Yesterday's blogpost was about
Flavan-3-ols Are Also Called Catechins, today, I'm moving on to learning about
flavonols. Flavonols are phenolic compounds found in the skins of grapes. They include kaempferol, quercetin, myricetin, and isorhamnetin. These compounds differ from each other by either an additional hydroxy group or a methoxy group as in the case of isorhamnetin. The chemical structures are shown below and the differences in the structures are noted by a red circle:
In addition, the flavonols shown above can also be modified at the hydroxy group in position 3 on the pyran ring by a glucose, galactose, or glucuronic acid. So, there are a considerable number of flavonol compounds that can exist in the skin of the grape.
1
Out of all of the flavonoid compounds, the flavonols occur in the lowest concentration, but they are important in absorbing ultraviolet radiation and play a role in protecting the inner tissues of the grape from UV damage. Leaf pulling to expose the grape bunch to sunlight has a consequence that results in the synthesis of flavonols in the skin of the grapes during fruit set and ripening.
2
References:
1. Douglas Adams, VI257, Lesson 8, pg. 27.
2. Jackson, Ronald S.,
Wine Science: Principles and Applications, Third Edition, Elsevier, Academic Press, 2008, pg. 284-5.
All structures were drawn by the freely available drawing program from ACD Labs called
ACD/ChemSketch Freeware.
Our capacity to provide pharmaceutical discovery services across the entire spectrum of the drug discovery process has assisted many of our esteemed clients in reaching their R&D goals. Quercetin-3-O-D-glucosyl]-(1-2)-L-rhamnoside
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