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oai:ir.kagoshima-u.ac.jp:00015471 2026-03-03T15:00:56Z 57:86

Antibacterial　activity of phellodendron bark against Streptococcus mutans オウバクの Streptococcus mutans に対する抗菌効果 辻井, 利弥 ツジイ, トシヤ Tsujii, Toshiya open access antibacterial agents and chemotherapy bacteriology pathogenesis Streptococcus mutans 博士論文全文, 博士論文要旨, 最終試験結果の要旨, 論文審査の要旨 Streptococcus mutans is a major cause of tooth decay due to its promotion of biofilm formation and acid production. Several plant extracts have been reported to have multiple biological activities such as anti‐inflammation and antibacterial effects. This study investigated the antibacterial activity of three plant extracts, phellodendron bark (PB), yucca, and black ginger, and found that PB had a stronger effect than the other extracts. Then, the minimum inhibitory concentration (MIC) of PB against 100 S. mutans strains was investigated. The MIC range of PB was 9.8–312.5 µg/mL. PB suppressed the growth kinetics of S. mutans in a dose‐dependent manner, even at sub‐MICs of PB. Then, we investigated the effect of PB on S. mutans virulence. The PB suppressed biofilm formation at high concentrations, although PB did not affect the expression of glucosyltransferase genes. Additionally, PB suppressed the decrease in pH from adding an excess of glucose. The expression of genes responsible for acid production was increased by the addition of excess glucose without PB, whereas their expression levels were not increased in the presence of 1× and 2× MIC of PB. Although PB showed a bacteriostatic effect on planktonic S. mutans cells, it was found that more than 2× MIC of PB showed a partial bactericidal effect on biofilm cells. In conclusion, PB not only showed antibacterial activity against S. mutans but also decreased the cariogenic activity in S. mutans. Toshiya Tsujii, Miki Kawada‐Matsuo, Hirono Migita, Kouji Ohta, Yuichi Oogai, Youichi Yamasaki, Hitoshi Komatsuzawa Antibacterial activity of phellodendron bark against Streptococcus mutans Microbiology and Immunology 64(6) p.424-434 2020 https://doi.org/10.1111/1348-0421.12787 The Societies and John Wiley & Sons 鹿児島大学 eng doctoral thesis VoR http://hdl.handle.net/10232/00031362 https://ir.kagoshima-u.ac.jp/records/15471 甲総研第569号 博士(歯学) Doctor of Philosophy in Dental Science 2020-08-20 17701 鹿児島大学 https://ir.kagoshima-u.ac.jp/record/15471/files/Diss_辻井_利弥_ISK569_2020.pdf application/pdf 496.6 kB 2021-05-13 2020-08-06 https://ir.kagoshima-u.ac.jp/record/15471/files/Abstract_辻井_利弥_4516800089_2020.pdf application/pdf 30.2 kB 2021-05-13 2020-08-06 https://ir.kagoshima-u.ac.jp/record/15471/files/Result_Tsujii_Toshiya_isk_569.pdf application/pdf 169.8 kB 2020-10-01 2020-08-06 https://ir.kagoshima-u.ac.jp/record/15471/files/Comments_Tsujii_Toshiya_isk_569.pdf application/pdf 88.1 kB 2020-10-01 2020-08-06