The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform

Shigeaki Kuwano - One of the best experts on this subject based on the ideXlab platform.

  • the synergistic purgative action of aloe emodin Anthrone and rhein Anthrone in mice synergism in large intestinal propulsion and water secretion
    Journal of Pharmacy and Pharmacology, 2011
    Co-Authors: Teruyo Yagi, Kazuko Yamauchi, Shigeaki Kuwano
    Abstract:

    This study aimed to explore the mechanism involved in the synergistic purgative action of aloe-emodin Anthrone and rhein Anthrone, the active metabolites of sennoside C. Aloe-emodin Anthrone and rhein Anthrone, and their equimolar mixture, induced excretion of an approximately equal number of faeces by intracaecal administration at a dose of 23.2 mumol kg-1 in mice (= 1.0 standard dose). The number of wet faeces induced by aloe-emodin Anthrone was less than those of rhein Anthrone and the mixture. At the same dose, rhein Anthrone and the mixture significantly stimulated large intestinal propulsion, though aloe-emodin Anthrone had little stimulatory effect. Aloe-emodin Anthrone and rhein Anthrone decreased net water absorption but could not reverse it to the net secretion at 1/2 dose. The mixture significantly decreased net water absorption and reversed it to the net secretion at this dose. These Anthrones did not stimulate mucus secretion in the colon at 1/2 dose. We concluded that the synergistic purgative effect of aloe-emodin Anthrone and rhein Anthrone in mice results from synergistic stimulation of large intestinal transit and large intestinal water secretion.

  • involvement of prostaglandin e like material in the purgative action of rhein Anthrone the intraluminal active metabolite of sennosides a and b in mice
    Journal of Pharmacy and Pharmacology, 2011
    Co-Authors: Teruyo Yagi, Kazuko Yamauchi, Yoshie Miyawaki, Tomoyo Nishikawa, Shigeaki Kuwano
    Abstract:

    Intracaecal administration of rhein Anthrone, the intraluminally active metabolite of sennosides A and B, to mice quickly induced severe diarrhoea. Pretreatment with the prostaglandin (PG) biosynthesis inhibitor, indomethacin, and PGE2 antagonist, SC-19220, prevented the onset of diarrhoea induced by rhein Anthrone, but the PGE2 antagonist polyphoretin phosphate (PPP) showed only a weak inhibitory effect. Rhein Anthrone stimulated the production of PGE-like material only in the colon and its large intestinal propulsive activity was depressed by indomethacin and SC-19220, but not by PPP which suggests that the release of PGE-like material has some role in its purgative action.

  • suppression of the purgative action of rhein Anthrone the active metabolite of sennosides a and b by indomethacin in rats
    Journal of Pharmacy and Pharmacology, 1991
    Co-Authors: Teruyo Yagi, Kazuko Yamauchi, Yoshie Miyawaki, Atsuko Nishikawa, Shigeaki Kuwano
    Abstract:

    — Rhein Anthrone (12.48 mg kg−1) produces watery and mucoid diarrhoea approximately 20 min after intracaecal administration to rats. Pretreatment with the prostaglandin (PG) biosynthesis inhibitor indomethacin (10 mg kg−1, i.p.) only delayed and did not completely block the onset of the induced diarrhoea. Rhein Anthrone stimulated PGE2 release into the rat colonic lumen and the increased release was depressed by indomethacin. Rhein Anthrone also accelerated large intestinal transit and this acceleration could be partly inhibited by indomethacin, which was probably responsible for the delay in the onset of diarrhoea. Indomethacin prevented the enhanced water, K+ and mucus secretion and the reduced Na+ absorption in the colon which were induced by rhein Anthrone. The net water secretion could not be reversed to net absorption and the mucus secretion was only slightly depressed by indomethacin. Thus, our findings suggest that other mechanisms, together with the PG-dependent mechanism, are involved in the purgative action of rhein Anthrone in rats.

Teruyo Yagi - One of the best experts on this subject based on the ideXlab platform.

  • the synergistic purgative action of aloe emodin Anthrone and rhein Anthrone in mice synergism in large intestinal propulsion and water secretion
    Journal of Pharmacy and Pharmacology, 2011
    Co-Authors: Teruyo Yagi, Kazuko Yamauchi, Shigeaki Kuwano
    Abstract:

    This study aimed to explore the mechanism involved in the synergistic purgative action of aloe-emodin Anthrone and rhein Anthrone, the active metabolites of sennoside C. Aloe-emodin Anthrone and rhein Anthrone, and their equimolar mixture, induced excretion of an approximately equal number of faeces by intracaecal administration at a dose of 23.2 mumol kg-1 in mice (= 1.0 standard dose). The number of wet faeces induced by aloe-emodin Anthrone was less than those of rhein Anthrone and the mixture. At the same dose, rhein Anthrone and the mixture significantly stimulated large intestinal propulsion, though aloe-emodin Anthrone had little stimulatory effect. Aloe-emodin Anthrone and rhein Anthrone decreased net water absorption but could not reverse it to the net secretion at 1/2 dose. The mixture significantly decreased net water absorption and reversed it to the net secretion at this dose. These Anthrones did not stimulate mucus secretion in the colon at 1/2 dose. We concluded that the synergistic purgative effect of aloe-emodin Anthrone and rhein Anthrone in mice results from synergistic stimulation of large intestinal transit and large intestinal water secretion.

  • involvement of prostaglandin e like material in the purgative action of rhein Anthrone the intraluminal active metabolite of sennosides a and b in mice
    Journal of Pharmacy and Pharmacology, 2011
    Co-Authors: Teruyo Yagi, Kazuko Yamauchi, Yoshie Miyawaki, Tomoyo Nishikawa, Shigeaki Kuwano
    Abstract:

    Intracaecal administration of rhein Anthrone, the intraluminally active metabolite of sennosides A and B, to mice quickly induced severe diarrhoea. Pretreatment with the prostaglandin (PG) biosynthesis inhibitor, indomethacin, and PGE2 antagonist, SC-19220, prevented the onset of diarrhoea induced by rhein Anthrone, but the PGE2 antagonist polyphoretin phosphate (PPP) showed only a weak inhibitory effect. Rhein Anthrone stimulated the production of PGE-like material only in the colon and its large intestinal propulsive activity was depressed by indomethacin and SC-19220, but not by PPP which suggests that the release of PGE-like material has some role in its purgative action.

  • suppression of the purgative action of rhein Anthrone the active metabolite of sennosides a and b by calcium channel blockers calmodulin antagonists and indometacin
    Pharmacology, 1993
    Co-Authors: Kazuko Yamauchi, Teruyo Yagi, S Kuwano
    Abstract:

    The involvement of Ca2+ in the mechanism of the purgative action of rhein Anthrone was studied. Among individual or combination pretreatments with calcium channel blockers, calmodulin antagonists and prostaglandin biosynthesis inhibitors, the combination of indometacin and nifedipine completely blocked the diarrhoea induced by rhein Anthrone and also inhibited its effects on colonic fluid and electrolyte transport, and large intestinal motility. Calmodulin antagonists were less active regarding suppression of the effects of rhein Anthrone. We concluded that, in addition to prostaglandins, diarrhoea induced by rhein Anthrone must also involve the calcium channel which can be blocked by nifedipine, but not verapamil.

  • suppression of the purgative action of rhein Anthrone the active metabolite of sennosides a and b by indomethacin in rats
    Journal of Pharmacy and Pharmacology, 1991
    Co-Authors: Teruyo Yagi, Kazuko Yamauchi, Yoshie Miyawaki, Atsuko Nishikawa, Shigeaki Kuwano
    Abstract:

    — Rhein Anthrone (12.48 mg kg−1) produces watery and mucoid diarrhoea approximately 20 min after intracaecal administration to rats. Pretreatment with the prostaglandin (PG) biosynthesis inhibitor indomethacin (10 mg kg−1, i.p.) only delayed and did not completely block the onset of the induced diarrhoea. Rhein Anthrone stimulated PGE2 release into the rat colonic lumen and the increased release was depressed by indomethacin. Rhein Anthrone also accelerated large intestinal transit and this acceleration could be partly inhibited by indomethacin, which was probably responsible for the delay in the onset of diarrhoea. Indomethacin prevented the enhanced water, K+ and mucus secretion and the reduced Na+ absorption in the colon which were induced by rhein Anthrone. The net water secretion could not be reversed to net absorption and the mucus secretion was only slightly depressed by indomethacin. Thus, our findings suggest that other mechanisms, together with the PG-dependent mechanism, are involved in the purgative action of rhein Anthrone in rats.

Peter Mulder - One of the best experts on this subject based on the ideXlab platform.

  • Anthrone and related hydroxyarenes tautomerization and hydrogen bonding
    Journal of Organic Chemistry, 2013
    Co-Authors: Hans-gert Korth, Peter Mulder
    Abstract:

    The keto–enolization of hydroxyl-substituted naphthols and 9-anthrols has been investigated by means of CBS-QB3 calculations. An excellent agreement between experiment and theory is found for the energetics for the Anthrone (5) ⇌ anthrol (6) equilibrium, with an enthalpy of tautomerization, ΔtH, of 3.8 kcal mol–1. In contrast, 1-naphthol is the preferred tautomer with a ΔtH = −9.0 kcal mol–1. Substitution of the hydrogens at the adjacent carbons by hydroxyl groups leads to the formation of strong intramolecular hydrogen bonds within a six-membered ring in the enones and the enols. Due to the difference in the intramolecular hydrogen bond enthalpy, ΔHBHintra, the equilibrium shifts further to the enone. Thus, for 1,8-dihydroxy-Anthrone (anthralin, dithranol) ΔtH increases to 12.7 kcal mol–1 with an enol/enone ratio of 10–10. The solvent effect on the 5 ⇌ 6 equilibrium has been quantified by considering the formation of intermolecular hydrogen bond(s), leading to an acidity parameter α2H for anthrol of 0.42...

  • Anthrone and Related Hydroxyarenes: Tautomerization and Hydrogen Bonding
    2013
    Co-Authors: Hans-gert Korth, Peter Mulder
    Abstract:

    The keto–enolization of hydroxyl-substituted naphthols and 9-anthrols has been investigated by means of CBS-QB3 calculations. An excellent agreement between experiment and theory is found for the energetics for the Anthrone (5) ⇌ anthrol (6) equilibrium, with an enthalpy of tautomerization, ΔtH, of 3.8 kcal mol–1. In contrast, 1-naphthol is the preferred tautomer with a ΔtH = −9.0 kcal mol–1. Substitution of the hydrogens at the adjacent carbons by hydroxyl groups leads to the formation of strong intramolecular hydrogen bonds within a six-membered ring in the enones and the enols. Due to the difference in the intramolecular hydrogen bond enthalpy, ΔHBHintra, the equilibrium shifts further to the enone. Thus, for 1,8-dihydroxy-Anthrone (anthralin, dithranol) ΔtH increases to 12.7 kcal mol–1 with an enol/enone ratio of 10–10. The solvent effect on the 5 ⇌ 6 equilibrium has been quantified by considering the formation of intermolecular hydrogen bond(s), leading to an acidity parameter α2H for anthrol of 0.42. It is shown that the hydrogen bond donating ability of bulk methanol is greatly attenuated through the formation of cyclic oligomers. The benzylic and phenolic bond dissociation enthalpies for Anthrone up to anthralin suggest some antioxidant potency but the precise (radical) mechanism of action remains uncertain

Kazuko Yamauchi - One of the best experts on this subject based on the ideXlab platform.

  • the synergistic purgative action of aloe emodin Anthrone and rhein Anthrone in mice synergism in large intestinal propulsion and water secretion
    Journal of Pharmacy and Pharmacology, 2011
    Co-Authors: Teruyo Yagi, Kazuko Yamauchi, Shigeaki Kuwano
    Abstract:

    This study aimed to explore the mechanism involved in the synergistic purgative action of aloe-emodin Anthrone and rhein Anthrone, the active metabolites of sennoside C. Aloe-emodin Anthrone and rhein Anthrone, and their equimolar mixture, induced excretion of an approximately equal number of faeces by intracaecal administration at a dose of 23.2 mumol kg-1 in mice (= 1.0 standard dose). The number of wet faeces induced by aloe-emodin Anthrone was less than those of rhein Anthrone and the mixture. At the same dose, rhein Anthrone and the mixture significantly stimulated large intestinal propulsion, though aloe-emodin Anthrone had little stimulatory effect. Aloe-emodin Anthrone and rhein Anthrone decreased net water absorption but could not reverse it to the net secretion at 1/2 dose. The mixture significantly decreased net water absorption and reversed it to the net secretion at this dose. These Anthrones did not stimulate mucus secretion in the colon at 1/2 dose. We concluded that the synergistic purgative effect of aloe-emodin Anthrone and rhein Anthrone in mice results from synergistic stimulation of large intestinal transit and large intestinal water secretion.

  • involvement of prostaglandin e like material in the purgative action of rhein Anthrone the intraluminal active metabolite of sennosides a and b in mice
    Journal of Pharmacy and Pharmacology, 2011
    Co-Authors: Teruyo Yagi, Kazuko Yamauchi, Yoshie Miyawaki, Tomoyo Nishikawa, Shigeaki Kuwano
    Abstract:

    Intracaecal administration of rhein Anthrone, the intraluminally active metabolite of sennosides A and B, to mice quickly induced severe diarrhoea. Pretreatment with the prostaglandin (PG) biosynthesis inhibitor, indomethacin, and PGE2 antagonist, SC-19220, prevented the onset of diarrhoea induced by rhein Anthrone, but the PGE2 antagonist polyphoretin phosphate (PPP) showed only a weak inhibitory effect. Rhein Anthrone stimulated the production of PGE-like material only in the colon and its large intestinal propulsive activity was depressed by indomethacin and SC-19220, but not by PPP which suggests that the release of PGE-like material has some role in its purgative action.

  • suppression of the purgative action of rhein Anthrone the active metabolite of sennosides a and b by calcium channel blockers calmodulin antagonists and indometacin
    Pharmacology, 1993
    Co-Authors: Kazuko Yamauchi, Teruyo Yagi, S Kuwano
    Abstract:

    The involvement of Ca2+ in the mechanism of the purgative action of rhein Anthrone was studied. Among individual or combination pretreatments with calcium channel blockers, calmodulin antagonists and prostaglandin biosynthesis inhibitors, the combination of indometacin and nifedipine completely blocked the diarrhoea induced by rhein Anthrone and also inhibited its effects on colonic fluid and electrolyte transport, and large intestinal motility. Calmodulin antagonists were less active regarding suppression of the effects of rhein Anthrone. We concluded that, in addition to prostaglandins, diarrhoea induced by rhein Anthrone must also involve the calcium channel which can be blocked by nifedipine, but not verapamil.

  • suppression of the purgative action of rhein Anthrone the active metabolite of sennosides a and b by indomethacin in rats
    Journal of Pharmacy and Pharmacology, 1991
    Co-Authors: Teruyo Yagi, Kazuko Yamauchi, Yoshie Miyawaki, Atsuko Nishikawa, Shigeaki Kuwano
    Abstract:

    — Rhein Anthrone (12.48 mg kg−1) produces watery and mucoid diarrhoea approximately 20 min after intracaecal administration to rats. Pretreatment with the prostaglandin (PG) biosynthesis inhibitor indomethacin (10 mg kg−1, i.p.) only delayed and did not completely block the onset of the induced diarrhoea. Rhein Anthrone stimulated PGE2 release into the rat colonic lumen and the increased release was depressed by indomethacin. Rhein Anthrone also accelerated large intestinal transit and this acceleration could be partly inhibited by indomethacin, which was probably responsible for the delay in the onset of diarrhoea. Indomethacin prevented the enhanced water, K+ and mucus secretion and the reduced Na+ absorption in the colon which were induced by rhein Anthrone. The net water secretion could not be reversed to net absorption and the mucus secretion was only slightly depressed by indomethacin. Thus, our findings suggest that other mechanisms, together with the PG-dependent mechanism, are involved in the purgative action of rhein Anthrone in rats.

Hans-gert Korth - One of the best experts on this subject based on the ideXlab platform.

  • Anthrone and related hydroxyarenes tautomerization and hydrogen bonding
    Journal of Organic Chemistry, 2013
    Co-Authors: Hans-gert Korth, Peter Mulder
    Abstract:

    The keto–enolization of hydroxyl-substituted naphthols and 9-anthrols has been investigated by means of CBS-QB3 calculations. An excellent agreement between experiment and theory is found for the energetics for the Anthrone (5) ⇌ anthrol (6) equilibrium, with an enthalpy of tautomerization, ΔtH, of 3.8 kcal mol–1. In contrast, 1-naphthol is the preferred tautomer with a ΔtH = −9.0 kcal mol–1. Substitution of the hydrogens at the adjacent carbons by hydroxyl groups leads to the formation of strong intramolecular hydrogen bonds within a six-membered ring in the enones and the enols. Due to the difference in the intramolecular hydrogen bond enthalpy, ΔHBHintra, the equilibrium shifts further to the enone. Thus, for 1,8-dihydroxy-Anthrone (anthralin, dithranol) ΔtH increases to 12.7 kcal mol–1 with an enol/enone ratio of 10–10. The solvent effect on the 5 ⇌ 6 equilibrium has been quantified by considering the formation of intermolecular hydrogen bond(s), leading to an acidity parameter α2H for anthrol of 0.42...

  • Anthrone and Related Hydroxyarenes: Tautomerization and Hydrogen Bonding
    2013
    Co-Authors: Hans-gert Korth, Peter Mulder
    Abstract:

    The keto–enolization of hydroxyl-substituted naphthols and 9-anthrols has been investigated by means of CBS-QB3 calculations. An excellent agreement between experiment and theory is found for the energetics for the Anthrone (5) ⇌ anthrol (6) equilibrium, with an enthalpy of tautomerization, ΔtH, of 3.8 kcal mol–1. In contrast, 1-naphthol is the preferred tautomer with a ΔtH = −9.0 kcal mol–1. Substitution of the hydrogens at the adjacent carbons by hydroxyl groups leads to the formation of strong intramolecular hydrogen bonds within a six-membered ring in the enones and the enols. Due to the difference in the intramolecular hydrogen bond enthalpy, ΔHBHintra, the equilibrium shifts further to the enone. Thus, for 1,8-dihydroxy-Anthrone (anthralin, dithranol) ΔtH increases to 12.7 kcal mol–1 with an enol/enone ratio of 10–10. The solvent effect on the 5 ⇌ 6 equilibrium has been quantified by considering the formation of intermolecular hydrogen bond(s), leading to an acidity parameter α2H for anthrol of 0.42. It is shown that the hydrogen bond donating ability of bulk methanol is greatly attenuated through the formation of cyclic oligomers. The benzylic and phenolic bond dissociation enthalpies for Anthrone up to anthralin suggest some antioxidant potency but the precise (radical) mechanism of action remains uncertain