Immunostimulatory Polysaccharides from Chlorella pyrenoidosa. A New Galactofuranan. Measurement of Molecular Weight and Molecular Weight Dispersion by DOSY NMR

Abstract

Fractionation of the hot water extract of Chlorella pyrenoidosa was performed using a combination of ethanol precipitation, size exclusion chromatography, and anion exchange chromatography. One fraction contained a new polysaccharide, and this compound was shown to be a 1-->2-linked beta-d-galactofuranan from its 1D and 2D (1)H and (13)C NMR spectra, with a molecular weight of 15 kDa from DOSY NMR measurements. A number of other fractions were shown to have the same repeating unit as the previously identified arabinogalactan. However, arabinogalactans from different fractions were shown by DOSY NMR to have different molecular weights, which ranged from 27 to 1020 kDa. Agreement with molecular weights measured for some of these fractions by SEC-MALS was very good, further confirming the relationship established by Viel et al. between molecular weights of neutral polysaccharides and self-diffusion coefficients. The smaller molecular weight polysaccharides, the galactofuranan and the 27 and 50 kDa arabinogalactans, were shown to be close to monodisperse by analysis of the distributions of the self-diffusion coefficients for the polymers. The larger arabinogalactans had considerable variation in their molecular weights (188 +/- 109 kDa and 1020 +/- 370 kDa). Only the two larger arabinogalactans showed immunostimulatory activity.

Quality analysis of commercial Chlorella products used as dietary supplement in human nutrition

“…Currently, Chlorella is produced by more than 70 companies (Spolaore et al 2006) and contains several novel properties. A special polysaccharide is considered as the most important substance and serves as active immunostimulator, free-radical scavenger and reducer of blood lipids (Suárez et al 2005;Suárez et al 2006). Other healthpromoting effects of Chlorella are the lowering of cholesterol (Fujiwara et al 1990), preventive action against artherosclerosis (Sano and Tanaka 1987) or antitumor action (Noda et al 1996).…”

Characterization, antioxidant and immunomodulatory activities of polysaccharides from Prunella vulgaris Linn

“…PV-P2 and PV-P3 also increased the production of NO, TNF-␣, and IL-6 in a dose-dependent manner, but were less effective than PV-P1. This may be attributed to the higher molecular weight and higher degree of branching of PV-P1 [12]. All three fractions had strong immunomodulatory activities.…”

“…Previous reports have shown that the anti-cancer activity and immunomodulatory activity are related to the triple helical conformation of (1→3)-␤-glucan main chain for some polysaccharides, such as lentinan isolated from the fruit body of Lentinula edodes [11]. The arabinogalactans with higher molecular weight, extracted from Chlorella pyrenoidosa cells, showed immune-stimulatory activity, but low molecular weight fractions did not [12]. To date, some polysaccharides have been isolated from the fruit clusters of P. vulgaris using different methods [3,4].…”

β-Glucan Contents and Anti-wrinkling Effects of Brown Rice <i>Phellinus linteus</i> Mycelium Extracts Fermented with Lactobacillus plantarum

“…The HOD signal was achieved by a presaturation for 0.5 s. NMR diffusion ordered spectroscopy (DOSY) experiments were carried out using the standard pulse sequence on the same AV-600 NB spectrometer for determination of molecular weight. The equation for DOSY experiments was as follows [17];…”

“…Recently, investigators developed NMR DOSY as a useful tool for measurement of molecular weights, including those of polysaccharides [17,23]. Using the equation in the experimental section, the estimated molecular weight of LMG is 3979 Da.…”