Protective effect of ursolic acid from Cornus officinalis on the hydrogen peroxide-induced damage of HEI-OC1 auditory cells.

The fruits of Cornus officinalis have been used in traditional oriental medicine for treatment of inner ear diseases, such as tinnitus and hearing loss. In the present study, we investigated the protective effect of C. officinalis on hydrogen peroxide-induced cytotoxicity in HEI-OC1 auditory cells. The results from bioassay-guided fractionation of methanol extract of C. officinalis fruits showed that ursolic acid is a major active component. Ursolic acid (0.05-2 microg/ml) had protective effect against the HEI-OC1 cell damage and reduced lipid peroxidation in a dose-dependent manner. In addition, pre-treatment with ursolic acid significantly attenuated the decrease of activities of catalase (CAT) and glutathione peroxidase (GPX), but superoxide dismutase (SOD) activity was not significantly affected by ursolic acid. These results indicate that ursolic acid protects hydrogen peroxide-induced HEI-OC1 cell damage through inhibition of lipid peroxidation and induction of antioxidant enzymes, CAT and GPX, and may be one of the active components responsible for these effects of C. officinalis fruits.

Anticariogenic properties of the extract of Cyperus rotundus.

Streptococcus mutans (S. mutans) is known as the causative bacteria in the formation of dental plaque and dental caries. The aim of this experiment was to investigate the effects of Cyperus rotundus (C. rotundus) tuber extract on the growth, acid production, adhesion, and water-insoluble glucan synthesis of S. mutans. The growth and acid production were reduced by the extract of C. rotundus in a dose dependent manner. The extract of C. rotundus markedly inhibited the adherence of S. mutans to saliva-coated hydroxyapatite beads (HAs). The adherence was repressed by more than 50% at the concentration of 0.5 mg/ml of the extract and complete inhibition was observed at the concentration of 4 mg/ml of the extract. On the activity of glucosyltransferase (GTFase) which synthesizes water-insoluble glucan from sucrose, the extract of C. rotundus showed more than 10% inhibition at a concentration of 2 mg/ml. These results suggest that C. rotundus may inhibit cariogenic properties of S. mutans. Further studies are necessary to clarify the active constituents of C. rotundus responsible for such biomolecular activities.

Protective effect of Rehmannia glutinosa on the cisplatin-induced damage of HEI-OC1 auditory cells through scavenging free radicals.

The steamed root of Rehmannia glutinosa has been used in traditional Oriental Medicine for treatment of inner ear diseases, such as tinnitus and hearing loss. In the present study, we showed that the ethanol extract of steamed roots of Rehmannia glutinosa (SRG) protected HEI-OC1 auditory cells from cisplatin cytotoxicity in a dose-dependent fashion. In addition, to investigate the protection mechanism of SRG on cisplatin cytotoxicity towards HEI-OC1, we measured the effects of SRG on lipid peroxidation of cisplatin treated cells as well as scavenging activities against superoxide radical, hydroxyl radical, hydrogen peroxide, and DPPH radical. SRG (5-100 microg/ml) had protective effect against the cisplatin-induced HEI-OC1 cell damage and reduced lipid peroxidation in a dose-dependent manner. Furthermore, SRG showed strong scavenging activity against superoxide radical, hydroxyl radical, hydrogen peroxide, and DPPH radical. These results indicate that SRG protects cisplatin-induced HEI-OC1 cell damage through inhibition of lipid peroxidation and scavenging activities of free radials.

Asarum sieboldii extracts attenuate growth, acid production, adhesion, and water-insoluble glucan synthesis of Streptococcus mutans.

Asarum sieboldii has been used in traditional folk medicine to treat dental caries and periodontal disease. In the present study, we investigated the inhibitory effect of the ethanol and aqueous extracts of A. sieboldii on the growth, acid production, adhesion, and water-insoluble glucan synthesis of Streptococcus mutans. The ethanol and aqueous extracts of A. sieboldii inhibited the growth and acid production of S. mutans. In the bacterial adherence assay, the ethanol and aqueous extracts of A. sieboldii significantly lowered the adherence of S. mutans. We also found that the ethanol and aqueous extracts of A. sieboldii significantly inhibited the synthesis of water-insoluble glucan by crude glucosyltransferase. These results suggest that A. sieboldii extracts may inhibit the caries-inducing properties of S. mutans. Further studies are necessary to clarify the active constituents of A. sieboldii extracts responsible for such biomolecular activities.

Antibacterial activity of Curcuma longa L. against methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) has been emerging worldwide as one of the most important hospital and community pathogens. Therefore, new agents are needed to treat MRSA associated infections. The present study investigated the antimicrobial activity of ethyl acetate, methanol and water extracts of Curcuma longa L. (C. longa) against MRSA. The ethyl acetate extract of C. longa demonstrated a higher antibacterial activity than the methanol extract or water extract. Since the ethyl acetate extract was more active than the other extracts, the study examined whether the ethyl acetate extract could restore the antibacterial activity of beta-lactams and alter the MRSA invasion of human mucosal fibroblasts (HMFs). In the checkerboard test, the ethyl acetate extract of C. longa markedly lowered the MICs of ampicillin and oxacillin against MRSA. In the bacterial invasion assay, MRSA intracellular invasion was significantly decreased in the presence of 0.125-2 mg/mL of C. longa extract compared with the control group. These results suggest that the ethyl acetate extract of C. longa may have antibacterial activity and the potential to restore the effectiveness of beta-lactams against MRSA, and inhibit the MRSA invasion of HMFs.