The key difference between condensed hydrolysable and phlorotannins is that condensed tannins refer to compounds that form from the condensation of falvan and hydrolysable tannins refer to compounds that yield gallic and ellagic acids upon heating with HCl or sulfuric acid whereas phlorotannins are oligomers of phloroglucinol.
Tannins are organic compounds having a yellowish or brownish appearance and a bitter taste. These compounds are mainly found in plant parts such as galls, barks, plant tissues that contain derivatives of gallic acid.
CONTENTS
1. Overview and Key Difference
2. What are Condensed Tannins
3. What are Hydrolyzable Tannins
4. What are Phlorotannins
5. Side by Side Comparison – Condensed Hydrolyzable vs Phlorotannins in Tabular Form
6. Summary
What are Condensed Tannins?
Condensed tannins are organic compounds and polymer materials made via condensation of flavan. These compounds have no sugar residues as a part of the compound. Other common names for condensed tannins include proanthocyanidins, polyflavonoid tannins, catechol-type tannins, pyrocatecollic type tannins, non-hydrolyzable tannins or flavolans.
Most condensed tannins are water-soluble compounds, and they are sometimes soluble in organic solvents such as octanol. However, some large condensed tannins are not soluble in water. Therefore, we can observe that the biological function of these compounds depends on water solubility.
Figure 01: A Type of Condensed Tannin
We can find condensed tannins naturally occurring in different plants such as Prunus species. These compounds form in tannosomes, which are specified organelles in vascular plants. There are different techniques we can use to characterize condensed tannins; for example, asymmetric flow field flow fractionation, small-angle X-ray scattering[13] and MALDI-TOF mass spectrometry.
What are Hydrolyzable Tannins?
Hydrolysable tannins are organic compounds that can yield gallic or ellagic acid upon heating with HCl or sulfuric acid. When considering the structure of hydrolysable tannins, these molecules contain a carbohydrate molecule at the centre. Generally, this carbohydrate is a D-glucose molecule. The hydroxide groups of the sugar molecule are either partially or completely esterified with phenolic groups. Therefore, these compounds are mixtures of polygalloyl glucose.
The name of these tannins comes from its ability to undergo hydrolysis upon reaction with weak acids and weak bases. The hydrolysis reaction produces carbohydrate and phenolic acid. The hydrolysable tannins are naturally occurring compounds. We can extract these compounds from vegetable plants such as chestnut wood, oak wood, tara pods, etc.
What are Phlorotannins?
Phlorotannins are a group of organic compounds which are oligomers of phloroglucinol. These compounds occur naturally in brown algae such as rockweeds. Also, these compounds can be found in low levels in red algae. These compounds have the ability to precipitate proteins like most other tannin types. Moreover, some phlorotannins are able to oxidize and form covalent bonds with some proteins.
Figure 02: Brown Algae
In plants, phlorotannins can be found in small vesicles called physodes. These compounds are water-soluble due to polar nature. But when these compound occur in cell walls (of brown algae), they are insoluble in water and act as structural components.
What is the Difference Between Condensed Hydrolyzable and Phlorotannins?
The key difference between condensed hydrolysable and phlorotannins is that condensed tannins are compounds that form from condensation of falvan and hydrolysable tannins are compounds that yield gallic and ellagic acids upon heating with HCl or sulfuric acid whereas phlorotannins are oligomers of phloroglucinol.
The below infographic presents more comparisons related to the difference between condensed hydrolysable and phlorotannins.
Summary – Condensed Hydrolyzable vs Phlorotannins
Tannins are organic compounds having a yellowish or brownish appearance and a bitter taste that can be found mainly in plant parts. The key difference between condensed hydrolysable and phlorotannins is that condensed tannins refer to the compounds that form from the condensation of falvan and hydrolysable tannins refer to the compounds that yield gallic and ellagic acids upon heating with HCl or sulfuric acid whereas phlorotannins are oligomers of phloroglucinol.
Reference:
1. “Condensed Tannin.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., Available here.
2. “Hydrolysable Tannin.” Wikipedia, Wikimedia Foundation, 19 Apr. 2020, Available here.
3. “Condensed Tannin.” Wikipedia, Wikimedia Foundation, 12 Feb. 2020, Available here.
Image Courtesy:
1. “Schematic condensed tannins” By Nono64 – Own work, Public Domain) via Commons Wikimedia
2. “Durvillaea antarctica 5220” By Erasmo Macaya – Own work (CC BY-SA 3.0) via Commons Wikimedia