caracterisation of the pectin, Cheat Sheet of Biochemistry

Download caracterisation of the pectin and more Cheat Sheet Biochemistry in PDF only on Docsity! 1 University of Monastir Faculty of Sciences of Monastir Department of ChemistryMR SRCO2 The pectin Academic year 2022-2023 the origin of pectin, structure, properties and his methods of extraction Chemical modifications on pectin The pharmacological applications of pectin Pectin as carrier of active substances Part I Part II Part III Part IV 2 HG RGI RG ll XG AG Vf I } OX) Lateral chain B eK Lateral chain A - COOH ~ OH * - <>) D-Galacturonic acid <)> L-Rhamnose 0 D-Dha @ 0-Xylose © O-acetyl ester © D-Galactose © D-Apiose @ 1- Galactose © L-Aceric acid oO Kdo** O L-Fucose 8 D-Glucuronic acid Borate © O-methyl ester <O arabinose *D-Dha = 3-deoxy-D-lyxo-2-heptulosaric acid **Kdo = 3-deoxy-D-manno-2-octulosonic acid 6 2.Pectin biopolymer This biopolymer is mainly composed of galacturonic acid monomers, which polymerize by 1-4 a-type glycosidic bonds to form pectin chains, known as the straight-chain homogalacturonic region . The glycosidic or osidic bond involves the hydroxyl functions of the monomer in the C1 and C4 position.This bond results from the condensation of 2 hydroxyl functions of 2 different monomers with the elimination of a molecule of water. 7 3.Degree of esterification Two types of pectins are then identified:  “highly methylated pectins” (HM), corresponding to more than 50% methylation of acid functions  “low methylated pectins” (LM) , corresponding to less than 50% methylation of acid functions . The DM of pectin depends on its vegetable origin, the type of tissue and its maturity. In the natural state, we essentially find HM pectin with a DM which varies between 60 and 90% . 10 3.Viscosifying properties Agents known as viscosifiers have the property of modifying the behavior of the continuous phase, without forming junction zones unlike gelling agents and certain stabilizers. HM pectin has this characteristic due to its high molecular weight. Also , we find its use in fruit drinks. 11 4.Gelling properties Pectin HM Pectin LM The gelation of HM pectins is enabled by a set of hydrogen bonds and hydrophobic interactions forming a three-dimensional network,comprising a solvent. The presence of cations with pectin LM leads to the formation of interactions between the chains, forming cationic bridges. These associations are responsible for the formation of a gel. 12 Source of pectin Selected pectins have a high carboxylic acid content. Requirements in the food and pharmaceutical industry are a minimum of 65% galacturonic acids. the main commercially acceptable sources apple pomace citrus zest It is found in jams to complement that made from the fruit. 15 Microwave extraction 15 min of microwave heating is equivalent, in quantity of pectin extracted, to an extraction of 3 h in an acid medium. In addition, microwave extraction would limit the pectin depolymerization phenomena that can be observed during acid extraction. In this method, during microwave heating, pressure builds up in the material to be extracted. This pressure modifies the cellular structure of the residue and allows better penetration of the extraction solvents . In this method : J.S. Quesnel, B.A. Arndtsen. Pure Appl. Chem. 2013, 85, 377–384 16 Ultrasound Assisted Heating Extraction Ultrasound-assisted hot extraction is a method studied to reduce:  the extraction time  increase the yield compared to conventional methods (hydrolysis in an acid medium). The research on this type of extraction remains limited. Indeed, it has been found that ultrasound tends to degrade polymers like pectin. 17 Chemical modifications on pectin 1 .Alkylation reactions The alkylation reaction is a reaction where the substituent is an alkyl group. For pectin, two sites favor this reaction:  the carboxylic group of galacturonic acids  the hydroxyl functions present on the pectin skeleton. This reaction aims to increase the hydrophobicity of the pectin, to modify the gelation as well as the rheological properties. 2.Amidation reactions this reaction brings a thermoreversible character to pectin gels.They can be liquefied by heating and then solidified again after cooling, which is not possible with conventional pectin gels. This modification can also be used for crosslinking preparation. . Nolte, P. Mayer and B. F. Straub, Angew. Chem. Int. Ed., 2007, 46, 2101. 20 In vitro studies, involving colonic adenocarcinoma cells incubated in the presence of pectin, have demonstrated that pectin is involved in the apoptotic phenomena of these cells. In vivo studies have also observed a decrease in tumor volume in subjects treated with pectin. 2.Anti-cancer activities a) J. E. Hein and V. V. Fokin, Chem. Soc. Rev., 2010, 39, 1302; (b) M. Meldal and C. W. Tornøe, Chem. Rev., 2008, 108, 2952. 21 Pectin as carrier of active substances Exemple : Tablets Pectin has been widely studied in the formulation of tablets for the oral route. This biopolymer has notably been used as a matrix or coating in controlled-release tablets. Work on this subject has thus demonstrated that the use of pectin in the formulation ensures the passage of the stomach , and ileum. 22 Conclusion In conclusion, pectin is a widely available polysaccharide among plant resources. It is also inexpensive, biodegradable, biocompatible and non-toxic. Its structure is mainly composed of galacturonic acids linked by glycosidic bonds. Its composition, depending on its plant origin, gives it many physical properties. The most important of its properties is the ability to gel, allowing it to form a three-dimensional network under certain conditions. Added to this are the therapeutic properties of pectin in the prevention of certain pathologies (in addition to conventional treatments (example: cancer, diabetes,,,, ), or even as therapeutic alternatives . Therefore, pectin is a polymer that offers the opportunity to create innovative materials with properties suitable for a wide variety of applications.