Masako,Sekiguchi, Yukiko,Kondo, Tadao,Yoshida, Kumi
, p. 3120 - 3130 (2015/05/04)
An efficient and versatile synthesis of 5-O-acylquinic acids from commercially available (-)-quinic acid was accomplished. We designed p-methoxybenzyl quinate as a key intermediate, and two problems, the esterification of the sterically hindered 5-OH group for the concise divergent synthesis and the low yield of the final deprotection step, were solved. For the first problem, we improved Tanabe's method, TsCl/NMI-mediated esterification using free carboxylic acids, by the addition of i-Pr2NEt. For the second problem, we established a TFA- or BCl3/C6HMe5-catalyzed deprotection reaction for the final deprotection step. 5-O-Acylquinic acids were synthesized in seven steps with 45-60% overall yield.
Polyphenols are intensively metabolized in the human gastrointestinal tract after apple juice consumption
Kahle, Kathrin,Huemmer, Wolfgang,Kempf, Michael,Scheppach, Wolfgang,Erk, Thomas,Richling, Elke
experimental part, p. 10605 - 10614 (2009/10/02)
Polyphenols are secondary plant compounds showing anticarcinogenic effects both in vitro and in animal experiments and may thus reduce the risk of colorectal cancer in man. The identification of polyphenol metabolites formed via their passage through the small intestine of healthy ileostomy subjects after apple juice consumption is presented. Identification and quantification of polyphenols and their metabolites were performed using HPLC-DAD as well as HPLC-ESI-MS/MS. Total procyanidin content (TPA) was measured, and additionally the mean degree of polymerization (DPm) of the procyanidins was determined in the apple juice and ileostomy effluents. As products of polyphenol metabolism, D-(-)-quinic acid and methyl esters of caffeic acid and p-coumaric acid are liberated from the corresponding hydroxycinnamic acid esters. 1-Caffeoylquinic acid and 3-caffeoylquinic acid were determined as products of isomerization. Phloretin 2′-O-glucoside (phloridzin) and phloretin 2′-O-xyloglucoside were metabolized into the corresponding aglycons phloretin and phloretin 2′-Oglucuronide and all were found in the ileostomy effluent. Ninety percent of the consumed procyanidins were recovered in the ileostomy effluent and therefore would reach the colon under physiologic circumstances. The DPm was reduced (DPm of apple juice = 5.7) and varied depending on the time point of excretion. The gastrointestinal passage seems to play an important role in the colonic availability of apple polyphenols.
Essential structure of co-pigment for blue sepal-color development of hydrangea
Kondo, Tadao,Toyama-Kato, Yuki,Yoshida, Kumi
, p. 6645 - 6649 (2007/10/03)
Blue sepal-color of Hydrangea macrophylla might be due to a supramolecular metal-complex pigment consisting of delphinidin 3-glucoside (1), co-pigments (5-O-caffeoylquinic acid (2), and/or 5-O-p-coumaroylquinic acid (3)) and Al 3+ in an aqueous
