ɇАɍЧɇИ ɌɊɍȾɈȼȿ ɌɈɆ LX “ХɊАɇИɌȿɅɇА ɇАɍɄА, ɌȿХɇИɄА И ɌȿХɇɈɅɈȽИИ – 2013“ 18-19 оɤтоɦври 2013, ɉɥовдив SCIENTIFIC WORKS VOLUME LX „FOOD SCIENCE, ENGINEERING AND TECHNOLOGIES – 2013“ 18-19 October 2013, Plovdiv 740 PECTINOLYTIC ENZYMES – APPLICATION FOR STUDYING AND PREPARATION OF IMMUNOMODULATING PECTIC POLYSACCHARIDES FROM FRUITS, VEGETABLES AND MEDICINAL PLANTS. A REVIEW Yordan N. Georgiev 1,3 , Manol H. Ognyanov 1,3 , Veselin K. Kussovski 2 , Maria G. Kratchanova 1,3, * 1 Laboratory of Biologically Active Substances, Institute of Organic Chemistry with Center of Phytochemistry, 139 Ruski Blvd., 4000 Plovdiv, Bulgaria 2 Department of Infectious Microbiology, Laboratory of Antimicrobial Resources, Institute of Microbiology “Stephan Angeloff“, 1113 Sofia, Bulgaria 3 Innovative-Technological Center – Plovdiv * Corresponding author. e-mail address: lbas@plov.omega.bg; tel/fax.: +359 32 64 27 59 Abstract Biogenic pectic polysaccharides are non-specific immunomodulators with beneficial and therapeutic potential as nutraceuticals. They consist of a linear acidic region - homogalacturonan and a highly branched domain with mainly neutral monosaccharide side chains – rhamnogalacturonan I and II. Pectinases form one of the biggest and most diverse in activity group of carbohydrate biocatalysts. They are a useful biochemical tool for fine exploration and modification of the native pectic structure. Owing to their strict specificity and unaggressive degradation ability some pectinases contribute to partly removal of homogalacturonan and different ester-linked groups, leading to preservation of the immunologically active hairy rhamnogalacturonan units. The bioactive fragments in the hairy regions are determined by using arabinogalactan-degrading enzymes. Summarized in the present review are the chemistry of pectins and the catalytic potential of pectinases for studying and modification of pectic immunogenicity. Keywords: arabinogalactan-degrading enzymes; immunomodulating nutraceuticals; non-specific immunomodulators; pectic polysaccharides; pectinases. Introduction Chemistry of pectic polysaccharides Pectic substances have been a natural ingredient in human nutrition in all stages of our evolutionary development, which has practically determined the ideal adaptation to them. They are administrated by consumption of fruits and vegetables and it is considered that they don’t have any nutritional value for humans. Pectins are contained in large amounts in apples (10-15%), citrus fruits (25-35%), sugar beet (10-20%) and sunflower heads (20-29%) [1; 2]. Pectic substances were discovered in 1790 by the French chemist Louis Vauquelin (1763-1829) and the name “pectin” (from greek “pektikos” - "congealed, curdled”) was given by the French scientist Henri Braconnot (1780-1855) [3; 4]. Pectin is presented in the primary cell wall and middle lamella of all higher plants, where it is responsible for different physiological processes [5]. Nowadays, it is well known that pectin is maybe the most complex heteropolysaccharide on the Earth. The most investigated and simply arranged fragment from pectic macromolecule is the unbranched homogalacturonan (HG). It is built from α-D-galacturonopyranosyl residues linked by (1→4)- glycosidic bonds, forming a linear chain [6]. HG could be composed of several hundred to one thousand monosaccharide units, that corresponds to molecular weight of 50 to 150 kDa [7]. The highest HG content have sunflower (< 90%), citrus (~ 78%) and apple pectins (~ 70%) [8; 9]. HG is water soluble at neutral and alkaline pH, but insoluble at acidic media and in presence of divalent metal ions [10]. Depending on the plant source, a different part of α-D-GalpA carboxyl groups could be methylesterified, which leads to low-