Toksikologi Pakan: Tannins Anuraga Jayanegara Outline A. Introduction B. Structure C. Interaction D. Analytical methods E. Biological effects F. Treatments/processing methods Department of Nutrition and Feed Technology A. Introduction Plant secondary compounds - Do not function in primary metabolism such as biosynthesis, biodegradation and other energy conversions of intermediary metabolism - Do have diverse biological activities ranging from toxicity to hormonal mimicry - May play a role in protecting plants from herbivory and disease Department of Nutrition and Feed Technology - May play a role in protecting plants from herbivory and disease - Examples: alkaloids, terpenes, phenolics Tannins, definition Water-soluble phenolic compounds that have ability to precipitate proteins Classification Condensed tannin (CT, proanthocyanidins) : oligomers of two or more flavan-3-ols such as catechin, epicatechin, or gallocatechin. Hydrolysable tannin (HT) : consisting of a central core of carbohydrate to which phenolic carboxylic acids are bound by ester linkage. Department of Nutrition and Feed Technology
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Toksikologi Pakan: Tannins
Anuraga Jayanegara
Outline
A. Introduction
B. Structure
C. Interaction
D. Analytical methods
E. Biological effects
F. Treatments/processing methods
Department of Nutrition and Feed Technology
A. Introduction
Plant secondary compounds
- Do not function in primary metabolism such as biosynthesis,
biodegradation and other energy conversions of intermediary
metabolism
- Do have diverse biological activities ranging from toxicity to hormonal
mimicry
- May play a role in protecting plants from herbivory and disease
Department of Nutrition and Feed Technology
- May play a role in protecting plants from herbivory and disease
- Examples: alkaloids, terpenes, phenolics
Tannins, definition
Water-soluble phenolic compounds that have ability to precipitate
proteins
Classification
Condensed tannin (CT, proanthocyanidins): oligomers of two or more
flavan-3-ols such as catechin, epicatechin, or gallocatechin.
Hydrolysable tannin (HT): consisting of a central core of carbohydrate to
which phenolic carboxylic acids are bound by ester linkage.
Department of Nutrition and Feed Technology
Department of Nutrition and Feed Technology
Why plants produce phenolics?
A strategy adopted by plants to deter attack by microorganisms,
insects and higher animals.
Factors affecting tannin levels:
- Nutrient stress (N, P, K, S deficiencies)
- High light intensityIncrease tannin
Department of Nutrition and Feed Technology
- High light intensity
- High temperature
- Severe drought
- Tissue damage
Increase tannin
levels
B. Structure
Department of Nutrition and Feed Technology
Condensed tannin (CT)
Hydrolysable tannin (HT)
Diversity of tannin structures
Department of Nutrition and Feed Technology
Source: Mueller-Harvey (2006)
J. Sci. Food Agric. 86, 2010-2037.
Multiple hydroxyl groups: enable phenolics to form complexes
with proteins, polysachharides and minerals.
Tannin-protein complex:
C. Interaction
Department of Nutrition and Feed Technology
Tannin-protein complex:
1. Hydrogen bonds: free phenolic hydroxyl groups
2. Hydrophobic bonds: aromatic ring structures
3. Covalent bonds: polymerization reactions due to heating,
exposure to UV radiation and the action of polyphenol
oxidase
Illustration of protein precipitation by tannins
Department of Nutrition and Feed Technology
Marangon et al. (2010)
Analytica Chimica Acta 660, 110-118
D. Analytical methods
- Categorized into: (1) chemical methods, (2) protein precipitation