New antioxidants incorporating indole and indoline chromophores

Synthesis and Crystal Structure of (4bRS,9bRS)-5-(2,4-dimethoxyphenyl)-4b,9b-7,7-dimethyldihydroxy-4b,5,6,7,8,9b-hexahydroindeno[1,2-b] indole-9,10-dione

A highly regiospecific synthesis and crystal structure of (4b RS,9b RS)-5-(2,4-dimethoxyphenyl)-7,7-dimethyl-4b,9b-dihydroxy-4b,5,6,7,8,9b-hexahydroindeno[1,2- b]indole-9,10-dione is reported. It was tested in vitro against six human tumour cell lines and two nontumourogenic cell lines. Their in vitro activity against Mycobacterium tuberculosis is also reported. In general, it was found to possess a marginal activity.

One-pot synthesis of new substituted 1,2,3,4-tetrahydrocarbazoles via Petasis reaction

The one-pot synthesis of a new substituted 1,2,3,4-tetrahydrocarbazoles has been described via Petasis reactions. These tetrahydrocarbazoles exhibits various medicinal importance and might be suitable for elaboration into larger peptides at carboxy termini. The scope and limitations of this method have been examined.

Protection from olanzapine-induced metabolic toxicity in mice by acetaminophen and tetrahydroindenoindole

OBJECTIVE

In mice and in humans, treatment with the second-generation antipsychotic drug olanzapine (OLZ) produces excessive weight gain, adiposity and secondary metabolic complications, including loss of glucose and insulin homeostasis. In mice consuming a high-fat (HF) diet, a similar phenotype develops, which is inhibited by the analgesic acetaminophen (APAP) and by the antioxidant tetrahydroindenoindole (THII). Therefore, we examined the ability of APAP and THII to prevent metabolic changes in mice receiving OLZ.

DESIGN AND MEASUREMENT

C57BL/6J mice received either a normal diet or a HF diet, and were administered daily dosages of OLZ (3 mg kg(-1) body weight), alone or with APAP (30 mg kg(-1) body weight) or THII (4.5 mg kg(-1) body weight), for 10 weeks. Parameters of body composition and metabolism, including glucose and insulin homeostasis and oxidative stress, were examined.

RESULTS

OLZ treatment doubled the HF diet-induced increases in body weight and percent body fat. These increases were partially prevented by both APAP and THII, although food consumption was constant in all groups. The THII protection was associated with an increase in whole body and mitochondrial respiration. OLZ also exacerbated, and both APAP and THII prevented, HF diet-induced loss of glucose tolerance and insulin resistance. As increased body fat promotes insulin resistance by a pathway involving oxidative stress, we evaluated production of reactive oxygen and lipid peroxidation in white adipose tissue (WAT). HF diet caused an increase in lipid peroxidation, NADPH-dependent O(2) uptake and H(2)O(2) production, which were further exacerbated by OLZ. APAP, THII and the NADPH oxidase inhibitor, diphenyleneiodonium chloride, each abolished oxidative stress in WAT.

CONCLUSIONS

We conclude that both APAP and THII intervene in the development of obesity and metabolic complications associated with OLZ treatment.

Tetrahydroindenoindole inhibits the progression of diabetes in mice

Diabetes is characterized by elevated fasting blood glucose (FBG) resulting from improper insulin regulation and/or insulin resistance. Herein we used female C57BL/6J mouse models for type 1 diabetes (streptozotocin [STZ] treatment) and type 2 diabetes (high-fat diet) to examine the ability of 4b,5,9b,10-tetrahydroindeno[1,2-b]indole (THII) to intervene in the progression of diabetes. THII (100 microM in drinking water) significantly diminished and partially reversed the increase in FBG levels produced by STZ. After 10 weeks on a high-fat diet, mice had normal FBG levels, but exhibited fasting hyperinsulemia and loss of glucose tolerance. THII significantly diminished these changes in glucose and insulin. In isolated liver mitochondria, THII inhibited succinate-dependent H(2)O(2) production, while in white adipose tissue, THII inhibited NADPH oxidase-mediated H(2)O(2) production and lipid peroxidation. Without intervention, such oxidative processes might otherwise promote diabetogenesis via inflammatory pathways. THII also increased O(2) consumption and lowered respiratory quotient (CO(2) produced/O(2) consumed) in vivo, indicating a greater utilization of fat for metabolic fuel. Increased metabolic utilization of fat correlated with a decrease in the rate of body weight gain in THII-treated mice fed the high-fat diet. We conclude that THII may retard the progression of diabetes via multiple pathways, including the inhibition of oxidative and inflammatory pathways.

Possible anti-oxidant and neuroprotective mechanisms of zolpidem in attenuating typical anti-psychotic-induced orofacial dyskinesia: a biochemical and neurochemical study

Tardive dyskinesia is a serious motor side effect of chronic anti-psychotic therapy. The pathophysiology of this disabling and commonly irreversible movement disorder continues obscure and may be caused due to GABAergic hypofunction or increased oxidative damage and free radical generation. Chronic treatment with typical antipsychotics leads to the development of abnormal hyperkinetic orofacial movements (vacuous chewing movements, tongue protrusions and facial jerking) in rats and is widely accepted as the animal model for tardive dyskinesia. Zolpidem, a GABA-mimetic drug is structurally related to melatonin and has been reported to possess anti-oxidant and neuroprotective effects both in vivo and in vitro. The study was carried out to investigate whether zolpidem can be used in the treatment of typical anti-psychotic-induced orofacial dyskinesia. Chronic haloperidol (1 mg/kg, i.p. for 21 days) and chlorpromazine (5 mg/kg, i.p. for 21 days) treatment significantly induced orofacial hyperkinetic movements and zolpidem [N, N, 6-trimethyl-2-p-tolyl-imidazo (1, 2-a) pyridine 3-acetamideL-(+)] dose dependently (1, 2, 5 mg/kg i.p. for 21 days) reduced these haloperidol and chlorpromazine-induced hyperkinetic orofacial movements. Biochemical analysis revealed that haloperidol and chlorpromazine treatment significantly induced increase in lipid peroxidation and decrease in the levels of total nitric oxide levels, non-protein thiols (NPSH) and of anti-oxidant defense enzymes, superoxide dismutase (SOD) and catalase in the striatum of rat brain. Co-administration of zolpidem (1, 2, 5 mg/kg i.p. for 21 days) significantly reduced the lipid peroxidation and restored the non-protein thiols and total nitric oxide levels induced by chronic haloperidol and chlorpromazine treatment. It also significantly reversed the haloperidol and chlorpromazine-induced decrease in brain SOD and catalase activity. Neurochemical analysis (Neurotransmitter and their metabolite level estimation) revealed that haloperidol and chlorpromazine significantly decreased the dopamine, norepinephrine and serotonin levels in brain homogenates where as it caused a significant increase in the metabolite (VMA and HVA) levels in urine, which were significantly reversed by zolpidem at higher doses. Result of the present study support the therapeutic use of zolpidem in the treatment of typical anti-psychotic-induced orofacial dyskinesia.

Antioxidant activity and neuroprotective effects of zolpidem and several synthesis intermediates

Structural relationship between the antioxidant melatonin and the non-benzodiazepine hypnotic zolpidem (ZPD) suggests possible direct antioxidant and neuroprotective properties of this compound. In the present work, these effects were analyzed for zolpidem and four of its synthesis intermediates. In vitro assays include lipid peroxidation and protein oxidation studies in liver and brain homogenates. Intracellular antioxidant effects were analyzed by evaluation of free radical formation prevention in HT-22 hippocampal cells treated with glutamate 10mM and measured by flow cytometer DCF fluorescence. The neuroprotective effect of these compounds was evaluated as neuronal death prevention of HT-22 cells treated with the same concentration of glutamate. Zolpidem was found to prevent induced lipid peroxidation in rat liver and brain homogenates showing figures similar to melatonin, although it failed to prevent protein oxidation. ZPD-I was the most effective out of the several zolpidem intermediates studied as it prevented lipid peroxidation with an efficiency higher than melatonin or zolpidem and with an effectiveness similar to estradiol and trolox. ZPD-I prevents protein oxidation, which trolox is known to be unable to prevent. When cellular experiments were undertaken, ZPD-I prevented totally the increase of intracellular free radicals induced by glutamate 10mM in culture medium for 12h, while zolpidem and ZPD-III partially prevented this increase. Also the three compounds protected hippocampal neurons from glutamate-induced death in the same conditions, being their comparative efficacy, ZPD-III > ZPD-I = ZPD.

Syntheses of 2-substituted indoles and fused indoles by photostimulated reactions of o-iodoanilines with carbanions by the SRN1 mechanism

2-Substituted indoles (5a,b and 7) and fused indoles (9a-c, 11a,b, and 12) have been obtained by the S(RN)1 mechanism from photostimulated reactions of o-iodoaniline (1) and 1-halo-2-naphthalen-2-ylamines (3a,b) with enolate ions of acyclic (acetophenone (6), 2- (4a) and 4-acetylpyridine (4b)) and cyclic ketones (1- (8a) and 2-indanone (10a), 1- (8b) and 2-tetralone (10b) and 1-benzosuberone (8c)) in DMSO and liquid ammonia as solvents. The carbanions derived from 4a,b, 8a, and 10b are novel nucleophiles that form new C-C bonds by the S(RN)1 mechanism.

The Synthesis of Highly Substituted Decahydrocarbazoles as Potential Chain-Breaking Antioxidants

Two methyl groups have been introduced into the positions α to the N-atom in 1,2,3,4,4a,5,6,7-octahydrobenzo [d]carbazoles in a ‘one-pot’ procedure; additionally bromination of 1H-2,3,4,4a-tetrahydro-6-isopropylcarbazoles has been shown to occur at C-8 and the derived bromides converted into 8-alkenylated derivatives as precursors of chain-breaking antioxidants of tuneable lipophilicity.

Structure-activity relationships in a series of melatonin analogues with the low-density lipoprotein oxidation model

Despite an increasing number of publications concerning the antioxidant activity of melatonin, little is known about the structural features responsible for this kind of activity. To understand the role played by the different elements of melatonin structure in its antioxidant activity, we have designed and tested several compounds related to this molecule in the low-density lipoprotein peroxidation model. We present here the results of this study in terms of structure-activity relationships focusing on the influence of the acetamidoethyl side chain, the methoxy group, and the indole heterocycle. In this model, we found that changing the acyl residue generally resulted in more active products. We obtained particularly good results with the nonanoyl derivative which showed a level of activity comparable to that of phenols despite lacking a phenolic function. The presence of a methoxy group in position 5 generally had a beneficial influence on the activity, but when located in position 6, the effects were various. The substitution of a hydroxy for the methoxy group led to phenolic compounds endowed with very high antioxidant activity. Replacing the amide with a ketone function did not affect the activity while replacement with an amine group in some cases resulted in prooxidant compounds. Finally, we compared the efficacy of different aromatic rings. The indole heterocycle proved to be better than benzofurane and naphthalene rings.

Characterization of novel indenoindoles. Part I. Structure-activity relationships in different model systems of lipid peroxidation

Structure-activity relationships are presented for some representative compounds from a novel series of potent inhibitors of lipid peroxidation. The compounds are indenoindole derivatives with oxidation potentials in organic solvents of between 0.2 and 1.5 V. Two of these compounds, cis-5,5a,6,10b-tetrahydro-9-methoxy-7-methylindeno[2,1-b]indole (H 290/51) with an oxidation potential of 0.32 V and cis-4b,5,9b,10- tetrahydro-8-methoxy-6-methylindeno[1,2-b]indole (H 290/30) with an oxidation potential of 0.30 V, have been tested more extensively and compared with reference compounds in several pharmacological models of lipid peroxidation. The inhibitory potencies (pIC50) of the compounds in respect to Fe/Ascorbate-induced production of thiobarbituric acid-reactive substances (TBARS) in a suspension of purified soybean lecithin were calculated. These data are 8.2 for H 290/51; 8.0 for H 290/30; 5.6 for vitamin E; and 6.6 for butylated hydroxytoluene (BHT). In isolated rat renal tissue subjected to hypoxia and reoxygenation, the potency for inhibition of TBARS formation is 6.9 for H 290/51, 6.9 for H 290/30, and <5 for vitamin E. In oxidative modification of low-density lipoproteins (LDL) induced by mouse peritoneal macrophages, the corresponding pIC50 values for TBARS inhibition for each compound are: 8.7, 8.3, <5, and 6.9, respectively. It is concluded that the synthetic indenoindoles are potent antioxidants. The results suggest that indenoindoles such as H 290/51 and H 290/30 could be useful as therapeutic agents in pathophysiological situations where lipid peroxidation plays an important role.

Response of [Ah] battery genes to compounds that protect against menadione toxicity

We have studied the response of genes in the dioxin-inducible [Ah] battery to three compounds that protect mouse hepatoma cells (Hepa-1c7c7 wild-type, wt) against menadione toxicity. Pretreatment of wt cells with 25 microM 5,10-dihydroindenol[1,2-b]indole (DHII), 25 microM tert-butylhydroquinone (tBHO) or 10 microM menadione itself, generated substantial protection against toxicity produced by subsequent menadione exposure. The gene response was examined in wt cells, and three mutant lines: CYP1A1 metabolism-deficient (c37 or P1-); nuclear translocation-impaired (c4 or nt-); and AHR-deficient (c2 or r-, containing < 10% of normal functional receptor levels). DHII treatment of wt cells for 12 hr markedly elevated the enzyme activities and mRNA levels of genes in the [Ah] battery: aryl hydrocarbon hydroxylase (Cyp1a1), NAD(P)H:menadione oxidoreductase (Nmol), cytosolic aldehyde dehydrogenase class 3 (Ahd4), and UDP-glucuronosyltransferase form 1*06 (Ugt1*06). Treatment of the c4 and c2 cells with DHII failed to induce mRNA levels of the genes, indicating that induction of the [Ah] gene battery by DHII is aromatic hydrocarbon receptor (AHR)-mediated. On the other hand, neither tBHO nor menadione caused increases in CYPlAl mRNA, but tBHQ significantly enhanced the NMO1, AHD4, and UGT1*06 mRNA levels in all three mutant cell lines. In conclusion, we expect one or more putative electrophile response elements (EpRE), previously found in the regulatory regions of the murine Nmol, Ahd4, and ugt1*06 genes, to be functional in responding to phenolic antioxidants.

Retardation of benzo[a]pyrene-induced epidermal tumor formation by the potent antioxidant 4b,5,9b,10-tetrahydroindeno[1,2-b]indole

The ability of the potent antioxidant, 4b,5,9b,10-tetrahydroindeno[1,2-b]indole (THII), to inhibit tumor formation by topically-applied benzo[a]pyrene was evaluated using a complete carcinogenicity mouse skin bioassay. THII was administered by direct application to the skin, in the food or through the drinking water. In each case, THII increased the average time until the appearance of tumors by 4 weeks, and also decreased the total number of tumors compared with benzo[a]pyrene alone. These protective effects corresponded with the ability of THII to inhibit benzo[a]pyrene- or 12-O-tetradecanoylphorbol-13-acetate-induced epidermal ornithine decarboxylase activity, a biomarker of tissue proliferation in skin of the treated animals. This is the first report of an antioxidant administered in food or water inhibiting chemically induced skin carcinogenesis.

Mechanisms of protection from menadione toxicity by 5,10-dihydroindeno[1,2,-b]indole in a sensitive and resistant mouse hepatocyte line

Established cell lines derived from newborn livers of c14CoS/c14CoS and cch/cch mice have been shown to be genetically resistant (14CoS/14CoS cells) or susceptible (ch/ch cells) to menadione toxicity. These differences are due in part to relatively higher levels of reduced glutathione (GSH) and NAD(P)H:menadione oxidoreductase (NMO1) activity in the 14CoS/14CoS cells. The indolic membrane-stabilizing antioxidant 5,10-dihydroindeno[1,2-b]indole (DHII) was shown previously to protect against various hepatotoxicants in vivo and in primary rat hepatocytes. This report describes how the 14CoS/14CoS and ch/ch cell lines provide a valuable experimental system to distinguish the mechanism of chemoprotection by DHII from menadione toxicity. The addition of 25 microM DHII produced a time-dependent decrease in menadione-mediated cell death in 14CoS/14CoS cells, with little effect on ch/ch cell viability. The maximum protective effect occurred at 24 hr, although the concentration of DHII remained constant for 48 hr. The protective effect of DHII correlated with enhanced glutathione levels (234% increase at 24hr), as well as induction of four enzymes involved in the detoxification and excretion of menadione: NAD(P)H:menadione oxidoreductase (NMO1, quinone reductase), glutathione reductase, glutathione transferase (GST1A1), and UDP glucuronosyltransferase (UGT1*06), with 24-hr maximum induction of 707, 201, 171 and 198%, respectively. Other biotransformation enzymes not directly involved in menadione metabolism (glutathione peroxidase, cytochromes P4501A1 and P4501A2, copper-, zinc-dependent superoxide dismutase, and NADPH cytochrome c oxidoreductase) were not induced by DHII. Menadione-stimulated superoxide production was inhibited 50% by DHII only in 14CoS/14CoS cells, and the inhibition required 24-hr preincubation. Pretreatment with DHII also protected both cell types against the menadione-mediated depletion of GSH, and the increase in percent (oxidized glutathione GSSG), an indicator of oxidative stress. These results suggest that DHII does not protect against menadione toxicity by virtue of its antioxidant or membrane-stabilizing properties. Rather, it acts by inducing a protective enzyme profile that migates redox cycling and facilitates excretion of menadione.