5-Hydroxyoxindole

Evaluation of ethnopharmacologically selected Vitex negundo L. for In vitro antimalarial activity and secondary metabolite profiling.[Pubmed:33789139]

J Ethnopharmacol. 2021 Jul 15;275:114076.

ETHANOPHARMACOLOGICAL RELEVANCE: Limited drugs, rise in drug resistance against frontline anti-malarial drugs, non-availability of efficacious vaccines and high cost of drug development hinders malaria intervention programs. Search for safe, effective and affordable plant based anti-malarial agents, thus becomes crucial and vital in the current scenario. The Vitex negundo L. is medicinal plant possessing a variety of pharmaceutically important compounds. The plant is used traditionally worldwide for the treatment of malaria including India and Malaysia by the indigenous tribes. In vitro studies have reported the anti-malarial use of the plant in traditional medicinal systems. AIM OF THE STUDY: The aim of the current study is to evaluate the traditionally used medicinal plants for in vitro anti-malarial activity against human malaria parasite Plasmodium falciparum and profiling secondary metabolite using spectroscopic and chromatographic methods. Chemical profiling of active secondary metabolites in the extracts was undertaken using LC-MS. MATERIALS AND METHODS: Based on the ethno-botanical data V. negundo L. was selected for in vitro anti-malarial activity against P. falciparum chloroquine-sensitive (3D7) and multidrug resistant (K1) strains using SYBR Green-I based fluorescence assay. Cytotoxicity of extracts was evaluated in VERO cell line using the MTT assay. Haemolysis assay was performed using human red blood cells. Secondary metabolites profiling was undertaken using chromatographic and spectroscopic analysis. Liquid chromatography analysis was performed using a C18, 150 X 2.1, 2.6 mum column with gradient mobile phase Solvent A: 95% (H2O: ACN), Solvent B: Acetonitrile, Solvent C: Methanol, Solvent D: 5 mM NH4 in 95:5 (H2O: ACN) at a constant flow rate of 0.250 ml/min. The LC-MS spectra were acquired in both positive and negative ion modes with electrospray ionization (ESI) source. RESULTS: The anti-malarial active extract of V. negundo L. leaf exhibited potent anti-malarial activity with IC50 values of 7.21 mug/ml and 7.43 mug/ml against 3D7 and K1 strains, respectively with no evidence of significant cytotoxicity against mammalian cell line (VERO) and no toxicity as observed in haemolysis assay. The HPLC-LC-MS analysis of the extract led to identification of 73 compounds. We report for the first time the presence of Sabinene hydrate acetate, 5-Hydroxyoxindole, 2(3,4-dimethoxyphenyl)-6, 7-dimethoxychromen-4-one, Cyclotetracosa-1, 13-diene and 5, 7-Dimethoxyflavanone in the anti-malarial active extract of V. negundo L. leaf. Agnuside, Behenic acid and Globulol are some of the novel compounds with no reports of anti-malarial activity so far and require further evaluation in pure form for the development of potent anti-malarial compounds. CONCLUSIONS: The result report and scientifically validate the traditional use of V. negundo L. for the treatment of malaria providing new avenues for anti-malarial drug development. Several novel and unknown compounds were identified that need to be further characterized for anti-malarial potential.

A 5-hydroxyoxindole derivative attenuates LPS-induced inflammatory responses by activating the p38-Nrf2 signaling axis.[Pubmed:29940171]

Biochem Pharmacol. 2018 Sep;155:182-197.

5-Hydroxyoxindole is a urinary metabolite of indole that exhibits antioxidant activity. In the present study, we found that a 5-Hydroxyoxindole derivative (5-HI) significantly inhibited LPS-induced inflammatory effects in the murine macrophage cell line, RAW264.7. 5-HI induced the expression of the transcription factor, Nrf2, which is typically ubiquitinated by Keap1, an adaptor component of the ubiquitin E3 ligase complex, resulting in its proteasomal degradation. By utilizing Keap1-/- MEFs reconstituted with Keap1 mutants harboring substitutions in their major cysteine residues, we clarified the importance of Cys151 in Keap1 as a sensor for 5-HI in the induction of Nrf2 expression. Furthermore, 5-HI induced the activation of the MKK3/6-p38 pathway, which is required for the transcriptional activation of Nrf2. The knockdown of Nrf2 enhanced the LPS-induced expression of inflammatory mediators, including iNOS, NO, and CCL2, and effectively repressed the inhibitory effects of 5-HI on their expression. Although 5-HI and antioxidant N-acetyl cysteine (NAC) both reduced LPS-induced ROS generation, the treatment with NAC did not affect the LPS-induced expression of inflammatory mediators, suggesting that the anti-inflammatory activity of 5-HI mediated by Nrf2 is independent of redox control. Furthermore, when injected into mice with 5-HI, the expression of Nrf2 was significantly increased, and the LPS-induced mRNA expression of CXCL1, CCL2, TNFalpha, and IL-6 were remarkably inhibited in the kidneys, liver, and lungs, and the production of these cytokines in serum was effectively reduced. Collectively, these results suggest that 5-HI has potential in the treatment of inflammatory diseases through the activation of Nrf2.

Preparation and antioxidant/pro-oxidant activities of 3-monosubstituted 5-hydroxyoxindole derivatives.[Pubmed:27895383]

J Clin Biochem Nutr. 2016 Nov;59(3):165-173.

Antioxidant treatments have been expected to be a novel therapeutics for various oxidative stress-mediated disorders. Our previous study revealed that 5-Hydroxyoxindole and its 3-phenacyl-3-hydroxy derivatives showed excellent antioxidant activities such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and lipid-peroxidation inhibitory activity. However, the DPPH radical scavenging activity of the 3,3-disubstituted derivatives was lower than that of the original 5-Hydroxyoxindole. In the present study, we synthesized novel 3-monosubstituted 5-Hydroxyoxindole derivatives that exhibited stronger DPPH radical scavenging activities and lipid peroxidation-inhibitory activities than the 3,3-disubstituted 5-Hydroxyoxindoles. Moreover, the 3-monosubstituted 5-Hydroxyoxindole derivatives showed neither an iron-mediated pro-oxidant effect nor a remarkable cytotoxicity against HL-60 cell lines except some of the highly lipophilic compounds. These results indicate that 3-monosubstituted 5-Hydroxyoxindoles can be used as a promising antioxidant scaffold for drug discovery.

Antioxidant activities of 5-hydroxyoxindole and its 3-hydroxy-3-phenacyl derivatives: the suppression of lipid peroxidation and intracellular oxidative stress.[Pubmed:24216095]

Bioorg Med Chem. 2013 Dec 15;21(24):7709-14.

The antioxidant activities of 5-Hydroxyoxindole (1) and newly synthesized 3,5-dihydroxy-3-phenacyl-2-oxindole derivatives against rat liver microsome/tert-butylhydroperoxide system-induced lipid peroxidation and hydrogen peroxide-induced intracellular oxidative stress were investigated. Compound 1 and its derivatives showed significant suppression of lipid peroxidation and an intracellular oxidative stress. The effects of the more lipophilic derivatives tended to be greater than that of the original compound 1. The cytotoxicity of all of the oxindole derivatives on human promyelocytic leukemia HL60 cells was lower than that of 2,6-di(tert-butyl)-4-hydroxytoluene (BHT), a widely used phenolic antioxidant. These results show that compound 1 and its 3-substituted derivatives could be good lead candidates for future novel antioxidant therapeutics.

Endogenous oxidized indoles share inhibitory potency against [3H]isatin binding in rat brain.[Pubmed:17982874]

J Neural Transm Suppl. 2007;(72):29-34.

Isatin is an endogenous oxidized indole that influences a range of processes in vivo and in vitro. It has a distinct and discontinuous distribution in the brain and [3H]isatin binding sites are widely distributed in rat brain sections. The highest labelling is found in hypothalamic nuclei and in the cortex, hippocampus, and cerebellum (Crumeyrolle-Arias et al., 2003). However, the properties of most isatin binding sites and their physiological ligands remain unknown. In the present study the effects of three endogenous oxidized indoles (oxindole, 5-hyxdoxyoxindole, and isatin) on [3H]isatin binding were investigated in rat brain sections. In most regions cold isatin (0.2 mM) significantly reduced [3H]isatin binding. In addition to isatin, the other endogenous oxidized indoles, 5-Hydroxyoxindole and oxindole were effective in displacing [3H]isatin. Total irreversible inhibition of monoamine oxidases caused inhibition of specific [3H]isatin binding in 7 of 10 brain region studied. This was accompanied by altered sensitivity of [3H]isatin binding to these indoles, including regions where a decrease of specific binding was not detected. The combinations of the three oxidized indoles produced two clear effects: augmentation (potentiation) and attenuation (blockade) of inhibitory activity compared with the independent effects of these compounds. The different effects of oxidized indoles and their combinations (isatin + 5-Hydroxyoxindole and isatin + oxindole) in various brain regions therefore suggest an interaction of [(3H]isatin with different and multiple isatin-binding sites, which exhibit different sensitivity to endogenous oxidizing indoles.

5-hydroxyoxindole, an indole metabolite, is present at high concentrations in brain.[Pubmed:17722070]

J Neurosci Res. 2008 Jan;86(1):202-7.

5-Hydroxyoxindole has been identified as a urinary metabolite of indole, which is produced from tryptophane via the tryptophanase activity of gut bacteria. We have demonstrated recently that 5-Hydroxyoxindole is an endogenous compound in blood and tissues of mammals, including humans. To date, 5-Hydroxyoxindole's role is unknown. The aim of this study was to compare 5-Hydroxyoxindole levels in plasma and cerebrospinal fluid (CSF) during day-night and seasonal changes, as a common approach to pilot physiological characterization of any compound. Simultaneous blood and CSF sampling was performed in the ewe, because its size allows collection in quantities suitable for 5-Hydroxyoxindole assay (HPLC-ED) in awake animals, without obvious physiological or behavioral disturbance. 5-Hydroxyoxindole concentration was quite stable in plasma (2-6 nM range), whereas, in CSF, it displayed marked day-night and photoperiodic variations (4-116 nM range). 5-Hydroxyoxindole levels in CSF were twofold higher at night than during the day and at least one order of magnitude higher during the long compared with the short photoperiod. These day/night and photoperiodic variations persisted after pinealectomy, indicating that 5-Hydroxyoxindole rhythms in CSF are independent of melatonin formation. In conclusion, high levels of 5-Hydroxyoxindole in the CSF during long photoperiod and its daily modulation suggest physiological involvement of 5-Hydroxyoxindole in rhythmic adjustments in the brain, independently of the pineal gland.

Inhibition of brain mitochondrial monoamine oxidases by the endogenous compound 5-hydroxyoxindole.[Pubmed:15104251]

Biochem Pharmacol. 2004 Mar 1;67(5):977-9.

5-Hydroxyoxindole is a recently identified endogenous compound. Its physiological role remains unclear but certain evidence exists, that it may share some regulatory properties with isatin, a known endogenous inhibitor of monoamine oxidase (MAO) type B (MAO-B). In this study several oxidized indoles were tested for their in vitro inhibition of MAO type A (MAO-A) and B of rat brain non-synaptic mitochondria. 5-Hydroxyoxindole was less potent MAO-A inhibitor (IC50 56.8 microM) than isatin (31.8 microM) and especially 5-hydroxyisatin (6.5 microM), but it was the only highly selective MAO-A inhibitor among the all compounds studied (IC50 MAO-A:IC50 MAO-B = 0.044). Thus, the in vitro data suggest that MAO-A may represent potential target for 5-Hydroxyoxindole.

Detection and quantification of 5-hydroxyoxindole in mammalian sera and tissues by high performance liquid chromatography with multi-electrode electrochemical detection.[Pubmed:12726931]

Clin Biochem. 2003 May;36(3):215-20.

OBJECTIVE: Since 5-Hydroxyoxindole structurally related indole metabolites play different roles in some hepatic and neurologic disorders we found necessary to develop an assay to further investigate the physiologic relevance of this compound. METHODS: We have designed a convenient assay to determine 5-Hydroxyoxindole in serum using solid phase extraction and a highly selective High Performance Liquid Chromatography system with multi-Electro Chemical Detection (HPLC-ECD). RESULTS: We have identified and quantified 5-Hydroxyoxindole in various mammalian species. Its distribution in tissues showed that the molecule is also present in brain, liver, kidney and spleen, but not in skeletal muscle. CONCLUSIONS: 5-Hydroxyoxindole is an endogenous tryptophan metabolite present in circulating blood and in some tissues at the nmol level, its determination using HPLC-ECD will be useful for elucidating the role of this molecule in normal and disease conditions.

[Effect of oxidized indoles on monoamine oxidase activity in the rat brain mitochondria].[Pubmed:12189628]

Vopr Med Khim. 2002 Mar-Apr;48(2):201-3.

There is increasing evidence, that oxidized indoles, isatin, 5-Hydroxyoxindole, 2-oxindole, play important regulatory functions in the brain. Isatin and 5-Hydroxyoxindole share some common regulatory properties in cell cultures (Cane et al., 2000, BBRC, 276, 379), however, their effects on brain mitochondrial monoamine oxidases, a potential target for their action, have not been compared yet. Isatin acted as a rather selective monoamine oxidase B inhibitor, whereas 5-Hydroxyoxindole was more selective monoamine oxidase A inhibitor, but it was less potent than that of 5-hydroxyisatin, a synthetic analogue of isatin.

The endogenous oxindoles 5-hydroxyoxindole and isatin are antiproliferative and proapoptotic.[Pubmed:11006132]

Biochem Biophys Res Commun. 2000 Sep 16;276(1):379-84.

Oxindole-core synthetic molecules are currently being developed as anticancer drugs that target protein tyrosine kinases associated with growth factor receptors. Oxindole, 5-Hydroxyoxindole, and 2, 3-dioxindole [isatin] are natural molecules found in mammalian body fluids and tissues and we addressed the question of similar properties of endogenous oxindoles. 5-Hydroxyoxindole and isatin, but not oxindole, inhibited N1E-115, BALB/c3T3, BBC, PC12, and HL60 proliferation at submicromolar concentrations. Acute treatment with 5-Hydroxyoxindole and isatin reduced the activity of extracellular signal regulated protein kinases (ERKs) by 35% at 100 microM and ERK1 activity was strongly inhibited by 5-Hydroxyoxindole at 10 microM. Survival of PMA-differentiated HL60 and FGF(2)-differentiated PC12 cells was not affected by 5-Hydroxyoxindole and isatin treatment, suggesting that endogenous oxindoles interact with growth factors signaling. The physiological implications of these data and the potential utility of 5-Hydroxyoxindole and isatin as antitumor agents are discussed.

The metabolism of [2-14C] indole in the rat.[Pubmed:5328168]

Biochem J. 1966 Jan;98(1):266-77.

1. [2-(14)C]Indole has been synthesized from [(14)C]formate and o-toluidine via N[(14)C]-formyltoluidine. 2. When fed to rats, the (14)C of [(14)C]indole (dose 70-80mg./kg. body wt.) is fairly rapidly excreted, and in 2 days an average of 81% appears in the urine, 11% in the faeces and 2.4% as carbon dioxide in the expired air. 3. Radioactivity is excreted in the urine as indoxyl sulphate (50% of the dose), indoxyl glucuronide (11%), oxindole (1.4%), isatin (5.8%), 5-Hydroxyoxindole conjugates (3.1%), N-formylanthranilic acid (0.5%) and unchanged indole (0.07%). The faeces contain indoxyl sulphate (0.4% of the dose) and indole (0.2%), but the major metabolites have not been identified. 4. Fed to rats with biliary cannulae an average of 5.6% of a dose of [(14)C]indole (20-60mg./kg. body wt.) is excreted in the bile in 2 days. Radioactivity is present as indoxyl sulphate (0.8% dose) and 5-Hydroxyoxindole conjugates (0.6%). 5. Rats further metabolize indoxyl into N-formylanthranilic acid and anthranilic acid, and oxindole into 5-Hydroxyoxindole. 6. With rat-liver microsomes plus supernatant under aerobic conditions, indole gives indoxyl, oxindole, possibly isatin, N-formylanthranilic acid and anthranilic acid, but under anaerobic conditions gives only oxindole. Similarly, under aerobic conditions, oxindole gives 5-Hydroxyoxindole, anthranilic acid and o-aminophenylacetic acid. 7. Indole is metabolized by two pathways, one via indoxyl to isatin, N-formylanthranilic acid and anthranilic acid, and the other via oxindole to 5-Hydroxyoxindole and possibly to o-aminophenylacetic and anthranilic acid. 8. The following new compounds are described: 4-hydroxy-2-nitrophenylacetic acid, 3-, 4- and 5-benzyloxy-2-nitrophenylacetic acid, 5- and 7-hydroxyoxindole and 5-aminoacridine indoxyl sulphate.