Natural Products from Acetate Pathway (Carbohydrates) PDF

NATURAL PRODUCTS FROM ACETATE PATHWAY (CARBOHYDRATES) Assoc. Prof. Dr. Juriyati Jalil Faculty of Pharmacy Universiti Kebangsaan Malaysia CARBOHYDRATES Hydrate of carbon CnH2nOn or Cn(H2O)n More frequently referred as saccharides. Class: Monosaccharides...

NATURAL PRODUCTS FROM ACETATE PATHWAY (CARBOHYDRATES) Assoc. Prof. Dr. Juriyati Jalil Faculty of Pharmacy Universiti Kebangsaan Malaysia CARBOHYDRATES Hydrate of carbon CnH2nOn or Cn(H2O)n More frequently referred as saccharides. Class: Monosaccharides Disaccharides Oligosaccharides Polysaccharides CARBOHYDRATES Most abundant constituents of plants, animals and microorganisms Monosaccharides and disaccharides: sweet-tasting and soluble Polysaccharides: not sweet & insoluble Functions Product of photosynthesis as food reserves Precursors of 2 metabolites CARBOHYDRATES Contain a carbonyl group as an aldehyde or ketone and more then one alcohol group. The two simplest carbohydrates molecules: MONOSACCHARIDES Monosaccharides Simple sugar – cannot be hydrolysed to simpler compounds. Acyclic monosaccharides pentose (C5H10O5) hexose (C6H12O6) Aldose has aldehyde group e.g. aldohexose, aldopentose Ketose has ketone group e.g. ketohexose, ketopentose ACYCLYIC ALDOSES ACYCLYIC KETOSES Monosaccharides Cyclic monosaccharides Furanose (cyclic pentose) Pyranose (cyclic hexose) Cyclic monosaccharides Monosaccharides in Pharmacy D-Glucose (dextrose) Occur in many plant species Obtained by enzymatic hydrolysis of starch Used as IV infusion for Prevention of dehydration & common rehydration Treatment of ketosis in malnutrition Parenteral feeding (caloric intake) Treatment of hypoglycaemia D-Sorbitol Occur in fruits of various Rosaceae (esp. Sorbus aucuparia) & thallus of certain seaweeds Obtained semi-synthetically from glucose Uses Treatment of constipation & dyspepsia (As glucose injectable solutions) Sweetener for diabetic products Pharmaceutical excipient D-Mannitol Occur naturally in manna (Fraxinus ornus, Oleaceae) Obtained semi-synthetically from glucose Used as diuretic Vitamin C (L-(+)-threo- ascorbic acid) Occur in fruits & vegetables but abundant in Rose hips (Rosa canina, Rosaceae) Roselle (Hibiscus sabdariffa, Malvaceae) Tamarind (Tamarindus indica, Fabaceae) Biosynthesised in plant from D- glucose DISACCHARIDES Disaccharides Derived from two monosaccharide units Non-reducing sucrose trehalose Reducing maltose cellobiose lactose lactulose sophorose Disaccharides in Pharmacy Sucrose -D-glucopyranosyl-(1→4)--D-fructofuranoside Obtained from various sources Sugar cane (Saccharum officinarum, Poaceae) Sugar beet (Beta vulgaris, Chenopodiaceae) Sugar maple (Acer saccharum, Aceraceae) Used as sweetening agent for syrups & drug preparations Disaccharides in Pharmacy Lactose -D-galactopyranosyl-(1→4)--D-glucopyranoside Obtained from cow’s milk as by-product from cheese-making (whey) Used as diluent in tablet formulations Lactulose -D-galactopyranosyl-(1→4)--D-fructofuranoside Obtained semi-synthetically from lactose Used as laxative & in hepatic encephalopathy Other Disaccharides Name Products of Hydrolysis Occurrence Maltose -Glucose, glucose Enzymic hydrolysis of starch Cellobiose -Glucose, glucose Enzymic hydrolysis of cellulose Trehalose Glucose, glucose Ergot, Rhodophyceae, yeasts Sophorose Glucose, glucose Sophora japonica, hydrolysis of stevioside OLIGOSACCHARIDES Oligosaccharides Derived from 3-10 monosaccharide units As food reserves & involved in formation of glycosides Simple oligosaccharides e.g. raffinose, umbelliferose, gypsoside A Cyclodextrin (cyclic oligosaccharide) Obtained semi-synthetically from starch Used as pharmaceutical excipient Trisaccharides & Tetrasaccharides Name Products of Hydrolysis Occurrence Gentianose Glucose, glucose, fructose Gentiana sp. Planteose Glucose, fructose, galactose Seeds of Psyllium sp. Raffinose Galactose, glucose, fructose Many seeds (e.g. cottonseed) Manneotriose Galactose, galactose, Manna of ash (Faxinus ornus) glucose Rhamninose Rhamnose, rhamnose, Rhamnus infectora galactose Scillatriose Rhamnose, glucose, glucose Glycoside of squill Stachyose Galactose, galactose, Tubers of Stachys japonica & glucose, fructose manna of ash POLYSACCHARIDES Polysaccharides High MW polymers of a large number of monosaccharide units linked through glycosidic linkage Type Examples Homegenous Amylose, amylopectin, starch, fructans Heterogenous Gums, mucilage, pectin, heparin Linear Amylose, cellulose Branched Amylopectin Polysaccharides Functions: Food reserves Protect tissues against dehydration Polysaccharides in Pharmacy Starch Obtained from various sources Maize (Zea mays, Gramineae) Wheat (Triticum aestivum, Gramineae) Potato (Solanum tuberosum, Solanaceae) Rice (Oryza sativa, Gramineae) Mostly consist of amylose (25%) & amylopectin (75%) Soluble starch is obtained by partial acid hydrolysis Used as dusting powder, swelling agent & disintegrant Polysaccharides in Pharmacy Cellulose Extracted from wood pulp & cotton (Gossypium sp., Malvaceae) Use of semi-synthetic derivatives Microcrystalline cellulose: tablet diluent Methylcellulose, hydroxymethylcellulose, CMC : emulsifying & suspending agents Cellulose acetate phtalate: acid-resistant enteric coating