Chlorogenic acids and other cinnamates - review
Three articles on chlorogenic acid: Chlorogenic acids and other cinnamates – nature, occurrence and dietary burden & Chlorogenic acids and other cinnamates – nature, occurrence, dietary burden, absorption and metabolism & Hierarchical Scheme for LC-MSn Identification of Chlorogenic Acids.
Chlorogenic acids and other cinnamates – nature, occurrence, dietary burden, absorption and metabolism
Clifford, Michael N. "Chlorogenic acids and other cinnamates–nature, occurrence, dietary burden, absorption and metabolism." Journal of the Science of Food and Agriculture 80.7 (2000): 1033-1043.
This paper summarises the occurrence in foods and beverages of the cinnamic acids, their associated conjugates and transformation products. Quantitative data are lacking for some commodities known to contain them, but it is clear that for many people coffee will be the major source. The daily dietary intake of total cinnamates may vary substantially from almost zero to perhaps close to 1 g. The data relating to their absorption and metabolism are presented along with a consideration of their possible in vivo effects. Data for true bioavailability are incomplete: in particular it is not clear whether availability differs markedly with the form of the conjugate, and whether as a consequence some dietary sources may be superior to others.
Chlorogenic acids and other cinnamates – nature, occurrence and dietary burden
Clifford, Michael N. "Chlorogenic acids and other cinnamates–nature, occurrence and dietary burden." Journal of the Science of Food and Agriculture 79.3 (1999): 362-372.
This review defines the range of forms in which cinnamates (p-coumarates, caffeates, ferulates and sinapates) occur in foods and beverages subdividing them into (i) the classic chlorogenic acids and close allies, (ii) other esters, amides and glycosides, and (iii) transformation products formed during processing. Cinnamate derivatives which would not release cinnamic acid by hydrolysis are excluded. The quantitative data are reviewed concisely and attention is drawn to certain shortcomings, in particular a complete absence of data for certain commodities (breakfast cereals, baked goods, tomato products and nuts) and minimal data for pulses, legumes and processed or cooked foods. In addition, more data are required for the edible portion of modern varieties. By extrapolating from such data as are available the important source(s) (i) of individual cinnamates (regardless of the conjugate type) and (ii) of each major class of conjugate, have been identified as follows:
(i) Cinnamates: caffeic acid: coffee beverage, blueberries, apples, ciders; p-coumaric acid: spinach, sugar beet fibre, cereal brans; ferulic acid: coffee beverage, citrus juices, sugar beet fibre, cereal brans; sinapic acid: broccoli, kale, other leafy brassicas, citrus juices.
(ii) Conjugates: caffeoylquinic acids: coffee beverage, blueberries, apples, ciders; p-coumaroylquinic acids: sweet cherries; feruloylquinic acids: coffee beverage; tartaric conjugates: spinach, lettuce, grapes and wines; malic conjugates: lettuce, spinach, possibly legumes; rosmarinic acid: culinary herbs, mixed herbs, possibly stuffings; cell wall conjugates: spinach, sugar beet fibre, cereal brans.
It seems likely that the UK population will fall into several categories depending on (i) their consumption of coffee, (ii) their consumption of bran, and (iii) their consumption of citrus. Those who drink several cups of coffee per day augmented by bran and citrus might easily ingest 500–800 mg cinnamates (or even 1 g for the greatest coffee ingest consumption) whereas those who eschew all these and take little fresh fruit or vegetables might struggle to consume 25 mg.
© 1999 Society of Chemical Industry
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Hierarchical Scheme for LC-MSn Identification of Chlorogenic Acids
Clifford, Michael N., et al. "Hierarchical scheme for LC-MS n identification of chlorogenic acids." Journal of Agricultural and Food Chemistry 51.10 (2003): 2900-2911.
The fragmentation behavior of 18 chlorogenic acids that are not substituted at position 1 has been investigated using LC-MS4 applied to a methanolic coffee bean extract and commercial cider (hard cider). Using LC-MS3, it is possible to discriminate between each of the three isomers of p-coumaroylquinic acid, caffeoylquinic acid, feruloylquinic acid, and dicaffeoylquinic acid, and a hierarchical key has been prepared to facilitate this process when standards are not available. MS4 fragmentations further support these assignments, but were not essential in reaching them. The distinctive behavior of 4-acyl and 3-acyl chlorogenic acids compared with the 5-acyl chlorogenic acids is a key factor permitting these assignments. The fragmentation patterns are dependent upon the particular stereochemical relationships between the individual substituents on the quinic acid moiety. Fragmentation is facilitated by 1,2-acyl participation and proceeds through quinic acid conformers in which the relevant substituents transiently adopt a 1,3-syn-diaxial relationship. Selected ion monitoring at m/z 529 clearly indicated the presence in coffee of six caffeoylferuloylquinic acid isomers, whereas previously only two or three had been demonstrated. The hierarchical key permitted specific structures to be assigned to each of the six isomers. These assignments are internally consistent and consistent with the limited data previously available.