**2. Evaluation of the anticariogenic effects of phytochemicals**

Evaluation of the anticariogenic effects of phytochemicals is often tested on animals and eventually in humans. The *in vitro* experiments should be first done using a simple method. Because the inducing factor of dental caries is complicate, some types of *in vitro* experiments have to be carried out and judged carefully to recognize characteristics of phytochemicals. Several typical methods are described below.

#### **2.1** *In-vitro* **experiments to evaluate anticariogenic effects**

222 Contemporary Approach to Dental Caries

ring of glucose. Then, DNJ has also been found in the leaves and fruits of *Morus alba* (Asano et al, 1994, 2001). Ever since, preventive effect of *Morus alba* on diabetes by α-glucosidase inhibitor has been extensively studied. Furthermore, *Morus alba* has been clarified multiple biological and physiological effects, as well as hypoglycemic, anti-oxidant and decrease in serum triacylglycerol (TG) level (Kojima et al, 2010). In a long term treatment study, intake

The roots and stems of *Salacia* species plants have been used in the Ayurvedic system of Indian medicine to treat diabetes mellitus (DM) (Li et al, 2008). *Salacia* is a woody climbing plant belonging to the Celastrceae family that is found in limited regions of India and Sri Lanka. Currently, extracts of *Salacia* are consumed in commercial foods and food supplements in Japan for the treatment of diabetes and obesity. The water soluble portion of the methanolic extract inhibits α-glucosidase. Moreover, Beppu et al have reported that *Salacia reticulata* has improvement effect of fasting blood glucose and HbA1c levels in human including mild type 2 diabetics and has no toxicity (Beppu et al, 2006). The potential genotoxicity of *Salacia oblonga* extract was evaluated and it was determined not to be

These phytochemicals, Alg53, ELM and ES competitively inhibit sucrase, maltase and trehalase of vesicles of the brush border membrane of rat intestine. The activity of GTase is inhibited by some polyphenols. We hypothesized that phytochemicals that inhibit αglucosidases such as sucrase may also inhibit the synthesis of glucan from sucrose by GTase, because the latter is also a type of enzyme related to carbohydrate metabolism. Conversely, acarbose and DNJ are known to competitively inhibit sucrase and GTase, and suppress the postprandial elevation of blood levels of glucose and insulin (Newbrun et al, 1983). These

We have investigated the anticariogenic effect of some phytochemicals using simple *in vitro*  methods. The inhibitory effect of phytochemicals on the production of glucan from sucrose by GTase can be used for screening of the anticariogenic effects of natural materials. Surveys of natural materials with anticariogenic effects are important for reduction of the development of dental caries. Discovering new materials to prevent dental caries could expand the repertoire of the development of functional foods for oral health. These functional foods for oral health should be used in combination with different types of

In this chapter, we introduce the procedures employed to evaluate the anticariogenic effects of phytochemicals. We also discuss the properties of three phytochemicals, Alg53, ELM and ES. Although many natural materials have been studied for anti-cariogenic effect, in our knowledge, this is the first and unique report that α-glucosidase inhibitor also inhibit GTase activity in natural materials. That is to say, Alg53, ELM and ES are expected as multiple functional food materials which have the effects of prevention to dental caries, diabetes and obesity. Moreover, if we search for natural materials that inhibit GTase, it might be a key

Evaluation of the anticariogenic effects of phytochemicals is often tested on animals and eventually in humans. The *in vitro* experiments should be first done using a simple method.

materials because the development of dental caries is related to multiple factors.

point that certain materials have inhibition of α-glucosidase activity.

**2. Evaluation of the anticariogenic effects of phytochemicals** 

of *Morus alba* does not cause harmful effects (Kimura et al, 2007).

chemicals are used as medicine for the treatment of DM.

genotoxic (Flammang et al, 2006).

*In vitro* experiments to evaluate the anticariogenic effects of phytochemicals include observations of pH decline by acid production, inhibitory effects on glucan production by GTase from mutans streptococci and sucrose-dependent cell adhesion on smooth surfaces by mutans streptococci*.* In addition, antibacterial effect and the evaluation of plaque accumulation or enamel demineralization by using artificial mouth also have been investigated (Hinoide et al, 1984; Pigman et al, 1952). We have evaluated the anticariogenic effects of phytochemicals based on pH decline, glucan production by GTase and sucrosedependent cell adhesion.
