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Yam tuber mucilage as a candidate substance for saliva substitute: in vitro study of its viscosity and influences on lysozyme and peroxidase activities

Authors

  • Hong-Seop Kho,

    Corresponding author
    1. Department of Oral Medicine and Oral Diagnosis, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea
    • Correspondence to:

      Prof. Hong-Seop Kho, Department of Oral Medicine and Oral Diagnosis, School of Dentistry and Dental Research Institute, Seoul National University, Yunkeun-Dong 28, Chongro-Ku, Seoul 110-749, Korea.

      Tel.: +82 2 2072 3989

      Fax: +82 2 744 9135

      E-mail: hkho@snu.ac.kr

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  • Moon-Soo Park,

    1. Department of Oral Medicine and Diagnosis, College of Dentistry, Kangnung-Wonju National University, Kangnung, Korea
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  • Ji-Youn Chang,

    1. Department of Oral Medicine and Oral Diagnosis, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea
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  • Yoon-Young Kim

    1. Department of Oral Medicine and Oral Diagnosis, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea
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Abstract

Objective

To investigate the viscosity of yam tuber mucilage (YTM) and its effects on lysozyme and peroxidase activities in solution phase and on surface phase.

Methods

Two kinds of YTM were extracted, one containing both protein and carbohydrate and the other containing mainly carbohydrate. Hen egg-white lysozyme and bovine lactoperoxidase were used as lysozyme and peroxidase sources, respectively. Viscosity was measured with a cone-and-plate digital viscometer. Lysozyme activity was determined using the turbidimetric method, and peroxidase activity was determined using the NbsSCN assay. Hydroxyapatite beads were used as a solid phase.

Results

The viscosity values of YTM followed a pattern of a non-Newtonian fluid. The carbohydrate concentration affected the viscosity values at all shear rates, while the protein concentration affected the viscosity values at low shear rates. It could be suggested that YTM composed of 1.0 mg/ml protein and 1.0 mg/ml carbohydrate has viscosity values similar to those of unstimulated whole saliva at shear rates present at routine oral functions. Hydroxyapatite-adsorbed YTM significantly increased the adsorption and subsequent enzymatic activities of lysozyme, but not those of peroxidase.

Conclusions

Yam tuber mucilage has viscoelastic properties similar to those of human saliva and enhances the enzymatic activity of lysozyme on hydroxyapatite surfaces.

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