PSE 406: Lecture 151 Wood Chemistry PSE 406 Lecture 15 Stilbenes, Flavonoids, Condensed and Hydrolysable Tannins, other Miscellaneous Extractives and Inorganic Compounds

PSE 406: Lecture 152 Stilbenes lPhenolic extractive found in the heartwood of softwoods »Particularly prevalent in Pinus lMost often 2 aromatic rings: occasionally more lPresence of double bond linkage »Naturally present most often in trans form

PSE 406: Lecture 153 Flavonoids lServe many roles in plants: »Protection »Coloration »Other unique roles.

PSE 406: Lecture 154 Flavonoids General Structural Information lPolyphenolic compounds found in softwoods and hardwoods lComposed of diphenylpropane units C 6 -C 3 -C 6 lEight structural classifications lFlavonoids differ through substitution on the rings »Typically OH or OCH 3 groups »Typical to have OH on positions: –5 and 7 –3’, 4’ and 5’ lAre also present as gylcosides

PSE 406: Lecture 155 Representative Structures of Flavonoid Classes

PSE 406: Lecture 156 Flavonoids Biological Significance lNot all flavonoids have same function in plants lAnti-fungal lAntioxidant lColor: bright colors in plants

PSE 406: Lecture 157 Flavonoids Location in Tree lFound in the heartwood of most tress »Often responsible for coloration lFound in lesser amounts in the sapwood lAre found in large amounts in bark and roots lLeaves: green tea can contain up to 30% flavonoids lFlowers: color is often due to flavonoids

PSE 406: Lecture 158 Flavonoids Medicinal Uses lHigher 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 159 Condensed Tannins lCondensed 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 1510 Condensed Tannins

PSE 406: Lecture 1511 Condensed Tannins Location in the Tree lWestern hemlock »Bark: 18% tannins »Wood: 2% tannins

PSE 406: Lecture 1512 Condensed Tannins Biological Significance lProtection of plants against insects/animals »Bad Taste (bitter taste) lToxic to bacteria lPine calluses: created by fungal invasion »Tree forms calluses as protective tissue »Calluses contain high levels of tannins lUses of condensed tannins »Leather tanning: 10,000+ year old industry »Adhesives

PSE 406: Lecture 1513 Hydrolyzable Tannins Structure lPolymers (esters) of a sugar (usually glucose) with one or more polyphenolic carboxylic acids. lGallotannins: Gallic acid polymer lEllagitannins: Ellagic Acid polymer

PSE 406: Lecture 1514 Hydrolyzable Tannins Polymer Structure Example Sugar

PSE 406: Lecture 1515 Hydrolyzable Tannins General Information lRare to nonexistent in softwoods. lHardwoods which contain large amounts: »Oak (gallic and ellagic tannins) »Eucalyptus (Ellagitannins) »Chestnut (gallic tannins) l Hydrolyzable tannins located in heartwood. l Pulp and paper problems: »Increased consumption of bleaching chemicals. »Coloration problems.

PSE 406: Lecture 1516 Tetraterpenes lPolymers of isoprene containing 40 carbons (8 isoprene units) lMost 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 1517  Carotene lTetraterpene carotenoid found in dark green and orange yellow vegetables. lIn the human body, it is converted to vitamin A lHas been shown to be have many health related benefits.

PSE 406: Lecture 1518 Alkaloids (1) lThese nitrogen containing compounds are found in a variety of different plants. »Located in the leaves, fruits, and bark. lQuinine »Used to treat malaria »Isolated from bark of cinchonas (South American Hardwood) – some eucalyptus species »Causes pulping problems lStrychnine »Found in seeds of tree Strychnos nux-vomica (Tropical hardwood)

PSE 406: Lecture 1519 Alkaloids (2) lYou 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. Nicotine Caffeine Cocaine

PSE 406: Lecture 1520 Inorganic Materials lInorganic materials »Plants contains small amounts of most metals. –Some are used by living cells –Some present as contaminants lAsh content gives a rough idea of the amounts of metals present. »Sugar cane: % ash »Corn Cobs: 2% ash lTemperate 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 1521 Inorganics in Grasses lGrasses contain high levels of inorganics particularly silica. lWheat 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