Atropoisomerism in Biflavones: The Absolute Configuration of (-)-Agathisflavone via Chiroptical Spectroscopy.

The first natural occurrence in optically active form of the dimeric flavonoid agathisflavone and definition of its axial chirality using chiroptical spectroscopic methods are described. The experimental electronic circular dichroism, electronic dissymmetry factor, optical rotatory dispersion, vibrational circular dichroism (VCD), and vibrational dissymmetry factor spectra of agathisflavone are presented and analyzed with their corresponding quantum chemical predictions to definitively assign the axial chirality of (-)-agathisflavone as (aS).

Genotoxic Maillard byproducts in current phytopharmaceutical preparations of Echinodorus grandiflorus.

Extracts of Echinodorus grandiflorus obtained from dried leaves by three different techniques were evaluated by bacterial lysogenic induction assay (Inductest) in relation to their genotoxic properties. Before being added to test cultures, extracts were sterilized either by steam sterilization or ultraviolet light. Only the extracts prepared by infusion and steam sterilized have shown genotoxic activity. The phytochemical analysis revealed the presence of the flavonoids isovitexin, isoorientin, swertisin and swertiajaponin, isolated from a genotoxic fraction. They were assayed separately and tested negative in the Inductest protocol. The development of browning color and sweet smell in extracts submitted to heat, prompted further chemical analysis in search for Maillard's reaction precursors. Several aminoacids and reducing sugars were cast in the extract. The presence of characteristic Maillard's melanoidins products was determined by spectrophotometry in the visible region and the inhibition of this reaction was observed when its characteristic inhibitor, sodium bisulfite, was added prior to heating. Remarkably, this is the first paper reporting on the appearance of such compounds in a phytomedicine preparation under a current phytopharmaceutical procedure. The genotoxic activity of such heat-prepared infusions imply in some risk of developing degenerative diseases for patients in long-term, uncontrolled use of such phytomedicines.

ESI(-)FT-ICR MS for the determination of best conditions for producing extract abundant in phenolic compounds from leaves of E. uniflora and FTIR-PCA as a sample screening method.

E. uniflora leaves are a rich source of phenolic compounds with biological activities, including myricitrin. In this study, the chemical profile of nine extracts prepared with leaves collected in three regions (mountain, beach, and mangrove) and at three different times of the day (8 am, 1 pm, and 6 pm) was evaluated from spectra originating from ultra-high resolution mass spectrometry (Fourier transform ion cyclotron resonance, FT-ICR) coupled to electrospray ionisation (ESI). The best time of the day and location for collecting the leaves of E. uniflora used as raw materials for producing extracts and the best ethanol concentration for obtaining an extract more abundant in compounds of interest were verified. Several flavonoids and phenolic acids were detected in their deprotonated form in the regions from m/z 200 to 1200. Myricitrin ([C21H20O12-H]-, m/ztheo 463.08820), its chloride adduct ([C21H20O12+Cl]-, m/ztheo 499.06488), other myricitrin derivatives, and some tannins were the main compounds detected. Considering obtaining an extract rich in phenolic compounds, including myricitrin, the best place and time of the day to collect E. uniflora leaves is in the beach region at 1 pm. In contrast, the best ethanol concentration for extract production is 70 wt%. Therefore, extraction at 96 wt% ethanol is better for obtaining an extract more abundant in phenolic acids, although 70 wt% ethanol also extracted these compounds. FTIR-PCA models were used to check for possible similarities in the data according to collection time of the day and location. These models demonstrated an excellent solution for sample screening.

The effects of drying methods and harvest season on piperine, essential oil composition, and multi-elemental composition of black pepper.

This study aimed to evaluate the piperine content, essential oil composition, and multi-elemental composition of black pepper samples according to different drying methods and harvest season. Differences in essential oil composition and B, Ca, K, Mg, and S were noted according to sampling campaign, indicating secondary metabolism plant alterations. Mechanical drying resulted in essential oil composition changes due to high temperature exposure during processing. Increases in Fe and Cr contents when employing mechanical dryers with direct heating were also observed, due to direct contact with metallic structures and particulate material from the burning process. The As and Pb contents of several samples were higher than the maximum permissible limits, reaching 0.46 and 0.56 mg kg-1, respectively, thus surpassing legislation safety limitations for human consumption.

Virucidal and antiviral activities of pomegranate (Punica granatum) extract against the mosquito-borne Mayaro virus.

BACKGROUND: The arthropod-borne Mayaro virus (MAYV) causes "Mayaro fever," a disease of medical significance, primarily affecting individuals in permanent contact with forested areas in tropical South America. Recently, MAYV has attracted attention due to its likely urbanization. There are currently no licensed drugs against most mosquito-transmitted viruses. Punica granatum (pomegranate) fruits cultivated in Brazil have been subjected to phytochemical investigation for the identification and isolation of antiviral compounds. In the present study, we explored the antiviral activity of pomegranate extracts in Vero cells infected with Mayaro virus. METHODS: The ethanol extract and punicalagin of pomegranate were extracted solely from the shell and purified by chromatographic fractionation, and were chemically identified using spectroscopic techniques. The cytotoxicity of the purified compounds was measured by the dye uptake assay, while their antiviral activity was evaluated by a virus yield inhibition assay. RESULTS: Pomegranate ethanol extract (CC50 = 588.9, IC50 = 12.3) and a fraction containing punicalagin as major compound (CC50 = 441.5, IC50 = 28.2) were shown to have antiviral activity (SI 49 and 16, respectively) against Mayaro virus, an alphavirus. Immunofluorescence analysis showed the virucidal effect of pomegranate extract, and transmission electron microscopy (TEM) revealed damage in viral particles treated with this extract. CONCLUSIONS: The P. granatum extract is a promising source of antiviral compounds against the alphavirus MAYV and represents an excellent candidate for future studies with other enveloped RNA viruses.

Antinociceptive constituents from Saccharum officinarum L. juice.

This work aimed to investigate the main components of methanol fractions (MFSC and MFSCf) from Saccharum officinarum L. juice and their in vivo antinociceptive potential. After LC-ESI-MS and ESI-MS/MS analysis, phenolic compounds, such as dicaffeoylquinic acid, schaftoside, vicenin-2, stilbene glycoside and the major compound tricin-7-O-(2″- α-L-rhamnopyranosyl)-α-D-galacturonide (1), were identified. MFSC and MFSCf significantly inhibited nociceptive responses in classical mice pain models. The isolated flavone, 1, inhibited strongly the neurogenic phase in formalin test without interfering with the inflammatory one. The co-administration of the opioid antagonist, naloxone, significantly reversed the antinociceptive effects on the neurogenic phase of both methanol fractions and 1, demonstrating the involvement of the opioid system on the antinociceptive effect. This work describes for the first time the antinociceptive effect of flavonoids present in sugarcane juice, highlighting the isolation and the structural elucidation of tricin-7-O-(2″-α-L-rhamnopyranosyl)-α-D-galacturonide through ESI-MS/MS, 1D- and 2D-NMR.

Chemical composition and anti-Mayaro virus activity of Schinus terebinthifolius fruits.

Brazilian traditional medicine has explored the antiviral properties of many plant extracts, including those from the Brazilian pepper tree, Schinus terebinthifolius. In the present study, we investigated the chemical composition and anti-mayaro virus (MAYV) activity of S. terebinthifolius fruit. Extensive virucidal activity (more than 95%) was detected for the ethyl acetate extract and the isolated biflavonoids. From the ethyl acetate extract of Schinus terebinthifolius fruits, two bioflavonoids were isolated ((2S, 2″S)-2,3,2″,3″-tetrahydroamentoflavone and agathisflavone), which showed strong virucidal activity against Mayaro virus. Furthermore, several other compounds like terpenes and phenolics were identified by hyphenated techniques (GC-MS, LC-MS and HPLC-UV), as well as by mass spectrometry. Immunofluorescence assay confirmed antiviral activity and transmission electron microscopy revealed damage in viral particles treated with biflavonoids. The data suggest the direct action of the extract and the biflavonoids on the virus particles. The biflavonoids tetrahydroamentoflavone and agathisflavone had strong virucidal activity and reduced MAYV infection. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13337-021-00698-z.

Piperine suppresses the Wnt/ß-catenin pathway and has anti-cancer effects on colorectal cancer cells.

More than 94% of colorectal cancer cases have mutations in one or more Wnt/ß-catenin signaling pathway components. Inactivating mutations in APC or activating mutations in ß-catenin (CTNNB1) lead to signaling overactivation and subsequent intestinal hyperplasia. Numerous classes of medicines derived from synthetic or natural small molecules, including alkaloids, have benefited the treatment of different diseases, including cancer, Piperine is a true alkaloid, derived from lysine, responsible for the spicy taste of black pepper (Piper nigrum) and long pepper (Piper longum). Studies have shown that piperine has a wide range of pharmacological properties; however, piperine molecular mechanisms of action are still not fully understood. By using Wnt/ß-catenin pathway epistasis experiment we show that piperine inhibits the canonical Wnt pathway induced by overexpression of ß-catenin, ß-catenin S33A or dnTCF4 VP16, while also suppressing ß-catenin nuclear localization in HCT116 cell line. Additionally, piperine impairs cell proliferation and migration in HCT116, SW480 and DLD-1 colorectal tumor cell lines, while not affecting the non-tumoral cell line IEC-6. In summary, piperine inhibits the canonical Wnt signaling pathway and displays anti-cancer effects on colorectal cancer cell lines.

Anti-Escherichia coli activity of extracts from Schinus terebinthifolius fruits and leaves.

Ethanol extracts obtained from Schinus terebinthifolius Raddi fruits and leaves were active against Escherichia coli with MIC of 78 µg mL-1 for both extracts. Phytochemical analyses revealed a major presence of phenolic acids, tannins, fatty acids and acid triterpenes in the leaves and phenolic acids, fatty acids, acid triterpenes and biflavonoids in the fruits. Major compounds isolated from the plant, such as the acid triterpene schinol, the phenolic acid derivative ethyl gallate and the biflavonoids agathisflavone and tetrahydroamentoflavone, showed very little activity against E. coli. Bioautography of the ethanol extracts on silica gel plate showed inhibition zones for E. coli. They were removed from the plate and the compounds identified as a mixture of myristic, pentadecanoic, palmitic, heptadecanoic, stearic, nonadecanoic, eicosanoic, heneicosanoic and behenic fatty acids.

Chemical characterization of synthetic cannabinoids by electrospray ionization FT-ICR mass spectrometry.

The synthetic cannabinoids (SCs) represent the most recent advent of the new psychotropic substances (NPS) and has become popularly known to mitigate the effects of the Δ(9)-THC. The SCs are dissolved in organic solvents and sprayed in a dry herbal blend. However, little information is reported on active ingredients of SCs as well as the excipients or diluents added to the herbal blend. In this work, the direct infusion electrospray ionization Fourier transform ion cyclotron mass spectrometry technique (ESI-FT-ICR MS) was applied to explore the chemical composition of nine samples of herbal extract blends, where a total of 11 SCs (UR-144, JWH-073, XLR-11, JWH-250, JWH-122, AM-2201, AKB48, JWH-210, JWH-081, MAM-2201 and 5F-AKB48) were identified in the positive ionization mode, ESI(+), and other 44 chemical species (saturated and unsaturated fatty acids, sugars, flavonoids, etc.) were detected in the negative ionization mode, ESI(-). Additionally, CID experiments were performed, and fragmentation pathways were proposed to identify the connectivity of SCs. Thus, the direct infusion ESI-FT-ICR MS technique is a powerful tool in forensic chemistry that enables the rapid and unequivocal way for the determination of molecular formula, the degree of unsaturation (DBE-double bond equivalent) and exact mass (<1ppm) of a total of 55 chemical species without the prior separation step.

In Vitro Antileukemic Activity of Xanthosoma sagittifolium (Taioba) Leaf Extract.

Xanthosoma sagittifolium Schott is a herb of the Araceae family, popularly known as taioba, which is consumed as food in some regions of Brazil, Africa, and Asia. This species has already been evaluated for the antifungal activities. However, based on its potential antitumor activity, the present study further aimed to examine the antitumor, as well as chelation, activity of X. sagittifolium leaf extract. Results showed that hydroethanolic extract of X. sagittifolium leaves (HEXs-L) exhibits cytotoxic effects against the immortalized line of human T-lymphocytic (Jurkat) and myelogenous (K562) leukemia cells, but not nontumor RAW 264.7 macrophages or NIH/3T3 fibroblasts. HEXs-L inhibited 50.3% of Jurkat cell proliferation, reducing by 20% cells in G2/M phase, but increasing cells in sub-G1 phase, thereby inducing apoptosis by 54%. In addition, HEXs-L inhibited NO production by 59%, as determined by Griess reaction, and chelated 93.8% of free Fe(II), as demonstrated by ferrozine assay. Phytochemical studies were carried out by ESI-MS, identifying apigenin di-C-glycosides as major compounds. Overall, this work revealed that leaf extract of Xanthosoma sagittifolium presented chelating activity and in vitro antitumor activity, arresting cell cycle and inducing apoptosis of leukemia cells, thus providing evidence that taioba leaves may have practical application in cancer therapy.

Derricin and derricidin inhibit Wnt/ß-catenin signaling and suppress colon cancer cell growth in vitro.

Overactivation of the Wnt/ß-catenin pathway in adult tissues has been implicated in many diseases, such as colorectal cancer. Finding chemical substances that can prevent this phenomenon is an emerging problem. Recently, several natural compounds have been described as Wnt/ß-catenin inhibitors and might be promising agents for the control of carcinogenesis. Here, we describe two natural substances, derricin and derricidin, belonging to the chalcone subclass, that show potent transcriptional inhibition of the Wnt/ß-catenin pathway. Both chalcones are able to affect the cell distribution of ß-catenin, and inhibit Wnt-specific reporter activity in HCT116 cells and in Xenopus embryos. Derricin and derricidin also strongly inhibited canonical Wnt activity in vitro, and rescued the Wnt-induced double axis phenotype in Xenopus embryos. As a consequence of Wnt/ß-catenin inhibition, derricin and derricidin treatments reduce cell viability and lead to cell cycle arrest in colorectal cancer cell lines. Taken together, our results strongly support these chalcones as novel negative modulators of the Wnt/ß-catenin pathway and colon cancer cell growth in vitro.

Cinnamon extract improves the body composition and attenuates lipogenic processes in the liver and adipose tissue of rats.

In models of metabolic disorders, cinnamon improves glucose and lipid metabolism. This study explores the effect of chronic supplementation with aqueous cinnamon extract (CE) on the lipid metabolism of rats. Male adult Wistar rats were separated into a control group (CTR) receiving water and a CE Group receiving aqueous cinnamon extract (400 mg of cinnamon per kg body mass per day) by gavage for 25 consecutive days. Cinnamon supplementation did not change the food intake or the serum lipid profile but promoted the following changes: lower body mass gain (P = 0.008), lower relative mass of white adipose tissue (WAT) compartments (P = 0.045) and higher protein content (percentage of the carcass) (P = 0.049). The CE group showed lower leptin mRNA expression in the WAT (P = 0.0017) and an important tendency for reduced serum leptin levels (P = 0.059). Cinnamon supplementation induced lower mRNA expression of SREBP1c (sterol regulatory element-binding protein 1c) in the WAT (P = 0.001) and liver (P = 0.013) and lower mRNA expression of SREBP2 (P = 0.002), HMGCoA reductase (3-hydroxy-3-methylglutaryl-CoA reductase) (P = 0.0003), ACAT1 (acetyl-CoA acetyltransferase 1) (P = 0.032) and DGAT2 (diacylglycerol O-acyltransferase 2) (P = 0.03) in the liver. These changes could be associated with the reduced esterified cholesterol and triacylglycerol content detected in this tissue. Our results suggest that chronic ingestion of aqueous cinnamon extract attenuates lipogenic processes, regulating the expression of key enzymes and transcriptional factors and their target genes, which are directly involved in lipogenesis. These molecular changes possibly promote adaptations that would prevent an increase in circulating cholesterol and triacylglycerol levels and prevent lipid accumulation in tissues, such as liver and WAT. Therefore, we speculate that cinnamon may also be useful for preventing or retarding the development of lipid disorders.

Anti-Mayaro virus activity of Cassia australis extracts (Fabaceae, Leguminosae).

BACKGROUND: The arthropod-borne Mayaro virus (MAYV) causes 'Mayaro fever', a disease of medical significance, primarily affecting individuals in permanent contact with forested areas in tropical South America. Studies showed that the virus could also be transmitted by the mosquito Aedes aegypti. Recently, MAYV has attracted attention due to its likely urbanization. To date, there are no drugs that can treat this illness. METHODS: Fractions and compounds were obtained by chromatography from leaf extracts of C. australis and chemically identified as flavonoids and condensed tannins using spectroscopic and spectrometric techniques (UV, NMR, and ESI-FT-ICR MS). Cytotoxicity of EtOAc, n-BuOH and EtOAc-Pp fractions were measured by the dye-uptake assay while their antiviral activity was evaluated by a virus yield inhibition assay. Larvicidal activity was measured by the procedures recommended by the WHO expert committee for determining acute toxicity. RESULTS: The following group of substances was identified from EtOAc, n-BuOH and EtOAc-Pp fractions: flavones, flavonols, and their glycosides and condensed tannins. EtOAc and n-BuOH fractions inhibited MAYV production, respectively, by more than 70% and 85% at 25 µg/mL. EtOAc-Pp fraction inhibited MAYV production by more than 90% at 10 µg/mL, displaying a stronger antiviral effect than the licensed antiviral ribavirin. This fraction had an excellent antiviral effect (IC90 = 4.7 ± 0.3 µg/mL), while EtOAc and n-BuOH fractions were less active (IC90 = 89.1 ± 4.4 µg/mL and IC90 = 40.9 ± 5.7 µg/mL, respectively). CONCLUSIONS: C. australis can be used as a source of compounds with anti-Mayaro virus activity. This is the first report on the biological activity of C. australis.

Quercetin and quercetin 3-O-glycosides from Bauhinia longifolia (Bong.) Steud. show anti-Mayaro virus activity.

BACKGROUND: The arthropod-borne Mayaro virus (MAYV) causes 'Mayaro fever', a disease of medical significance, primarily affecting individuals in permanent contact with forested areas in tropical South America. Recently, MAYV has attracted attention due to its likely urbanization. Currently, there are no licensed drugs against most mosquito-transmitted viruses. Here, we investigated the in vitro anti-MAYV activity of the flavonoids quercetin and its derivatives from the Brazilian shrub Bauhinia longifolia (Bong.) Steud. METHODS: Flavonoids were purified by chromatographic fractionation from leaf extracts of B. longifolia and chemically identified as quercetin and quercetin glycosides using spectroscopic techniques. Cytotoxicity of purified flavonoids and of EtOAc- and n-BuOH-containing flavonoid mixtures was measured by the dye-uptake assay while their antiviral activity was evaluated by a virus yield inhibition assay. RESULTS: The following flavonoids were purified from B. longifolia leaves: non-glycosylated quercetin and its glycosides guaijaverin, quercitrin, isoquercitrin, and hyperin. EtOAc and n-BuOH fractions containing these flavonoids demonstrated the highest antiviral activity of all tested substances, while quercetin had the highest antiviral activity amongst purified flavonoids. Quercetin, EtOAc, or n-BuOH fractions inhibited MAYV production by more than 90% at 25 µg/mL, displaying a stronger antiviral effect than the licensed antiviral ribavirin. A mixture of the isomers isoquercitrin and hyperin had a modest antiviral effect (IC90 = 104.9), while guaijaverin and quercitrin did not show significant antiviral activity. CONCLUSIONS: B. longifolia is a good source of flavonoids with anti-Mayaro virus activity. This is the first report of the activity of quercetin and its derivatives against an alphavirus.

Hypoglycemic effect of Bumelia sartorum polyphenolic rich extracts.

Bumelia sartorum (Sapotaceae) is used ethnomedicinally for treatment of several diseases, including diabetes mellitus. The aim of this work was to investigate the hypoglycemic effect of B. sartorum extracts, rich in polyphenolic compounds, and the possible mechanisms of action. Assessment of B. sartorum hypoglycemic activity was performed from the blood glucose level in normoglycemic mice after administration of the extract by oral gavage. The hypothesis that sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) inhibition could prolong the increase in cytoplasmic Ca2+ concentration, thus leading to an increase of insulin release was evaluated. The enzyme inhibition was measured by ATP hydrolysis using SERCA1 isolated from rabbit skeletal muscle. The total content of phenolic compounds was determined by the Folin-Ciocalteau method. The ethyl acetate (EtOAc) partition and F5 fraction obtained from B. sartorum, both of them rich in polyphenolics, were shown to have a hypoglycemic effect on normoglycemic mice, more significant than that of the known antidiabetic drug, glibenclamide used as a standard comparable compound. Both samples significantly inhibited SERCA activity. Different extracts of B. sartorum, rich in polyphenolic compounds, were able to reduce blood glucose in normoglycemic mice and inhibit SERCA activity. SERCA inhibition may be one of the possible mechanisms involved in glucose decrease.

Dendranthema grandiflorum, a hybrid ornamental plant, is a source of larvicidal compounds against Aedes aegypti larvae

Abstract In hybrid cultivated form, Dendranthema grandiflorum (Ramat.) Kitam., Asteraceae, flowers (Chrysanthemum morifolium Ramat.) were utilized in the production of extracts, which were analyzed for larvicidal activity against Aedes aegypti third instar larvae. Methanol and dichloromethane extracts showed LC50 values of 5.02 and 5.93 ppm, respectively. Using GC–MS, phytochemical analyses of the dichloromethane extract showed the presence of triterpenoids and fatty acids, while flavonoids and caffeoylquinic acids were shown to occur in the methanol extract by ESI Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (ESI-FT-ICR-MS). Triterpenoids and fatty acids are well known insecticidal compounds. From this study, it can be concluded that D. grandiflorum grown for floriculture, as an agribusiness, can have additional applications as raw material for the production of insecticidal products.

Production of flavonoids in organogenic cultures of Alpinia zerumbet.

Alpinia zerumbet plantlets were cultured in vitro in MS medium supplemented with growth regulators, including IAA, TDZ and BAP. Using high performance liquid chromatography (HPLC), the production of rutin, kaempferol-3-O-glucuronide, and kaempferol-3-O-rutinoside was evaluated, based on leaf hydroalcoholic extracts of three-month-old plantlets. The relative concentration of phenolics from the hydroalcoholic extracts of plantlets cultured in control medium reached 100% compared with plantlets treated with growth regulators and donor plants (80%). The in vitro rutin production was more pronounced than the other flavonoids. While no direct relation between the content of phenolic compounds and increased flavonoid production was observed, the combination of IAA + TDZ enhanced the production of rutin (83.2 microg/g dried leaves) and kaempferol-3-O-glucuronide (29 microg/g dried leaves), compared with growth regulators used alone. Overall, these findings suggest the value of in vitro cultivation as a means of enriching phenolic and flavonoid production in medicinal plants.

Genotoxicity and mutagenicity of Echinodorus macrophyllus (chapéu-de-couro) extracts.

Echinodorus macrophyllus, commonly known as chapéu-de-couro, is a medicinal plant used in folk medicine to treat inflammation and rheumatic diseases. In this work, we used short-term bacterial assays based on the induction of SOS functions to examine the genotoxicity and mutagenicity of an aqueous extract of E. macrophyllus leaves. Whole extract and an ethyl acetate fraction showed similar genotoxicity and caused an ~70-fold increase in lysogenic induction. The extract also gave a positive result in the SOS chromotest with an increase of 12-fold in ß-Galactosidase enzymatic units. There was a strong trend towards base substitutions and frameshifts at purine sites in the mutations induced by the extract in Escherichia coli (CC103 and CC104 strains) and Salmonella typhimurium test strains (22-fold increase in histidine revertants in TA98 strain). Since reactive oxygen species may be implicated in aging process and in degenerative diseases, we used antioxidant compounds as catalase, thiourea and dipyridyl in the lysogenic induction test. All this compounds were able to reduce the induction factor observed in the treatment with chapéu-de-couro, thus suggesting that the genotoxicity and mutagenicity were attributable to the production of reactive oxygen species that targeted DNA purines.

Antinociceptive activity of fractions from Couroupita guianensis Aubl. leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: Couroupitaguianensis Aubl. (Lecythidaceae) is popularly known in Brazil as "abricó-de-macaco". Infusions or teas obtained from its leaves, flowers, and barks are used in South America for the treatment of several disorders such as pain and inflammatory processes. AIM OF THE STUDY: Evaluate antinociceptive effects of crude ethanol extract (CEE) and its fractions in three analgesic models (acetic acid-induced contortions, tail flick, and hot plate) and study the possible mechanism of their action. MATERIALS AND METHODS: CEE, hexane, dichloromethane, ethyl acetate, and butanol fractions (10, 30, and 100mg/kg, p.o.) and the reference drug morphine (5mg/kg, s.c.) were evaluated. To elucidate the mechanism of action from the fractions, animals were pre-treated (30 min) with atropine (muscarinic receptor antagonist, 1mg/kg, s.c.), mecamylamine (nicotinic receptor antagonist, 2mg/kg, s.c.), naloxone (opioid receptor antagonist, 1mg/kg, s.c.) or L-nitro arginine methyl ester (L-NAME, nitric oxide synthase inhibitor, 3mg/kg, s.c.). RESULTS: CEE and fractions significantly inhibited the number of contortions induced by acetic acid. All fractions showed antinociceptive activity in the tail flick model, being the hexane and ethyl acetate the most potent and long acting fractions. In the hot plate method the highest effect observed was at the dose of 100mg/kg from all fractions. Administration of naloxone inhibited the antinociceptive effect of fractions. Pre-treatment of mice with atropine reduced the antinociceptive activity of CEE and its fractions, the exception being the dichloromethane fraction. Mecamylamine did not inhibited the effect of dichloromethane fraction. L-NAME reduced the anti-hyperalgesic effect of all fractions, but the most prominent effect was observed in the antinociceptive activity caused by CEE and butanol fraction. CONCLUSIONS: Results obtained demonstrated that Couroupita guianensis CEE and its fractions have antinociceptive activity that is mediated, at least in part, by opioid and cholinergic systems and nitric oxide pathway.