During screening for anti-plaque agents of plant origin, ethanolic extracts from Melaphis chinensis (Bell), the Chinese Nutgall, exhibited strong inhibition of glucosyltransferase (GTF), in vitro adherence and glucan-induced agglutination of Streptococcus mutans 3209 and S. sobrinus B13. More than 91% inhibition of water-insoluble glucan synthesis from sucrose by GTF was noted at a concentration as low as 7.8 micrograms/mL. Bactericidal effects on other mutans streptococci, S. salivarius, and Actinomyces viscosus were also evident. Through chemical fractionation and analyses, along with bioassays, the active components were identified as gallotannins.

Six extracts from Chinese medicinal plants: Tin Men Chu, Sey Lau Pai, Siu Mao Heung, Bak Tao Yung, Kam Chin Chiu and Liao Ya, were tested for their inhibitory effect on selected food-borne bacteria by the well assay technique. Among them, Tin Men Chu, Siu Mao Heung and Sey Lau Pai inhibited the growth of Staphylococcus aureus, Klebsiella pneumonia, Escherichia coli, Shigella flexneri, Streptococcus faecalis, Salmonella paratyphi, Salm. enteritidis, Enterobacter aerogenes, Pseudomonas fluorescens, Proteus vulgaris, Alcaligenes faecalis, and three strains of Listeria monocytogenes. Two of these three extracts, Tin Men Chu and Siu Mao Heung, suppressed the growth of L. monocytogenes Scott A in cabbage juice. This inhibition was prevented by the addition of protein but not sodium chloride. Plant extracts show potential to control the growth of food-borne bacteria.

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The rodlet layer of the microconidial wall of Trichophyton mentagrophytes was isolated and partially characterized. The purified microconidial walls were first extracted with urea (8 M), mercaptoethanol (1%), and sodium dodecyl sulfate (1%) followed by enzymatic digestion with glusulase (snail intestinal enzymes) and purified (1-*3)-,8-D-glucanase and chitinase. The purified rodlet layer was 15 to 30 nm thick and accounted for approximately 10% ofthe original wall weight. The pattern of rodlet patches, as revealed by electron microscopy of freeze-etched preparations ofthe isolated layer, was essentially the same as that observed on the intact microconidial wall. The rodlet layer was found to be resistant to most of the common organic solvents, cell wall lytic enzymes, mild acid treatments, and surface-active agents, but was solubilized in boiling 1 N NaOH with concomitant disorientation of the rodlet patterns. A melanin or melanin-like pigment appeared to be intimately associated with this rodlet layer and was solubilized during a hot-alkali treatment. Protein (80 to 85%) and glucomannan (7 to 10%) were the major components of the rodlet layer. The rodlet layer did not contain any appreciable amounts of lipid or phosphorus.

Many plant extracts or derivatives have been incorporated into commercial toothpastes to treat oral diseases related to caries or periodontal diseases in China. However, no information is available concerning their in vitro effects on oral bacteria. Thirty-one Chinese medicinal toothpastes were selected for this study Their ability to inhibit growth, in vitro plaque formation and glucosyltransferase (GTF) activity of Streptococcus sobrinus B13 and Streptococcus mutans 3209 were examined. Eighty-seven percent of the tested toothpastes inhibited the growth of the mutans streptococci, with zones ranging from 0.8 to 2.5 cm. At 10 mg/ml, 74% of the toothpastes inhibited in vitro plaque formation by S. mutans. Among these, 60% completely suppressed water-insoluble glucan synthesis from sucrose by GTF. Based on data obtained from our study, the incorporation of natural plant products or their derivatives into dentifrices seems a feasible means of promoting oral health and controlling dental diseases.