Antibacterial property of isoflavonoids isolated from Erythrina variegata against cariogenic oral bacteria.
The antibacterial property of 7 compounds, isolated from Erythrina variegata (Leguminosae) by repeated silica gel column chromatography, against cariogenic oral bacteria was investigated. Extensive spectroscopic study revealed that all were isoflavonoids. Among them, 3,9-dihydroxy-2,10-di(gamma,gamma-dimethylallyl)-6a,11a-dehydropterocarpan (erycristagallin) showed the highest antibacterial activity against mutans streptococci, other oral streptococci, Actinomyces and Lactobacillus species with a minimum inhibitory concentration (MIC) range of 1.56-6.25 microg/ml, followed by 3,6a-dihydroxy-9-methoxy-2,10-di(gamma,gamma-dimethylallyl)pterocarpan (erystagallinA) and 9-hydroxy-3-methoxy-2-gamma,gamma-dimethylallylpterocarpan (orientanol B) (MIC range: 3.13-12.5 microg/ml). The antibacterial effect of erycristagallin to mutans streptococci was based on a bactericidal action. Erycristagallin (6.25 microg/ml: MIC) completely inhibited incorporation of radio-labelled thymidine into Streptococcus mutans cells. Incorporation of radio-labelled glucose into bacterial cells was also strongly inhibited at MIC, and 1/2 MIC of the compound reduced the incorporation approximately by half. The findings indicate that erycristagallin has a potential as potent phytochemical agent for prevention of dental caries by inhibiting the growth of cariogenic bacteria and by interfering with incorporation of glucose responsible for production of organic acids.
Sato
M
M
Department of Oral Pathology, Asahi University School of Dentistry, Gifu, Japan. riyama@dent.asahi-u.ac.jp
Tanaka
H
H
Fujiwara
S
S
Hirata
M
M
Yamaguchi
R
R
Etoh
H
H
Tokuda
C
C
D000190:Actinomyces / Q000187:drug effects*; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D003731:Dental Caries / Q000382:microbiology*; D004895:Erythrina / Q000737:chemistry*; D006576:Heterocyclic Compounds, 4 or More Rings; D007529:Isoflavones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D007778:Lactobacillus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D013291:Streptococcus / Q000187:drug effects*
D000900:Anti-Bacterial Agents; D006576:Heterocyclic Compounds, 4 or More Rings; D007529:Isoflavones; C477693:erycristagallin