1 / 21

Wood Chemistry PSE 406

Wood Chemistry PSE 406. Lecture 15 Stilbenes, Flavonoids, Condensed and Hydrolysable Tannins, other Miscellaneous Extractives and Inorganic Compounds. Stilbenes. Phenolic extractive found in the heartwood of softwoods Particularly prevalent in Pinus

eman
Télécharger la présentation

Wood Chemistry PSE 406

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Wood ChemistryPSE 406 Lecture 15 Stilbenes, Flavonoids, Condensed and Hydrolysable Tannins, other Miscellaneous Extractives and Inorganic Compounds PSE 406: Lecture 15

  2. Stilbenes • Phenolic extractive found in the heartwood of softwoods • Particularly prevalent in Pinus • Most often 2 aromatic rings: occasionally more • Presence of double bond linkage • Naturally present most often in trans form PSE 406: Lecture 15

  3. Flavonoids • Serve many roles in plants: • Protection • Coloration • Other unique roles. PSE 406: Lecture 15

  4. FlavonoidsGeneral Structural Information • Polyphenolic compounds found in softwoods and hardwoods • Composed of diphenylpropane units C6-C3-C6 • Eight structural classifications • Flavonoids differ through substitution on the rings • Typically OH or OCH3 groups • Typical to have OH on positions: • 5 and 7 • 3’, 4’ and 5’ • Are also present as gylcosides PSE 406: Lecture 15

  5. Representative Structures of Flavonoid Classes PSE 406: Lecture 15

  6. FlavonoidsBiological Significance • Not all flavonoids have same function in plants • Anti-fungal • Antioxidant • Color: bright colors in plants PSE 406: Lecture 15

  7. FlavonoidsLocation in Tree • Found in the heartwood of most tress • Often responsible for coloration • Found in lesser amounts in the sapwood • Are found in large amounts in bark and roots • Leaves: green tea can contain up to 30% flavonoids • Flowers: color is often due to flavonoids PSE 406: Lecture 15

  8. FlavonoidsMedicinal Uses • Higher flavonoid content in diet reduces chance of: • Heart Disease • Strengthen capillaries • Dilates blood vessels • Stroke • Cancer: all types reduced • Finnish study = ½ rate of cancer PSE 406: Lecture 15

  9. Condensed Tannins • Condensed tannins are formed through the polymerization of flavan-3-ol (catechin) and flavan–3,4-diols (leucoanthocyanidins) • 2-50 units • Typically 2-8 • Linkages can be through a variety of sites PSE 406: Lecture 15

  10. Condensed Tannins PSE 406: Lecture 15

  11. Condensed TanninsLocation in the Tree • Western hemlock • Bark: 18% tannins • Wood: 2% tannins PSE 406: Lecture 15

  12. Condensed TanninsBiological Significance • Protection of plants against insects/animals • Bad Taste (bitter taste) • Toxic to bacteria • Pine calluses: created by fungal invasion • Tree forms calluses as protective tissue • Calluses contain high levels of tannins • Uses of condensed tannins • Leather tanning: 10,000+ year old industry • Adhesives PSE 406: Lecture 15

  13. Hydrolyzable TanninsStructure • Polymers (esters) of a sugar (usually glucose) with one or more polyphenolic carboxylic acids. • Gallotannins:Gallic acid polymer • Ellagitannins: Ellagic Acid polymer PSE 406: Lecture 15

  14. Hydrolyzable TanninsPolymer Structure Example Sugar PSE 406: Lecture 15

  15. Hydrolyzable TanninsGeneral Information • Rare to nonexistent in softwoods. • Hardwoods which contain large amounts: • Oak (gallic and ellagic tannins) • Eucalyptus (Ellagitannins) • Chestnut (gallic tannins) • Hydrolyzable tannins located in heartwood. • Pulp and paper problems: • Increased consumption of bleaching chemicals. • Coloration problems. PSE 406: Lecture 15

  16. Tetraterpenes • Polymers of isoprene containing 40 carbons (8 isoprene units) • Most common are the carotenoids • Generally derivatives of lycopene • This is a carontenoid which is in high concentration in red fruits (gives color): tomatoes, watermelon, guava, etc. PSE 406: Lecture 15

  17. b Carotene • Tetraterpene carotenoid found in dark green and orange yellow vegetables. • In the human body, it is converted to vitamin A • Has been shown to be have many health related benefits. PSE 406: Lecture 15

  18. Alkaloids (1) • These nitrogen containing compounds are found in a variety of different plants. • Located in the leaves, fruits, and bark. • Quinine • Used to treat malaria • Isolated from bark of cinchonas (South American Hardwood) • some eucalyptus species • Causes pulping problems • Strychnine • Found in seeds of tree Strychnos nux-vomica (Tropical hardwood) PSE 406: Lecture 15

  19. Alkaloids (2) • You are all aware of the alkaloids shown on this page you probably have never seen their structures. These are typically found in small amounts in plants but are worth large sums of cash. Caffeine Nicotine Cocaine PSE 406: Lecture 15

  20. Inorganic Materials • Inorganic materials • Plants contains small amounts of most metals. • Some are used by living cells • Some present as contaminants • Ash content gives a rough idea of the amounts of metals present. • Sugar cane: 1.7-3.8% ash • Corn Cobs: 2% ash • Temperate woods contain 0.1-1% ash while tropical and subtropical species contain up to 5% ash. • Main components Ca (50%), potassium and magnesium. PSE 406: Lecture 15

  21. Inorganics in Grasses • Grasses contain high levels of inorganics particularly silica. • Wheat straw: Reported values 4-12+% ash • Leaves: 14-19% ash, 10-14% silica • Nodes: 8-14% ash, 5-7% silica • Internodes: 3+% ash, 2+% silica PSE 406: Lecture 15

More Related