Effects of Elm Es Alg53 and oolong on glucan production by GTase from S sobrinus 6715 and S mutans MT8148

Oolong has been used as a functional food to prevent dental caries. Oolong was therefore used to compare the inhibitory effects of other phytochemicals on glucan production by GTase. The inhibitory effect of phytochemicals on water-insoluble glucan synthesis by GTase from S.sobrinus 6715 is illustrated in Fig. 6A. The original ELM solution reduced the production of water-insoluble glucan to 66% of that of the control (ELM-free). ES also significantly reduced the synthesis of water-insoluble glucan. The inhibitory effect of ES was remarkable compared with that of ELM. The inhibitory effect of oolong on the production of water-insoluble glucan by GTase was stronger than that of ELM and of a similar level to that of ES. Fig. 6B shows water-insoluble glucan synthesis by GTase from S. mutans MT8148. ELM significantly inhibited the glucan production by GTase from S. mutans MT8148, and the ratio of inhibition of production of water-insoluble glucan was 64% that of the control (ELM-free). The inhibitory effect of ES and oolong on glucan production by GTase from S. sobrinus 6715 was stronger than that by GTase from S. mutans MT8148. The inhibitory effect of ELM was of a similar level on glucan production by GTase from S. sobrinus 6715 and S. mutans MT8148.

Open circle, positive control (no production of acid); open square, negative control (no inhibition); closed triangle, with Alg53

In the positive control (no production of acid), Stephan's buffer (pH 7.0) was added instead of glucose. In the negative control (no inhibition), distilled water was added instead of Alg53. Data are mean values of duplicate assays (Hashiguchi-Ishiguro et al, 2009).

Incubation time (min)

Open circle, positive control (no production of acid); open square, negative control (no inhibition); closed triangle, with Alg53

In the positive control (no production of acid), Stephan's buffer (pH 7.0) was added instead of glucose. In the negative control (no inhibition), distilled water was added instead of Alg53. Data are mean values of duplicate assays (Hashiguchi-Ishiguro et al, 2009).

Fig. 4. Time-course of pH decrease with acid production by S. sobrinus 6715 from glucose with and without partially decomposed alginate by V. alginolyticus SUN53

The inhibitory effect of Alg53 on water-insoluble and water-soluble glucan synthesis by GTase from S.sobrinus 6715 is illustrated in Fig. 7. The original Alg53 solution and a ten-fold dilution of Alg53 solution reduced the production of water-insoluble glucan to 21% and 23%, respectively. However, Alg53 barely affected the production of water-soluble glucan by GTase. These results demonstrated that Alg53 clearly inhibits the synthesis of water-

insoluble (but not water-soluble) glucan by GTase from S. sobrinus 6715. Water-insoluble glucan is closely associated with the formation of biofilms on teeth surface. In addition, Alg53 has inhibitory effects on acid production and synthesis of glucan by mutans streptococci. That is, Alg53 has two types of anticariogenic effects. Accordingly, Alg53 may demonstrate considerable anticariogenic effects.

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