Inhibitory effects of macrocarpals on the biological activity of Porphyromonas gingivalis and other periodontopathic bacteria.

BACKGROUND/AIMS: Macrocarpals, which are phloroglucinol derivatives contained in eucalyptus leaves, exhibit antimicrobial activity against a variety of bacteria including oral bacteria. This study examined effects of macrocarpals A, B, and C on periodontopathic bacteria, especially Porphyromonas gingivalis. METHODS: Macrocarpals A, B, and C were purified from a 60% ethanol-extract of Eucalyptus globules leaves. To investigate antibacterial activity, representative periodontopathic bacteria were cultured in media with or without various amounts of macrocarpals; subsequently, the optical density at 660 nm was measured. Macrocarpal inhibition of P. gingivalis Arg- and Lys-specific proteinases was assessed by spectrofluorophotometric assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. The effect of macrocarpals on P. gingivalis binding to saliva-coated hydroxyapatite beads was examined with (3)H-labeled P. gingivalis. RESULTS: Growth of P. gingivalis was inhibited more strongly than growth of Prevotella intermedia or Prevotella nigrescens and Treponema denticola by macrocarpals, however, Actinobacillus actinomycetemcomitans and Fusobacterium nucleatum were much more resistant. Macrocarpals inhibited P. gingivalis Arg- and Lys-specific proteinases in a dose-dependent manner. The enzyme-inhibitory effect of macrocarpals was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis in which hemoglobin degradation by P. gingivalis proteinase was inhibited by macrocarpals. P. gingivalis binding to saliva-coated hydroxyapatite beads was also strongly attenuated by macrocarpals. CONCLUSIONS: Macrocarpals A, B and C demonstrated antibacterial activity against periodontopathic bacteria. Among tested bacteria, P. gingivalis displayed the greatest sensitivity to macrocarpals; additionally, its trypsin-like proteinase activity and binding to saliva-coated hydroxyapatite beads were inhibited by macrocarpals. These results indicate that eucalyptus leaf extracts may be useful as a potent preventative of periodontal disease.

Inhibition by the essential oils of peppermint and spearmint of the growth of pathogenic bacteria.

The effects of the, essential oils of peppermint (Mentha piperita L.), spearmint Mentha spicata L.) and Japanese mint (Mentha, arvensis L.), of four major constituents of the esssential oil of peppermint, and of three major constituents of the essential oil of spearmint, on the proliferation of Helicobacter pylori, Salmonella enteritidis, Escherichia coli O157:H7, methicillin-resistant Staphylococcus aureus (MRSA) and methicillin sensitive Staphylococccus aureus (MSSA) were examined. The essential oils and the various constituents inhibited the proliferation of each strain in liquid culture in a dose-dependent manner. In addition, they exhibited bactericidal activity in phosphate-buffered saline. The antibacterial activities varied among the bacterial species tested but were almost the same against antibiotic-resistant and antibiotic-sensitive strains of Helicobacter pylori and S. aureus. Thus, the essential oils and their constituents may be useful as potential antibacterial agents for inhibition of the growth of pathogens.

Identification of cariostatic substances in the cacao bean husk: their anti-glucosyltransferase and antibacterial activities.

The cacao bean husk has been shown to possess two types of cariostatic substances, one showing anti-glucosyltransferase (GTF) activity and the other antibacterial activity, and to inhibit experimental dental caries in rats infected with mutans streptococci. In the present study, chromatographic purification revealed high-molecular-weight polyphenolic compounds and unsaturated fatty acids as active components. The former, which showed strong anti-GTF activity, were polymeric epicatechins with C-4beta and C-8 intermolecular bonds estimated to be 4636 in molecular weight in an acetylated form. The latter, which showed bactericidal activity against Streptococcus mutans, were determined to be oleic and linoleic acids, and demonstrated a high level of activity at a concentration of 30 microgram/mL. The cariostatic activity of the cacao bean husk is likely caused by these biologically active constituents.

Caries inhibitory activity of cacao bean husk extract in in-vitro and animal experiments.

Cacao bean husk extract (CBH) was examined for inhibitory effects on the caries-inducing properties of mutans streptococci in vitro and on caries development in specific pathogen-free Sprague-Dawley rats infected with mutans streptococci. CBH reduced the growth rate of almost all oral streptococci examined, which resulted in the reduction of acid production. Furthermore, insoluble glucan synthesis by the glucosyltransferases from Streptococcus mutans MT8148R and Streptococcus sobrinus 6715 was significantly inhibited by CBH. Hence, the sucrose-dependent cell adherence of mutans streptococci was also depressed by CBH. The administration of CBH in drinking water resulted in significant reductions of caries development and dental plaque accumulation in rats infected with either Strep. sobrinus 6715 or Strep. mutans MT8148R, and the minimum cariostatic concentration was 1.0 mg/ml. These results indicate that CBH possesses powerful anticariogenic potential.

Cariostatic activity of cacao mass extract.

Chocolate is suspected to contain some caries-inhibitory substances. The cariostatic activity of cacao mass extract (CM), the main component of chocolate, was examined in vitro and in experimental animals. CM showed no detectable effects on the cellular growth and acid production of mutans streptococci. On the other hand, the cell-surface hydrophobicity of mutans streptococci was significantly reduced by the presence of CM. Furthermore, insoluble glucan synthesis by the glucosyltransferases from either Streptococcus mutans MT8148R or Strep. sobrinus 6715 was inhibited by CM, but not significantly. Hence, the sucrose-dependent cell adherence of mutans streptococci was also depressed by CM. Finally, CM in both a 40% sucrose diet and drinking water resulted in reductions of caries development and plaque accumulation in rats infected with Strep. sobrinus 6715, but not significantly. These results indicate that cacao mass extract possesses some anticariogenic potential, but its anticaries activity is not strong enough to suppress significantly the cariogenic activity of sucrose.

Macrocarpals H, I, and J from the Leaves of Eucalyptus globulus.

A 50% EtOH extract of Eucalyptus globulus leaves yielded eight phloroglucinol--sesquiterpene-coupled constituents, including three novel compounds named macrocarpals, H, I, and J. Some of these compounds possessed antibacterial activity against oral pathogenic microorganisms with MIC values ranging from 0.20 micrograms/mL to 6.25 micrograms/mL. Inhibition of glucosyltransferase activity by these compounds was also noted.

Eucalyptone from Eucalyptus globulus.

A new cariostatic compound named eucalyptone was isolated from the leaves of Eucalyptus globulus. The structure of this compound was elucidated by spectroscopic methods.

An investigation of diterpenes from the leaves of Rabdosia trichocarpa and their antibacterial activity against oral microorganisms.

The ethanolic extract of Rabdosia trichocarpa leaves showed antibacterial activity against cariogenic mutans streptococci and periodontopathic Porphyromonas gingivalis. Chromatographic separation and purification of the extract afforded ten diterpenes, including one novel ent-kauren type compound named trichoranin. Some of these compounds possess potent antibacterial activity against these oral micro-organisms, indicating that these diterpenes may be useful natural substances for the maintenance of oral health.

[Determination of sennoside A in oriental pharmaceutical decoctions containing Rhei Rhizoma by ion-pair high-performance liquid chromatography].

A simple method using ion-pair high-performance liquid chromatography was established for the rapid and precise determination of sennoside A in oriental pharmaceutical decoctions containing Rhei Rhizoma. This method was compared with other two methods, i.e. ion-suppression and phosphate buffer methods. Sennoside A was eluted without interference in this ion-pair method, while the determination of sennoside A was interfered by co-existing components in the other two methods.

The inhibitory effect of plant extracts on the collagenolytic activity and cytotoxicity of human gingival fibroblasts by Porphyromonas gingivalis crude enzyme.

It is well known that plant extracts inhibit some enzymatic activities. The present study examined the inhibitory effects of natural plant extracts against the collagenolytic activity of Porphyromonas gingivalis. The enzyme was isolated from a culture supernatant of P. gingivalis 381. The aqueous and 50% ethanolic extracts of Ginkgo biloba, Mosla chinensis, Salvia officinalis, Cinnamomum cassia, and a catechin extract of Camellia sinensis exhibited strong inhibitory effects on collagenolytic activity. The activities of these plant extracts were higher than that of tetracycline-HCl. They also inhibited the cytotoxicity of P. gingivalis crude enzyme against human gingival fibroblasts. C. sinensis catechin was the most effective agent in neutralizing the cytotoxicity of P. gingivalis. The aqueous and 50% ethanolic extracts of C. cassia had relatively strong anti-cytotoxic activity. Although the other samples strongly inhibited the collagenolytic activity of P. gingivalis, they were not effectively anti-cytotoxic. The present findings suggest that C. sinensis and C. cassia extracts are effective in reducing the pathogenicity of periodontopathic bacteria.

Calmodulin antagonistic action of KS-504a, a novel metabolite of the fungus Mollisia ventosa.

KS-504a inhibited bovine brain calmodulin-dependent cyclic nucleotide phosphodiesterase (CaM-PDE) with an IC50 value of 122 microM. The inhibition was reversed by a high concentration of calmodulin. Calmodulin-independent activities of the enzyme were not affected by the compound at the same concentration ranges. Ca2(+)-dependent interaction of the compounds with calmodulin was shown using hydrophobic fluorescence probes. These data indicated that the compound exerted its effects on CaM-PDE by interacting with calmodulin. KS-504a also inhibited other calmodulin-dependent enzymes at different concentration ranges; myosin light chain kinase was inhibited at the lowest concentrations with an IC50 value of 6.3 microM. The inhibition mechanism was competitive with respect to calmodulin and non-competitive to ATP.

Inhibitory effects of aqueous extract of cacao bean husk on collagenase of Bacteroides gingivalis.

Natural materials containing tannin were examined to determine whether they possessed any inhibitory activity against collagenase obtained from the culture supernatant of Bacteroides gingivalis. The collagenolytic activity was determined with Collagenokit CLN-100 (Collagen Technological Co., Tokyo) using FITC-conjugated collagen type 1. Among the test samples, only an aqueous extract of cacao (Theobroma cacao) bean husk strongly inhibited the bacterial collagenase. This inhibitory potency was at the same level as that of tetracycline-HCl.

Studies of the antibacterial activity of plant extracts and their constituents against periodontopathic bacteria.

Plant extracts and their constituents were tested for antibacterial activity against periodontopathic bacteria, including Actinobacillus, Capnocytophaga, Fusobacterium, Eikenella and Bacteroides species. The essential oils of two labiatae plants, Mosla chinensis Maxim. and Pogostemon cablin Benth., and five terpenoids, hinokitiol, thymol, carvacrol, patchoulialcohol and pogostone, showed antibacterial activity. The terpenoids were especially effective against Bacteroides species.