Cinobufagin Suppresses Lipid Peroxidation and Inflammation in Osteoporotic Mice by Promoting the Delivery of miR-3102-5p by Macrophage-Derived Exosomes.

Background: Cinobufagin, the primary active compound in toad venom, is commonly used for anti-tumor, anti-inflammatory, and analgesic purposes. However, its specific bone-protective effects remain uncertain. This research aims to ascertain the bone-protective properties of cinobufagin and investigate underlying mechanisms. Methods: Mice were ovariectomized to establish an osteoporosis model, followed by intraperitoneal injections of cinobufagin and cinobufagin-treated RAW.264.7-derived exosomes for therapy. MicroCT, HE staining, and TRAP staining were employed to evaluate bone mass and therapeutic outcomes, while mRNA sequencing and immunoblotting were utilized to assess markers of bone metabolism, inflammation, and lipid peroxidation. Osteoblast and osteoclast precursor cells were differentiated to observe the impact of cinobufagin-treated exosomes derived from RAW264.7 cells on bone metabolism. Exosomes characteristics were studied using transmission electron microscopy and particle size analysis, and miRNA binding targets in exosomes were determined by luciferase reporting. Results: In ovariectomized mice, cinobufagin and cinobufagin-treated exosomes from RAW264.7 cells increased trabecular bone density and mass in the femur, while also decreasing inflammation and lipid peroxidation. The effect was reversed by an exosomes inhibitor. In vitro experiments revealed that cinobufagin-treated exosomes from RAW264.7 cells enhanced osteogenic and suppressed osteoclast differentiation, possibly linked to Upregulated miR-3102-5p in RAW-derived exosomes. MiR-3102-5p targets the 3'UTR region of alox15, thereby suppressing its expression and reducing the lipid peroxidation process in osteoblasts. Conclusion: Overall, this study clarified cinobufagin's bone-protective effects and revealed that cinobufagin can enhance the delivery of miR-3102-5p targeting alox15 through macrophage-derived exosomes, demonstrating anti-lipid peroxidation and anti-inflammatory effects.

[Mechanism of Huachansu Injection against colorectal cancer based on network pharmacology and cellular experimental].

This study aimed to elucidate the mechanism of Huachansu Injection(HCSI) against colorectal cancer(CRC) using network pharmacology, molecular docking technology, and cellular experimental. This research group initially used LC-MS/MS to detect the content of 16 bufadienolides in HCSI. Ten bufadienolide components were selected based on a content threshold of greater than 10 ng·mL~(-1). Their potential targets were further predicted using the SwissTargetPrediction database. CRC-related targets were obtained through GeneCards, OMIM, TTD, and PharmGKB databases. The intersection targets of HCSI in the treatment of CRC were obtained through Venny. The "active component-target-disease" network and target protein-protein interaction(PPI) network were constructed via Cytoscape software. Core targets were screened based on the degree values. Gene Ontology(GO) function and Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway enrichment analyses were performed on these key targets. Molecular docking was conducted using AutoDock software on major bufadienolide active components and key targets. Different concentrations of HCSI, psi-bufarenogin(BUF), and bufotalin(BFT) were tested for their effects on cell viability, migration, and apoptosis rates in CRC HCT116 cells. Western blot was conducted to detect the expression of proteins related to the PI3K/Akt/mTOR signaling pathway in HCT116 cells. Eight main active components of HCSI, including arenobufagin, BUF, and BFT, as well as 20 key targets of HCSI in combating CRC, such as EGFR, IL6, and mTOR, were identified. Based on KEGG pathway enrichment and molecular docking results, the PI3K/Akt/mTOR signaling pathway was selected for further verification. Cellular experimental demonstrated that HCSI, BUF, and BFT significantly inhibited the proliferation and migration abilities of HCT116 cells, induced apoptosis in these cells, and downregulated the expression of PI3K/Akt/mTOR pathway-related proteins. This result suggests that HCSI, BUF, and BFT may exert their anti-CRC effects by regulating the PI3K/Akt/mTOR signaling pathway through targets such as mTOR and PIK3CA. This study provides theoretical evidence for exploring the active ingredients and mechanism of HCSI against CRC.

Rod-shaped mesoporous silica nanoparticles reduce bufalin cardiotoxicity and inhibit colon cancer by blocking lipophagy.

BACKGROUND: Bufalin (BA) is a potent traditional Chinese medicine derived from toad venom. It has shown significant antitumor activity, but its use is limited by cardiotoxicity, which necessitates innovative delivery methods, such as rod-shaped mesoporous silica nanoparticles (rMSNs). rMSNs have been extensively employed for reducing drug toxicity and for controlled or targeted drug delivery in tumor therapy. However, their potential in delivering BA has not been completely elucidated. Therefore, in this study, BA-loaded rMSNs (BA-rMSNs) were developed to investigate their potential and mechanism in impairing colon cancer cells. METHODS: rMSNs were developed via the sol‒gel method. Drug encapsulation efficiency and loading capacity were determined to investigate the advantages of the rMSN in loading BA. The antiproliferative activities of the BA-rMSNs were investigated via 5-ethynyl-2'-deoxyuridine and CCK-8. To evaluate cell death, Annexin V-APC/PI apoptotic and calcein-AM/PI double staining were performed. Western blotting, oil red O staining, and Nile red solution were employed to determine the ability of BA-rMSNs to regulate lipophagy. RESULTS: The diameter of the BA-rMSNs was approximately 60 nm. In vitro studies demonstrated that BA-rMSNs markedly inhibited HCT 116 and HT-29 cell proliferation and induced cell death. In vivo studies revealed that BA-rMSNs reduced BA-mediated cardiotoxicity and enhanced BA tumor targeting. Mechanistic studies revealed that BA-rMSNs blocked lipophagy. CONCLUSIONS: rMSNs reduced BA-mediated cardiotoxicity and impaired the growth of colon cancer cells. Mechanistically, antitumor activity depends on lipophagy.

Bufalin CaCO3 Nanoparticles Triggered Pyroptosis through Calcium Overload via Na+/Ca2+ Exchanger Reverse for Cancer Immunotherapy.

Bufalin is a promising active ingredient in traditional Chinese medicine but has shown limited anticancer applications due to its toxicity. Here, we report BCNPs@gel, a bufalin-containing CaCO3 nanoparticle hydrogel, for enhancing cancer treatment through inducing cellular pyroptosis. Under the tumor microenvironment's low pH conditions, bufalin and Ca2+ are released from the delivery system. Bufalin serves as a direct anticancer drug and a Na+/K+-ATPase inhibitor by forcing the Na+/Ca2+ exchanger to reverse its function, which transfers Ca2+ into cytoplasm and ultimately causes Ca2+ overload-triggered pyroptosis. Meanwhile, we found that bufalin can upregulate PD-L1 in tumor cells. In combination with the PD-1 antibody, the delivery system showed a greater performance during the cancer treatment. BCNPs@gel enhances antitumor efficiency, reduces systemic side effects, extends antitumor mechanism of bufalin, and provides new strategies for inducing pyroptosis and calcium overload in cancer immunotherapy via Na+/K+-ATPase inhibitor. This work provides an application model for numerous other traditional Chinese medicine ingredients.

Simplified Method for Kinetic and Thermodynamic Screening of Cardiotonic Steroids through the K+-Dependent Phosphatase Activity of Na+/K+-ATPase with Chromogenic pNPP Substrate.

The antitumor effect of cardiotonic steroids (CTS) has stimulated the search for new methods to evaluate both kinetic and thermodynamic aspects of their binding to Na+/K+-ATPase (IUBMB Enzyme Nomenclature). We propose a real-time assay based on a chromogenic substrate for phosphatase activity (pNPPase activity), using only two concentrations with an inhibitory progression curve, to obtain the association rate (kon ), dissociation rate (koff ), and equilibrium (Ki ) constants of CTS for the structure-kinetics relationship in drug screening. We show that changing conditions (from ATPase to pNPPase activity) resulted in an increase of Ki of the cardenolides digitoxigenin, essentially due to a reduction of kon In contrast, the Ki of the structurally related bufadienolide bufalin increased much less due to the reduction of its koff partially compensating the decrease of its kon When evaluating the kinetics of 15 natural and semisynthetic CTS, we observed that both kon and koff correlated with Ki (Spearman test), suggesting that differences in potency depend on variations of both kon and koff A rhamnose in C3 of the steroidal nucleus enhanced the inhibitory potency by a reduction of koff rather than an increase of kon Raising the temperature did not alter the koff of digitoxin, generating a ΔH‡ (koff ) of -10.4 ± 4.3 kJ/mol, suggesting a complex dissociation mechanism. Based on a simple and inexpensive methodology, we determined the values of kon , koff , and Ki of the CTS and provided original kinetics and thermodynamics differences between CTS that could help the design of new compounds. SIGNIFICANCE STATEMENT: This study describes a fast, simple, and cost-effective method for the measurement of phosphatase pNPPase activity enabling structure-kinetics relationships of Na+/K+-ATPase inhibitors, which are important compounds due to their antitumor effect and endogenous role. Using 15 compounds, some of them original, this study was able to delineate the kinetics and/or thermodynamics differences due to the type of sugar and lactone ring present in the steroid structure.

Bufalin-Loaded Multifunctional Photothermal Nanoparticles Inhibit the Anaerobic Glycolysis by Targeting SRC-3/HIF-1α Pathway for Improved Mild Photothermal Therapy in CRC.

Purpose: Compared with traditional photothermal therapy (PTT, >50°C), mild PTT (≤45°C) is a promising strategy for tumor therapy with fewer adverse effects. Unfortunately, its anti-tumor efficacy is hampered by thermoresistance induced by overexpression of heat shock proteins (HSPs). In our previous study, we found bufalin (BU) is a glycolysis inhibitor that depletes HSPs, which is expected to overcome thermotolerance of tumor cells. In this study, BU-loaded multifunctional nanoparticles (NPs) were developed for enhancing the mild PTT of colorectal cancer (CRC). Methods: Fe3O4 NPs coated with the polydopamine (PDA) shell modified with polyethylene glycol (PEG) and cyclic arginine-glycyl-aspartic peptide (cRGD) for loading BU (Fe3O4@PDA-PEG-cRGD/BU NPs) were developed. The thermal variations in Fe3O4@PDA-PEG-cRGD/BU NPs solution under different conditions were measured. Glycolysis inhibition was evaluated by measuring the glucose uptake, extracellular lactate, and intracellular adenosine triphosphate (ATP) levels. The cellular cytotoxicity of Fe3O4@PDA-PEG-cRGD/BU NPs was analyzed using a cell counting kit-8 assay, Calcein-AM/PI double staining, and flow cytometry in HCT116 cells. The magnetic resonance imaging (MRI) performance and anti-tumor therapeutic efficacy of Fe3O4@PDA-PEG-cRGD/BU NPs were evaluated in HCT116-tumor bearing mice. Results: Fe3O4@PDA-PEG-cRGD/BU NPs had an average diameter of 260.4±3.5 nm, the zeta potential of -23.8±1.6 mV, the drug loading rate of 1.1%, which had good thermal stability, photothermal conversion efficiencies and MRI performance. In addition, the released BU not only killed tumor cells but also interfered with glycolysis by targeting the steroid receptor coactivator 3 (SRC-3)/HIF-1α pathway, preventing intracellular ATP synthesis, and combating HSP-dependent tumor thermoresistance, ultimately strengthening the thermal sensitivity toward mild PTT both in vitro and in vivo. Conclusion: This study provides a highly effective strategy for enhancing the therapeutic effects of mild PTT toward tumors.

Advances on Delivery System of Active Ingredients of Dried Toad Skin and Toad Venom.

Dried toad skin (TS) and toad venom (TV) are the dried skin of the Bufo bufo gargarizans Cantor and the Bufo melanostictus Schneider, which remove the internal organs and the white secretions of the skin and retroauricular glands. Since 2005, cinobufacini preparations have been approved by the State Food and Drug Administration for use as adjuvant therapies in the treatment of various advanced cancers. Meanwhile, bufalenolides has been identified as the main component of TS/TV, exhibiting antitumor activity, inducing apoptosis of cancer cells and inhibiting cancer cell proliferation or metastasis through a variety of signaling pathways. However, clinical agents frequently face limitations such as inherent toxicity at high concentrations and insufficient tumor targeting. Additionally, the development and utilization of these active ingredients are hindered by poor water solubility, low bioavailability, and rapid clearance from the bloodstream. To address these challenges, the design of a targeted drug delivery system (TDDS) aims to enhance drug bioavailability, improve targeting within the body, increase drug efficacy, and reduce adverse reactions. This article reviews the TDDS for TS/TV, and their active components, including passive, active, and stimuli-responsive TDDS, to provide a reference for advancing their clinical development and use.

Bufadienolide-Fatty Acid Conjugates from the Fertilized Eggs of Toad Bufo gargarizans: Isolation, Characterization, Toxicity, and Antiproliferative Evaluation.

Bufadienolides (BDs) are a class of naturally occurring toxins present in amphibian toads. Serving as the chemical weapons, they exist not only in the adult toads but also in toad eggs. Guided by mass spectrometry (MS)-based component analysis and feature-based molecular networking (FBMN), 30 bufadienolide-fatty acid conjugates (BDFs) were isolated from the fertilized eggs of toad Bufo gargrizans, including 25 previously undescribed compounds (1-25). Their chemical structures were elucidated by extensive spectroscopic analysis, chemical methods, and GC-MS. The toxicities of all BDFs and their corresponding free BDs were assessed using the zebrafish model. The structure-toxicity relationship analysis showed that the modification of BDs by hydroxy fatty acids can cause a significant increase of the toxicity. Furthermore, all the isolated compounds were evaluated for their antiproliferative activities in pancreatic cancer cell lines ASPC-1 and PANC10.05. The structure-activity relationship (SAR) analysis revealed that BDFs with hellebrigenin as the bufogenin moiety (6 and 7) exhibited the most potent antiproliferative effect. Further investigation into their functional mechanism demonstrated that 6 and 7 induced apoptosis in pancreatic cancer cells PANC10.05 and significantly suppressed the expression of the apoptosis-related gene c-MYC. In addition, 6 and 7 effectively inhibited the expression of the PI3K/Akt/mTOR pathway in PANC10.05. Moreover, we assessed the efficacy of 6 and 7 on cancer cells from various tissues and observed their broad-spectrum antiproliferative activity.

Comparative study on pharmacokinetics of extract from Bufonis venenum and its liposomes.

Bufadienolides and indolealkylamines, the primary active components in Bufonis venenum, have rapid clearance from the body with a short half-life, leading to low bioavailability. Moreover, Bufadienolides and indolealkylamines are associated with serious adverse effects. In order to reduce the toxicities, minimize the adverse effects and simultaneously load lipophilic bufadienolides and hydrophilic indolealkylamines with satisfactory drug loading and encapsulation rate, we prepared Bufonis venenum extract-liposomes (BVE-LP). To compare the pharmacokinetic differences between Bufonis venenum extract (BVE) and its liposomes, ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay was established to simultaneously detect the 12 chemical components in rat plasma. Results of pharmacokinetic study in SD rats showed that the highest exposure based on the area under the plasma concentration-time curve (AUC0-t) was obtained by 5-hydroxytryptamine with a mean value of 267.097 µg/L*h in BVE-LP group, which was 72.36 % higher as compared to that obtained in Bufonis venenum extract (BVE) group with a mean value of AUC0-t of 154.966 µg/L*h. The exposure (AUC0-t) of desacetylcinobufotalin, desacetylcinobufagin, arenobufagin and telocinobufagin in BVE-LP group was 111.89 %, 94.13 %, 134.08 %, and 92.94 % higher when compared to that in BVE group. With the employment of liposomes, there was an obvious decrease in the clearance of bufotenidine, desacetylcinobufotalin, gamabufotalin, arenobufagin, and telocinobufagin. The terminal half life (t1/2) of desacetylcinobufotalin, gamabufotalin, arenobufagin, and telocinobufagin in BVE-LP group was increased by 185.96 %, 292.64 %, 196.78 % and 131.29 % when compared to that in BVE group. All the results above indicated that a slower elimination rate and more exposure of some bufadienolides and indolealkylamines was obtained by BVE-LP when compared to BVE group, which verified BVE-LP could provide a therapeutic option for effective delivery of Bufonis venenum in clinical. DATA AVAILABILITY: The data will be shared on reasonable request to the corresponding author.

Separation of bufadienolides from Helleborus thibetanus Franch. by a combination approach involving macroporous resin column chromatography and gradient countercurrent chromatography.

In this study, a combination approach involving macroporous resin (MR) column chromatography and gradient countercurrent chromatography (CCC) was employed to enrich and purify bufadienolides from the roots and rhizomes of Helleborus thibetanus Franch. Initially, a D101 MR-packed column chromatography was utilized for fractionation and enrichment of the bufadienolides, which were effectively eluted from the column using a 60% ethanol solution. CCC was subsequently introduced to separate the enriched product using the ethyl acetate/n-butanol/water (EBuWat, 4:1:5, v/v) and EBuWat (5:0:5, v/v) solvent systems in a gradient elution mode. As results, five bufadienolides, including 6.1 mg of hellebrigenin-3-O-ß-D-glucoside (1), 2.2 mg of tigencaoside A (2), 8.3 mg of deglucohellebrin (3), 3.5 mg of 14 ß-hydroxy-3ß-[ß-D-glucopyranosyl-(1→6)-(ß-D-glucopyranosyl)oxy]-5α-bufa-20,22-dienolide (4), and 3.0 mg of 14ß-hydroxy-3ß-[(ß-D-glucopyranosyl)oxy]-5α-bufa-20,22-dienolide (5), were effectively separated from 300 mg of the enriched product. The respective high-performance liquid chromatography purities were as follows: 95.2%, 75.8%, 85.7%, 82.3%, and 92.8%. This study provides valuable insights for the efficient enrichment and separation of bufadienolides from Helleborus thibetanus Franch.

Validation of Core Ingredients and Molecular Mechanism of Cinobufotalin Injection Against Liver Cancer.

Purpose: Cinobufotalin injection has obvious curative effects on liver cancer patients with less toxicity and fewer side effects than other therapeutic approaches. However, the core ingredients and mechanism underlying these anti-liver cancer effects have not been fully clarified due to its complex composition. Methods: Multidimensional network analysis was used to screen the core ingredients, key targets and pathways underlying the therapeutic effects of cinobufotalin injection on liver cancer, and in vitro and in vivo experiments were performed to confirm the findings. Results: By construction of ingredient networks and integrated analysis, eight core ingredients and ten key targets were finally identified in cinobufotalin injection, and all of the core ingredients are tightly linked with the key targets, and these key targets are highly associated with the cell cycle-related pathways, supporting that both cinobufotalin injection and its core ingredients exert anti-liver cancer roles by blocking cell cycle-related pathways. Moreover, in vitro and in vivo experiments confirmed that either cinobufotalin injection or one of its core ingredients, cinobufagin, significantly inhibited cell proliferation, colony formation, cell cycle progression and xenograft tumor growth, and the key target molecules involved in the cell cycle pathway such as CDK1, CDK4, CCNB1, CHEK1 and CCNE1, exhibit consistent changes in expression after treatment with cinobufotalin injection or cinobufagin. Interestingly, some key targets CDK1, CDK4, PLK1, CHEK1, TTK were predicted to bind with multiple of core ingredients of cinobufotalin injection, and the affinity between one of the critical ingredients cinobufagin and key target CDK1 was further confirmed by SPR assay. Conclusion: Cinobufotalin injection was confirmed to includes eight core ingredients, and they play therapeutic effects in liver cancer by blocking cell cycle-related pathways, which provides important insights for the mechanism of cinobufotalin injection antagonizing liver cancer and the development of novel small molecule anti-cancer drugs.

Cytochrome P450 Mining for Bufadienolide Diversification.

Bufadienolides are a class of steroids with a distinctive α-pyrone ring at C17, mostly produced by toads and consisting of over 100 orthologues. They exhibit potent cardiotonic and antitumor activities and are active ingredients of the traditional Chinese medicine Chansu and Cinobufacini. Direct extraction from toads is costly, and chemical synthesis is difficult, limiting the accessibility of active bufadienolides with diverse modifications and trace content. In this work, based on the transcriptome and genome analyses, using a yeast-based screening platform, we obtained eight cytochrome P450 (CYP) enzymes from toads, which catalyze the hydroxylation of bufalin and resibufogenin at different sites. Moreover, a reported fungal CYP enzyme Sth10 was found functioning in the modification of bufalin and resibufogenin at multiple sites. A total of 15 bufadienolides were produced and structurally identified, of which six were first discovered. All of the compounds were effective in inhibiting the proliferation of tumor cells, especially 19-hydroxy-bufalin (2) and 1ß-hydroxy-bufalin (3), which were generated from bufalin hydroxylation catalyzed by CYP46A35. The catalytic efficiency of CYP46A35 was improved about six times and its substrate diversity was expanded to progesterone and testosterone, the common precursors for steroid drugs, achieving their efficient and site-specific hydroxylation. These findings elucidate the key modification process in the synthesis of bufadienolides by toads and provide an effective way for the synthesis of unavailable bufadienolides with site-specific modification and active potentials.

Quality Evaluation of Shexiang Tongxin Dropping Pill Based on HPLC Fingerprints Combined with HPLC-Q-TOF-MS/MS Method.

Shexiang Tongxin Dropping Pill (STP) is a composite formula of traditional Chinese medicine that is widely used for the treatment of cardiovascular diseases. It consists of seven medicinal extracts thereof or materials, including Bufonis venenum, synthetic Moschus, Panax ginseng, Bovis calculus artifactus, Bear bile powder, Salvia miltiorrhiza Bge and synthetic borneol. However, it is considerably difficult to evaluate the quality of STP due to its complex chemical compositions. This paper was designed to explore a comprehensive and systematic method combining fingerprints and chemical identification for quality assessment of STP samples. Twenty batches of STP samples were analyzed by high-performance liquid chromatography (HPLC) and high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry. Ten common peaks were detected by HPLC fingerprint similarity evaluation system. Meanwhile, 100 compounds belonging to 4 structural characteristics, including 23 bufadienolides, 36 organic acids, 34 saponins and 7 other types, were systematically identified as the basic components in STP. This study could be used for clarifying the multiple bioactive substances and developing a comprehensive quality evaluation method of STP.

Liposome-enabled bufalin and doxorubicin combination therapy for trastuzumab-resistant breast cancer with a focus on cancer stem cells.

Breast cancer stem cells (BCSCs) play a key role in therapeutic resistance in breast cancer treatments and disease recurrence. This study aimed to develop a combination therapy loaded with pH-sensitive liposomes to kill both BCSCs and the okbulk cancer cells using trastuzumab-sensitive and resistant human epidermal growth factor receptor 2 positive (HER2+) breast cancer cell models. The anti-BCSCs effect and cytotoxicity of all-trans retinoic acid, salinomycin, and bufalin alone or in combination with doxorubicin were compared in HER2+ cell line BT-474 and a validated trastuzumab-resistant cell line, BT-474R. The most potent anti-BCSC agent was selected and loaded into a pH-sensitive liposome system. The effects of the liposomal combination on BCSCs and bulk cancer cells were assessed. Compared with BT-474, the aldehyde dehydrogenase positive BCSC population was elevated in BT-474R (3.9 vs. 23.1%). Bufalin was the most potent agent and suppressed tumorigenesis of BCSCs by ∼50%, and showed strong synergism with doxorubicin in both BT-474 and BT-474R cell lines. The liposomal combination of bufalin and doxorubicin significantly reduced the BCSC population size by 85%, and inhibited both tumorigenesis and self-renewal, although it had little effect on the migration and invasiveness. The cytotoxicity against the bulk cancer cells was also enhanced by the liposomal combination than either formulation alone in both cell lines (p < 0.001). The liposomal bufalin and doxorubicin combination therapy may effectively target both BCSCs and bulk cancer cells for a better outcome in trastuzumab-resistant HER2+ breast cancer.

Hellebrigenin triggers death of promyelocytic leukemia cells by non-genotoxic ways.

Bufadienolides are digitalis-like aglycones mainly found in skin secretions of toads. Among their biological properties, the mechanisms of antiproliferative action on tumor cells remain unclear for many compounds, including against leukemia cells. Herein, it was evaluated the mechanisms involved in the antiproliferative and genotoxic actions of hellebrigenin on tumor cell lines and in silico capacity to inhibit the human topoisomerase IIa enzyme. Firstly, its cytotoxic action was investigated by colorimetric assays in human tumor and peripheral blood mononuclear cells (PBMC). Next, biochemical and morphological studies were detailed by light microscopy (trypan blue dye exclusion), immunocytochemistry (BrdU uptake), flow cytometry and DNA/chromosomal damages (Cometa and aberrations). Finally, computational modelling was used to search for topoisomerase inhibition. Hellebrigenin reduced proliferation, BrdU incorporation, viability, and membrane integrity of HL-60 leukemia cells. Additionally, it increased G2/M arrest, internucleosomal DNA fragmentation, mitochondrial depolarization, and phosphatidylserine externalization in a concentration-dependent manner. In contrast to doxorubicin, hellebrigenin did not cause DNA strand breaks in HL-60 cell line and lymphocytes, and it interacts with ATPase domain residues of human topoisomerase IIa, generating a complex of hydrophobic and van der Waals interactions and hydrogen bonds. So, hellebrigenin presented potent anti-leukemic activity at concentrations as low as 0.06 µM, a value comparable to the clinical anticancer agent doxorubicin, and caused biochemical changes suggestive of apoptosis without genotoxic/clastogenic-related action, but it probably triggers catalytic inhibition of topoisomerase II. These findings also emphasize toad steroid toxins as promising lead antineoplasic compounds with relatively low cytotoxic action on human normal cells.

Toad venom bufadienolides and bufotoxins: An updated review.

Bufadienolides, naturally found in toad venoms having steroid-like structures, reveal antiproliferative effects at low doses. However, their application as anticancer drugs is strongly prevented by their Na+ /K+ -ATPase binding activities. Although several kinds of research were dedicated to moderating their Na+ /K+ -ATPase binding activity, still deeper fundamental knowledge is required to bring these findings into medical practice. In this work, we reviewed data related to anticancer activity of bufadienolides such as bufalin, arenobufagin, bufotalin, gamabufotalin, cinobufotalin, and cinobufagin and their derivatives. Bufotoxins, derivatives of bufadienolides containing polar molecules mainly belonging to argininyl residues, are reviewed as well. The established structures of bufotoxins have been compiled into a one-page figure to review their structures. We also highlighted advances in the structure-modification of the structure of compounds in this class. Drug delivery approaches to target these compounds to tumor cells were discussed in one section. The issues related to extraction, identification, and quantification are separated into another section.

Bufadienolides from the Bufo viridis toad venom exert cytotoxic effects on cancer cells by inducing cell apoptosis and cell cycle arrest.

A series of bufadienolides were isolated from the Bufo viridis toad venom, and their cytotoxic activities against three human cancer cell lines (HeLa, HT-29, MCF7) and a non-cancer cell line (L-O2) were explored using the MTT assay in vitro. All of nine compounds exhibited cytotoxic activities against the three cancer cell lines, with compound D4 exhibiting potent cytotoxic activity against HeLa cells and was better than positive control. Herein, we further evaluated the effect of compound D4 on HeLa cells. The results revealed that compound D4 has excellent cytotoxic effect on HeLa cells by inhibiting cell colony formation and migration, promoting cell apoptosis, increasing reactive oxygen species (ROS) levels and arresting of HeLa cells in S and G2/M phases. These findings encourage further work on the chemistry and bioactivity of the Bufo viridis toad venom.

Discovery of Novel 3,11-Bispeptide Ester Arenobufagin Derivatives with Potential in Vivo Antitumor Activity and Reduced Cardiotoxicity.

Arenobufagin, one of the bufadienolides isolated from traditional Chinese medicine Chan'su, exhibits potent antitumor activity. However, serious toxicity and small therapeutic window limits its drug development. In the present study, to our knowledge, novel 3,11-bispeptide ester arenobufagin derivatives have been firstly designed and synthesized on the base of our previous discovery of active 3-monopeptide ester derivative. The in vitro antiproliferative activity evaluation revealed that the moiety at C3 and C11 hydroxy had an important influence on cytotoxic activity and selectivity. Compound ZM350 notably inhibited tumor growth by 58.8 % at a dose 10 mg/kg in an A549 nude mice xenograft model. Therefore, compound ZM350 also presented a concentration-dependent apoptosis induction and low inhibitory effect against both hERG potassium channel and Cav1.2 calcium channel. Our study suggests that novel 3,11-bispeptide ester derivatives will be a potential benefit to further antitumor agent development of arenobufagin.

Chemistry and the Potential Antiviral, Anticancer, and Anti-Inflammatory Activities of Cardiotonic Steroids Derived from Toads.

Cardiotonic steroids (CTS) were first documented by ancient Egyptians more than 3000 years ago. Cardiotonic steroids are a group of steroid hormones that circulate in the blood of amphibians and toads and can also be extracted from natural products such as plants, herbs, and marines. It is well known that cardiotonic steroids reveal effects against congestive heart failure and atrial fibrillation; therefore, the term "cardiotonic" has been coined. Cardiotonic steroids are divided into two distinct groups: cardenolides (plant-derived) and bufadienolides (mainly of animal origin). Cardenolides have an unsaturated five-membered lactone ring attached to the steroid nucleus at position 17; bufadienolides have a doubly unsaturated six-membered lactone ring. Cancer is a leading cause of mortality in humans all over the world. In 2040, the global cancer load is expected to be 28.4 million cases, which would be a 47% increase from 2020. Moreover, viruses and inflammations also have a very nebative impact on human health and lead to mortality. In the current review, we focus on the chemistry, antiviral and anti-cancer activities of cardiotonic steroids from the naturally derived (toads) venom to combat these chronic devastating health problems. The databases of different research engines (Google Scholar, PubMed, Science Direct, and Sci-Finder) were screened using different combinations of the following terms: "cardiotonic steroids", "anti-inflammatory", "antiviral", "anticancer", "toad venom", "bufadienolides", and "poison chemical composition". Various cardiotonic steroids were isolated from diverse toad species and exhibited superior anti-inflammatory, anticancer, and antiviral activities in in vivo and in vitro models such as marinobufagenin, gammabufotalin, resibufogenin, and bufalin. These steroids are especially difficult to identify. However, several compounds and their bioactivities were identified by using different molecular and biotechnological techniques. Biotechnology is a new tool to fully or partially generate upscaled quantities of natural products, which are otherwise only available at trace amounts in organisms.

Tunable Toxicity of Bufadienolides is Regulated through a Configuration Inversion Catalyzed by a Short-Chain Dehydrogenase/Reductase.

Bufadienolides are toxic components widely found in amphibious toads that exhibit a wide range of biological activities. Guided by UPLC-QTOF-MS analysis, several 3-epi-bufadienolides with unique structures were isolated from the bile of the Asiatic toad, Bufo gargarizans. However, the enzymatic machinery of this epimerization in toads and its significance in chemical ecology remains poorly understood. Herein, we firstly compared the toxicities of two typical bufadienolides, bufalin (featuring a 14ß-hydroxyl) and resibufogenin (containing a 14, 15-epoxy group), with their corresponding 3-epi isomers in a zebrafish model. The results of the toxicology assays showed that the ratio of maximum non-toxic concentrations of these two pairs of compounds are 256 and 96 times, respectively, thereby indicating that 3-hydroxyl epimerization leads to a significant decrease in toxicity. Aiming to investigate the biotransformation of 3-epi bufadienolides in toads, we applied liver lysate to transform bufalin and found that it could stereoselectively catalyze the conversion of bufalin into its 3α-hydroxyl epimer. Following this, we cloned and characterized a short-chain dehydrogenase/reductase, HSE-1, from the toad liver cDNA library and verified its 3(ß→α)-hydroxysteroid epimerization activity. To the best of our knowledge, this is the first hydroxyl epimerase identified from amphibians that regulates the toxicity of animal-derived natural products.