Comparative Analysis of Hydrophilic Ingredients in Toad Skin and Toad Venom Using the UHPLC-HR-MS/MS and UPLC-QqQ-MS/MS Methods Together with the Anti-Inflammatory Evaluation of Indolealkylamines

Chemical Composition, Pharmacological Effects and Clinical Applications of Cinobufacini

Chinese medicine cinobufacini is an extract from the dried skin of Bufo bufo gargarizans Cantor, with active ingredients of bufadienolides and indole alkaloids. With further research and clinical applications, it is found that cinobufacini alone or in combination with other therapeutic methods can play an anti-tumor role by controlling proliferation of tumor cells, promoting apoptosis, inhibiting formation of tumor neovascularization, reversing multidrug resistance, and regulating immune response; it also has the functions of relieving cancer pain and regulating immune function. In this paper, the chemical composition, pharmacological effects, clinical applications, and adverse reactions of cinobufacini are summarized. However, the extraction of monomer components of cinobufacini, the relationship between different mechanisms, and the causes of adverse reactions need to be further studied. Also, high-quality clinical studies should be conducted.

A metabologenomics approach to unlock the metabolome of the novel Antarctic deep-sea isolate Lacinutrix shetlandiensis sp. nov. WUR7

The South Shetland Trough, Antarctica, is an underexplored region for microbiological and biotechnological exploitation. Herein, we describe the isolation and characterization of the novel bacterium Lacinutrix shetlandiensis sp. nov. WUR7 from a deep-sea environment. We explored its chemical diversity via a metabologenomics approach, wherein the OSMAC strategy was strategically employed to upregulate cryptic genes for secondary metabolite production. Based on hybrid de novo whole genome sequencing and digital DNA-DNA hybridization, isolate WUR7 was identified as a novel species from the Gram-negative genus Lacinutrix. Its genome was mined for the presence of biosynthetic gene clusters with limited results. However, extensive investigation of its metabolism uncovered an unusual tryptophan decarboxylase with high sequence homology and conserved structure of the active site as compared to ZP_02040762, a highly specific tryptophan decarboxylase from Ruminococcus gnavus. Therefore, WUR7's metabolism was directed toward indole-based alkaloid biosynthesis by feeding it with L-tryptophan. As expected, its metabolome profile changed dramatically, by triggering the extracellular accumulation of a massive array of metabolites unexpressed in the absence of tryptophan. Untargeted LC-MS/MS coupled with molecular networking, followed along with chemoinformatic dereplication, allowed for the annotation of 10 indole alkaloids, belonging to β-carboline, bisindole, and monoindole classes, alongside several unknown alkaloids. These findings guided us to the isolation of a new natural bisindole alkaloid 8,9-dihydrocoscinamide B (1), as the first alkaloid from the genus Lacinutrix, whose structure was elucidated on the basis of extensive 1D and 2D NMR and HR-ESIMS experiments. This comprehensive strategy allowed us to unlock the previously unexploited metabolome of L. shetlandiensis sp. nov. WUR7.

Biomarkers of 4-hydroxy-N,N-methylpropyltryptamine (4-OH-MPT) intake identified from human hepatocyte incubations

BACKGROUND

4-Hydroxy-N,N-methylpropyltryptamine (4-OH-MPT) is a psychedelic tryptamine whose use is regulated in several countries. Due to unspecific effects, consumption can be ascertained only through toxicological analyses. However, the trace amounts of tryptamines are usually challenging to detect in biological samples. 4-OH-MPT metabolism was characterized to identify optimal metabolite markers of intake in clinical/forensic toxicology.

RESEARCH DESIGN AND METHODS

4-OH-MPT was incubated with 10-donor-pooled human hepatocytes to simulate in vivo conditions; samples were analyzed by liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS), and data were processed with Compound Discoverer from Thermo Scientific. LC-HRMS/MS and data mining were supported by in silico metabolite predictions (GLORYx).

RESULTS

Three phase I and four phase II metabolites were identified, including N-oxidation and N-demethylation at the alkylamine chain, and O-glucuronidation and sulfation at the hydroxylindole core.

CONCLUSIONS

4-OH-MPT metabolic fate was consistent with the human metabolism of tryptamine analogues: we suggest 4-OH-MPT-N-oxide and 4-hydroxy-N,N-propyltryptamine (4-OH-PT) as metabolite biomarkers of 4-OH-MPT consumption after glucuronide/sulfate hydrolysis in biological samples to improve detection of 4-OH-MPT and phase I metabolites; 4-OH-MPT-glucuronide is suggested as an additional biomarker when hydrolysis is not performed. Further research on the metabolism of structural analogues is necessary to evaluate the specificity of 4-OH-MPT metabolite biomarkers.

A paraguayan toad Rhinella schneideri preparation based on Mbya tradition increases mitochondrial bioenergetics with migrastatic effects dependent on AMPK in breast cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

In Paraguay, healers from the Mbya culture treat cancer with a recipe prepared with the native toad Rhinella schneideri. However, the chemical composition and biological effects of the recipe remain unknown.

AIM OF THE STUDY

The aim is to determine the composition of the traditional preparation made using the toad R. schneideri and to evaluate its effect on human breast cancer (BC) cells.

MATERIALS AND METHODS

The metabolites contained in the preparation were concentrated using XAD-7 resin, and the concentrate was analyzed by HPLC-MS/MS. The effect of the preparation was assessed in normal (MCF10F) and BC cells (MDA-MB-231 and MCF7). The mitochondrial membrane potential (Δψm), reactive oxygen species (ROS) levels, and cell cycle progression were determined by flow cytometry. The oxygen consumption rate (OCR) was measured by Clark electrode, and fibronectin-dependent migration in normoxia and hypoxia-like conditions were evaluated by transwell assay.

RESULTS

From the Amberlite-retained extract from the preparation, 24 compounds were identified, including alkaloids, amino acids, bufadienolides, and flavonoids, among others. The crude extract (CE) did not affect cell cycle progression and viability of BC cell lines. Moreover, it did not make cancer cells more sensitive to the cytotoxic effect of the chemotherapeutics doxorubicin and teniposide. On the other hand, the CE reduced the menadione-induced ROS production and increased NADH, Δψm, and the OCR. Respiratory complexes I and III as well as ATP synthase levels were increased in an AMPK-dependent manner. Moreover, the CE inhibited the migration of BC cells in normoxia and a hypoxia-like condition using CoCl₂ as a HIF1α-stabilizing agent. This latter effect involved an AMPK-dependent reduction of HIF1α levels.

CONCLUSIONS

The Paraguayan toad recipe contains metabolites from the toad ingredient, including alkaloids and bufadienolide derivatives. The CE lacks cytotoxic effects alone or in combination with chemotherapeutics. However, it increases mitochondrial bioenergetics and inhibits the cancer cell migration in an AMPK-dependent manner in BC cells. This is the first report of the in vitro anticancer effect of a traditional Rhinella sp. toad preparation based on Mbya tradition.

Rapid identification of chemical components in Zhizi Baipi decoction by ultra performance liquid chromatography quadrupole time-of-flight mass spectrometry coupled with a novel informatics UNIFI platform

Zhizi Baipi Decoction is a classic traditional Chinese medicine formula for the treatment of jaundice and various liver diseases. The chemical components of Zhizi baipi decoction were not clear resulting from the paucity of relevant studies, which hindered the elucidation of the pharmacological mechanism, the comprehensive development and utilization of Zhizi baipi decoction in clinical. In this study, ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry combined with UNIFI natural product information analysis platform was used to rapidly analyze and identify the chemical components in Zhizi baipi decoction. A total of 122 chemical components, including 53 flavonoids, 16 alkaloids, 25 terpenoids, 5 phenylpropanoids, 14 organic acids, and 7 others, were identified from Zhizi baipi decoction. These compounds may be the active components of Zhizi baipi decoction. The method established in this study can systematically, rapidly, and accurately resolve the chemical components in Zhizi baipi decoction, which lays the foundation for further establishment of the pharmacodynamic substance basis and quality control of Zhizi baipi decoction. This article is protected by copyright. All rights reserved.

Human Hepatocyte 4-Acetoxy-N,N-Diisopropyltryptamine Metabolite Profiling by Reversed-Phase Liquid Chromatography Coupled with High-Resolution Tandem Mass Spectrometry

Tryptamine intoxications and fatalities are increasing, although these novel psychoactive substances (NPS) are not controlled in most countries. There are few data on the metabolic pathways and enzymes involved in tryptamine biotransformation. 4-acetoxy-N,N-diisopropyltryptamine (4-AcO-DiPT) is a synthetic tryptamine related to 4-hydroxy-N,N-diisopropyltryptamine (4-OH-DiPT), 4-acetyloxy-N,N-dipropyltryptamine (4-AcO-DPT), and 4-acetoxy-N,N-dimethyltryptamine (4-AcO-DMT). The aim of this study was to determine the best 4-AcO-DiPT metabolites to identify 4-AcO-DiPT consumption through human hepatocyte metabolism and high-resolution mass spectrometry. 4-AcO-DiPT metabolites were predicted in silico with GLORYx freeware to assist in metabolite identification. 4-AcO-DiPT was incubated with 10-donor-pooled human hepatocytes and sample analysis was performed with reversed-phase liquid chromatography coupled with high-resolution tandem mass spectrometry (LC-HRMS/MS) in positive- and negative-ion modes. Software-assisted LC-HRMS/MS raw data mining was performed. A total of 47 phase I and II metabolites were predicted, and six metabolites were identified after 3 h incubation following ester hydrolysis, O-glucuronidation, O-sulfation, N-oxidation, and N-dealkylation. All second-generation metabolites were derived from the only first-generation metabolite detected after ester hydrolysis (4-OH-DiPT). The metabolite with the second-most-intense signal was 4-OH-iPT-sulfate followed by 4-OH-DiPT-glucuronide, indicating that glucuronidation and sulfation are common in this tryptamine’s metabolic pathway. 4-OH-DiPT, 4-OH-iPT, and 4-OH-DiPT-N-oxide are suggested as optimal biomarkers to identify 4-AcO-DiPT consumption.

Microbial liberation of N-methylserotonin from orange fiber in gnotobiotic mice and humans

Plant fibers in byproduct streams produced by non-harsh food processing methods represent biorepositories of diverse, naturally occurring, and physiologically active biomolecules. To demonstrate one approach for their characterization, mass spectrometry of intestinal contents from gnotobiotic mice, plus in vitro studies, revealed liberation of N-methylserotonin from orange fibers by human gut microbiota members including Bacteroides ovatus. Functional genomic analyses of B. ovatus strains grown under permissive and non-permissive N-methylserotonin "mining" conditions revealed polysaccharide utilization loci that target pectins whose expression correlate with strain-specific liberation of this compound. N-methylserotonin, orally administered to germ-free mice, reduced adiposity, altered liver glycogenesis, shortened gut transit time, and changed expression of genes that regulate circadian rhythm in the liver and colon. In human studies, dose-dependent, orange-fiber-specific fecal accumulation of N-methylserotonin positively correlated with levels of microbiome genes encoding enzymes that digest pectic glycans. Identifying this type of microbial mining activity has potential therapeutic implications.

Comparative transcriptomes of three different skin sites for the Asiatic toad (Bufo gargarizans)

Toads release toxic dry secretions from glands in their skin. Toxin possesses a wide range of biological effects, but little is known about its specific gene expression pattern and regulatory mechanisms. The Asiatic toad (Bufo gargarizans) is widely used to produce toxin. Here, we explored the gene expression of 30 tissue samples from three different skin sites (parotoid gland, dorsal skin, and abdomen skin) of B. gargarizans. After de novo assembly, 783,130 unigenes with an average length of 489 bp (N50 = 556 bp) were obtained. A total of 9,248 significant differentially expressed genes (DEGs) were detected. There were 8,819 DEGs between the parotoid gland and abdomen skin and 1,299 DEGs between the dorsal skin and abdomen skin, while only 1,283 DEGs were obtained between the parotoid gland and dorsal skin. Through enrichment analysis, it was found that the detected differential gene expressions corresponded to the different functions of different skin sites. Our key findings were the genetic expression of toxin secretion, the protection function of skin, and the related genes such as HSD3B, Cyp2c, and CAT, LGALS9. In conclusion, we provide useful transcript resources to study the gene expression and gene function of B. gargarizans and other amphibians. The detected DEGs between different sites of the skin provided better insights into the genetic mechanisms of toxin secretion and the protection function of skin for amphibians.

Psychedelics and Anti-inflammatory Activity in Animal Models

The serotonin (5-hydroxytryptamine, 5-HT) 2A receptor is most well known as the common target for classic psychedelic compounds. Interestingly, the 5-HT_2A receptor is the most widely expressed mammalian serotonin receptor and is found in nearly every examined tissue type including neural, endocrine, endothelial, immune, and muscle, suggesting it could be a novel and pharmacological target for several types of disorders. Despite this, the bulk of research on the 5-HT_2A receptor is focused on its role in the central nervous system (CNS). Recently, activation of 5-HT_2A receptors has emerged as a new anti-inflammatory strategy. This review will describe recent findings regarding psychedelics as anti-inflammatory compounds, as well as parse out differences in functional selectivity and immune regulation that exist between a number of well-known hallucinogenic compounds.

A target lipidomics approach to investigate the acute inflammatory irritation induced by indolealkylamines from Chansu water fraction in rats

Chansu has demonstrated adverse reactions in clinical settings, which is associated with its toxicity and limits its clinical applications. But there are methodological limitations for drug safety evaluation. In the current study, ultra-high performance liquid chromatography, lipidomic profiling, and molecular docking were used to systemically assess Chansu-induced acute inflammatory irritation and further identify the underlying drug targets. Compared with the EtOAc extract, Chansu water fraction containing indolealkylamines caused acute inflammatory irritation in rats, including acute pain (spontaneous raising foot reaction), and inflammation (paw edema). At the molecular level, lipids analysis revealed significantly higher levels of pro-inflammatory mediators of the COX and LOX pathways. However, anti-inflammatory mediators from the CYP 450, ALA, and DHA pathways markedly decreased after exposure to Chansu water fraction. Moreover, four indolealkylamines from Chansu showed a high theoretical affinity to a known irritation target, 5-HT_2AR. These results suggest that Chansu-induced inflammatory irritation is related to the distinct dysregulation of inflammatory lipids, and peripheral 5-HT_2AR is a potential target for irritation therapy. The strategy used in this study can be a crucial approach in the safety evaluation of natural medicinal substances.

Cytotoxic Effects of Hellebrigenin and Arenobufagin Against Human Breast Cancer Cells

Development of new therapeutic strategies for breast cancer is urgently needed due to the sustained emergence of drug resistance, tumor recurrence and metastasis. To gain a novel insight into therapeutic approaches to fight against breast cancer, the cytocidal effects of hellebrigenin (Helle) and arenobufagin (Areno) were investigated in human estrogen receptor (ER)-positive breast cancer cell line MCF-7 and triple-negative breast cancer cell line MDA-MB-231. Helle exhibited more potent cytotoxicity than Areno in both cancer cells, and MCF-7 cells were more susceptible to both drugs in comparison with MDA-MB-231 cells. Apoptotic-like morphological characteristics, along with the downregulation of the expression level of Bcl-2 and Bcl-xL and the upregulation of the expression level of Bad, were observed in Helle-treated MCF-7 cells. Helle also caused the activation of caspase-8, caspase-9, along with the cleavage of poly(ADP-ribose) polymerase in MCF-7 cells. Helle-mediated necrosis-like phenotype, as evidenced by the increased propidium iodide (PI)-positive cells was further observed. G₂/M cell cycle arrest was also induced by Helle in the cells. Upregulation of the expression level of p21 and downregulation of the expression level of cyclin D1, cyclin E1, cdc25C and survivin were observed in MCF-7 cells treated with Helle and occurred in parallel with G₂/M arrest. Autophagy was triggered in MCF-7 cells and the addition of wortmannin or 3-MA, two well-known autophagy inhibitors, slightly but significantly rescued the cells. Furthermore, similar alterations of some key molecules associated with the aforementioned biological phenomena were observed in MDA-MB-231 cells. Intriguingly, the numbers of PI-positive cells in Helle-treated MCF-7 cells were significantly reduced by wortmannin and 3-MA, respectively. In addition, Helle-triggered G₂/M arrest was significantly corrected by wortmannin, suggesting autophagy induction contributed to Helle-induced cytotoxicity of breast cancer cells by modulating necrosis and cell cycle arrest. Collectively, our results suggested potential usefulness of both Helle and Areno in developing therapeutic strategies to treat patients with different types of breast cancer, especially ER-positive breast cancer.

Anti-inflammatory and analgesic actions of bufotenine through inhibiting lipid metabolism pathway

Inflammation is a primary defense and immune response. However, under pathological conditions, the inflammation processes always become uncontrolled and lead to chronic diseases. Bufotenine, as a natural component from toad venom, showed great potential for development as a novel anti-inflammation and analgesia agent. This study aimed to investigate the therapeutic effects of bufotenine against inflammation and pain on animal models with a focus on lipid metabolism. In pharmacological studies, bufotenine significantly inhibited the swelling rates on formalin-induced paw edema model, and increased paw withdrawal mechanical thresholds (PWMTs) in von Frey test and thermal pain thresholds (TPTs) in hot-plate test. High-sensitivity lipidomics analysis revealed the effects might be related to the down-regulation of inflammatory mediators from cyclooxygenase (COX), lipoxygenase (LOX), cytochrome P450 (CYP450), linoleic acid (LA), docosahexaenoic acid (DHA) and other pathways. The activities might result from the binding of bufotenine and its receptors, including sigma-1 receptor and 5-Hydroxytryptamine receptor 3A, thus regulating lipid metabolism pathway. The research provided a systemic evidence for the actions and mechanism of bufotenine. It suggested that the natural compound might be a potential candidate for reducing inflammatory pain disorders.

Bufothionine induces autophagy in H22 hepatoma-bearing mice by inhibiting JAK2/STAT3 pathway, a possible anti-cancer mechanism of cinobufacini

ETHNOPHARMACOLOGICAL RELEVANCE

Cinobufacini is extracted from the skins and parotid venom glands of the toad for treating symptoms like swelling and pain in ancient times. Nowadays, cinobifucini injection has also achieved satisfactory therapeutic effects on hepatocellular carcinoma (HCC) in China.

AIM OF THE STUDY

Our previous work found that bufothionine, an alkaloid abundant in cinobufacini injection, induced mitochondria-mediated apoptosis. In this work, the underlying effects of bufothionine on autophagy in HCC and its possible dependent pathway were investigated.

METHODS

CCK-8 and Hoechst staining assays were performed to verify effects of drugs on proliferation and apoptosis of SMMC7721 cell. H₂₂-tumor-bearing mice model was established by inoculating ascites fluid. HE staining was used to observe pathological changes in liver and tumor tissues. ELISA and Western blot experiments were conducted to investigate IL-6/JAK2/STAT3 signaling pathway. The effects of drugs on expressions of autophagic relative proteins were investigated by Western blot in vitro and in vivo.

RESULTS

In vitro, CCK-8 and Hoechst staining assays showed that bufothionine inhibited SMMC7721 cell proliferation and promoted apoptosis at 100 μM. In vivo, bufothionine relieved symptoms of H₂₂-tumor-bearing mice and exerted anti-inflammation activity. ELISA and Western blot demonstrated that bufothionine significantly reduced serum IL-6 concentration, suppressed p-Stat3tyr705, p-Stat3ser727 and Jak2 expressions in tumor tissues and upregulated Atg5, Atg7 and LC3Ⅱ expressions in SMMC7721 cell and H₂₂ tumor.

CONCLUSION

This is the first report showing that bufothionine might induce autophagy in HCC by inhibiting JAK2/STAT3 pathway, presenting a possible anti-cancer mechanism of bufothionine in cinobufacini injection.

Evaluation of analgesic and anti-inflammatory actions of indolealkylamines from toad venom in mice using lipidomics and molecular docking

ETHNOPHARMACOLOGICAL RELEVANCE

Toad venom is one of widely used traditional Chinese medicines due to its analgesic and anti-inflammatory activities. However, hydrophilic alkaloids from toad venom, which may have certain pharmacological activities, have not been systematic studied.

AIM OF THE STUDY

The aim of the study was to identify the indolealkylamines (IAAs) from toad venom and investigate the analgesic and anti-inflammatory actions.

MATERIALS AND METHODS

The alkaloids were extracted and identified by high-resolution mass spectrometry. The analgesic abilities were determined using hot-plate test, formalin test and von Frey test. High-sensitivity lipidomics was used to investigate the regulatory function of IAAs on inflammatory eicosanoids. Besides, network pharmacology and molecular docking were used to demonstrate the candidate targets of IAAs.

RESULTS

22 constituents have been characterized by high performance liquid chromatography (HPLC)-Triple TOF 5600, including six specific IAAs (serotonin, N-methyl serotonin, bufotenine, bufotenidine, bufothionine and dehydrobufotenine). Pharmacological studies showed that the IAAs from toad venom exerted significant analgesic activities at doses of 5, 15 and 45 mg/kg in vivo. Moreover, lipids analysis revealed IAAs might down-regulate inflammatory mediators from COX, LOX, DHA and LA pathways in formalin models, thus showing anti-inflammatory effect. The potent pharmacological function might because of the binding of IAAs and protein targets, such as sigma-1 receptor.

CONCLUSION

The studies provided a systemic evidence for the analgesic and anti-inflammatory activities of IAAs from toad venom. It suggested that IAAs might be a potential candidate to reduce inflammatory pain disorders.

The effect of salt stress on the production of apocarotenoids and the expression of genes related to their biosynthesis in saffron

Saffron stigmas are widely used as food additives and as traditional medicine in Iran and many other countries. The unique taste, flavor and pharmaceutical properties of saffron stigmas are due to the presence of three apocarotenoids secondary metabolites crocin, picrocrocin and safranal. There is limited knowledge about the effect of environmental stresses on the metabolism of apocarotenoids in saffron. We analyzed the content of crocin and picrocrocin and the expression of key genes of apocarotenoid biosynthesis pathways (CsCCD2, CsCCD4, CsUGT2, CsCHY-β and CsLCYB) in saffron plants exposed to moderate (90 mM) and high (150 mM) salt (NaCl) concentrations. Measuring ion concentrations in leaves showed an increased accumulation of Na⁺ and decreased uptake of K⁺ in salt treated compared to control plants indicating an effective salt stress. HPLC analysis of apocarotenoids revealed that crocin production was significantly halted (P < 0.05) with increasing salt concentration while picrocrocin level did not change with moderate salt but significantly dropped by high salt concentration. Real-time PCR analysis revealed a progressive decrease in transcript levels of CsUGT2 and CsLCYB genes with increasing salt concentration (P < 0.05). The expression of CsCCD2 and CsCHY-β tolerated moderate salt concentration but significantly downregulated with high salt concentration. CsCCD4 however responded differently to salt concentration being decreased with moderate salt but increased at higher salt concentration. Our result suggested that salt stress had an adverse effect on the production of saffron apocarotenoids and it is likely influencing the quality of saffron stigma produced.

The Insecticidal Activity of Rhinella schneideri (Werner, 1894) Paratoid Secretion in Nauphoeta cinerea Cocroaches

Rhinella schneideri is a common toad found in South America, whose paratoid toxic secretion has never been explored as an insecticide. In order to evaluate its insecticidal potential, Nauphoeta cinerea cockroaches were used as an experimental model in biochemical, physiological and behavioral procedures. Lethality assays with Rhinella schneideri paratoid secretion (RSPS) determined the LD₅₀ value after 24 h (58.07µg/g) and 48 h exposure (44.07 µg/g) (R² = 0.882 and 0.954, respectively). Acetylcholinesterase activity (AChE) after RSPS at its highest dose promoted an enzyme inhibition of 40%, a similar effect observed with neostigmine administration (p < 0.001, n= 5). Insect locomotion recordings revealed that RSPS decreased the distance traveled by up to 37% with a concomitant 85% increase in immobile episodes (p < 0.001, n = 36). RSPS added to in vivo cockroach semi-isolated heart preparation promoted an irreversible and dose dependent decrease in heart rate, showing a complete failure after 30 min recording (p < 0.001, n ≥ 6). In addition, RSPS into nerve-muscle preparations induced a dose-dependent neuromuscular blockade, reaching a total blockage at 70 min at the highest dose applied (p < 0.001, n ≥ 6). The effect of RSPS on spontaneous sensorial action potentials was characterized by an increase in the number of spikes 61% (p < 0.01). Meanwhile, there was 42% decrease in the mean area of those potentials (p < 0.05, n ≥ 6). The results obtained here highlight the potential insecticidal relevance of RSPS and its potential biotechnological application.

The Parotoid Gland Secretion from Peruvian Toad Rhinella horribilis (Wiegmann, 1833): Chemical Composition and Effect on the Proliferation and Migration of Lung Cancer Cells

Since Rhinella sp. toads produce bioactive substances, some species have been used in traditional medicine and magical practices by ancient cultures in Peru. During several decades, the Rhinella horribilis toad was confused with the invasive toad Rhinella marina, a species documented with extensive toxinological studies. In contrast, the chemical composition and biological effects of the parotoid gland secretions (PGS) remain still unknown for R. horribilis. In this work, we determine for the first time 55 compounds from the PGS of R. horribilis, which were identified using HPLC-MS/MS. The crude extract inhibited the proliferation of A549 cancer cells with IC₅₀ values of 0.031 ± 0.007 and 0.015 ± 0.001 µg/mL at 24 and 48 h of exposure, respectively. Moreover, it inhibited the clonogenic capacity, increased ROS levels, and prevented the etoposide-induced apoptosis, suggesting that the effect of R. horribilis poison secretion was by cell cycle blocking before of G2/M-phase checkpoint. Fraction B was the most active and strongly inhibited cancer cell migration. Our results indicate that the PGS of R. horribilis are composed of alkaloids, bufadienolides, and argininyl diacids derivatives, inhibiting the proliferation and migration of A549 cells.

Chemical and Pharmacological Screening of Rhinella icterica (Spix 1824) Toad Parotoid Secretion in Avian Preparations

The biological activity of Rhinella icterica parotoid secretion (RIPS) and some of its chromatographic fractions (RI18, RI19, RI23, and RI24) was evaluated in the current study. Mass spectrometry of these fractions indicated the presence of sarmentogenin, argentinogenin, (5β,12β)-12,14-dihydroxy-11-oxobufa-3,20,22-trienolide, marinobufagin, bufogenin B, 11α,19-dihydroxy-telocinobufagin, bufotalin, monohydroxylbufotalin, 19-oxo-cinobufagin, 3α,12β,25,26-tetrahydroxy-7-oxo-5β-cholestane-26-O-sulfate, and cinobufagin-3-hemisuberate that were identified as alkaloid and steroid compounds, in addition to marinoic acid and N-methyl-5-hydroxy-tryptamine. In chick brain slices, all fractions caused a slight decrease in cell viability, as also seen with the highest concentration of RIPS tested. In chick biventer cervicis neuromuscular preparations, RIPS and all four fractions significantly inhibited junctional acetylcholinesterase (AChE) activity. In this preparation, only fraction RI23 completely mimicked the pharmacological profile of RIPS, which included a transient facilitation in the amplitude of muscle twitches followed by progressive and complete neuromuscular blockade. Mass spectrometric analysis showed that RI23 consisted predominantly of bufogenins, a class of steroidal compounds known for their cardiotonic activity mediated by a digoxin- or ouabain-like action and the blockade of voltage-dependent L-type calcium channels. These findings indicate that the pharmacological activities of RI23 (and RIPS) are probably mediated by: (1) inhibition of AChE activity that increases the junctional content of Ach; (2) inhibition of neuronal Na+/K+-ATPase, leading to facilitation followed by neuromuscular blockade; and (3) blockade of voltage-dependent Ca2+ channels, leading to stabilization of the motor endplate membrane.

Distribution of major toxins in Rhinella marina parotoid macroglands using Desorption-Electrospray-Ionization mass spectrometry imaging (DESI-MSI)

Amphibian cutaneous glands secrete toxins used in different vital functions including passive defense. Through Desorption Electrospray Ionization-Imaging we analyzed the distribution of the major toxins of the toad Rhinella marina parotoid macroglands. Alkaloids and steroids showed characteristic distribution and intensity within the glands and were also present at lower levels on the skin surface. A comprehensive overview of toxins distribution in toads’ skin might help to understand their full biological role within the amphibians.

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Amphibians possess granular glands associated to chemical defense.

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Actual tissue distribution of toads' toxins remains unknown.

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We have pinpointed some toad toxins in the parotoid macroglands.

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Alkaloids are distributed throughout the gland; whereas steroids are peripheral.

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Toxins are stored within the macrogland, presenting large concentration variation.