Effects of indole-3-acetic acid on croton oil- and arachidonic acid-induced mouse ear edema

Indole-3-Acetic Acid Protects Against Lipopolysaccharide-induced Endothelial Cell Dysfunction and Lung Injury through the Activation of USP40

Lung microvascular endothelial cell (EC) dysfunction is the pathological hallmark of acute respiratory distress syndrome. Heat shock protein 90 (HSP90) is a key regulator in control of endothelial barrier disruption and inflammation. Our recent study has demonstrated that ubiquitin-specific peptidase 40 (USP40) preserves endothelial integrity by targeting HSP90β for its deubiquitination and inactivation. Indole-3-acetic acid (IAA), a plant hormone of the auxin class, can also be catabolized from dietary tryptophan by the intestinal microbiota. Accumulating evidence suggests that IAA reduces oxidative stress and inflammation and promotes intestinal barrier function. However, little is known about the role of IAA in endothelial cells and acute lung injury. In this study, we investigated the role of IAA in lung endothelial cell function in the context of acute lung injury. IAA exhibited EC barrier protection against LPS-induced reduction in transendothelial electrical resistance and inflammatory responses. The underlying mechanism of IAA on EC protective effects was investigated by examining the influence of IAA on degrees of HSP90 ubiquitination and USP40 activity. We identified that IAA, acting as a potential activator of USP40, reduces HSP90 ubiquitination, thereby protecting against LPS-induced inflammation in human lung microvascular endothelial cells as well as alleviating experimental lung injury. Furthermore, the EC protective effects of IAA against LPS-induced EC dysfunction and lung injury were abolished in USP40-deficient human lung microvascular endothelial cell and lungs of USP40 EC-specific knockout (USP40cdh5-ECKO) mice. Taken together, this study reveals that IAA protects against LPS-induced EC dysfunction and lung injury through the activation of USP40.

Eugenia sonderiana O. Berg leaves: Phytochemical characterization, evaluation of in vitro and in vivo antidiabetic effects, and structure-activity correlation

Several medicinal plants have drawn the attention of researchers by its phytochemical composition regarding their potential for treating chronic complications of diabetes mellitus. In this context, plants of the Myrtaceae family popularly used in Brazil for the treatment of diabetes mellitus, including Eugenia sonderiana, have shown beneficial effects due to the presence of phenolic compounds and saponins in their chemical constitution. Thus, the present work aimed to perform the phytochemical characterization of the hydroethanolic extract of E. sonderiana leaves using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS), along with in vitro and in vivo studies of antidiabetic activity. The chemical characterization revealed the presence of phenolic compounds, flavonoids, neolignans, tannins, and saponins. In addition, the extract exhibited minimum inhibitory concentrations of alpha-amylase and alpha-glycosidase higher than the acarbose in the in vitro tests. Also, the in vivo tests revealed a slight increase in body mass in diabetic rats, as well as a significant decrease in water and feed consumption provided by the extract. Regarding serum biochemical parameters, the extract showed significant activity in decreasing the levels of glucose, hepatic enzymes, and triglycerides, in addition to maintaining HDL cholesterol levels within normal ranges, protecting the cell membranes against oxidative damage. Thus, the extract of E. sonderiana leaves was considered promising pharmaceutical ingredient in the production of a phytotherapy medication.

Indole-3-Acetic Acid Alters Intestinal Microbiota and Alleviates Ankylosing Spondylitis in Mice

Ankylosing spondylitis (AS) is a systemic, chronic, and inflammatory autoimmune disease associated with the disorder of intestinal microbiota. Unfortunately, effective therapies for AS are lacking. Recent evidence has indicated that indole-3-acetic acid (IAA), an important microbial tryptophan metabolite, can modulate intestinal homeostasis and suppress inflammatory responses. However, reports have not examined the in vivo protective effects of IAA against AS. In this study, we investigated the protective effects and underlying mechanisms through which IAA acts against AS. We constructed a proteoglycan (PG)-induced AS mouse model and administered IAA (50 mg/kg body weight) by intraperitoneal injection daily for 4 weeks. The effects of IAA on AS mice were evaluated by examining disease severity, intestinal barrier function, aryl hydrocarbon receptor (AhR) pathway, T-helper 17 (Th17)/T regulatory (Treg) balance, and inflammatory cytokine levels. The intestinal microbiota compositions were profiled through whole-genome sequencing. We observed that IAA decreased the incidence and severity of AS in mice, inhibited the production of pro-inflammatory cytokines (tumor necrosis factor α [TNF-α], interleukin [IL]-6, IL-17A, and IL-23), promoted the production of the anti-inflammatory cytokine IL-10, and reduced the ratios of pro-/anti- inflammatory cytokines. IAA ameliorated pathological changes in the ileum and improved intestinal mucosal barrier function. IAA also activated the AhR pathway, upregulated the transcription factor forehead box protein P3 (FoxP3) and increased Treg cells, and downregulated the transcription factors retinoic acid receptor–related orphan receptor gamma t (RORγt) and signal transducer and activator of transcription 3 (STAT3) and decreased Th17 cells. Furthermore, IAA altered the composition of the intestinal microbiota composition by increasing Bacteroides and decreasing Proteobacteria and Firmicutes, in addition to increasing the abundances of Bifidobacterium pseudolongum and Mucispirillum schaedleri. In conclusion, IAA exerted several protective effects against PG-induced AS in mice, which was mediated by the restoration of balance among the intestinal microbial community, activating the AhR pathway, and inhibiting inflammation. IAA might represent a novel therapeutic approach for AS.

Bacterial Natural Compounds with Anti-Inflammatory and Immunomodulatory Properties (Mini Review)

Inflammation is part of the body's complex biological response to harmful stimuli such as damaged cells, pathogens, or irritants. It is a protective response involving blood cells, immune cells, and molecular mediators. The inflammation not only can eliminate the primary cause of cell injury but also clears out necrotic cells, tissue damaged from the original insults and inflammatory process. Furthermore, it can initiate tissue repair. Pro-inflammatory cytokines are produced predominantly by activated macrophages and are involved in the up-regulation of inflammatory reactions. They are involved in further regulating inflammatory reactions. There is ample evidence that some pro-inflammatory cytokines, such as interleukin 1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), are involved in the pathological pain process. Some of the natural compounds promote cytokines production and inhibit inflammatory responses. The natural compounds which are produced from microorganisms such as omega-3 fatty acid, cyclic peptide, antimicrobial peptide, oligosaccharides, and polysaccharides can reduce inflammation and could be easily incorporated into the diet without any adverse effects. For example, SCFA (short-chain fatty acids), peptide bacteriocin, and polycyclic peptide bacteriocin (nisin) could be used in the treatment of atherosclerosis, orthopedic postoperative infections, and mycobacterium tuberculosis infection, respectively. Also, fatty acids (saturated and unsaturated fatty acids) can be introduced as anti-inflammatory drugs. This review article summarizes bacterial natural compounds with modulating effects on cytokines that are surveyed which may have potential anti-inflammatory drug-like activity.

Anti-Inflammatory and Anti-Oxidative Activity of Indole-3-Acetic Acid Involves Induction of HO-1 and Neutralization of Free Radicals in RAW264.7 Cells

The cellular and molecular mechanisms by which indole-3-acetic acid (IAA), a tryptophan-derived metabolite from gut microbiota, attenuates inflammation and oxidative stress has not been fully elucidated. The present study was to unearth the protective effect and underlying mechanism of IAA against lipopolysaccharide (LPS)-induced inflammatory response and free radical generation in RAW264.7 macrophages. IAA significantly ameliorated LPS-induced expression of interleukin-1β (IL-1β), interleukin-6 (IL-6), and monocyte chemoattractant protein-1 (MCP-1) as well as generation of reactive oxidative species (ROS) and nitric oxide (NO). LPS-triggered nuclear translocation of nuclear factor kappa B (NF-κB) p65 was mitigated by IAA treatment. Further, an up-regulation of heme oxygenase-1 (HO-1) was observed in IAA-treated cells in dose-dependent manner under both normal and LPS-stimulated condition. Interference of HO-1 activity by tin protoporphyrin IX (SnPP) impeded the alleviative effects of IAA on expression of IL-1β and IL-6 induced by LPS, whereas demonstrated no effect on its suppression of ROS and NO production. This result suggests a HO-1-dependent anti-inflammatory effect of IAA and its direct scavenging action on free radicals. Treatment with CH-223191, a specific antagonist of aryl hydrocarbon receptor (AhR), showed no significant effects on the beneficial role of IAA against inflammation and free radical generation. In summary, our findings indicate that IAA alleviates LPS-elicited inflammatory response and free radical generation in RAW264.7 macrophages by induction of HO-1 and direct neutralization of free radicals, a mechanism independent of AhR.

Screening of metabolites from endophytic fungi of some Nigerian medicinal plants for antimicrobial activities

Endophytic fungi associated with Nigerian plants have recently generated significant interest in drug discovery programmes due to their immense potential to contribute to the discovery of new bioactive compounds. This study was carried out to investigate the secondary metabolites of endophytic fungi isolated from leaves of Newbouldia laevis, Ocimum gratissimum, and Carica papaya The plants were collected from Agulu, Anambra State, South-East Nigeria. Endophytic fungal isolation, fungal fermentation; and extraction of secondary metabolites were carried out using standard methods. The crude extracts were screened for antimicrobial activities using the agar well diffusion method, and were also subjected to high performance liquid chromatography (HPLC) analysis to identify their constituents. A total of five endophytic fungi was isolated, two from N. laevis (NL-L1 and NL-L2), one from O. gratissimum (SL-L1), and two from C. papaya (PPL-LAC and PPL-LE2). In the antimicrobial assay, the extracts of NL-L2, SL-L1, and PPL-LE2 displayed mild antibacterial activity against both Gram negative and Gram positive test bacteria. PPL-LAC extract showed mild activity only against S. aureus, while no antimicrobial activity was recorded for NL-L1 extract. All the endophytic fungal extracts showed no activity against the test fungi C. albicans and A. fumigatus HPLC analysis of the fungal extracts revealed the presence of ethyl 4-hydroxyphenyl acetate and ferulic acid in NL-L1; ruspolinone in NL-L2; protocatechuic acid, scytalone, and cladosporin in SL-L1; indole-3-acetic acid and indole-3-carbaldehyde in PPL-LE2; and indole-3-acetic acid in PPL-LAC. The findings of this study revealed the potentials possessed by these plants as source of endophytes that express biological active compounds. These endophytes hold key of possibilities to the discovery of novel molecules for pharmaceutical, agricultural and industrial applications.

The Protective Effect of Indole-3-Acetic Acid (IAA) on H2O2-Damaged Human Dental Pulp Stem Cells Is Mediated by the AKT Pathway and Involves Increased Expression of the Transcription Factor Nuclear Factor-Erythroid 2-Related Factor 2 (Nrf2) and Its Downstream Target Heme Oxygenase 1 (HO-1)

Indole-3-acetic acid (IAA) is the most common plant hormone of the auxin class and is known to have many effects including cell proliferation enhancement and antioxidant property. However, no study has revealed its defensive effects against oxidative toxicity in human dental pulp stem cells (hDPSCs). In this study, we investigated the effects of IAA on hydrogen peroxide- (H₂O₂-) induced oxidative toxicity in hDPSCs. H₂O₂-induced cytotoxicity was attenuated after IAA treatment. Cell cycle analysis using FACS showed that the damaged cell cycle and increased number of apoptotic cells by H₂O₂ treatment were recovered after the treatment of IAA. The H₂O₂-mediated increased expression of the proapoptotic genes, BAX and p53, was attenuated by IAA treatment, while IAA treatment increased antiapoptotic genes, BCL-2 and ATF5 expression. The increases of cleaved caspase-3 and ROS by H₂O₂ were also decreased after treatment of IAA. To further investigate the mechanism of IAA, Nrf2-related antioxidant pathway was examined and the results showed that the level of Nrf2 and HO-1 expressions, stimulated by H₂O_2, decreased after treatment of IAA. Moreover, IAA treatment protected hDPSCs against H₂O₂-induced oxidative stress via increased expression of Nrf2 and HO-1, mediated by the AKT pathway.

Topical anti-inflammatory effects of isorhamnetin glycosides isolated from Opuntia ficus-indica

Opuntia ficus-indica (OFI) has been widely used in Mexico as a food and for the treatment of different health disorders such as inflammation and skin aging. Its biological properties have been attributed to different phytochemicals such as the isorhamnetin glycosides which are the most abundant flavonoids. Moreover, these compounds are considered a chemotaxonomic characteristic of OFI species. The aim of this study was to evaluate the effect of OFI extract and its isorhamnetin glycosides on different inflammatory markers in vitro and in vivo. OFI extract was obtained by alkaline hydrolysis of OFI cladodes powder and pure compounds were obtained by preparative chromatography. Nitric oxide (NO), cyclooxygenase-2 (COX-2), tumor necrosis factor- (TNF-) α, and interleukin- (IL-) 6 production were measured. NO production was tested in lipopolysaccharide-stimulated RAW 264.7 cells while in vivo studies were carried on croton oil-induced ear edema model. OFI extract and diglycoside isorhamnetin-glucosyl-rhamnoside (IGR) at 125 ng/mL suppressed the NO production in vitro (73.5 ± 4.8% and 68.7 ± 5.0%, resp.) without affecting cell viability. Likewise, IGR inhibited the ear edema (77.4 ± 5.7%) equating the indomethacin effects (69.5 ± 5.3%). Both IGR and OFI extract significantly inhibited the COX-2, TNF-α, and IL-6 production. IGR seems to be a suitable natural compound for development of new anti-inflammatory ingredient.

Conventional (MG-BR46 Conquista) and transgenic (BRS Valiosa RR) soybeans have no mutagenic effects and may protect against induced-DNA damage in vivo

In the present study, we evaluated the pesticide and metal concentrations as well as the antimutagenic and mutagenic properties of commercial soybeans (Glycine max). Male Swiss mice were fed diets containing 1%, 10%, or 20% (w/w) transgenic soybeans (BRS Valiosa RR) or parental isogenic conventional soybeans (MG-BR46 Conquista). Cyclophosphamide (50 mg kg⁻¹ b.w.) was added in a single dose 24 h before euthanasia as an induction agent. There was no difference in the composition (ash, total fat, protein, moisture, and carbohydrates) of the diets containing the same soybean concentration. The results show that the commercially available Brazilian soybeans tested are free of organochlorine, organophosphate, and carbamate pesticides and contain acceptable heavy metal concentrations. Both cyclophosphamide and soybean treatments were not sufficient to cause detectable oxidative damage on liver by the levels of malondialdehyde and protein carbonyl. The transgenic soybeans are also nonmutagenic and have protective effects against DNA damage similar to those of conventional soybeans but to a lesser percentage (64%-101% for conventional and 23%-33% for transgenic diets).

Anti-inflammatory effects of caper (Capparis spinosa L.) fruit aqueous extract and the isolation of main phytochemicals

Caper (Capparis spinosa L.) fruits have been used as food as well as folk medicine in the treatment of inflammatory disorders, such as rheumatism. The present study was carried out to study the anti-inflammatory activities of C. spinosa L. fruit (CSF) aqueous extract and to isolate main phytochemicals from its bioactive fractions. The CSF aqueous extract were separated into three fractions (CSF1-CSF3) by macroporous adsorption resins. The fractions CSF2 and CSF3 effectively inhibited the carrageenan-induced paw edema in mice. Systematic fractionation and isolation from CSF2+3 led to the identification of 13 compounds (1-13). Their chemical structures were elucidated by spectroscopic analyses including nuclear magnetic resonance (NMR) and mass spectrometry (MS) and literature comparisons. Major compounds found in the bioactive fraction CSF2+3 are flavonoids, indoles, and phenolic acids. To our knowledge, 8 of these 13 compounds (1-4, 6-7, 10, and 13) were identified from caper fruits for the first time. The anti-inflammatory effects of these purified compounds are currently under investigation.

Influence of Marolo (Annona crassiflora Mart.) pulp intake on the modulation of mutagenic/antimutagenic processes and its action on oxidative stress in vivo

Brazilian savanna constitutes a valuable ecoregion that contributes to the supply of fruit known worldwide for its nutritional value and peculiar flavors. Among them, the Marolo (Annona crassiflora Mart.) fruit is known for its use in folk medicine. In order to establish the safety of Marolo for human consumption, this study evaluated the following: the chemical composition of Marolo pulp; its mutagenic and antimutagenic activities using micronucleus test; and the oxidative stress induced in the livers of mice fed a diet containing 1%, 10% or 20% pulp. It was observed that the chemical composition of marolo pulp was similar to that of common fruit; nevertheless, its lipidic content and energetic values were higher. In the mice fed experimental diets, the biochemical parameters of the blood serum showed normal levels of glucose, triglycerides, and cholesterol. The micronucleus test indicated neither mutagenic nor antimutagenic effects of Marolo consumption on bone marrow cells but showed potentialization of cyclophosphamide (CP). The oxidative stress levels observed indicated that CP was not exerting a great influence on the induction of reactive oxygen species. As the whole fruit is a complex matrix, the interactions between its components could be responsible for its negative and positive biological effects.

Protective action of indole-3-acetic acid on induced hepatocarcinoma in mice

In this study, we report the protective effects of IAA on diethylnitrosamine (DEN)-induced hepatocarcinogenesis. BALB/c mice received daily IAA at 50 (T(50)), 250 (T(250)), and 500 (T(500)) mg Kg(-1) per body mass by gavage for 15 days. At day 15, animals were administered DEN and sacrificed 4 h later. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were analyzed in sera. In addition, hepatomorphologic alterations, activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR), gene expression of antioxidant enzymes and DNA integrity were evaluated in the liver. IAA administration did not show any alterations in any of the parameters available, except for a reduction of the gene expression for antioxidant enzymes by 55, 56, 27, and 28% for SOD, CAT, GPx, and GR upon T(500), respectively compared with the control. Several hepatic alterations were observed by DEN exposure. Moreover, IAA administration at 3 doses was shown to provide a total prevention of the active reduction of CAT and GR induced by DEN exposure compared with the control. IAA at T(500) was shown to give partial protection (87, 71, 57, and 90% for respectively SOD, CAT, GPx, and GR) on the down-regulation of the enzymes induced by DEN and this auxin showed a partial protection (50%) on DEN-induced DNA fragmentation for both parameters when compared to DEN alone. This work showed IAA hepatocarcinogenesis protection for the first time by means of a DEN-protective effect on CAT and GR activity, and by affecting antioxidant gene expression and DNA fragmentation.

Indole-3-propionate: a potent hydroxyl radical scavenger in rat brain

The hydroxyl radical scavenging activity of indole-3-propionate was evaluated by kinetic competition studies with the hydroxyl radical trapping reagent 2,2'-azino-bis-(3-ethyl-benz-thiazoline-6-sulfonic acid) (ABTS) and by measuring hydroxyl radical-initiated lipid peroxidation in the rat striatum. Using ABTS, the indole was shown to act as a potent hydroxyl radical scavenger with a rate constant of 7.8x1010 mol l-1 s-1. Hydroxyl radical-initiated lipid peroxidation, determined by measuring tissue malondialdehyde formation, was inhibited dose-dependently both in vitro and in vivo. Indole-3-propionate reacts with hydroxyl radicals at a diffusion controlled rate and can thereby provide on-site protection against the oxidative damage of biomolecules induced by these highly reactive and toxic oxygen intermediates. While it remains to be established if endogenous brain tissue levels of indole-3-propionate are sufficiently high to have a significant impact on total antioxidative capacity, the compound itself or a structurally related agent may be useful as an antioxidant adjuvant to combat hydroxyl radical-mediated oxidative stress.

Effect of indole acetic acid on oxygen metabolism in cultured rat neutrophil

1. Indole acetic acid (IAA) stimulates O2.- and H2O2 production in cells with peroxidase activity, such as neutrophils. The effect of pharmacological IAA concentration on oxygen metabolism and neutrophil functioning and viability in culture was investigated. 2. The results led to the conclusion that: (1) IAA causes death and marked ultrastructural changes in cultured neutrophils but does not affect lymphocytes; (2) these effects are not due to a reduction in the enzymatic antioxidant capacity of the cell, as indicated by catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px); (3) these effects are mainly due to an increase in the production of O2.- and H2O2, as suggested by the protective effect exhibited by the addition of CAT and SOD to cultured neutrophils, and (4) other reactive species (possibly peroxyl radicals) might play a role in the IAA effect on cultivated neutrophil viability.

Arachidonic acid (AA) and tetradecanoylphorbol acetate (TPA) exert systemic effects when applied topically in the mouse

We studied the systemic actions of topically applied arachidonic acid (AA) and tetradecanoylphorbol acetate (TPA) in the mouse. AA or TPA-induced ear edema, increases in vascular permeability, eicosanoid levels, neutrophil and mononuclear influx were determined in both phlogogen-treated and contralateral vehicle-treated ear of each mouse and were compared with vehicle-treated ears from control mice. Edema and vascular permeability increases appeared only in AA- or TPA-applied ears. Moreover, in contralateral ears from AA-treated mice an increase in 6-keto-PGF1 alpha and LTB4 was found. Only LTB4 increased in the contralateral ear after TPA. Contralateral ears from AA- or TPA-treated mice also showed a significant increase in MPO levels. The increased levels of 6-keto-PGF1 alpha but not those of LTB4 in contralateral ears were reduced by indomethacin applied simultaneously with the phlogogen. AA also increased plasma and serum levels of LTB4, but not those of 6-keto-PGF1 alpha. In contrast, TPA increased plasma and serum levels of 6-keto-PGF1 alpha and LTB4. The results show that both AA and TPA applied topically exert systemic effects.