Abstract:

The extraction of crude polysaccharides from Hemerocallis citrina Baroni (CPH) by water extraction and alcohol
precipitation was optimized using one-factor-at-a-time and orthogonal array methods. After CPH was deproteinized by
Sevag method and decolorized by H2O2 oxidation method, the physicochemical properties and structure of the deproteinized
polysaccharides from (DPH) were analyzed and characterized by UV spectrometry, infrared (IR) spectrometry and high
performance liquid chromatography (HPLC). Meanwhile, the inhibitory activities of DPH against Pseudomonas aeruginosa,
Escherichia coli, Staphylococcus aureus, Candida albicans and Aspergillus niger were investigated. The results showed that
the optimal conditions for CPH extraction were determined as two extraction cycles with distilled water at a solvent/solid
ratio of 20:1 (mL/g) at 75 ℃ for 3 h. Under these conditions, the extraction yield of CPH was 28.36%. Meanwhile, DPH was
water-soluble heteropolysaccharides which possessed the structure of α-pyranosides and consisted of L-rhamnose, D-xylose,
L-arabinose, D-mannose, D-glucose and D-galactose. DPH was probably formed by conjugation of polysaccharides with
proteins or polypeptides through peptide bonds. Furthermore, DPH had strong inhibitory activities against Staphylococcus
aureus, Pseudomonas aeruginosa, and Escherichia coli, their corresponding minimum inhibitory concentrations (MICs)
were 10, 10, and 25 mg/mL, respectively.

Key words: Hemerocallis citrina Baroni, polysaccharides, extraction process, characterization, antimicrobial activity