Determining Methyl-Esterification Patterns in Plant-Derived Homogalacturonan Pectins

Abstract

Homogalacturonan (HG)-type pectins are nutrient components in plants and are widely used in the food industry. The methyl-esterification pattern is a crucial structural parameter used to assess HG pectins in terms of their nutraceutical activity. To better understand the methyl-esterification pattern of natural HG pectins from different plants, we purified twenty HG pectin-rich fractions from twelve plants and classified them by their monosaccharide composition, Fourier transform-infrared spectroscopy (FT-IR) signatures, and NMR analysis. FT-IR shows that these HG pectins are all minimally esterified, with the degree of methyl-esterification (DM) being 5 to 40%. To examine their methyl-esterification pattern by enzymatic fingerprinting, we hydrolyzed the HG pectins using endo-polygalacturonase. Hydrolyzed oligomers were derivatized with 2-aminobenzamide and subjected to liquid chromatography-fluorescence-tandem mass spectrometry (HILIC-FLR-MSn). Twenty-one types of mono-/oligo-galacturonides having DP values of 1–10 were found to contain nonesterified monomers, dimers, and trimers, as well as oligomers with 1 to 6 methyl-ester groups. In these oligo-galacturonides, MSn analysis demonstrated that the number of methyl-ester groups in the continuous sequence was 2 to 5. Mono- and di-esterified oligomers had higher percentages in total methyl-esterified groups, suggesting that these are a random methyl-esterification pattern in these HG pectins. Our study analyzes the characteristics of the methyl-esterification pattern in naturally occurring plant-derived HG pectins and findings that will be useful for further studying HG structure-function relationships.

Toxicological evaluation of a pumpkin-derived pectin preparation: in vitro genotoxicity studies and a 13-week oral toxicity study in Sprague-Dawley rats

“…The most abundant component of pectin is homogalacturonan (HG), which is composed of galacturonic acid (GalA) residues; GalA residues exist in methyl esterified and/or acetylated states. 13 Another component of pectin, rhamnogalacturonan-I (RG-I), is a heteropolymer consisting of a backbone of alternating rhamnose and GalA residues with arabinose- and/or galactose-containing sidechains, and possible O -methyl- and acetyl esterified GalA residues 14 , 15 ( Fig. 1 ).…”

Physicochemical and antioxidant properties of pectin from Actinidia arguta Sieb.et Zucc (A. arguta) extracted by ultrasonic

“…Its galacturonic acid residues are often esterified by some groups such as methoxyl and amide. The degree of esterification is also called methoxylation, which refers to the sum of the proportions of methylesterification, acetylation, and amidation in pectin ( 3 ). Although the esterification degree of UAP (66.6%) is lower than the SAP (75%), indicating that the cavity effect of ultrasound may have broken the ester bond, resulting in the esterification degree of pectin decreasing the UAP and the SAP all belong to the high ester pectin (≥50%) ( 7 ).…”

“…The molecular main chain and branch chain structures of pectin are different. They are divided into four configurations, namely, homocysteine, rhamnogalacturonan I, rhamnogalacturonan II, and xylogalacturonan ( 3 ). The backbone of RG-I is different: it is composed of repeating units of galacturonic acid (GalA) residues and rhamnose (Rha).…”

“…Studies have shown that the configuration is an important parameter of pectin, which is closely related to the physical and chemical properties and biological activity of pectin ( 1 ). Studies have shown that substituting rhamnose-galacturonic acid (RGs) for pectin can prevent cancer ( 4 ) by inducing cancer cell apoptosis ( 3 ).…”

Chemical Characterization Analysis, Antioxidants, and Anti-Diabetic Activity of Two Novel Acidic Water-Soluble Polysaccharides Isolated from Baobab Fruits

“…The two medium peaks shown in regions 1425.72 cm −1 and 1415.2 cm −1 proved the existence connected to the stretching of the methyl ester group in the pectin–CH3. These perhaps indicate the esterification of some of the uronic acid carboxyl [ 27 ].…”