Toksikologi Pakan: Tannins

Transcription

1 Outline Toksikologi Pakan: Tannins A. Introduction B. Structure C. Interaction D. Analytical methods E. Biological effects F. Treatments/processing methods Anuraga Jayanegara 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 - Examples: alkaloids, terpenes, phenolics 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. Tannins, definition Water-soluble phenolic compounds that have ability to precipitate proteins

2 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 intensity - High temperature - Severe drought - Tissue damage Increase tannin levels B. Structure Diversity of tannin structures Hydrolysable tannin (HT) Condensed tannin (CT) Source: Mueller-Harvey (2006) J. Sci. Food Agric. 86,

3 C. Interaction Illustration of protein precipitation by tannins Multiple hydroxyl groups: enable phenolics to form complexes with proteins, polysachharides and minerals. 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 Marangon et al. (2010) Analytica Chimica Acta 660, D. Analytical methods - Categorized into: (1) chemical methods, (2) protein precipitation methods, (3) gravimetric assays, (4) tannin bioassay, (5) Others. - Chemical assays: - Total phenols and total tannins: Folin-Ciocalteu (oxidation-reduction), ferric chloride (metal-complexing property of phenolics) - Condensed tannins: vanilin assay, butanol-hcl assay - Hydrolysable tannins: rhodanine method, HPLC - Protein precipitation assays: ninhydrin assay, BSA method, radial diffusion assay - Gravimetric methods: ytterbium acetate, PVPP - Tannin bioassay: in vitro gas production + PEG (e.g. Jayanegara & Sofyan, 2008) E. Biological effects Negative effects: - Decreasing nutrient utilization, in particular protein utilization - Decreasing feed intake - Toxicity and death of animals Positive effects: - Prevention of bloat - Protection of protein from rumen degradation - Mitigating methane emission - Modulation of PUFA biohydrogenation in the rumen - Controling of gastro-intestinal nematode parasites More detailed methods...

4 Decreasing nutrient utilization Toxicity problems Prevention of bloat Protection of protein from rumen degradation

5 Mitigating methane emission Global warming Loss of energy Evidences: - Jayanegara et al. (2009), Animal Feed Science and Technology 150, Jayanegara et al. (2009), Media Peternakan 32, Jayanegara et al. (2010), Sustainable Improvement of Animal Production and Health (Odongo, N.E., Garcia, M., Viljoen, G.J. (Eds.)), FAO, Rome, pp Jayanegara et al. (2011), Animal Feed Science and Technology 163, Jayanegara et al. (2012), Journal of Animal Physiology and Animal Nutrition 96, Jayanegara et al. (online first), British Journal of Nutrition Source: Morgavi et al. (2010) Animal 4, Ruminal methanogens attached to protozoal species interspecies H transfer Protozoa-associated methanogens contribute up to 37% of total rumen methane emissions Removal of protozoa from the rumen (defaunation) may CH 4 emission Source: Bhatta et al. (2009) J. Dairy Sci. 92, Phenolics and microbial population Protozoa colonized by methanogens

6 Modulation of PUFA biohydrogenation Reduce the risk of cardiovascular disease Lowering plasma cholesterol level Linoleic acid α-linolenic acid Rumenic acid Vaccenic acid Prevent cancer proliferation Decrease atherosclerosis Improve immune system Stearic acid Source: Chilliard et al. (2007) Eur. J. Lipid Sci. Technol. 109, Condensed tannins (CT) Source: Khiaosa-ard et al. (2009) J. Dairy Sci. 92, CH: grass-clover hay (control) TF: dried sainfoin (7.9% CT) TH: CH + A. mearnsii extract (7.9% CT) SH: CH + Y. schidigera extract (1.1% saponins) Influence of tannins on biohydrogenating bacteria Inhibition of phenolics on lipase activity Containing 6.4% tannins from quebracho powder Source: Vasta et al. (2010) Appl. Environ. Microbiol. 76, Source: Van Ranst et al. (2011) Animal 5,

7 F. Treatment methods Other evidences: - Jayanegara et al. (2011), Animal Production Science 51, Jayanegara et al. (2012), Livestock Science 147, Palupi et al. (online first), Journal of the Science of Food and Agriculture - Wood ash: a good source of alkali; 10% solution of oak wood ash decreased the content of TP, CT and protein precipitation capacity by 66, 80 and 75% in oak leaves, respectively. - Urea-ammoniation: 4% urea in fresh leaves. - Drying: but not effective. - Chemicals: extraction with organic solvents (30% acetone, 50% methanol, 40% ethanol) removed ca 70% tannins from oak leaves. - Solid-state fermentation: biodegradation of tannins using white-rot fungi. - Addition of tannin-binding polymers: PEG (polyethylene glycol) incorporation, PVPP.

8 Thank you for your attention!