TY - JOUR
T1 - Specific inhibition of cytotoxicity of Shiga-like toxin 1 of enterohemorrhagic Escherichia coli by gallocatechin gallate and epigallocatechin gallate
AU - Miyamoto, Takahisa
AU - Toyofuku, Seiyo
AU - Tachiki, Narumi
AU - Kimura, Etsuko
AU - Zhou, Ting
AU - Ozawa, Tadahiro
AU - Nakayama, Motokazu
AU - Shigemune, Naofumi
AU - Shimatani, Kanami
AU - Tokuda, Hajime
AU - Honjoh, Ken-ichi
PY - 2014/8
Y1 - 2014/8
N2 - Mechanism of inhibitory action of 8 catechins and teaflavin was investigated at low concentration against Shiga-like toxin (Stx). Viability of Vero cells largely decreased in the presence of Stx1 and Stx2 preparations. Cytotoxicity of Stx1 decreased after preincubation with gallocatechin gallate (GCg) and epigallocatechin gallate (EGCg) at 100mg/L. However, the cytotoxicity of Stx2 was not inhibited by the preincubation with catechins and teaflavin tested. The inhibitory activity of GCg and EGCg at 15mg/L (0.0327mM) was investigated against Stx preparations with various concentrations. The cytotoxicity of Stx1 at the concentration ranging from 1.6 to 50ng/mL significantly reduced (p<0.01) by the preincubation of Stx1 with GCg at 15mg/L. Similarly, the cytotoxicity of Stx1 at the concentration ranging from 3.1 to 25ng/mL was significantly reduced (p<0.01) by the preincubation with EGCg at 15mg/L. In contrast, GCg and EGCg did not inhibit cytotoxicity of Stx2 at any concentrations tested. On the other hand, EGC showed no significant effects on cytotoxicity of both Stx1 and Stx2 at the same concentrations tested. The pocket sizes formed at the center of the Stx1B and Stx2B pentamers were calculated to be 778Å3 and 475Å3, respectively. Docking simulations were conducted with EGCg positioned in the center of the pore of StxB pentamers. The docking models showed that EGCg formed 7 hydrogen bonds with side chains of amino acids faced inside the pocket of the Stx1B pentarmer with the lowest intramolecular energy (strain energy+electrostatic energy) of-0.1kcal/mol. In contrast, in the case of Stx2B pentamer, EGCg formed 6 hydrogen bonds with the lowest intramolecular energy of 5.2kcal/mol. In silico study suggested that EGCg forms more stable structure with Stx1B pentamer than Stx2B pentamer. These results indicated that both GCg and EGCg specifically inhibited cytotoxicity of Stx1 but not of Stx2.
AB - Mechanism of inhibitory action of 8 catechins and teaflavin was investigated at low concentration against Shiga-like toxin (Stx). Viability of Vero cells largely decreased in the presence of Stx1 and Stx2 preparations. Cytotoxicity of Stx1 decreased after preincubation with gallocatechin gallate (GCg) and epigallocatechin gallate (EGCg) at 100mg/L. However, the cytotoxicity of Stx2 was not inhibited by the preincubation with catechins and teaflavin tested. The inhibitory activity of GCg and EGCg at 15mg/L (0.0327mM) was investigated against Stx preparations with various concentrations. The cytotoxicity of Stx1 at the concentration ranging from 1.6 to 50ng/mL significantly reduced (p<0.01) by the preincubation of Stx1 with GCg at 15mg/L. Similarly, the cytotoxicity of Stx1 at the concentration ranging from 3.1 to 25ng/mL was significantly reduced (p<0.01) by the preincubation with EGCg at 15mg/L. In contrast, GCg and EGCg did not inhibit cytotoxicity of Stx2 at any concentrations tested. On the other hand, EGC showed no significant effects on cytotoxicity of both Stx1 and Stx2 at the same concentrations tested. The pocket sizes formed at the center of the Stx1B and Stx2B pentamers were calculated to be 778Å3 and 475Å3, respectively. Docking simulations were conducted with EGCg positioned in the center of the pore of StxB pentamers. The docking models showed that EGCg formed 7 hydrogen bonds with side chains of amino acids faced inside the pocket of the Stx1B pentarmer with the lowest intramolecular energy (strain energy+electrostatic energy) of-0.1kcal/mol. In contrast, in the case of Stx2B pentamer, EGCg formed 6 hydrogen bonds with the lowest intramolecular energy of 5.2kcal/mol. In silico study suggested that EGCg forms more stable structure with Stx1B pentamer than Stx2B pentamer. These results indicated that both GCg and EGCg specifically inhibited cytotoxicity of Stx1 but not of Stx2.
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U2 - 10.1016/j.foodcont.2014.02.017
DO - 10.1016/j.foodcont.2014.02.017
M3 - Article
AN - SCOPUS:84897704726
VL - 42
SP - 263
EP - 269
JO - Food Control
JF - Food Control
SN - 0956-7135
ER -