An update review on monoterpene indole alkaloids and biological activities of Tabernaemontana species occurring in Brazil.

ETHNOPHARMACOLOGICAL RELEVANCE: The Tabernaemontana genus belongs to the Apocynaceae family of which 30 species are found in Brazil. Some Tabernaemontana species are used by Brazilian indigenous people and other communities, or are listed in the Yanomami Pharmacopeia. Ethnopharmacological data include use(s) for muscle problems, depressed sternum, back pain, abscess, indigestion, eye irritation, earache, itching, vaginal discharge, as an aid for older people who are slow and forgetful, mosquito and snake bites, infection by the human botfly larvae, calmative, and fever. Obviously, many of these uses are attributed to the alkaloids found in Tabernaemontana species. AIM OF THE REVIEW: The aim is to gather information on Tabernaemontana species occurring in Brazil, as sources of monoterpene indole alkaloids (MIAs). In addition, we aim to collect reported experimental demonstrations of their biological activity, which may provide the foundation for further studies, including phytochemistry, the development of medicinal agents, and validation of phytopreparations. MATERIAL AND METHODS: The Brazilian Flora 2020 database was used as source for Tabernamontana species occurring in Brazil. The literature review on these species was collected from Web of Science, Scopus, PubMed, and Scifinder. The keywords included names and synonyms of Tabernaemontana species found in Brazil, which were validated by the Word Flora Online Plant List. RESULTS: A literature survey covering the time frame from 1960 until June 2023 resulted in 121 MIAs, including 48 not yet reported in the last review published in 2016. Some alkaloid extracts, fractions, and isolated alkaloids present evidenced biological activity, such as anticancer, anti-inflammatory, antinociceptive, antimicrobial, antiparasitic, antiviral, and against snake venoms, among others. Notably, ethnopharmacological based information has been the basis of some reports on Tabernaemontana species. CONCLUSIONS: Our literature survey shows that Tabernaemontana species present bioactive MIAs, such as voacamine and affinisine, demonstrating significant cytotoxicity activity against several tumoral cell lines. Those compounds can be considered promising candidates in the search for new anticancer drugs. However, the Amazonian plant biome is increasingly damaged, which may lead to the extinction of biological diversity. This threat may also affect Tabernaemontana species, which have scarcely been investigated regarding the potential of their phytochemicals for the development of new drugs.

Central nervous system activity of a Tabernaemontana arborea alkaloid extract involves serotonergic and opioidergic neurotransmission in murine models.

Tabernaemontana arborea (Apocynaceae) is a Mexican tree species known to contain ibogan type alkaloids. This study aimed at determining central nervous system-related activities of an alkaloid extract obtained from the root bark of T. arborea. A gas chromatography-mass spectrometry (GC-MS) analysis was performed to describe the alkaloid profile of the extract. A wide dosing range (0.1 to 56.2 mg/kg) of this extract was evaluated in different murine models. Electrical brain activity was examined by electroencephalography (EEG). The extract's effects on motor coordination, ambulatory activity, and memory were analyzed based on the rotarod, open field (OFT), and object recognition tests (ORT), respectively. Antidepressant and antinociceptive activities were determined using the forced swimming test (FST) and the formalin assay, respectively. In order to elucidate the underlying mechanisms of action, the 5-HT1A receptor antagonist WAY100635 (1 mg/kg) or the opioid receptor antagonist naloxone (1 mg/kg) was included in the latter experiments. GC-MS analysis (µg/mg extract) confirmed the presence of the monoterpenoid indole alkaloids (MIAs) voacangine (207.00), ibogaine (106.33), vobasine (72.81), coronaridine (30.72), and ibogamine (24.2) as principal constituents of the extract, which exhibited dose- and receptor-dependent antidepressant (0.1 to 1 mg/kg; 5-HT1A) and antinociceptive (30 and 56.2 mg/kg; opioid) effects, without altering motor coordination, ambulatory activity, and memory. EEG indicated CNS depressant activity at high doses (30 and 56.2 mg/kg). The root bark of T. arborea contains a mixture of alkaloids that may hold therapeutic value in pain relief and the treatment of psychiatric diseases without causing neurotoxic activity at effective doses.

Reactivity of the Iboga Skeleton: Oxidation Study of Ibogaine and Voacangine.

The iboga alkaloids scaffold shows great potential as a pharmacophore in drug candidates for the treatment of neuropsychiatric disorders. Thus, the study of the reactivity of this type of motif is particularly useful for the generation of new analogs suitable for medicinal chemistry goals. In this article, we analyzed the oxidation pattern of ibogaine and voacangine using dioxygen, peroxo compounds, and iodine as oxidizing agents. Special focus was placed on the study of the regio- and stereochemistry of the oxidation processes according to the oxidative agent and starting material. We found that the C16-carboxymethyl ester present in voacangine stabilizes the whole molecule toward oxidation in comparison to ibogaine, especially in the indole ring, where 7-hydroxy- or 7-peroxy-indolenines can be obtained as oxidation products. Nevertheless, the ester moiety enhances the reactivity of the isoquinuclidinic nitrogen to afford C3-oxidized products through a regioselective iminium formation. This differential reactivity between ibogaine and voacangine was rationalized using computational DFT calculations. In addition, using qualitative and quantitative NMR experiments combined with theoretical calculations, the absolute stereochemistry at C7 in the 7-hydroxyindolenine of voacangine was revised to be S, which corrects previous reports proposing an R configuration.

Iboga Inspired N-Indolylethyl-Substituted Isoquinuclidines as a Bioactive Scaffold: Chemoenzymatic Synthesis and Characterization as GDNF Releasers and Antitrypanosoma Agents.

The first stage of the drug discovery process involves the identification of small compounds with biological activity. Iboga alkaloids are monoterpene indole alkaloids (MIAs) containing a fused isoquinuclidine-tetrahydroazepine ring. Both the natural products and the iboga-inspired synthetic analogs have shown a wide variety of biological activities. Herein, we describe the chemoenzymatic preparation of a small library of novel N-indolylethyl-substituted isoquinuclidines as iboga-inspired compounds, using toluene as a starting material and an imine Diels-Alder reaction as the key step in the synthesis. The new iboga series was investigated for its potential to promote the release of glial cell line-derived neurotrophic factor (GDNF) by C6 glioma cells, and to inhibit the growth of infective trypanosomes. GDNF is a neurotrophic factor widely recognized by its crucial role in development, survival, maintenance, and protection of dopaminergic neuronal circuitries affected in several neurological and psychiatric pathologies. Four compounds of the series showed promising activity as GDNF releasers, and a leading structure (compound 11) was identified for further studies. The same four compounds impaired the growth of bloodstream Trypanosoma brucei brucei (EC50 1-8 µM) and two of them (compounds 6 and 14) showed a good selectivity index.

In vitro antiproliferative activity of alkaloids isolated from Tabernaemontana catharinensis A.DC (Apocynaceae).

In this work, four alkaloids from the stem bark of T. catharinensis were isolated, namely: voacangine (1); ethyl apovincaminate (2); affinisine (3) and voachalotine (4). The alkaloids were tested in vitro for antiproliferative capacity in eight tumor cell lines: U251 (glioma), MCF-7 (breast), NCI-ADR/RES (drug resistant ovary), 786-0 (kidney), NCI-H460 (lung), HT-29 (colon), K562 (leukemia) and PC-3 (prostate) and a non-tumor keratinocyte cell line (HaCat). Antiproliferative activity was observed after 48 hours and results expressed as the concentration needed to induce 50% growth inhibition (GI50) in µM. The chemotherapy drug Doxorubicin was used as a standard. The alkaloid affinisine (3) was the most promising, showing moderate inhibition rates in addition to the cytotoxic and cytocidal effect against all strains tested. It also proved to be a very promising compound, showing high selectivity rates when compared to the non-tumor keratinocyte cell line (HaCat).

Molecular Human Targets of Bioactive Alkaloid-Type Compounds from Tabernaemontana cymose Jacq.

Alkaloids are a group of secondary metabolites that have been widely studied for the discovery of new drugs due to their properties on the central nervous system and their anti-inflammatory, antioxidant and anti-cancer activities. Molecular docking was performed for 10 indole alkaloids identified in the ethanol extract of Tabernaemontana cymosa Jacq. with 951 human targets involved in different diseases. The results were analyzed through the KEGG and STRING databases, finding the most relevant physiological associations for alkaloids. The molecule 5-oxocoronaridine proved to be the most active molecule against human proteins (binding energy affinity average = -9.2 kcal/mol) and the analysis of the interactions between the affected proteins pointed to the PI3K/ Akt/mTOR signaling pathway as the main target. The above indicates that indole alkaloids from T. cymosa constitute a promising source for the search and development of new treatments against different types of cancer.

Precursor-directed Biosynthesis in Tabernaemontana catharinensis as a New Avenue for Alzheimer's Disease-modifying Agents.

Plants produce a high diversity of metabolites that can act as regulators of cholinergic dysfunction. Among plants, the potential of species of the genus Tabernaemontana to treat neurological disorders has been linked to iboga-type alkaloids that are biosynthesized by those species. In this context, precursor-directed biosynthesis approaches were carried out using T. catharinensis plantlets to achieve new-to-nature molecules as promising agents against Alzheimer's disease. Aerial parts of T. catharinensis, cultured in vitro, produced 7 unnatural alkaloids (5-fluoro-ibogamine, 5-fluoro-voachalotine, 5-fluoro-12-methoxy-Nb-methyl-voachalotine, 5-fluoro-isovoacangine, 5-fluoro-catharanthine, 5-fluoro-19-(S)-hydroxy-ibogamine, and 5-fluoro-coronaridine), while root extracts showed the presence of the same unnatural iboga-type alkaloids and 2 additional ones: 5-fluoro-voafinine and 5-fluoro-affinisine. Moreover, molecular docking approaches were carried out to evaluate the potential inhibition activity of T. catharinensis' natural and unnatural alkaloids against AChE and BChE enzymes. Fluorinated iboga alkaloids (5-fluoro-catharanthine, 5-fluoro-voachalotine, 5-fluoro-affinisine, 5-fluoro-isovoacangine, 5-fluoro-corinaridine) were more active than natural ones and controls against AchE, while 5-fluoro-19-(S)-hydroxy-ibogamine, 5-fluoro-catharanthine, 5-fluoro-isovoacangine, and 5-fluoro-corinaridine showed better activity than natural ones and controls against BChE. Our findings showed that precursor-directed biosynthesis strategies generated "new-to-nature" alkaloids that are promising Alzheimer's disease drug candidates. Furthermore, the isotopic experiments also allowed us to elucidate the initial steps of the biosynthetic pathway for iboga-type alkaloids, which are derived from the MEP and shikimate pathways.

Extraction of Phenolic Compounds from Tabernaemontana catharinensis Leaves and Their Effect on Oxidative Stress Markers in Diabetic Rats.

The aim of this study was to evaluate the most effective extraction condition (temperature, solvent type and time) for recovery of high-value phytochemicals present in the Tabernaemontana catharinensis leaves (TC) and to assess their effect on biochemical parameters in streptozotocin-induced diabetic rats. The extraction of phenolic compounds from TC using a factorial design (FD) 2³, high performance liquid chromatography (HPLC), response surface methodology (RSM) and principal component analysis (PCA) were studied. It was found that the optimal conditions for extraction of phenolics were higher temperature (65 °C) and time (60 min) using ethanol as extractor solvent. In this condition of extraction (A8), total phenolic compounds (TPC) and antioxidant activity (AA) were determined. Additionally, this extract was used to evaluate their effect on antioxidant enzyme activities (superoxide dismutase (SOD) and catalase (CAT)) as well as lipid peroxidation (LP) and protein thiols level (PSH) in the liver and kidneys of normal and diabetic rats. As result, T. catharinensis extract presented TPC content of 23.34 mg EAG/g (equivalent gallic acid) and AA of 34.26 µmol Trolox/g. Phenolic acids (ferulic acid and coumaric acid) and flavonoids (quercetin, rutin and pinocembrin) could be recovered and identified by HPLC. This study indicated an important role of the T. catharinensis extract on free radical inactivation and on the antioxidant defense system in diabetic rats. In fact, the use of T. catharinensis extract restored the normal activity of SOD (p < 0.05) and suppressed malondialdehyde levels in liver and kidney tissues. Thus, the T. catharinensis extract, rich in phenolic compounds, can be responsible for the recover the enzymatic changes in the liver and kidney tissues provoked by diabetes in rats. In addition, the lipid peroxidation rate decreased in the diabetic rats treated with T. catharinensis.

Quantitative Evaluation of a Mexican and a Ghanaian Tabernaemontana Species as Alternatives to Voacanga africana for the Production of Antiaddictive Ibogan Type Alkaloids.

In continuation of our efforts to provide quantitative information on antiaddictive ibogan type alkaloid-producing Tabernaemontana species, we used gas chromatography-mass spectrometry (GC/MS) to compare the alkaloid profiles of the barks and/or leaves of one Mexican and one African species - T. arborea and T. crassa, respectively, with the primary sources of commercially available semisynthetic ibogaine, Voacanga africana root and stem bark. The qualitative and quantitative similarities between T. arborea and V. africana barks consolidate previous reports regarding the potential of the former as a promising alternative source of voacangine and ibogaine. The results also suggest that T. crassa could be used to produce conopharyngine and ibogaline, two compounds with the same basic skeletal structure and possibly similar antiaddictive properties as ibogaine.

Extraction and Conversion Studies of the Antiaddictive Alkaloids Coronaridine, Ibogamine, Voacangine, and Ibogaine from Two Mexican Tabernaemontana Species (Apocynaceae).

Several species from the Apocynaceae family, such as Tabernanthe iboga, Voacanga africana, and many Tabernaemontana species, produce ibogan type alkaloids, some of which present antiaddictive properties. In this study, we used gas chromatography/mass spectrometry (GC/MS) to examine the efficiency of methanol, acetone, ethyl acetate, dichloromethane, chloroform, and hydrochloric acid in extracting the antiaddictive compounds coronaridine, ibogamine, voacangine, and ibogaine (altogether the CIVI-complex) from the root barks of Tabernaemontana alba and Tabernaemontana arborea. These Mexican species have recently shown great potential as alternative natural sources of the aforementioned substances. Methanol proved to be the most suitable solvent. Furthermore, the crude methanolic extracts could be engaged in a one-step demethoxycarbonylation process that converted coronaridine and voacangine directly into its non-carboxylic counterparts ibogamine and ibogaine, respectively, without the intermediacy of their carboxylic acids. The established protocol straightforwardly simplifies the alkaloid mixture from four to two majority compounds. In summary, our findings facilitate and improve both the qualitative and quantitative analysis of CIVI-complex-containing plant material, as well as outlining a viable method for the bulk production of these scientifically and pharmaceutically important substances from Mexican Tabernaemontana species.

Antinociceptive and antioxidant effects of extract enriched with active indole alkaloids from leaves of Tabernaemontana catharinensis A. DC.

ETHNOPHARMACOLOGICAL RELEVANCE: Ethnopharmacological knowledge is important for the identification of active compounds from natural products. Pain may have different aetiologies with complex mechanisms. Tabernaemontana catharinensis A. DC. is well known for indole alkaloids, being used empirically in folk medicine, with antimicrobial and anti-inflammatory as well as antiofidic actions among others. AIM OF THE STUDY: This work aims to evaluate the antinociceptive and antioxidant effect in mice of the alkaloids extract from leaves of Tabernaemontana catharinensis A. DC. (AITc). MATERIALS AND METHODS: The AITc was produced by ultrasound and acid-base extraction, and the chemical composition was evaluated by high resolution mass spectrometry. Male mice (Mus musculus), Swiss, were used for in vivo tests. The AITc was administrated at doses of 1.0, 5.0, and 10.0 mg/kg in acetic acid model, formalin, tail-immersion, hot plate, and open field tests, and compared to saline, morphine, or diazepam controls, depending on the test. The toxicological, biochemical, haemogram and antioxidant effect were evaluated in mouse organs such as liver, brain, kidneys, spleen and stomach. RESULTS: In total, 10 compounds were identified in the AITc, being from the indole alkaloids from the ibogan and corynanthean classes. The extract in doses ranging from 5.0 to 10.0 mg/kg showed an antinociceptive effect for acetic acid, inhibiting by 47.7% and 61.6%. In the same line, reductions of 47.1% (first phase) and 43.6% (second phase) were observed for the 5.0 mg/kg dose in the formalin test. However, tail-immersion and hot plate tests did not show considerable modifications in the latency period, while in the open field test there was an inhibition of only 5.1%. It was observed no differences in NO levels and total antioxidant status of the mice in any of the studie tissues. CONCLUSIONS: The results justify the use of this plant in traditional medicine. in vivo tests indicate that these compounds possess central and peripheral mechanisms of action. This is study that reports the nociceptive action of these alkaloids, also including toxicity tests, which are intended to guarantee the safety of use of extracts of this plant.

TRPA1 involvement in analgesia induced by Tabernaemontana catharinensis ethyl acetate fraction in mice.

BACKGROUND: Ionic channels such as the transient receptor potential ankyrin 1 (TRPA1) are essential for the detection and transmission of painful stimuli. In this sense, new TRPA1 antagonists have been searched as analgesics. PURPOSE: Preclinical studies support the antinociceptive activity of Tabernaemontana catharinensis ethyl acetate fraction (Eta), which has constituents previously identified as TRPA1 antagonists (gallic acid). It was verified for the first time the involvement of the TRPA1 on Eta's antinociceptive and anti-inflammatory effects in mice pain models. STUDY DESIGN: It was evaluated the Eta's effect (0.01-100 mg/kg, oral route) on nociceptive (spontaneous nociception, mechanical and cold allodynia) and inflammatory (paw edema) parameters in pain models involved with TRPA1 activation. METHODS: Firstly, it was investigated the ability of Eta to act on TRPA1 or TRPV1 channels (Ca2+influx and binding assays in mice spinal cords). Next, it was evaluated the Eta's antinociceptive and anti-inflammatory effects after intraplantar injection of TRPA1 agonists (hydrogen peroxide, cinnamaldehyde or allyl isothiocyanate) in male Swiss mice (30-35 g). Moreover, the Eta's antinociceptive effects were evaluated on complete Freund's adjuvant (CFA)-induced chronic inflammatory pain (CIP), postoperative pain and on paclitaxel-induced peripheral neuropathy (PIPN). Oxidative parameters were evaluated in mice paw utilized for CFA induced-CIP model. RESULTS: Eta inhibited the TRPA1 agonist-induced Ca2+ influx [Imax = 72.4 ±â€¯1.5%; IC50 = 0.023(0.004-0.125)µg/ml], but not TRPV1 agonist-induced, nor was able to displace [3H]-resiniferatoxin (TRPV1 agonist) binding. Eta (0.1-100 mg/kg) inhibited the spontaneous nociception [ID50 = 0.043(0.002-0.723)mg/kg], mechanical [ID50 = 7.417(1.426-38.570)mg/kg] and cold allodynia, and edema development caused by TRPA1 agonists. Moreover, Eta (100 mg/kg) prevented and reversed the CFA-induced CIP (Imax = 55.8 ±â€¯13.7%, Imax = 80.4 ±â€¯5.1%, respectively) and postoperative pain (Imax = 88.0 ±â€¯11.6%, Imax = 51.3 ±â€¯14.9%, respectively), been also effective in reversing the acute (Imax = 94.4 ±â€¯12.4%) and chronic (Imax = 86.8 ±â€¯8.6%) PIPN. These effects seem to occur by TRPA1 channels pathway, and independently of TRPV1 or oxidative mechanisms. CONCLUSION: Our results demonstrate that Eta-induced antinociception and anti-inflammatory effects occur by TRPA1 inhibition making possible the use of this preparation as a potential therapeutic agent to treat pathological pains.

Bio-guided search of active indole alkaloids from Tabernaemontana catharinensis: Antitumour activity, toxicity in silico and molecular modelling studies.

Active plant metabolites have been used as prototype drugs. In this context, Tabernaemontana catharinensis (Apocynaceae) has been highlighted because of the presence of active indole alkaloids. Thus, this study aims the bio-guided search of T. catharinensis cytotoxic alkaloids. The chemical composition was identified by high-resolution mass spectrometry, and fractionation was performed by open column and preparative thin-layer chromatography, from plant stems. The enriched fractions were tested in vitro in tumour cells A375 (melanoma cell line) and A549 (adenocarcinomic human alveolar basal epithelial cells), and non-tumour Vero cells (African green monkey kidney epithelial cells). The alkaloids identified as active were submitted to in silico toxicity prediction by ADME-Tox and OSIRIS programs and, also, to molecular docking, using topoisomerase I (PDB ID: 1SC7) by iGEMDOCK. As a result, six sub-fractions were obtained, which were identified as containing 16-epi-affinine, 12-methoxy-n-methyl-voachalotine, affinisine, voachalotine, coronaridine hydroxyindoline and ibogamine, respectively. The affinisine-containing sub-fraction showed selective toxicity against A375, with an IC50 of 11.73 µg mL-1, and no cytotoxicity against normal cells (Vero). From the in silico toxicity test results, all indole alkaloid compounds had a low toxicity risk. The molecular docking data provided structural models and binding affinities of the plant's indole alkaloids and topoisomerase I. In summary, this bio-guided search revealed that the indole alkaloids from T. catharinensis display selective cytotoxicity in A375 tumour cells and toxicity in silico. Particularly, affinisine might be a chemotherapeutic for A375 melanoma cells.

Metabolite Profiling of Anti-Addictive Alkaloids from Four Mexican Tabernaemontana Species and the Entheogenic African Shrub Tabernanthe iboga (Apocynaceae).

Ibogaine and other ibogan type alkaloids present anti-addictive effects against several drugs of abuse and occur in different species of the Apocynaceae family. In this work, we used gas chromatography-mass spectrometry (GC/MS) and principal component analysis (PCA) in order to compare the alkaloid profiles of the root and stem barks of four Mexican Tabernaemontana species with the root bark of the entheogenic African shrub Tabernanthe iboga. PCA demonstrated that separation between species could be attributed to quantitative differences of the major alkaloids, coronaridine, ibogamine, voacangine, and ibogaine. While T. iboga mainly presented high concentrations of ibogaine, Tabernaemontana samples either showed a predominance of voacangine and ibogaine, or coronaridine and ibogamine, respectively. The results illustrate the phytochemical proximity between both genera and confirm previous suggestions that Mexican Tabernaemontana species are viable sources of anti-addictive compounds.

Tabernaemontana catharinensis leaves exhibit topical anti-inflammatory activity without causing toxicity.

BACKGROUND: Tabernaemontana catharinensis, popularly known as snake skin, has been empirically used as an anti-inflammatory to treat cutaneous skin disorders. However, no study proves its effectiveness as a topical anti-inflammatory. STUDY DESIGN: We investigated the topical anti-inflammatory effect of T.catharinensis leaves crude extract (TcE) in irritant contact dermatitis models in mice and its preliminary toxicity profile. METHODS: The topical anti-inflammatory effect was evaluated by ear thickness measurement, inflammatory cell infiltration (MPO activity measurement and histological procedure) and cytokines levels. TcE qualitative phytochemical analysis was performed by UHPLC-ESI-HRMS and the TcE effect (therapeutic dose; 10 µg/ear) on preliminary toxicological parameters was also evaluated (on the 14°â€¯day of experiment). RESULTS: TcE (10 µg/ear) prevented the development of ear edema induced by cinnamaldehyde, capsaicin, arachidonic acid, phenol, and croton oil with maximum inhibition of 100% to cinnamaldehyde, arachidonic acid, phenol, and croton oil and 75 ±â€¯6% to capsaicin. Besides, the TcE (10 µg/ear) also prevented the increase of MPO activity by 96 ±â€¯2%, 48 ±â€¯7%, 100%, 87 ±â€¯8%, and 93 ±â€¯4%, respectively, to the same irritant agents. The positive controls also prevented both ear edema and the increased of MPO activity by 100% and 42 ±â€¯8% (HC-030031), 54 ±â€¯6% and 80 ±â€¯4% (SB-366791), 100% and 54 ±â€¯5% (indomethacin), 100% and 80 ±â€¯4% (dexamethasone in skin inflammation model induced by phenol) and 100% and 97 ±â€¯3% (dexamethasone in inflammation model induced by croton oil), respectively. TcE also prevented the inflammatory cells infiltration and the increase of MIP-2, IL-1ß and TNF-α levels irritant agents-induced. TcE topical anti-inflammatory effect may be attributed to the combined effect of indole alkaloids, terpenes, and phenolic compounds found in the extract and identified by dereplication method. The TcE' therapeutic dose proved to be safe in preliminary toxicological tests. CONCLUSION: Our results suggest that TcE could be an interesting strategy for the treatment of inflammatory diseases.

Tabernaemontana catharinensis leaves effectively reduce the irritant contact dermatitis by glucocorticoid receptor-dependent pathway in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Tabernaemontana catharinensis, popularly known as snakeskin, is used in traditional medicine to treat skin inflammatory disorders. To confirm the topical anti-inflammatory effect of T. catharinensis leaves, we evaluated the therapeutic effect of crude extract (TcE) and its different fractions on irritant contact dermatitis model in mice and verified its anti-inflammatory action mechanism. MATERIALS AND METHODS: The qualitative phytochemical analysis of TcE and its dichloromethane, n-butanol and ethyl acetate fractions was performed by UHPLC-ESI-HRMS. The gel accelerated stability was performed to ensure the effectiveness formulation. We investigated the TcE' inhibitory effect, its fractions and a gel formulation containing TcE in irritant contact dermatitis models induced by unique (1000 µg/ear) and multiple (400 µg/ear) croton oil application, evaluated by the ear edema formation, inflammatory cell infiltration (MPO activity measurement and histological procedure) and pro-inflammatory cytokines levels. The action glucocorticoid-like of TcE was investigated using a glucocorticoid receptor antagonist (mifepristone; 50 mg/kg, s.c.). RESULTS: The treatments (10 µg/ear) reduced the ear edema and MPO activity by 100% and 94 ± 3% (TcE) 85 ± 4% and 88 ± 3% (dichloromethane fraction), 83 ± 6% and 73 ± 11% (n-butanol fraction) and 86 ± 6% and 93 ± 4% (ethyl acetate fraction) and 100% (dexamethasone solution), respectively to the acute ICD model. The TcE and dexamethasone gel (15 mg/ear) also reduced by 66 ± 6% and 70 ± 5% the ear edema and by 58 ± 14% and 84 ± 4% the MPO activity, respectively. To the chronic ICD model, the TcE and dexamethasone (10 µg/ear) also reduced the ear edema (66 ± 6% and 70 ± 5%) and the MPO activity (58 ± 14% and 84 ± 4%); on the 9th day of the experiment. TcE and dexamethasone also reduced the pro-inflammatory cytokines (MIP-2, IL-1ß and TNF-α) levels in acute ICD model induced by croton oil. Besides, mifepristone prevented the topical anti-edematogenic effect of TcE' and dexamethasone' solutions by 97 ± 9% to TcE and 75 ± 15% to dexamethasone. The accelerated stability study of T.catharinensis gels showed no relevant changes at low temperatures. The dereplication of the TcE and fractions revealed the presence of indole alkaloids, triterpenes, and flavonoids by UHPLC-ESI-HRMS. These classes of compounds are known in the literature for present potential anti-inflammatory action, supporting the results obtained. CONCLUSION: The results confirm the topical popular use ofT.catharinensis leaves in the treatment of skin inflammation and demonstrate the TcE' potential for the development of a promising topical anti-inflammatory agent to treat inflammatory disorders.

Phytochemical Analysis by HPLC-HRESI-MS and Anti-Inflammatory Activity of Tabernaemontana catharinensis.

Tabernaemontana catharinensis (Apocynaceae) has been popularly used by folk medicine because of its anti-inflammatory, analgesic, and antiophidic properties. This study aims to analyze the flavonoids composition of the hydroethanolic extract and of the ethyl acetate (EtOAc) and butanol (BuOH) fractions of T. catharinensis leaves, as well as to evaluate their anti-inflammatory activity using in vivo models. The phytochemical profile, determined by High-Performance Liquid Chromatography-High-Resolution Electrospray Ionization-Mass Spectrometry (HPLC-HRESI-MS), showed the presence of flavonoids mainly having an isorhamnetin nucleus. The anti-inflammatory activity was evaluated in carrageenan-induced paw edema (pre- and post-treatment) with oral administration of a T. catharinensis hydroethanolic extract (50, 100, and 150 mg/kg) and of organic fractions (50 mg/kg). The extract and fractions showed antiedematogenic activity by decreasing myeloperoxidase (MPO) production. In the zymosan-air-pouch model, the extract and fractions inhibited leukocyte migration and significantly decreased the levels of various proteins, such as MPO, interleukin (IL)-1ß, and tumor necrosis factor (TNF)-α. The cytotoxicity was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, which revealed no cytotoxicity of the extract and the fractions. These results suggest that the hydroethanolic extract and organic fractions of T. catharinensis leaves have sufficient anti-inflammatory activity to support the popular use of this plant in the treatment of inflammatory disorders.

Characterisation of phenolic compounds of the ethyl acetate fraction from Tabernaemontana catharinensis and its potential antidepressant-like effect.

This study evaluates the antidepressant-like effect and analysed the qualitative and quantitative 74 phenolic standards of ethyl acetate fraction from Tabernaemontana catharinensis leaves. Acute administration of fraction in mice reduced the immobility time in forced swimming and tail suspension tests confirming its antidepressant-like activity. The anti-immobility effect elicited by this fraction was prevented by the pretreatment of mice with PCPA (100 mg kg-1), ketanserin (5 mg kg-1), SCH 23,390 (0.05 mg kg-1) or yohimbine (1 mg kg-1). A sub effective dose of the fraction produced a synergistic effect with fluoxetine (5 mg kg-1). Chromatographic analysis identified 4-hydroxybenzoic and p-coumaric acids in the ethyl acetate fraction from T. catharinensis. Capillary electrophoresis presented 7.34 ± 0.02 mg g-1 of p-coumaric acid concentration in the fraction. Therefore, it is possible that antidepressant-like effect elicited by ethyl acetate fraction from T. catharinensis be dependent on the p-coumaric acid.

Antiviral effect of compounds derived from the seeds of Mammea americana and Tabernaemontana cymosa on Dengue and Chikungunya virus infections.

BACKGROUND: The transmission of Dengue virus (DENV) and Chikungunya virus (CHIKV) has increased worldwide, due in part to the lack of a specific antiviral treatment. For this reason, the search for compounds with antiviral potential, either as licensed drugs or in natural products, is a research priority. The objective of this study was to identify some of the compounds that are present in Mammea americana (M. americana) and Tabernaemontana cymosa (T. cymosa) plants and, subsequently, to evaluate their cytotoxicity in VERO cells and their potential antiviral effects on DENV and CHIKV infections in those same cells. METHODS: Dry ethanolic extracts of M. americana and T. cymosa seeds were subjected to open column chromatographic fractionation, leading to the identification of four compounds: two coumarins, derived from M. americana; and lupeol acetate and voacangine derived from T. cymosa.. The cytotoxicity of each compound was subsequently assessed by the MTT method (at concentrations from 400 to 6.25 µg/mL). Pre- and post-treatment antiviral assays were performed at non-toxic concentrations; the resulting DENV inhibition was evaluated by Real-Time PCR, and the CHIKV inhibition was tested by the plating method. The results were analyzed by means of statistical analysis. RESULTS: The compounds showed low toxicity at concentrations ≤ 200 µg/mL. The compounds coumarin A and coumarin B, which are derived from the M. americana plant, significantly inhibited infection with both viruses during the implementation of the two experimental strategies employed here (post-treatment with inhibition percentages greater than 50%, p < 0.01; and pre-treatment with percentages of inhibition greater than 40%, p < 0.01). However, the lupeol acetate and voacangine compounds, which were derived from the T. cymosa plant, only significantly inhibited the DENV infection during the post-treatment strategy (at inhibition percentages greater than 70%, p < 0.01). CONCLUSION: In vitro, the coumarins are capable of inhibiting infection by DENV and CHIKV (with inhibition percentages above 50% in different experimental strategies), which could indicate that these two compounds are potential antivirals for treating Dengue and Chikungunya fever. Additionally, lupeol acetate and voacangine efficiently inhibit infection with DENV, also turning them into promising antivirals for Dengue fever.

Brazilian Tabernaemontana genus: Indole alkaloids and phytochemical activities.

The Tabernaemontana genus belongs to the family Apocynaceae comprising about 100 species spread throughout tropical and subtropical regions around the world including Brazil, which contains around 40 species spread all over its territory. Because of the territorial space and climate diversity, these species already identified in Brazil are the largest collection of Tabernaemontana, which are representative (about 30%) of worldwide distribution. The monoterpene indole alkaloids present as major secondary components in all parts of the plants of the genus Tabernaemontana, have attracted the attention of the scientific community for new alkaloids derivatives and bioactivities. This review covers relevant references about Tabernaemontana species found in Brazil, its geographical distribution, occurrence of monoterpene alkaloids and phytochemical activities. Additional information about the South American species activities are also reported in this review.