Inhibitory effect of oolong tea polyphenols on glycosyltransferases of mutans Streptococci

Abstract

Oolong tea extract (OTE) was found to inhibit the water-insoluble glucan-synthesizing enzyme, glucosyltransferase I (GTase-I), of Streptococcus sobrinus 6715. The GTase-inhibitory substance in the OTE was purified by successive adsorption chromatography on Diaion HP-21 and HP-20 columns; this was followed by further purification by Sephadex LH-20 column chromatography. A major fraction that inhibited GTase activity (fraction OTF10) was obtained, and the chemical analysis of OTF10 indicated that it was a novel polymeric polyphenol compound that had a molecular weight of approximately 2,000 and differed from other tea polyphenols. Catechins and all other low-molecular-weight polyphenols except theaflavin derived from black tea did not show significant GTase-inhibitory activities. It was found that OTE and OTF1O markedly inhibit GTase-I and yeast a-glucosidase, but not salivary ol-amylase. Various GTases purified from S. sobrinus and Streptococcus mutans were examined for inhibition by OTE and OTF10. It was determined that S. sobrinus GTase-I and S. mutans cell-free GTase synthesizing water-soluble glucan were most susceptible to the inhibitory action of OTF10, while S. sobrinus GTase-Sa and S. mutans cell-associated GTase were moderately inhibited; no inhibition of S. sobrinus GTase-Sb was observed. Inhibition of a specific GTase or specific GTases of mutants streptococci resulted in decreased adherence of the growing cells of these organisms. The inhibitory effect of OTF1O on cellular adherence was significantly stronger than that of OTE.

Preventive effects of an original combination of grape seed polyphenols with amine fluoride on dental biofilm formation and oxidative damage by oral bacteria

“…Therefore, we next examined the inhibitory activity of the compounds on these enzymes. The inhibition of insoluble glucan synthesis >90% obtained with GSE was in agreement with results described for another grape seed extract (Toukairin et al 1991) and for other polyphenolic extracts (Otake et al 1991;Nakahara et al 1993). Numerous studies have identified oligomeric proanthocyanidins (or condensed tannins) as most active in the GTFs inhibition, and one characteristic of the grape seeds is to be rich in these molecules, which could explain the observed results (Nakahara et al 1993).…”

Oolong tea extract as a substitute for uranyl acetate in staining of ultrathin sections

“…Both tannic acid and the constituents of OTE are polyphenols. However, the molecular weight of the main polyphenolic constituent in OTE (2 kDa) is lower than that of tannic acid (Nakahara et al, 1993). Therefore, the fine structure in cells can be clearly visible with OTE staining, but is slightly obscure with tannic acid staining (Sato et al, 2003).…”

Peroxidase-catalyzed generation of catechin oligomers that inhibit glucosyltransferase from Streptococcus sobrinus

“…The active substance present in OTE was determined to be polymeric polyphenols with a molecular mass of 2000, which is not found in green tea extract (GTE). D-(+)-Catechin, a monomeric polyphenol found in GTE, was shown to exhibit only a weak inhibitory effect on GTase activity from mutans streptococci in a dose-dependent fashion [4]. It was later demonstrated that D-(+)-catechin was quickly glucosylated when incubated with GTase and sucrose, which resulted in blockage of GTase inhibitory activities of catechin [5].…”

“…GTase synthesizing water-insoluble glucan from sucrose was prepared from culture supernatants of S. sobrinus 6715 (serotype g) by ammonium sulfate precipitation as described by Furuta et al [8]. The inhibitory activities of polyphenolic substances against GTase were measured as described previously [4]. Briefly, GTase (50 mu), sucrose (1.0% w/v), dextran TlO (1 .O mg ml-' ; Pharmacia Biotech), and sodium azide (0.1% w/v) in 3.0 ml of 0.1 M phosphate buffer (pH 6.0) was incubated at matic action of peroxidases present in tea leaves.…”