Purification, characterization, and determination of biological activities of water-soluble polysaccharides from Mahonia bealei

Abstract

Mahonia bealei is one of the important members of the genus Mahonia and Traditional Chinese Medicine (TCM). Several compounds isolated from this plant have exhibited useful biological activities. Polysaccharides, an important biomacromolecule have been underexplored in case of M. bealei. In this study, hot water extraction and ethanol precipitation were used for the extraction of polysaccharides from the stem of M. bealei, and then extract was purified using ultrafiltration membrane at 50,000 Da cut off value. Characterization of the purified M. bealei polysaccharide (MBP) was performed using Fourier Transform Infrared Spectroscopy (FT-IR), along with Scanning Electron Microscopy (SEM), X-ray crystallography XRD analysis and Thermal gravimetric analysis (TGA). The purified polysaccharide MBP was tested for antioxidant potential by determining its reducing power, besides determining the DPPH, ABTS, superoxide radical, and hydroxyl radical scavenging along with ferrous ion chelating activities. An increased antioxidant activity of the polysaccharide was reported with increase in concentration (0.5 to 5 mg/ml) for all the parameters. Antimicrobial potential was determined against gram positive and gram-negative bacteria. 20 µg/ml MBP was found appropriate with 12 h incubation period against Escherichia coli and Bacillus subtilis bacteria. We conclude that polysaccharides from M. bealei possess potential ability of biological importance; however, more studies are required for elucidation of their structure and useful activities.

Figure 1

Ultrafiltration setup: 1—Tank (containing nitrogen), 2—Regulator (for pressure), 3—Manometer, 4—Membrane, 5—Stirred ultrafiltration cell, 6—Magnetic stirrer, 7—Container (for permeate), Figure adopted from.

Figure 2

Schematic representation of the experimental process used in the study.

Figure 3

FT-IR spectra of the MBP.

Figure 4

SEM micrographs of the materials. (a) The morphology of MBP shown at 100. (b) The morphology of MBP shown at 5000 magnifications.

Figure 5

X-ray diffraction patterns of the polysaccharide.

Figure 6

TGA analysis of the obtained polysaccharide.

Figure 7

Reducing power of the MBP.

Figure 8

DPPH free radical scavenging activity of the MBP.

Figure 9

ABTS radical scavenging activity of the polysaccharide.

Figure 10

Superoxide scavenging ability of the MBP.

Figure 11

Hydroxyl scavenging ability of MBP polysaccharide.

Figure 12

Ferrous ion chelating activity of the polysaccharide.

Figure 13

Results of E. coli (A–D) and B. subtilis (E–H) treated with various concentration at 0, 5, 10 and 20 µg/mL of MBP at 0.5, 1, 2, 4, 8, & 16, that is, different intervals of time (hours).

Figure 14

Colonies forming unit of (CFU) method to colonies (A) E. coli and (B) B. subtilis treated with various concentration at 0, 5, 10 and 20, µg/ml of MBP at 0, 3, 6, 9, and 12 different intervals of time (hour).

Figure 15

Measured OD curves of (A) E. coli and (B) B. subtilis treated with different concentrations of Mahonia bealei polysaccharides (MBP) at different interval times 0, 3, 6, 9, 12 h.