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Biomass Fundamentals Modules 6-11: Carbohydrates: a major building block for biomass A capstone course for BioSUCCEED: Bio products S ustainability: a.

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Presentation on theme: "Biomass Fundamentals Modules 6-11: Carbohydrates: a major building block for biomass A capstone course for BioSUCCEED: Bio products S ustainability: a."— Presentation transcript:

1 Biomass Fundamentals Modules 6-11: Carbohydrates: a major building block for biomass A capstone course for BioSUCCEED: Bio products S ustainability: a U niversity C ooperative C enter of E xcellence in ED ucation The USDA Higher Education Challenge Grants program gratefully acknowledged for support

2 This course would not be possible without support from: USDA Higher Education Challenge (HEC) Grants Program

3 Emil Fischer: Father of Carbohydrate Chemistry ( ) Prof. of Organic Chemistry University of Berlin Known for his monumental work on configuration of sugars Also worked on aminoacids, proteins, indoles & stereochemistry As a Grad. student he discovered phenylhydrazine Nobel prize for Chemistry 1902

4 What is a carbohydrate? Carbohydrates are polyhydroxyl compounds general formula C n (H 2 O) n “Hydrates of Carbon” All contain hydroxyl groups -OH primary -CH 2 OH and secondary =CHOH Quiz M6/

5 What is a saccharide? A carbohydrate possessing the empirical formula, C m (H 2 O) n, or hydrates of carbon analogous to inorganic hydrates (e.g., Fe 2 (SO 4 ) 3 *6H 2 O) Shown at left is open chain form (Fischer Projection formula) of D-Glucose, isomer in which the hydroxy on C5 is RIGHT D-Glucose is a stereospecific form of glucose having the orientation specified by the Fisher Projection formula shown at left.

6 Abundance Quiz M6/11.2 Carbohydrates are the most abundant living biomaterial (a substance derived from living systems) on the planet They comprise the bulk of plants, while constituting a significant portion of the cellular membrane of animals (yet, lesser than proteins and lipids) They are however, a significant source of stored energy 1.

7 Typical carbohydrates D-glucose, D-fructose Sucrose: common table sugar that is a disaccharide synthesized from dehydration of D-glucose & D-fructose Lactose: common milk sugar that is a disaccharide of D-glucose & D-galactose

8 Structure of carbohydrates 1. Based on glyceraldehyde Quiz M6/11.1

9 Common carbohydrates ESSAY At this point, describe in a page or less, how XXX contributes to your lifestyle or how you would like it to

10 Common carbohydrate: sucrose Dimer Disaccharide Indispensable to our way of life! Notice  -acetal linkage The linkage between glucose and fructose responsible for the formation of this dimer known as sucrose is known as a glycosidic bond.

11 Nomenclature 1. Quiz M6/11.4 Monosaccharides - characterized in terms of the number of carbons

12 Nomenclature: part II Shown above are two forms of a generic amino acid (where R = carbon-containing groups) that are said to be “enantiomeric.”

13 Nomenclature: part III C1: Anomeric Carbon α : Axial configuration (vertical to the seat of the chair) β : Equatorial configuration (parallel to the seat of the chair)

14 Most Important Chemical Consideration of Sugars Consider the anomeric carbon! The aldehyde on the one position can be nucleophilically attacked by any of the hydroxyls!

15 Hemiacetalization Concept Key to Carbohydrate Ring Structures

16 Nomenclature of Carbohydrates D, L Defines the configuration at C5 D has the OH at Right in Fischer projection L has the OH at Left in Fischer projection Gluco defines the configuration of the OH at C2, C4, C5. These OH’s are on same side while the C3-OH is opposite to others α,β defines the configuration of the OH at C1, the anomeric carbon Pyran indicates 6 member ring size Furan indicates 5 member ring size Examples follow

17 In Glucuronic acid C2, C4, C5 OH’s are on same side

18 Alditols In Mannitol C2, C4, C5 OH’s are not at same side in Fisher Projection

19 Conformations [a][a][a][a] 25 D +19 o +112 o Anomers For aged solutions [a][a][a][a] 25 D = o Rotations of Fresh Solutions Reason: Mutarotation is the best evidence for the cyclic hemiacetal structure of D-(+)-glucose

20 Monosaccharides,Hemiacetal Formation II C5 OH attacks aldehyde giving a pyranose ring (6 member structure) C4 OH attacks aldehyde giving a furanose ring (5 member structure)

21 Ring closure between C1 and C4 -OH Ring closure between C1 and C5 -OH

22 Hemiacetalization Concept Key to Carbohydrate Ring Structures

23 Oligosaccharides – consist of several monosaccharide residues joined together with glycosidic linkages – di, tri, tetrasaccharides (depending on the number of monosaccharides) – up to monosaccharides (depending on analytical techniques i.e GC vs LC/MS)

24 Polysaccharides – refer to polymers composed of a large number of monosaccharides linked by glycosidic linkages

25 Cellulose  -D-anhydroglucopyranose units linked by (1,4)-glycosidic bonds

26 Polysaccharides Polysaccharides are polymers composed of many monosaccharide units linked by glycosidic bonds The glycosidic bond can can have either the α or a β-configuration and be joined to any of the hydroxyl groups at C-2, C-3, C-4 or C-6 LinearBranched The chain can either be Linear or Branched –branches can be single monosaccharide units, chains of two or more units, or chains of a variable number of units

27 Polysaccharides Polysaccharides can be divided into two classes –Homopolysaccharides celluloseconsist of only one kind of monosaccharide ex cellulose –Heteropolysaccharides consist of two or more kinds of monosaccharides galactoglucomannans ex galactoglucomannans

28 Homopolysaccharides Homopolysaccharides can be further divided by the type(s) of glycosidic linkages Homolinkages Homolinkages - either an α or a β configuration to a single position (exclusive of any branch linkages) that is a single kind of monosaccharide linked by one type of bond α-1  4, β-1  4, and so on Heterolinkages Heterolinkages - a mixture of a- and b- configurations and/or mixture of positions usually have a definite pattern for the arrangement of the linkages

29 Heteropolysaccharides Heteropolysaccharides can have the same kind of linkage diversity as with homopolysaccharides, but now associated with one or more of the different kinds of monosaccharide units – infinite degree of diversity of structure

30 Polysaccharides Polysaccharides can not only have different sequences of monosaccharide units, but also different sequences of glycosidic linkages and different kinds of branching –a very high degree of diversity for polysaccharides and their structure- function relationships

31 Plant Polysaccharides The conformation of individual monosaccharide residues in a polysaccharide is relatively fixed, however, joined by glycosidic linkages, they can rotate to give different chain conformations. 1,4 glycosidic linkage 1,6 glycosidic linkage

32 The different kinds of primary structures that result in secondary and tertiary structures give different kinds of properties – water solubility, aggregation and crystallization, viscosity, gelation, etc. Polysaccharides have a variety of functions – Storage of chemical energy in photosynthesis – Inducing Structural Integrity in plant cell walls Plant Polysaccharides

33 Starch Starch is composed completely of D-glucose – found in the leaves, stems, roots, seeds etc in higher plants – stores the chemical energy produced by photosynthesis Most starches are composed of two types of polysaccharides - amylose and amylopectin – amylose - a mixture of linear polysaccharides of D-glucose units linked  -(1-4) to each other between 250-5,000 glucose residues

34 The Components of Starch Amylose

35 Amylopectin – Amylopectin - a mixture of branched polysaccharides of D- glucose units linked  -(1-4), with ~ 5%  -(1-6) branch linkages between 10, ,000 glucose residues

36 Starch Polymer Components Amylose Amylopectin (1 residue in every 20 is 1  6 linked to branch off)

37 The Components of Starch Amylose Amylopectin Starch tertiary structure (Helix)

38 Building Blocks of Life

39 Hemiacetalization Concept Key to Carbohydrate Ring Structures

40 Fructose is Bane of Our Civilization Glycoproteins (biomaterial) from food sugars are sticky – adhere to teeth enamel Streptococcus mutans also adhere to biomaterial The glucose of the sucrose is polymerized by glucosyl transferase (enzyme of bacteria) to form plaque Fructose from the above hydrolysis is released Bacteria needs anaerobic conditions which are partially supprted by plaque to hydrolyze fructose for energy Ca 3 (PO 4 ) 2 + CH 3 CH 2 (OH)COOH  CaHPO 4 + Ca +2  loss of enamel

41 Alditols: Reduction Products D-Mannitol Reduced aldehyde end-group

42 Aldaric Acids: Oxidation Products Above is oxidation product of D-galactose Galactaric acid Why is it not labeled as “D- ?”

43 Sorbitol (D-Glucitol) It is a polyol discovered in the berries of the mountain ash in 1872 commercially produced by the hydrogenation (reduction) of glucose). It does not lead to tooth decay. WHY? 60% as sweet as sucrose with 1/3 fewer calories Good sugar substitute

44 Relative Sweetness COMPOUNDRELATIVE SWEETNESS Lactose0.2 D-Galactose0.3 Maltose0.3 D-Glucose0.7 Sucrose1.0 (Standard) D-Fructose1.7 Sodium cyclamate (procarcinogen)30 Aspartame190 Sodium saccharin (possible carcinogen)500 Sucralose (brand name = Splenda)600 Neohespiridin dihydrochalcone1,000 5-nitro-2-propoxyaniline4,000

45 Glucose Derivative Spotlight: Glucosamine Found in mucin, a glycoprotein constituent of saliva Plays important role in production, maintenance, and repair of cartilage (prevents bone ends from rubbing) Used in Europe since 1980s to “offset” onset of osteoarthritis USA is now touting its benefits (perform search – 906K hits) Nitrogen

46 Most Important Chemical Consideration of Sugars Consider the anomeric carbon! The aldehyde on the one position can be nucleophilically attacked by any of the hydroxyls!

47 Important Oligosaccharides ,  -tetrahalose: glucose disaccharide found in the circulatory systems of insects; energy for insect eggs, larvae, and pupae. Found in fungi & yeasts Raffinose: widely distributed in plants at low concentration – 1:1:1 D-galactose:D- glucose:D-fructose (galactose+sucrose in which it is on C6 of glucose moiety)

48 Starch (Amylose) High MW polyglucoside that is plant energy Can be hydrolyzed to specific oligosaccharides  -Amylase (saliva & pancreatic juice) converts it to maltose and glucose  -Amylase (in plants only) converts it to maltose – NOTE: malt from barley is its common source to BREW BEER

49 Starch, Part Deux Noncrystalline Partially water soluble 25% amylose (linear polysaccharide), 75% amylopectin (branched polysaccharide)

50 Starch Polymer Components Amylose Amylopectin (1 residue in every 20 is 1  6 linked to branch off)

51 Homework Questions Draw structure of raffinose by only consulting these notes! Provide an explanation for the “sweetness” of saccharides – you may consult the literature Using your explanation, design a molecule that may compete with commercial sugars for market share!

52 Article of Interest for Discussion “Chemically modified chitin and chitosan as biomaterials” – Sashiwa, H.; Aiba, S.-I. Prog. Polym. Sci. 29 (2204) &_cdi=5578&_user=290868&_orig=search&_coverDate=09%2F30%2F2004&_qd=1&_sk = &view=c&wchp=dGLbVzb- zSkzS&md5=e9e66537b26f5f d9f01635b8&ie=/sdarticle.pdf 6&_cdi=5578&_user=290868&_orig=search&_coverDate=09%2F30%2F2004&_qd=1&_sk = &view=c&wchp=dGLbVzb- zSkzS&md5=e9e66537b26f5f d9f01635b8&ie=/sdarticle.pdf Chitosan-derivatized  -CD (2-position) Slow radiative iodine release in blood of rats Decontamination of textile dye-laden waters Absorbent matrix Positive cholesterol interaction

53 Structure of Starch Unbranched chains K  -(1  4)-D- glucose units Extended shape has possible 7-22 nm hydrodynamic radius Usually forms stiff left- handed single helix

54 Hydrogen Bonding in Amylose Single helical amylose has H-bonding between O2  O6 atoms on outside Syneresis (release of water) occurs Double-stranded crystallites formed resistant to amylase Fairly hydrophobic & low solubility Interior is like cyclodextrins – hydrophobic

55 Cyclodextrins (CDs) Cyclic oligomers of  -D- glucopyranose Glycosidic bonds Discovered in 1891 by Villiers Synthesized by the enzymatic conversion of amylose & selective precipitation Cavity volume: 0.174, 0.262, & nm 2 for , , &  -CDs, respectively

56 CD Formation Precipitating Agent Yield (%)  -CD 1-decanol40  -CD toluene50-60  -CD Cyclohexadec- 8-en-1-ol 40-50

57 Interesting Properties Formation of inclusion (host/guest) complexes with lipophilics –  -CD: aliphatic chains –  -CD: small aromatics (toluene) –  -CD: larger molecules Low toxicity Biodegradable

58 From Frömming and Szejtli: Cyclodextrins in Pharmacy, Kluwer, Acad. Press, Dordrecht, 1994.

59 Cyclodextrin Derivatives of Pharmaceutical Interest CyclodextrinRDS HP  CD CH 2 CHOHCH SBE  CD (CH 2 ) 4 SO 3 - Na RM  CD CH Also the CD derivative: HPCD

60 Some cyclodextrin-containing products CyclodextrinProductTrade name  CD PEG 1 iv infusionProstavastin (Eur.), Caverject (USA)  CD Piroxicam tabletsBrexin (Eur.) HP  CD Intraconazole oral solution and iv soln. Sporanox (Eur. and USA) SBE  CD Ziprasidone maleate im solution Zeldox (Eur.), Geodon (USA) RM  CD Estradiol nasal sprayAerodiol (Eur.)  CD OP-1206 tabletsOpalmon (Japan) HP  CD Diclofenac sodium eye drop solution Voltaren (EUR.) World-wide there are close to 30 cyclodextrin containing pharmaceutical products on the market and most of them are marketed in more than one country. Almost half of them contain the natural CD.

61 What are cyclodextrins used for? To increase aqueous solubility of drugs. To increase chemical stability of drugs. To enhance drug delivery to and through biological membranes. To increase physical stability of drugs. To convert liquid drugs to microcrystalline powders. To prevent drug-drug and drug-excipient interactions. To reduce local irritation after topical or oral administration. To prevent drug absorption into skin or after oral administration. And so on.

62 Cyclodextrin complexation: conventional wisdom  -Cyclodextrin: Seven  -1,4-linked gluco- pyranose units form a cone with a hydrophilic outer surface and a lipophilic cavity in the center.

63 From Frömming and Szejtli: Cyclodextrins in Pharmacy Kluwer Acad. Press, Dordrecht, Complex Formation

64 Cyclodextrin Complexes Doxorubicin-  CD complex Aspirin-  CD complex

65 Why are cyclodextrins better than organic solvents? Frequently less irritating after iv and im injection. Frequently less toxic. The drug does not precipitate after iv injection. Can be used in solid dosage forms.

66 Homework Questions Describe why CD is in “Fabreeze” (P&G product) and how you think it works. How do K 1:3 complexes form? Give an example.


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