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The present article reviews the research progress of three major polyphenols (tannins, flavonoids and lignin carbohydrate complexes), chromone (backbone structure of flavonoids) and herbal extracts. Chemical modified chromone derivatives showed highly specific toxicity against human oral squamous cell carcinoma cell lines, with much lower toxicity against human oral keratinocytes, as compared with various anticancer drugs. QSAR analysis suggests the possible correlation between their tumor-specificity and three-dimensional molecular shape. Condensed tannins in the tea extracts inactivated the glucosyltransferase enzymes, involved in the biofilm formation. Lignin-carbohydrate complexes (prepared by alkaline extraction and acid-precipitation) and crude alkaline extract of the leaves of Sasa species (SE, available as an over-the-counter drug) showed much higher anti-HIV activity, than tannins, flavonoids and Japanese traditional medicine (Kampo). Long-term treatment with SE and several Kampo medicines showed an anti-inflammatory and anti-oxidant effects in small size of clinical trials. Although the anti-periodontitis activity of synthetic angiotensin II blockers has been suggested in many papers, natural angiotensin II blockers has not yet been tested for their possible anti-periodontitis activity. There should be still many unknown substances that are useful for treating the oral diseases in the natural kingdom.

Abstract. Background For the exploration of new anticancer drugs, experiments with tumor-bearing animals are mandatory. However, the results obtained with animals have to be carefully evaluated, since drug metabolisms are quite different between animals and humans (1, 2). The other approach is to use cell cultures that mimic whole body. We have established an in vitro assay method of anti-tumor activity, based on the relative cytotoxicity against human oral squamous cell carcinoma (OSCC) cell lines (Ca9-22, HSC-2, HSC-3, HSC-4) and human normal oral mesenchymal cells (gingival fibroblast, HGF; periodontal ligament fibroblast, HPLF; pulp cell, HPC) (3). The validity of this model for estimating the antitumor activity was obtained by our finding that anticancer drugs such as topoisomerase I inhibitors (camptothecin, SN-38) and topoisomerase II inhibitors (etoposide, teniposide), anthracyclines (doxorubicin, daunorubicin, epirubicin, mitoxantrone), mitomycin C, docetaxel, 5-FU and bacterial products (nocobactin NA-a, -b) showed one or two-orders higher tumor-specificity than hundreds of other natural products including tannins, flavonoids and other lower molecular weight polyphenols (3).We recently found that doxorubicin showed very potent cytotoxicity against human normal oral epithelial cells (mucosa keratinocyte, HOK; primary gingival epithelial cell, HGEP) (4-6). However, the mechanism of keratinocyte toxicity is obscure. In the present study, we investigated whether keratinocyte toxicity is reproducibly observable, regardless the culturing conditions and types of anticancer drugs, and whether it is coupled with apoptosis induction. We also present our preliminary data that searched natural products for their ability to alleviate the keratinocyte toxicity.

Previous studies of the neuroprotective activity of polyphenols have used ununiform culture systems, making it difficult to compare their neuroprotective potency. We have established a new and simple method for preparing differentiated PC12 cells by removing the toxic coating step. Cells were induced to differentiate with the nerve growth factor (NGF) in a serum-free medium, without a medium change, but with a one-time overlay supplementation of NGF. The optimal inoculation density of the cells was 6–12 × 103 cells/cm2, and the presence of serum inhibited the differentiation. Neuroprotective activity could be quantified by the specific index (SI) value, that is, the ratio of the 50% cytotoxic concentration to the 50% effective concentration. Alkaline extract from the leaves of Sasa senanensis Rehder (SE), having had hormetic growth stimulation, showed the highest SI value, followed by epigallocatechin gallate. The SI value of curcumin and resveratrol was much lower. This simple overly method, that can prepare massive differentiated neuronal cells, may be applicable for the study of the differentiation-associated changes in intracellular metabolites, and the interaction between neuronal cells and physiological factors.

Background: Herpes simplex virus (HSV) is usually dormant and becomes apparent when body conditions decline. We investigated the anti-HSV activity of various natural and synthetic compounds for future clinical application. Methods: Mock- and HSV-infected Vero cells were treated for three days with various concentrations of samples. For short exposure, 100-fold concentrated virus were preincubated for 3 min with samples, diluted to normal multiplicity of infection (MOI), before the addition to the cells. Anti-HSV activity was evaluated by the chemotherapy index. Results: Alkaline extracts of the leaves of Sasa sp. (SE) and pine cone (PCE) showed higher anti-HSV activity than 20 Japanese traditional herb medicines (Kampo formulas), four popular polyphenols, and 119 chromone-related compounds. Exposure of HSV to SE or PCE for 3 min almost completely eliminated the infectivity of HSV, whereas much longer exposure time was required for Kakkonto, the most active Kampo formulae. Anti-HSV activity of PCE and Kakkonto could be detected only when they were dissolved by alkaline solution (pH 8.0), but not by neutral buffer (pH 7.4). Anti-HSV activity of SE and povidone iodine was stable if they were diluted with neutral buffer. Conclusions: The present study suggests the applicability of SE and PCE for treatment of oral HSV and possibly other viruses.