Stereochemical Structure Determination of Caffeine Complexes with Galloylated and Non-galloylated Catechins

Ishizu, Tomoko; Satō, Takashi; Tsutsumi, Hiroyuki; Yamamoto, Hideji

doi:10.1246/cl.2010.607

Cited by 18 publications

(24 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…108 The remaining phenolic substituent on ring B is hydrogen bonded to the oxygen atom of ring C. In comparison, the only stable hydrate seen for catechin (4.5) is the one in which three of the hydroxy substituents interact with water molecules, whereas the remaining two hydroxy substituents are involved in phenol O-H … O phenol hydrogen bonds (LUXWOR). 109 Cocrystal formation in epicatechincaffeine dihydrate (WUSFIA) 110 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 44 There are two known hydrated molecular complexes of catechin gallate with caffeine. 1 2 3 4 5 6 7 8 9 10 11 1...…”

Section: Polyphenols (Including Coumarin Stilbenes Flavonoids and Lmentioning

confidence: 99%

Cocrystallization of Nutraceuticals

Sinha

Maguire

Lawrence

2015

Crystal Growth & Design

View full text Add to dashboard Cite

Cocrystallization has emerged over the past decade as an attractive technique for modification of the physicochemical properties of compounds used as active pharmaceutical ingredients (APIs), complementing more traditional methods such as salt formation. Nutraceuticals, with associated health benefits and / or medicinal properties, are attractive as coformers due to their ready availability, known pharmacological profile and natural origin, in addition to offering a dual therapy approach. Successful studies of favorably altering the physicochemical properties of APIs through cocrystallization with nutraceuticals are highlighted in this review. Many of the key functional groups commonly seen in nutraceuticals (e.g. acids, phenols), underpin robust supramolecular synthons in crystal engineering. This review assesses the structural data available to date across a diverse range of nutraceuticals, both in pure form and in multicomponent materials, identifies the persistent supramolecular features present. This insight will ultimately enable predictive and controlled assembly of functional materials incorporating nutraceuticals together with APIs.

show abstract

Section: Polyphenols (Including Coumarin Stilbenes Flavonoids and Lmentioning

confidence: 99%

Cocrystallization of Nutraceuticals

Sinha

Maguire

Lawrence

2015

Crystal Growth & Design

View full text Add to dashboard Cite

show abstract

“…5). 15) One unit cell dimensions were a=27.2246(12) Å, b=6.6953(3) Å and c=17.4322(8) Å, respectively. An ORTEP drawing of a unit of the 1 : 1 complex of EC and caffeine is shown in Fig.…”

Section: X-ray Crystallographic Analysis Of the Complex Of Ec Ecg Anmentioning

confidence: 99%

Characterization of Creaming Precipitate of Tea Catechins and Caffeine in Aqueous Solution

Satō

Kinoshita

Tsutsumi

et al. 2012

CHEMICAL & PHARMACEUTICAL BULLETIN

Self Cite

View full text Add to dashboard Cite

The content of a crude precipitate formed by creaming, which was made from a catechin mixture and caffeine, was investigated by an integral volume of H-2 proton signals of tea catechins in the 1 H-NMR spectrum. Gallated catechins formed a crude precipitate more predominantly than non-gallated catechins. The 2,3-cis-non-gallated catechin ( )-epicatechin (EC) formed a 1 : 1 complex with caffeine, and 2,3-cis-gallated catechin ( )-epicatechin gallate (ECg) formed a 2 : 4 complex with caffeine. The π-π complexation site of EC with caffeine was only the A ring, whereas that of ECg included all aromatic rings, A, B, and B′. It was thought that the hydrophobicity of the 2 : 4 complex of ECg and caffeine was stronger than that of the 1 : 1 complex of EC and caffeine, with the result that the 2 : 4 complex of ECg and caffeine precipitated by creaming more predominantly than the 1 : 1 complex of EC and caffeine in aqueous solution.Key words creaming down; (−)-epicatechin; (−)-epicatechin-3-O-gallate; caffeine; π-π interaction; X-ray crystallographic analysisTea has been consumed in many countries throughout the world since ancient times for taste and to maintain and improve health. It is well known that tea protects against lifestyle-related diseases such as cancer, high blood pressure, diabetes, obesity, and arteriosclerosis. 1) Tea is made from leaves of the tea plant, Camellia sinensis, Theaceae, which includes caffeine, catechins, tannins, vitamins, theanine, etc. Catechins are a group of polyphenols that show various physiologically modulating effects, such as anti-carcinogenic, anti-metastatic, and anti-oxidative.2-7) The eight major tea catechins are classified into four categories by the existence of a galloyl group on the oxygen atom at the C-3 position and the relative stereochemistry between the C-2 and C-3 positions:2,3-cis-gallated, 2,3-trans-gallated, 2,3-cis-non-gallated, and 2,3-trans-non-gallated 8) (Fig. 1). Generally, gallated catechins show higher activities than non-gallated catechins. 9-12)When a hot tea beverage cools down, it becomes turbid and brown-white particles settle out. This phenomenon is called "creaming" or "creaming down (reaction)." Since creaming is a trigger to deform the original appearance and color of tea, it is one of the most serious problems in making a tea beverage. Caffeine has been suggested to form a cream with tea polyphenols such as catechins, theaflavins and thearubigins. ; however, creaming down in tea beverages has not been chemically elucidated sufficiently. In this paper, we describe a new method for quantitative analysis of a crude precipitate of creaming made from a catechin mixture and caffeine using an integral volume of the proton signal of the 1 H-NMR spectrum. The catechin mixture is a fraction of extracted catechins included in green tea. The stereochemical structure of the complexes of tea catechins (−)-epicatechin (EC), ECg and caffeine was determined by X-ray crystallography, and the molecular interactions between the tea catechins and caffeine were invest...

show abstract

“…it was still soluble. The mixture was lyophilized to afford a colorless powder, which was recrystallized from methanol to give a colorless block crystal 17,22) (Fig. 3b).…”

Section: Crystallization Of the Creaming Down Precipitate Made From Cmentioning

confidence: 99%

“…This was recrystallized from water to afford colorless blocks, which were determined to be a 2 : 4 complex of caffeine and ECg by X-ray crystallographic analysis. 17,22) An ORTEP drawing of a unit cell of the 2 : 4 complex of caffeine and ECg is shown in Fig. 10a.…”

Section: Stereochemical Structure Of the Complex Of Caffeine And Ecgmentioning

confidence: 99%

“…It was therefore thought that the sticky precipitate formed by creaming down was produced from the aqueous solution of EGCg, ECg and caffeine due to its high hydrophobicity. 20,21) On the other hand, such a hydrophobic space did not exist in the 1 : 1 complex of caffeine and EC, so it was thought that the precipitate formed by creaming down was not produced from the aqueous solution containing equimolar amounts of caffeine and EC 17,22) (Fig. 12c).…”

Section: The Mechanism Of Creaming Down By Caffeine and Tea Catechinsmentioning

confidence: 99%

See 1 more Smart Citation

Mechanism of Creaming Down Based on Chemical Characterization of a Complex of Caffeine and Tea Catechins

2016

Self Cite

View full text Add to dashboard Cite

The component of a precipitate resulting from creaming down, which was made from caffeine and a catechin mixture, was determined by an integrated value of H2 proton signals of tea catechins in the quantitative 1 H-NMR spectrum. The results showed that gallate-type catechins formed a precipitate by creaming down more predominantly than non-gallate-type catechins. X-ray crystallographic analysis showed that the gallate-type catechin ( )-epigallocatechin-3-O-gallate (EGCg), ( )-epicatechin-3-O-gallate (ECg) formed 2 : 2 and 2 : 4 complexes with caffeine, respectively, and the non-gallate-type catechin ( )-epicatechin (EC) and caffeine formed a 1 : 1 complex. The 2 : 2, 2 : 4 complexes of caffeine and EGCg, ECg formed a hydrophobic space with three aromatic A, B, and B′ rings of two EGCg, ECg molecules, and one caffeine molecule was captured in this hydrophobic space. However, no such hydrophobic space in the 1 : 1 complex of caffeine and EC formed. It was thought that the hydrophobicity of the 2 : 2, 2 : 4 complexes of caffeine and EGCg, ECg was stronger than that of the 1 : 1 complex of caffeine and EC, with the result that the 2 : 2, 2 : 4 complexes of caffeine and EGCg, ECg precipitated by creaming down more predominantly than the 1 : 1 complex of caffeine and EC in an aqueous solution. Furthermore, the molecular capture of various heterocyclic compounds by formation of the 2 : 2 complex of EGCg from the aqueous solution was investigated using the quantitative 1 H-NMR spectrum.

show abstract

Stereochemical Structure Determination of Caffeine Complexes with Galloylated and Non-galloylated Catechins

Cited by 18 publications

References 12 publications

Cocrystallization of Nutraceuticals

Cocrystallization of Nutraceuticals

Characterization of Creaming Precipitate of Tea Catechins and Caffeine in Aqueous Solution

Mechanism of Creaming Down Based on Chemical Characterization of a Complex of Caffeine and Tea Catechins

Contact Info

Product

Resources

About