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PubMed1979

[Metabolism of antipsoriatic anthrone derivatives].

The metabolisation of the antipsoriatically active molecules 1,8,9-triacetoxy-anthracene und 1,8-diacetoxy-9-anthrone by serum is described. Under these conditions 1,8-dihydroxy-9-anthrone, 1-hydroxy-8-acetoxy-9-anthrone, 1,8,1',8'-tetrahydroxy-bisanthrone, 1,8-dihyroxy-anthraquinone, 1,8-diacetoxy-anthraquinone and 1-hydroxy-8-acetoxy-anthraquinone arise from both educts. Quantitative determinations of these metabolites indicate that hydrolytic reactions occur prior to oxidation. Contrary to 1,8-dihydroxy-9-anthrone, 1,8,9-triacetoxyanthracene and 1,8-diacetoxy-9-anthrone are effective against psoriatic lesions without accompanying inflammations of the skin. 1,8,9-Trimethoxy-anthracene, however, is ineffective, also indicating that at least 1,8,9-triacetoxy-anthracene is a prodrug.--In agreement with Krebs' hypothesis 10,10-dialkylated 1,8-dihydroxy-9-anthrones described in this paper are ineffective against psoriasis.

Anthracenes↗
PubMed1992

Influence of rhein anthrone and rhein on small intestine transit rate in rats: evidence of prostaglandin mediation.

The present study was undertaken to investigate the role of prostaglandins in the shortening of transit time observed after intraduodenal administration of rhein anthrone and rhein. After intraduodenal administration of rhein anthrone (0.5-10 mg/rat), a dose-dependent acceleration of small intestinal transit was observed. The effect for rhein (1-10 mg/rat) was far less pronounced. In the same test conditions, analysis of small intestinal tissue revealed a significant increase of prostaglandin E2 (PGE2), reaching its maximum value 30 min after administration of rhein anthrone. The increase in PGE2 found 30 min after administration of rhein was not significant. The effects provoked by rhein anthrone could be largely prevented by pretreatment of the animals with indomethacin (1-3 mg rat) or cortisol (10 mg/rat). It is concluded that prostaglandins play an important role in the acceleration of the transit provoked in rats by rhein anthrone.

Animals↗
PubMed1991

Suppression of the purgative action of rhein anthrone, the active metabolite of sennosides A and B, by indomethacin in rats.

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.

Animals↗
PubMed1988

Instability of rhein-9-anthrone as a problem in pharmacological and analytical use.

The stability of rhein-9-anthrone, one of the main and most active metabolites of the sennosides A + B, was studied under physiological conditions. A high-pressure liquid chromatographic method for the determination of rhein-9-anthrone and its oxidation products, rhein and sennidins A + B, was developed. Rhein-9-anthrone, dissolved in Tyrode buffer at pH 6.5 or 7.5 at a concentration of 10(-4) mol/l, completely disappeared from a solution warmed to 37 degrees C within 30 min. More than 90% were transformed into rhein and sennidins A + B. Pharmacological experiments in rats showed that net water absorption in the small intestine was reversed to net secretion by rhein-9-anthrone, whereas rhein and sennidins in corresponding concentrations were ineffective. As at least rhein is known to stimulate secretion under different experimental conditions, all pharmacological results with rhein-9-anthrone must be interpreted with caution and should be checked whether they essentially differ from those of its main oxidation products.

Animals↗
PubMed1993

Conventionalization of germ-free rats reverses the disability of rhein anthrone to induce laxation.

This study shows that rhein anthrone has no laxative potency in germ-free rats because after intracaecal administration of a dose of 50 mg/kg the large intestine transit exceeded 240 min. The time course of the laxative potency of rhein anthrone injected intracaecally was evaluated after peroral inoculation of germ-free rats with the caecal contents of conventional rats. Large intestine transit was measured at consecutive periods, on days 0, 1, 2, 3 and 5 after peroral inoculation. It appeared that 1 day after peroral inoculation the laxative potency of rhein anthrone was already established (large intestinal transit < 10 min) and laxation remained on the following days (days 2, 3 and 5). We concluded that rhein anthrone is inactive in germ-free rats and acquires laxative potency after peroral inoculation of germ-free rats with caecal contents of conventional rats.

Animals↗
PubMed1993

Suppression of the purgative action of rhein anthrone, the active metabolite of sennosides A and B, by calcium channel blockers, calmodulin antagonists and indomethacin.

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 indomethacin 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.

Animals↗
PubMed1993

Antioxidant and radical scavenging effects of anthraquinones and anthrones.

The activity of seven anthraquinones and four anthrones against nonenzymatic and enzymatic lipid peroxidation in vitro and their ability to scavenge free radicals have been studied. In nonenzymatic peroxidation in rat hepatocytes induced by t-butyl hydroperoxide, dithranol and anthrone were the strongest antioxidants, having IC50 values of 8 +/- 1 and 24 +/- 5 mumol/l, respectively. Rhein (IC50 64 +/- 2 mumol/l) and aloe-emodin (IC50 65 +/- 3 mumol/l) showed the highest inhibitory activity against peroxidation of linoleic acid catalyzed by soybean 15-lipoxygenase. Anthrone (IC50 62 +/- 2 mumol/l), dithranol (IC50 72 +/- 1 mumol/l) and rhein anthrone (IC50 76 +/- 6 mumol/l) were the most effective radical scavengers of the diphenylpicrylhydrazyl radical. The antioxidant activities in hepatocytes and the radical scavenging activities were correlated, whereas the inhibition of enzymatic lipid peroxidation showed no correlation with the two other effects.

Animals↗
PubMed1996

Antipsoriatic anthrones: aspects of oxygen radical formation, challenges and prospects.

1. Antipsoriatic anthrones are among the most commonly used topical agents for the treatment of psoriasis. 2. These drugs generate reactive oxygen species during their auto-oxidation under physiological conditions. 3. Recent studies have indicated that activation of molecular oxygen by anthrones may play a critical role in their mechanism of action at the molecular level. 4. This article summarizes the evidence pointing toward the significance of oxygen activation and radical formation in the antipsoriatic action and induction of skin inflammation of anthrones. 5. Also, the role of oxygen radical formation in the development of novel anthrones devoid of inflammatory and staining properties is discussed.

Administration, Topical↗
PubMed1989

Development of Anthron, an antithrombogenic coating for angiographic catheters.

A new heparinized hydrophilic polymer (Anthron) which contains a large amount of heparin ionically bound to the polymer matrix has been developed. Anthron showed excellent and long-term blood compatibility both in animal and clinical tests. It has been clarified that the long-term blood compatibility of Anthron results from its negative membrane potential and continuous release of heparin from its surface into the blood at the rate of more than 0.01 unit/cm2 min. The application of Anthron for angiographic catheters was studied, and we evaluated the effects of our antithrombogenic angiographic catheter (AAC). As controls, polyurethane catheters (PUC), and polyethylene catheters (PEC), were studied in a similar manner. In addition, the mechanisms of thrombus formation and its complications are discussed.

Angiography↗
PubMed1996

A purgative action of barbaloin is induced by Eubacterium sp. strain BAR, a human intestinal anaerobe, capable of transforming barbaloin to aloe-emodin anthrone.

Orally administered barbaloin (100 mg/kg) did not induce any diarrhea in male Wistar rats, in spite of severe diarrhea with sennoside B (40 mg/kg). Also, in gnotobiote rats mono-associated with Peptostreptococcus intermedius, a human intestinal anaerobe capable of reducing sennidins to rhein anthrone, barbaloin did not induce diarrhea; the faecal water content (71.9%) 8 h after the administration of barbaloin was not increased, compared with that (73.9%) just before the treatment. However, severe diarrhea was induced with barbaloin in gnotobiote rats mono-associated with Eubacterium sp. strain BAR, another human intestinal anaerobe capable of transforming barbaloin to aloe-emodin anthrone; the faecal water content was significantly increased to 85.5% 8 h after the administration, from 73.2% before the treatment. At this time, barbaloin was transformed to aloe-emodin anthrone in the feces from the gnotobiote rats mono-associated with the strain BAR, but not in feces from the conventional rats or the gnotobiote rats mono-associated with P. intermedius. These facts indicate that barbaloin is inactive as a laxative itself but is activated to aloe-emodin anthrone, a genuine purgative component, by Eubacterium sp. strain BAR.

Animals↗
PubMed1995

The effects of calcium antagonists on anthrone skin tumor promotion and promoter-related effects in SENCAR mice.

The present study investigated a possible role for Ca2+ in skin tumor promotion by anthrones. This was accomplished by testing the effects of two Ca2+ antagonists, verapamil and 3,4,5-trimethoxybenzoic acid 8-(diethylamino) octyl ester (TMB-8), on tumor promotion and promoter-related effects induced by the anthrone chrysarobin in SENCAR mice. Verapamil and TMB-8 both effectively inhibited epidermal ornithine decarboxylase (ODC) induction by a single application of chrysarobin. Both Ca2+ antagonists inhibited anthrone-induced skin edema and epidermal hyperplasia. Additionally, both verapamil and TMB-8 slightly inhibited (20-21% at the highest doses) tumor promotion with chrysarobin. Although the inhibition by both Ca2+ antagonists was not statistically significant (P > 0.05) in either case, the fact that both compounds produced a similar inhibition suggests that this effect may be biologically relevant. Collectively, the data suggest a possible role for Ca2+ in the process of skin tumor promotion by anthrones.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

In vitro reduction of rhein anthraquinone to rhein anthrone by rat cecal microflora and some intestinal bacterial strains.

After in vitro incubation of cecal content from CVL or gnotobiotic rats with rhein anthraquinone (1 mg g-1) for 18 h at 37 degrees, the anthraquinone was converted to rhein anthrone for 23.5 (SD +/- 3.4) per cent and 19.4 (+/- 4.7) per cent, respectively. Liquid cultures of some strictly anaerobic fecal bacteria of man and mouse incubated with rhein anthraquinone (62.5 micrograms ml-1) for 48 h at 37 degrees, revealed only small amounts of reduced substance. Although the underlying mechanisms of the differences in both conditions remain unclear, the experimental data accentuate the need for using cecal content when exploring the in vitro metabolism of anthranoids by the intestinal microflora. The conversion was chemically proven by derivatization of the anthrone with 4-nitroso-N-N-dimethylaniline in pyridine, followed by hydrolysis and identification of the released anthranoid by mass spectrometry. The in vitro reduction capacity of the cecal content of CVL rats was drastically decreased by oral administration to rats of different combinations of neomycin sulfate, metronidazole, bacitracin and Na-penicillin G. In these cases the conversion ranked between 0.2 per cent and 5.2 per cent the first day after administration. It is concluded that rhein anthraquinone in cecal content is reduced to the highly reactive and labile rhein anthrone, which accounts for the in vivo disappearance of dihydroxy-anthranoid equivalents in routine analysis after oral administration of anthraquinones to experimental animals.

Animals↗
PubMed1992

The effect of rhein and rhein anthrone on intestinal fluid transport and on large intestine transit in germ-free rats.

The effect of rhein and rhein anthrone on the transit and the transport of water and electrolytes in the large intestine was investigated in germ-free rats. After intracaecal administration, neither of the two compounds was found to accelerate the transit of a colour marker through the large intestine. Both drugs reduced the net absorption of sodium and chloride in the colon and enhanced net potassium secretion. Net water absorption was decreased by rhein and even reversed into net secretion by rhein anthrone. Our results show that the secretagogue activity of the compounds is not sufficient to induce laxation in germ-free rats. Furthermore rhein and rhein anthrone had no laxative properties under our experimental conditions.

Animals↗
PubMed1995

Treatment of psoriasis with anthrones-chemical principles, biochemical aspects, and approaches to the design of novel derivatives.

Antipsoriatic anthrones are probably the most commonly used topical agents in the treatment of psoriasis. There is growing evidence that the biochemical basis for their mechanism of action at the molecular level is related to their redox activity leading to the production of active oxygen species, which include singlet oxygen, superoxide anion radical, and hydroxyl radical. These species are involved in a variety of oxidative effects affecting cellular targets that have been implicated both in the mode of action and the skin-irritating properties of antipsoriatic anthrones: interaction with DNA, inhibition of various enzyme systems associated with cell proliferation and inflammation, such as glucose-6-phosphate dehydrogenase and inflammation, such as glucose-6-phosphate dehydrogenase and 5-lipoxygenase, and destruction of membrane lipids. Furthermore, the application of this information to the design of novel derivatives is discussed. In particular, compounds with diminished oxygen radical-generating properties have been developed, which may permit a separation of antipsoriatic and inflammatory effects. Some of the novel anthrone analogs which produced significantly less amounts of oxygen radicals than dithranol compared favorably in biological tests with this known antipsoriatic drug as an alternative method of treating psoriasis.

Anthracenes↗
PubMed2005

[Research on energy transfer between riboflavin and anthrone derivative].

According to Forster's theory about energy transfer, the energy transfer between riboflavin and anthrone derivative was investigated. It was found that there is a notable energy transfer between riboflavin and anthrone derivative, and the energy transfer efficiency is affected by the following factors: heating temperature, heating time, and mass ratio. And the best ratio of riboflavin and anthrone derivative is 1:3. At the same time the energy transfer efficiency drops with increasing heating temperature and time.

Anthracenes↗
PubMed2006

Chiral bicyclic guanidine-catalyzed enantioselective reactions of anthrones.

Chiral bicyclic guanidine 1 was found to be an excellent catalyst for reactions between anthrones and various dienophiles. The catalyst can tolerate a range of substituents and substitution patterns, making several anthrone derivatives suitable for this reaction. Both Diels-Alder and Michael adducts were obtained in excellent yields, high regioselectivities, and high enantioselectivities. This is the first case of a highly enantioselective base-catalyzed anthrone Diels-Alder reaction.

Journal Article↗
PubMed1990

Differential mechanism for the inhibition of epidermal growth factor binding to its receptor on mouse keratinocytes by anthrones and phorbol esters.

1,8-Dihydroxy-3-methyl-9-anthrone (chrysarobin), a potent anthrone tumor promoter, reduced [125I] epidermal growth factor (EGF) binding to its receptor in primary epidermal cells from SENCAR mice maintained in low Ca2+ containing medium. The time course for this effect with chrysarobin was different from that of 12-O-tetradecanoylphorbol-13-acetate (TPA). Maximum inhibition of [125I]EGF binding was observed at 18 h versus 1 h respectively. Scatchard analyses revealed that the inhibition by chrysarobin was due to a decrease in the number of both high- and low-affinity classes of EGF receptors. In contrast, TPA caused a rapid inhibition of EGF binding, primarily due to a loss of high-affinity receptors. The mechanism by which chrysarobin inhibited the binding of EGF to its receptor involved neither direct activation nor membrane translocation of epidermal protein kinase C, whereas the rapid decrease in EGF binding induced by TPA was consistent with its ability to activate protein kinase C. Structure-activity relationships for EGF binding inhibition by anthrones revealed that inhibition was inversely proportional to chain length at the C10-position, which correlated closely with oxidation rate and skin tumor-promoting activity. alpha-Tocopherol was able to block partially the effect of chrysarobin but not TPA on EGF binding. These results suggest that oxidation at position C10 is at least partially responsible for the inhibition of EGF binding induced by chrysarobin. Furthermore, these studies support the hypothesis that changes in EGF receptor binding and/or function may play a role in skin tumor promotion by diverse classes of promoting agents.

Animals↗
PubMed1988

Involvement of prostaglandin E-like material in the purgative action of rhein anthrone, the intraluminal active metabolite of sennosides A and B in mice.

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.

Animals↗