[Effect of origin species, body weight, and gender on quality of Bufonis Venenum]

Based on standard sampling for Bufonis Venenum, this study analyzed the effect of the origin, and body weight and gender of Bufo bufo gargarizans on the quality of Bufonis Venenum. To be specific, mass spectrometry(MS) and the content determination methods in Chinese Pharmacopoeia(2020) were adopted. First, MS was performed on 76 Bufonis Venenum samples collected from 40 cities/counties in 17 provinces/autonomous regions which were derived from B. bufo gargarizans and B. melanostictus. Based on content determination, the body weight and gender of B. bufo gargarizans, which influenced the quality of Bufonis Venenum, were evaluated. Multivariate statistical analysis suggested huge difference in the material basis of the medicinal material derived from B. bufo gargarizans and B. melanostictus, and 9 differential compounds were identified. The content of components specified in Chinese Pharmacopoeia was higher in the medicinal material derived from B. bufo gargarizans than in the medicinal material derived from B. melanostictus. The content of the components specified in Chinese Pharmacopoeia was low in Bufonis Venenum derived from heavy B. bufo gargarizans, and higher in the Bufonis Venenum produced by male B. bufo gargarizans than in that produced by female B. bufo gargarizans irrespective of time and geographic location. In summary, this study provide new ideas and reference for the quality control of Bufonis Venenum, collection and processing of Bufonis Venenum, artificial breeding of B. bufo gargarizans, and biosynthesis mechanism of Bufonis Venenum.

[Distribution characteristics of Bufo bufo gargarizans resources in China based on quality evaluation of Bufonis Venenum]

On the premise of strictly controlling the harvesting conditions of Bufonis Venenum, we studied the relationship between the quality and resource distribution of Bufonis Venenum in China, aiming to provide the data for comprehensively understanding the geographical distribution and characteristics of Bufonis Venenum in China. In this study, 105 samples of Bufonis Venenum were collected from 42 counties and cities in 19 provinces in China, and the material basis and index components were determined by mass spectrometry and high performance liquid chromatography. The obtained data formed the quality database of Bufonis Venenum from different producing areas in China. The analysis of the material basis showed that Bufonis Venenum was mainly produced in two characteristic regions(north area and south area) divided by Qinling Mountains, northern edge of Huaiyang hills and the connecting area of Huang-Huai Plain, Huangshan Mountains, and Tianmu Mountains. Eight differential components were identified in the Bufonis Venenum samples from the south area and the north area. All the Bufonis Venenum samples from the north area showed the content of index components above the requirements of Chinese Pharmacopoeia(2020 edition), while those from the south area had the content of index components lower than the standards of Chinese Pharmacopoeia(2020 edition). The quality evaluation showed uneven distribution of Bufonis Venenum quality, which was high in the north and low in the south. The results provided a research basis for the breeding base selection of Bufo bufo gargarizans.

Cytotoxic compounds from the leaf of Bersama abyssinica subspecies abyssinica

From the leaves of Kenyan medicinal plant Bersama abyssinica Subspecies abyssinica, four previously undescribed compounds namely, three bufadienolides, 10β-formylpaulliniogenin B, 10β-formylpaulliniogenin A and 1β-acetoxy-3β,5β-dihydroxy-15-methoxy-16,19-dioxobufa-14(15),20,22-trienolide, and a phenolic compound 2,6,4'-trihydroxybenzophenone-4-O-(6‴-cinnamoyl)-β-D-glucoside were isolated together with four known compounds. The structural elucidation of the compounds was based on 1D and 2D NMR spectroscopy and HRMS data analyses. The relative configurations were defined by NOESY correlations. Cytotoxic activities on L929 and KB3.1 cell lines of the isolated compounds were investigated using MTT assay. The 1β-acetoxy-3β,5β-dihydroxy-15-methoxy-16,19-dioxobufa-14(15),20,22-trienolide showed significant cytotoxic activity against KB3.1 cell lines with IC₅₀ of 3.9 ± 0.99 μM.

Quantitative analysis of fourteen bufadienolides in Venenum Bufonis crude drug and its Chinese patent medicines by ultra-high performance liquid chromatography coupled with tandem mass spectrometry

ETHNOPHARMACOLOGICAL RELEVANCE

Venenum Bufonis, a product of the secretions of Bufo gargarizans Cantor or B. melanostictus Schneider, possessed an array of pharmacological activities, such as cardiotonic, anti-tumor, antinociceptive, anti-inflammatory, anesthetic and antimicrobial activities. However, there were few efficient methods for quality evaluation of Venenum Bufonis medicinal materials and its related Chinese patent medicines.

AIM OF THE STUDY

To establish an effective method for quality assessment of crude drugs and Chinese proprietary medicines of Venenum Bufonis, and explore the relationship of primary compounds - target - pathway - disease through a series of network databases.

MATERIALS AND METHODS

An ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-QqQ-MS/MS) method was developed and validated to simultaneously determine 14 bufadienolides for quantitative analysis of 71 batches of crude drugs and 20 kinds of Chinese patent medicines of Venenum Bufonis. Multiple reaction monitoring with good specificity and accuracy was applied to monitor the 14 bufadienolides in positive mode.

RESULTS

The methodology was validated with good specificity, precision, stability, repeatability and recovery. The low limits of quantification were in the range of 0.1-2.7 ng/mL. The relative standard deviation values for intra- and inter-day precisions ranged from 0.98% to 6.3% and from 2.39% to 6.76%, respectively. The recovery was varied from 87.78% to 110.57% for crude drugs and 88.32%-100.96% for Chinese proprietary medicine (Shexiang Baoxin Pill). The contents of 14 analytes in 71 batches of crude drugs and 20 sorts of Chinese proprietary medicines were procured, the results showed that the contents of crude drugs collected from the market exhibited great variations. Furthermore, 13 batches of crude drugs were identified as counterfeit with no bufadienolides detected. In addition, the total contents of bufadienolides in the same drug showed great difference among products from various manufacturers or brands. Subsequently, 9 bufadienolides with the higher contents were applied to screen the anti-tumor effect by network pharmacology, and 8 pathways which had prior correlation with bufadienolides were disclosed.

CONCLUSION

This method could be used for quality assessment of crude drugs and Chinese patent medicines of Venenum Bufonis, and the data could be served as the fundamental basis for drug research and development of Venenum Bufonis.

Implementation of a Single Quadrupole Mass Spectrometer for Fingerprint Analysis: Venenum bufonis as a Case Study

The mass spectrometry (MS) has been widely used for profiling chemical components of traditional Chinese medicine (TCM). However, there are few studies reporting quality control of TCM based on mass spectrometry fingerprint (MSF) due to its complicated operation and high cost. The aim of this study was to extend the application of MSF for quality evaluation of TCM. In this study, an MSF based on single quadrupole mass spectrometry method was established, and was successfully used for the quality control of Venenum bufonis (VB), a famous TCM which was used clinically for cancer treatment in China. The results showed that the superiority of MSF for more chemical information exposure and the finding of more potential chemical markers (eight versus four) compared with the traditional photo-diode array (a kind of ultra violet detector, PDA). Besides, the performance of MSF was also validated by similarity and principle component analysis (PCA) of MS data acquired on two other mass spectrometry (low-resolution, triple quadrupole, QQQ, and high-resolution, quadruple time-of-flight, Q-TOF), showing high consistency with QQQ and Q-TOF, but robustness with few parameters' settings. Based on our study, MSF could be widely applied for the quality control of TCM.

Age- and environment-dependent changes in chemical defences of larval and post-metamorphic toads

BACKGROUND

Chemical defences are widespread in animals, but how their production is adjusted to ecological conditions is poorly known. Optimal defence theory predicts that inducible defences are favoured over constitutive defences when toxin production is costly and the need for it varies across environments. However, if some environmental changes occur predictably (e.g. coupled to transitions during ontogeny), whereas others are unpredictable (e.g. predation, food availability), changes in defences may have constitutive as well as plastic elements. To investigate this phenomenon, we raised common toad (Bufo bufo) tadpoles with ad libitum or limited food and in the presence or absence of chemical cues on predation risk, and measured their toxin content on 5 occasions during early ontogeny.

RESULTS

The number of compounds showed limited variation with age in tadpoles and was unaffected by food limitation and predator cues. The total amount of bufadienolides first increased and later decreased during development, and it was elevated in young and mid-aged tadpoles with limited food availability compared to their ad libitum fed conspecifics, whereas it did not change in response to cues on predation risk. We provide the first evidence for the active synthesis of defensive toxin compounds this early during ontogeny in amphibians. Furthermore, the observation of increased quantities of bufadienolides in food-restricted tadpoles is the first experimental demonstration of resource-dependent induction of elevated de novo toxin production, suggesting a role for bufadienolides in allelopathy.

CONCLUSIONS

Our study shows that the evolution of phenotypic plasticity in chemical defences may depend on the ecological context (i.e. predation vs. competition). Our results furthermore suggest that the age-dependent changes in the diversity of toxin compounds in developing toads may be fixed (i.e., constitutive), timed for the developmental stages in which they are most reliant on their chemical arsenal, whereas inducible plasticity may prevail in the amount of synthesized compounds.

Quantification of Bufadienolides in Bryophyllum pinnatum Leaves and Manufactured Products by UHPLC-ESIMS/MS

A quantitative assay for determination of the main bufadienolides bersaldegenin-1-acetate (1), bersaldegenin-3-acetate (2), bryophyllin A (3), and bersaldegenin-1,3,5-orthoacetate (4) in Bryophyllum pinnatum leaves and manufactured products was developed and validated. The assay involved extraction by pressurised liquid extraction, followed by quantification by ultrahigh performance liquid chromatography-tandem mass spectroscopy. The ultrahigh performance liquid chromatography-tandem mass spectroscopy method was applied to various batches of leaves harvested on several dates from plants grown at two locations (Brazil and Germany). In addition, press juices prepared from plants cultivated in Germany and Brazil were analysed. The total bufadienolide content ranged from 16.28 to 40.50 mg/100 g dry weight in leaves from plants grown in Brazil. The total content of these four bufadienolides was significantly lower in plants cultivated in Germany (3.78-12.49 mg/100 g dry weight, resp.). The total amounts of bufadienolides were 0.091-0.163 mg/100 mL and 0.89-1.16 mg/100 mL in press juices obtained from plants cultivated in Germany and Brazil, respectively. When analysing single leaves from individual plants, the content of bufadienolides was markedly higher in young leaves. For comparative purposes, the content of these bufadienolides was also determined in Bryophyllum daigremontianum and Bryophyllum tubiflorum. Bersaldegenin-1,3,5-orthoacetate (4) was predominant in the leaves of B. daigremontianum and in the stems of B. tubiflorum, while the leaves of B. tubiflorum contained very low amounts of 1-4.

Death of a South American fur seal (Arctocephalus australis) after the ingestion of toads--evaluation of toad poisoning by toxicological analysis

Animals in zoological gardens are at risk of severe and even lethal poisoning when they accidentally ingest toads. Here we report the case of an eleven month old male South American fur seal (Arctocephalus australis) which was found dead in its outdoor enclosure in the zoo of Dortmund, Germany. Autopsy revealed the presence of two adult, partly digested common toads (Bufo bufo) in the stomach. Toxicological analysis of the stomach content using high performance liquid chromatography coupled to time-of-flight mass spectrometry (LC-TOF MS) proved the presence of bufadienolides, the major cardiotoxic components of toad poisons. Using electrochemical luminescens immunoassay (ECLIA) compounds equivalent to digitoxin were detected in the blood sample confirming the absorption of toad poison components from the intestines into the circulation potentially leading to cardiac failure. In zoological gardens special precautions are necessary to protect non-native animals from encountering toads and the risk of poisoning, particularly in early spring, the spawning period of the toads.

Pharmacokinetics and tissue distribution of five bufadienolides from the Shexiang Baoxin Pill following oral administration to mice

ETHNOPHARMACOLOGICAL RELEVANCE

Shexiang Baoxin Pill (SBP) is a well-known composite formula of traditional Chinese medicine (TCM), widely used to treat cardiovascular diseases such as angina pectoris and myocardial infarction. Bufadienolides are major active compounds of Venenum Bufonis, which is one of the seven materiamedicas that comprise the Shexiang Baoxin Pill. Previous pharmacokinetics studies of bufadienolides have typically used a single medicinal material delivered to rats. In this study, we have chosen the mouse, a more proper animal model than the rat, to investigate the in vivo pharmacokinetics and tissue distribution of bufadienolides from the Shexiang Baoxin Pill.

MATERIALS AND METHODS

The concentrations of bufadienolides in plasma and tissues were identified using high performance liquid chromatography-tandem mass spectrometry (HPLC-ESI-MS/MS). The samples were prepared by liquid-liquid extraction with ethyl acetate, and the separation of bufadienolides was achieved using an ACQUITY HSS T3 column by gradient elution using water (containing 0.1% formic acid) and acetonitrile as the mobile phase at a flow rate of 0.3 mL/min. The pharmacokinetic parameters were determined using non-compartmental analysis.

RESULTS

The results showed that the five bufadienolides were rapidly absorbed and distributed into the body. The pharmacokinetic curve showed double peaks after oral administration. The major tissue depots for resibufogenin, bufalin, and bufotalin in mice were the intestines, lung and kidney, whereas the major tissue depots of gamabufotalin and arenobufagin were the intestines, liver and kidney.

CONCLUSION

The information gained from this research provides a meaningful insight for the clinical applications of the Shexiang Baoxin Pill.

[Identification of bufadienolides profiling in cinobufacino by HPLC-DAD-FT-ICR-MS method]

Cinobufacino injection is a significant anti-tumor medicine for the treatment of various tumors in clinic, which was made from water extraction of the skin of Bufo bufo gargarizans. In present paper, HPLC-DAD-FT-ICR-MS method was used to identify the major bufadienolides in cinobufacino for the first time. Solid-phase extraction with dichloromethane and silica was used to enrich the total bufadienolides in cinobufacino. Based on the UV and high resolution MS/MS data, 33 bufadienolides were analyzed and characterized. Among them, eight compounds were identified by comparing with standard references unambiguously. This study elucidated the major bufadienolides in cinobufacino, which provided material foundation of cinobufacino and will be benefit for the further pharmacological research.

[Determination of cinobufagin and resibufogenin in liver tissue by HPLC-MS/MS]

OBJECTIVE

To develop a sensitive and accurate assay for detecting cinobufagin and resibufogenin in liver tissue using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).

METHODS

The homogenization of liver tissue with internal standard dexamethasone was extracted with dichloromethane. The extracts with methanol were purified through ProElut C18 solid phase extraction and tested in positive electrospray ionization with multiple reaction monitoring of HPLC-MS/MS.

RESULTS

The good linear relationship of cinobufagin and resibufogenin in liver tissue were 1-204 ng/g and 1-206 ng/g, respectively. The minimal detection threshold (S/N > or = 3) of this method was 0.3 ng/g for both cinobufagin and resibufogenin. The matrix effect was 96.5%-126.7%. The extraction recovery coefficient was 70.0%-82.3%. The precision of intra-day and inter-day was less than 10%.

CONCLUSION

This method is sensitive and reliable, and can be used in forensic toxicological analysis.

Simultaneous Determination of Bufadienolides in the Traditional Chinese Medicine Preparation, Liu-Shen-Wan, by Liquid Chromatography

The bufadienolide compounds (bufalin, cinobufagin and resibufogenin), major constituents of Chansu in Liu-Shen-Wan (LSW), were determined by reverse phase high performance liquid chromotography. The procedure involves a preliminary extraction of the bufadienolides from LSW with chloroform using ultrasonication and subsequent evaporation to dryness of the chloroform extract. The residue of the chloroform extract was dissolved in methanol and separated on a Merck LiChrosorb RP-18 column. Methanol: water (74:26) was used as mobile phase. The compounds were satisfactorily separated with good chromatographic peaks. Good coefficients of correlation (r > 0·999) were obtained from the calibration of peak areas with concentrations for the 3 bufadienolides. Results of analysis showed that there were differences between the contents of bufadienolides in 11 LSW samples of different origin available to the public in Hong Kong where at present there is no legal control over the sale of traditional Chinese medicines. The variability of quantities of bufadienolides in Chansu may be a hazard to the public.

Comparison of toad venoms from different Bufo species by HPLC and LC-DAD-MS/MS

ETHNOPHARMACOLOGICAL RELEVANCE

Toad venom, called Chansu in China, has been widely used for the treatment of heart failure, sores, pains, and various cancers for a long time in clinic.

AIM OF THE STUDY

The aim of the study is to investigate the chemical differences among a variety of toad venoms from different geographic locations and related Bufo species.

MATERIALS AND METHODS

Ten batches of commercial toad venom collected from different regions in China, one batch of fresh toad venom obtained from Bufo bufo gargarizans, and six batches of related Bufo species were analyzed by HPLC and LC-DAD-MS/MS. Individual components were identified by comparison of retention times, UV spectra, and mass spectra with authentic compounds, standard addition, as well as summarized MS fragmentation rules. Based on the profile of identified constituents and the content of cinobufagin and resibufogenin, the chemical differences observed among different samples are discussed.

RESULTS

Overall, 43 compounds were identified in the methanolic extracts of the different samples of toad venom. Besides of suberoyl arginine, several free bufadienolides, bufadienolide sulfates, and suberoyl esters of bufadienolides were found. The total amounts of cinobufagin and resibufogenin, which are the only two control markers according to the current Chinese Pharmacopoeia, varied widely from 0.7% to 10.9% in the commercial Chansu samples collected in the different locations in China. Low levels of resibufogenin, but no cinobufagin was observed in the samples from Bufo melanosticus and Bufo marinus, and even neither of both compounds was found in the sample from Bufo viridis.

CONCLUSIONS

The chemical profiles of the different commercial and collected toad venoms from related Bufo species differed significantly, not only in the absolute and relative contents, but also in the number and type of the constituents. The main reason for this variation are species-specific differences, but additional factors, such as the harvest and post-harvest processing, and adaption to environmental factors in different geographic locations, also seem to contribute.

Rapid structural identification of cytotoxic bufadienolide sulfates in toad venom from Bufo melanosticus by LC-DAD-MS(n) and LC-SPE-NMR

Toad venom, namely, "Chansu" in China, has been widely used for the treatment of heart failure, sores, pains, and various cancers. Upon LC-MS analysis of the venom from Bufo melanosticus collected in Indonesia, new bufadienolide sulfates were identified. For a complete characterization, the MeOH extract of the toad venom from B. melanosticus was fractionated by preparative HPLC, and the structures of five new buadienolide sulfates (1-5) along with one new bufogenin (6) were rapidly elucidated on the basis of LC-DAD-MS(n) and LC-SPE-NMR data. The in vitro growth inhibitory activity of these six compounds along with hellebrin (positive control) has been assayed by means of the MTT colorimetric assay in four human and two mouse cancer cell lines. Compound 3 and hellebrin displayed similar and marked in vitro cytotoxicity.

[Study on quality standards for Lingmaoxiang Jiedu pills]

OBJECTIVE

To establish the quality standards of Linmaoxiang Jiedu pills.

METHOD

Cinobufagin and bufogenin were determined by HPLC simultaneously.

RESULT

The average recoverys of Cinobufagin and bufogenin was 100.5% and 100.3%, their linear range were 48.74-731.10 ng and 49.90-748.50 ng, respectively.

CONCLUSION

The method for quantification is reproducible and realizable. The method can be used to control quality of Linmaoxiang Jiedu pills as the quality standards.

[Determination of three bufogenins in toad venom using reversed-phase high performance liquid chromatography]

A reversed-phase high performance liquid chromatographic method for the quantitative determination of three bufogenins in toad venom was established. An Alltech Alltima C18 column (250 mm x 4.6 mm, 5 microm) was used. The mobile phase was acetonitrile-0.1 mol/L acetate buffer (pH 3.2) (50:50, v/v), and the flow rate was 0.8 mL/min. The detection wavelength was set at 299 nm. The method has good linearity in the ranges of 0. 25 -0.875 microg for cinobufagin (r = 0.999 0), 0.25 -0.875 microg for resibufogenin (r = 0.999 1), and 0.15 - 0.525 microg for bufalin (r = 0. 999 0). The average recoveries were 100.3%, 100.0% and 98.0% for cinobufagin, resibufogenin, and bufalin, respectively. The results indicate that the method is simple, accurate, reproducible, and can be used for the quality control of bufogenins in toad venom.

Simultaneous determination of cytotoxic bufadienolides in the Chinese medicine ChanSu by high-performance liquid chromatography coupled with photodiode array and mass spectrometry detections

ChanSu (toad venom) is a traditional Chinese medicine for the treatment of serious liver and gastric cancers. The major cytotoxic compounds in ChanSu are bufadienolides. In this paper, a strategy combining qualitative LC/MS analysis and quantitative HPLC determination of major bufadienolides was used for global quality control of ChanSu crude drug. Majority of the bufadienolides in methanol extract of ChanSu were unambiguously characterized by high-performance liquid chromatography coupled with atmospheric pressure chemical ionization tandem mass spectrometry (HPLC/APCI-MS/MS), and by comparing with pure compounds. In addition, eight major bufadienolides were simultaneously determined in one single HPLC run within 30 min with photodiode array detection (DAD). All compounds showed good linearity in a wide concentration range, and their limits of detection (LOD) were around 1 ng. Thus, > 95% of the bufadienolides in ChanSu could be characterized, and > 90% of them were quantitated. The established method is rapid, simple and sensitive, and could be used for the routine analysis of ChanSu crude drug and its preparations. This research sets a good example for the comprehensive quality control of traditional medicine.

Microemulsion electrokinetic chromatographic determination of bufadienolides in toad venom and in traditional Chinese medicine

A microemulsion electrokinetic chromatographic (MEEKC) method has been developed and validated for determination of resibufogenin and cinobufagin in toad venom and in traditional Chinese medicine prepared from the venom. The MEEKC method involved use of sodium dodecyl sulfate (SDS) as surfactant, heptane as organic solvent, and butan-1-ol as co-solvent. To improve the separation, the effect of temperature and running buffer pH were evaluated. The optimized conditions (heptane 0.81% (w/w), SDS 3.31% (w/w), butan-1-ol 6.61% (w/w), and 10 mmol L(-1) sodium tetraborate buffer, pH 9.2, and 298 nm as the detection wavelength) enabled useful and repeatable separation of the analytes.

Rapid separation and determination of resibufogenin and cinobufagin in toad venom and Liushen tablet by beta-cyclodextrin modified micellar electrokinetic chromatography

A rapid cyclodextrin modified micellar electrokinetic chromatography (CD-MEKC) method was proposed for the determination of resibufogenin and cinobufagin in the Chinese herbal extracts from toad venom and its medicinal preparation (Liushen tablet). The two components have the close structural similarity and similar hydrophobicity, which result in poor resolution in normal MEKC. The addition of neutral beta-CD to the MEKC system was found to improve the separation of the studied compounds. The effects of several CD-MEKC parameters on the resolutions were evaluated systematically. Based on the investigation, a background electrolyte solution consisting of 10 mM borate buffer adjusted to pH 8.5, 40 mM sodium dodecyl sulfate (SDS), 12 mM beta-CD and 10% (v/v) of methanol was found to be optimal conditions for the fast separation. The contents of resibufogenin and cinobufagin were successfully determined within 5 min, with satisfactory repeatability and recovery.

A novel endogenous digitalis, telocinobufagin, exhibits elevated plasma levels in patients with terminal renal failure

BACKGROUND AND OBJECTIVES

There are several potential endogenous digitalis-like factors (EDLF) in mammalian body fluids, and marinobufagenin (MBG) may be the most potent EDLF. Improved assays are needed to confirm the potency of these metabolites. In the present study, we have identified MBG and telocinobufagin (TCB) in human plasma by high-resolution mass spectrometry (MS) and nuclear magnetic resonance (NMR).

METHODS AND RESULTS

The high-resolution MS analysis revealed the molecular masses of TCB and MBG to be the same as their respective theoretical values. Using a tandem mass spectrometer, the mass-charge ratio for TCB was determined to be 403.2 for the parent ion and 349.2 for the daughter ion. The mass-charge ratio for MBG was m/z 383.2 and m/z 401.2. The NMR study revealed that the signals for MBG and TCB were the same as those obtained by MS analysis. In human blood, MBG and TCB were also identified by liquid chromatography (LC) as well as MS. In the LC/MS assay, proscillaridin A was used as an internal standard. The plasma was pretreated with Sep-Pak C18, and then 50 microL was applied to the C8 high-performance liquid chromatography (HPLC) column. The mean plasma concentration of MBG in healthy volunteers (0.94 +/- 0.28 ng/mL) was significantly lower than that in patients undergoing regular hemodialysis (3.81 +/- 1.92 ng/mL). The concentration of TCB in the healthy volunteers (1.80 +/- 0.55 ng/mL) was also significantly lower than that in patients with terminal renal failure (6.86 +/- 4.30 ng/mL).

CONCLUSION

These results indicate that the major EDLF is TCB because its plasma concentration is the highest among the reported endogenous digitalis candidates.

Analysis of bufadienolides in the Chinese drug ChanSu by high-performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry

The qualitative analysis of bufadienolides in the Chinese drug ChanSu was performed using high-performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS/MS). Bufadienolides are the major bioactive constituents of ChanSu, which is used to treat heart failure and cancer in traditional Chinese medicine. The APCI-MS fragmentation behavior of bufadienolides was studied. For bufadienolides with only hydroxyl substituents, the fragmentation was characterized by successive eliminations of H(2)O and CO molecules, and the profile of MS/MS product ions was correlated with the number of hydroxyl groups. If a C-16 acetoxyl group was present, the fragmentation of [M+H](+) ions was triggered by initial loss of 60 Da (HOAc). The elimination of CO was significant for bufadienolides with a 19-formyl group, and the 19-hydroxyl group could be characterized by the loss of 30 Da (HCHO). These fragmentation rules were applied to the identification of bufadienolides in a methanolic extract of ChanSu, which was separated on a C(18) column with gradient elution. A total of 35 bufadienolides were identified, including four new constituents. The method established here facilitated the convenient and rapid quality control of ChanSu crude drug and its pharmaceutical preparations.

Simultaneous determination of four bufadienolides in human liver by high-performance liquid chromatography

A high-performance liquid chromatographic method for the simultaneous quantitation of four bufadienolides-cinobufotalin, bufalin, cinobufagin and resibufogenin-in human liver was investigated. The procedure involved solid phase extraction of human liver with an Oasis HLB cartridge coupled with reversed-phase HPLC and photodiode array detection. Recoveries obtained from spiked liver for the bufadienolides were better than 70%. The linearity was studied up to 1.2 mg/kg and the detection limits of the method were 0.4 ng for cinobufotalin and bufalin and 0.5 ng for cinobufagin and resibufogenin. The developed method was successfully applied to a lethal poisoning case.

Study on mechanism of action of Chinese medicine Chan Su: dose-dependent biphasic production of nitric oxide in trophoblastic BeWo cells

BACKGROUND

Chan Su, a traditional Chinese medicine, is used for treating the heart diseases and other systemic illnesses. Our studies with animal model have revealed its role in increasing intracellular calcium concentration in cardiomyocytes. Nitric oxide (NO), a second messenger molecule, and its metabolites have been demonstrated to maintain and modulate multiple physiologic functions including the cardiovascular and reproductive systems. In order to explore the mechanism of action of Chan Su, we studied the ability of Chan Su to stimulate NO production in cultured trophoblastic BeWo cells.

MATERIALS AND METHODS

BeWo cell is a cloned established cell line purified from human choriocarcinoma. These cells have some similarities in biological behavior with endothelial cells. Therefore, BeWo cell line may act as a model system for production of nitric oxide by Chan Su both in placenta and in cardiovascular tissue, and the results can easily be extrapolated to cardiomyocytes. Very small amount of ethanol extract of Chan Su was added to the cultured cells in KBM buffer and a chemiluminescence system was used for the measurement of nitric oxide. The amounts of Chan Su extract added to cultured cells were comparable to expected level of Chan Su in human serum after ingestion. We also repeated these experiments with bufalin, the active component of Chan Su.

RESULTS

The ethanol extract of Chan Su (5 and 10 microg/ml) significantly increased NO production up to 110% of basal control value, but higher concentrations (40 and 80 microg/ml) of Chan Su (as expected in an overdose) resulted in decreased NO production below the control level. This biphasic effect on nitric oxide production was also observed with bufalin, the active component of Chan Su responsible for its digoxin-like immunoreactivity. The presence of bufalin in Chan Su preparation was confirmed by thin layer chromatography (TLC) analysis.

CONCLUSIONS

Chan Su as well as bufalin is able to modulate the production of NO in BeWo cell line.

Effect of the traditional Chinese medicines Chan Su, Lu-Shen-Wan, Dan Shen, and Asian ginseng on serum digoxin measurement by Tina-quant (Roche) and Synchron LX system (Beckman) digoxin immunoassays

Chan Su, Lu-Shen-Wan, Dan Shen, and Asian ginseng are traditionally used to treat a number of conditions, including cardiovascular disease. All of these traditional Chinese medicines exhibit cardioactive properties. Digoxin is a cardioactive drug with a narrow therapeutic range (0.8-1.9 ng/mL). A patient taking digoxin may also take these Chinese medicines for their cardiotonic effects. Moreover, the active components of these medicines that are responsible for cardiotonic effects bear structural similarities to digoxin. Therefore, we studied the potential interference of these Chinese medicines with two digoxin immunoassays--the Tina-quant (Roche Diagnostics) and the Beckman (Synchron LX system)--and compared the values with the fluorescence polarization immunoassay (FPIA; Abbott Laboratories). When very small amounts (2-5 microL) of aqueous extract of Chan Su or Lu-Shen-Wan were added to drug-free serum, we observed high digoxin-like immunoreactivity with the FPIA. In contrast, when ethyl acetate extract of Dan Shen or microliter amounts of ginseng extract were added to drug-free serum, we observed modest digoxin-like immunoreactivity with the FPIA, but no apparent digoxin activity with the Roche and Beckman digoxin immunoassays. When aliquots of a digoxin pool prepared from patients receiving digoxin were supplemented with these Chinese medicines, we observed the most significant interference with the FPIA. The presence of endogenous digoxin-like immunoreactive substances can have additive effects with these Chinese medicines and falsely increase apparent digoxin levels by the FPIA. On the other hand, the Roche and Beckman assays were free from interference from DLIS but showed significant interference from Chan Su and Lu-Shen-Wan. We conclude that the FPIA showed the most significant interference from all four of the Chinese medicines we studied. However, the Roche and Beckman assays showed no interference from two (Dan Shen and Asian ginseng) of the four Chinese medicines we studied.

Effect of Chinese medicines Chan Su and Danshen on EMIT 2000 and Randox digoxin immunoassays: wide variation in digoxin-like immunoreactivity and magnitude of interference in digoxin measurement by different brands of the same product

Chan Su is a Chinese medicine prepared from the skin gland of a Chinese toad and is used in treating arrhythmia and other heart diseases. Danshen is prepared from the Chinese medicinal plant and is used for various cardiovascular diseases including angina pectoris. The authors studied the potential interference of such medicines with the widely used EMIT 2000 (Dade Behring; Deerpark, IL) digoxin assay and the recently marketed Randox digoxin assay (Randox Laboratories Ltd, Antrim, United Kingdom) (both run on the Bayer ADVIA 1650 analyzer) (Bayer Diagnostics, Tarrytown, NY) and compared their results with an FPIA (Abbott Laboratories) and a chemiluminescent immunoassay (CLIA; Bayer Diagnostics) for digoxin. Aliquots of drug-free serum were supplemented with 1 microL ethyl acetate extract of Danshen or aqueous extract of Chan Su, and apparent digoxin concentrations were measured by all four digoxin immunoassays (FPIA, EMIT, Randox, CLIA). The authors also supplemented aliquots of several different serum pools prepared from patients taking digoxin with very small amounts of Chan Su or Danshen extract and compared digoxin values with the control digoxin values (serum pool containing no Chinese medicine). The authors observed no interference of Danshen in either EMIT, Randox, or CLIA assay but observed an interference with the FPIA assay. On the other hand, the authors observed high interference of Chan Su in the FPIA assay but moderate interference with the EMIT 2000 and Randox digoxin assays. CLIA assay was again free from any interference. The authors also observed a wide variation in digoxin-like immunoreactivity and magnitude of interference in digoxin immunoassay in different brands of Chan Su and Danshen, indicating poor quality control in manufacturing of these Chinese medicines. Taking advantage of the high protein binding of digoxin-like immunoreactive components of Chan Su, the authors further demonstrated that interference of Chan Su in EMIT 2000 and Randox assays can be mostly eliminated by monitoring free digoxin.

Studies on toad venom (3): effect of metals on the quality of toad venom torrefied on a metal plate

To study the quality of toad venom dried on different metal plates by heating at 105 degrees C, each 20 g sample of fresh toad venom collected in Hei-Long-Jiang Province, China, was dried on (1) brass, (2) copper, (3) glass, (4) acrylic resins, (5) aluminum and (6) stainless-steel, respectively. Twelve bufadienolides, including bufalin and bufotalin, in each sample were then quantitatively analyzed by HPLC. The total levels of bufadienolides in 1000.0 mg of the dried samples were (1) > (2) > (3) > (4) > (5) > (6), varying from 303.44 mg to 420.72 mg. Besides, the color of dried venom became darker in the order of (2), (4), (6), (3), (1) and (5). Though (1) was not in good color, it was superior to the others in chemical quality. These results suggest that it is possible to dry toad venom in short period by heating it at a high temperature on a tray made of brass. This will be a better method for making high quality toad venom than the traditional method. Moreover, the removal of impurities in the fresh venom by the process of filtration through silk succeeded in raising the bufadienolides content significantly.

Bufadienolides and a new lignan from the bulbs of Urginea maritima

Thirty three compounds were obtained from the bulbs of Urginea maritima (Liliaceae). The compounds were identified by means of fast atom bombardment mass spectrometry (FAB-MS), nuclear magnetic resonance (1H-NMR), (13C-NMR), nuclear overhauser effects (NOE) and two dimensional (2D) NMR. Ten of them were new natural compounds. Nine were bufadienolides and only one was lignan in these compounds.

Seasonal variation in cotyledoside concentration of Tylecodon wallichii (Harv.) Tölken subsp. wallichii sampled in a krimpsiekte-prevalent region

Krimpsiekte, an economically important neuromuscular affliction of small stock, follows upon ingestion of certain members of the Crassulaceae (plakkies) containing cumulative neurotoxic bufadienolides. Tylecodon wallichii (Harv.) Tölken subsp. wallichii is probably the most important species of the group of plants causing krimpsiekte. The growing tip of the stem and various other plant parts of T. wallichii, when available, were collected monthly. The seasonal variation in cotyledoside content of the plant was measured. Cotyledoside concentration was determined by high performance liquid chromatographic-electrospray mass spectrometry analysis (HPLC-ESMS). The cotyledoside concentration in the plant stems fluctuated substantially during the year, but tended to be higher in the cold winter months and increased again in the spring and early summer. Elevated plant stem concentrations corresponded with natural field outbreaks of krimpsiekte, which usually occur during the winter to early summer. The highest cotyledoside concentrations were detected in the flowering stalk. Cotyledoside was not the only component of this type in the plant, as mass spectrometry revealed the presence of other, possibly related, compounds.

Studies on toad venom (2): Examination of the drying processing method

To examine the influence on the quality of toad venom processed by different drying methods, each 10 g sample of fresh toad venom collected in Shang-Dong Province, China, were dried, (1) in the sun for 133 h, (2) in the shade for 224 h, (3) heated at 60 degrees C for 33 h, (4) heated at 105 degrees C for 4 h, (5) freeze-dried for 6 h. Twelve bufadienolides, including bufalin and bufotalin, in each sample were then quantitatively analyzed by HPLC. The total contents of bufadienolides in 1000 mg of the dried samples were as follows: 235.39 mg for dehydrolyzed fresh toad venom, 94.39 mg for (1), 148.46 mg for (2), 59.22 mg for (3), 133.40 mg for (4), and 184.77 mg for (5), respectively. The color of dried venom became darker in the order of (5), (2), (1), (3) and (4). Though the color of (4) should be the worst as a standard quality evaluation in Shang-Dong Province, as far as bufadienolides was concerned, (4) was superior to (1) in the contents and was almost same to (2). These results suggest that it is possible to dry toad venom by heating at high temperature for several hours. This will remarkably shorten the term for making high quality toad venom, in comparison to the traditional processing method in China that needed more than two years for drying venom.

[Determination of resibufogenin in xinli pills by RP-HPLC]

A method has been developed for the quantitative determination of Resibufogenin in Xinli pills by RP-HPLC. The stainless steel column(200 x 4.6 mm) was packed with ODS-3 (particle size 5 microns). The mobile phase was a mixture of methanol-water (60:40). The flow rate was 1 ml/min. The column temperature was 30 degrees C. The detection wavelength was 299 nm. The retention time for recibufogenin was 5.6 min. The average recovery for resibufogenin was 99.9%. The linear calibration curve for resibufogenin was obtained in the range 53.0-159.0 micrograms with the correlation coefficient 0.9998.

Determination of resibufogenin and cinobufagin in heart-protecting musk pill by HPLC

A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of resibufogenin and cinobufagin in traditional Chinese medicine (heart-protecting musk pill, shexiang baoxin wan in Chinese) was developed. A reversed-phase system with a Hypersil (ODS2) C(18) column and tetrahydrofuran: methanol: water (8:31:61) mobile phase was employed for the separation of resibufogenin and cinobufagin. The detection was set at 299 nm and ethinyl estradiol was chosen as the internal standard. The limit of detection was 1.5 ng for resibufogenin and 2.0 ng for cinobufagin at a signal-to-noise ratio of 4:1. It is a rapid, simple and accurate method for quantitative analysis of resibufogenin and cinobufagin in heart-protecting musk pill.

Efficacy of digoxin specific Fab fragments (Digibind) in the treatment of toad venom poisoning

Chan Su, a traditional Chinese medication, and Love Stone, a topical aphrodisiac, are both made from dried venom of the toad bufo bufo gargarizans and contain bufalin, cinobufotalin, cinobufagin, and other cardioactive steroids of the bufadienolide class. Deaths have occurred following ingestion of these products and the clinical course resembles digoxin toxicity. The purpose of this study was to determine the efficacy of digoxin specific Fab fragments in treating Chan Su poisoning. An ethanolic extract was prepared from Chan Su. Digoxin specific Fab fragments were reconstituted in normal saline to a concentration of 80 mg/ml. An approximate LD90 dose was determined in preliminary experiments. Mice were then randomly divided into a treatment group of 15 mice and a control group of 30 mice. The treatment group was pretreated with 20 ml/kg of digoxin specific Fab fragment solution by intraperitoneal injection at t = 0, followed by 10 ml/kg of digoxin specific Fab fragments intraperitoneal at t = 30 min. The control group was pretreated with equal volumes of intraperitoneal normal saline at the same times. Immediately following the 30 min injection, both groups were given the estimated LD90 dose of Chan Su extract by subcutaneous injection. An endpoint of survival at 6 h was chosen after preliminary results showed that all deaths occurred in the first 4 h. All 30 of the control mice had seizures followed by death compared to 11 seizures and 7deaths in the 15 treatment mice. These results were statistically significant by Fisher's exact test (p = 0.00003 for mortality and p = 0.009 for seizures). Digoxin specific Fab fragments are effective in the treatment of Chan Su poisoning in mice and may be effective for poisoning by other cardioactive steroids of the bufadienolide class.

[Determination of resibufogenin and cinobufagin in venenum Bufonis by HPLC]

OBJECTIVE

To establish a HPLC method to determine the contents of active constituents in Venenum Bufonis.

METHOD

In determining the contents of resibufogenin and cinobufagin in the traditional Chinese medicine Venenum Bufonis, the mobile phase was acetonitrile-0.5% KH2PO4 solution(50:50)(pH adjusted with value phosphoric acid to 3.25 +/- 0.02).

RESULT

The constituents thus determined have good linearity and separation. The average recovery of resibufogenin was 100.35%, RSD 1.86%; the average recovery of cinobufagin was 100.38%, RSD 2.09%.

CONCLUSION

The method was convenient, rapid, accurate and practicable.

Neutralization of cardiac toxins oleandrin, oleandrigenin, bufalin, and cinobufotalin by digibind: monitoring the effect by measuring free digitoxin concentrations

Oleandrin plant poisoning is common in children and the plant extract is used in Chinese medicines. The toxicity is due to oleandrin and the deglycosylated metabolite oleandrigenin. Bufalin and cinobufotalin (toad cardiac toxins) are also widely used in Chinese medicines like Chan SU, and Lu-Shen -WU. Severe toxicity from bufalin after consumption of toad soup has been reported. Taking advantage of structural similarities of these toxins with digitoxin, we demonstrated that these compounds can be rapidly detected in blood by the fluorescence polarization immunoassay for digitoxin. The cross reactivities of these compounds with digoxin assay were much lower. For example, when a drug free serum was supplemented with 10 microg/ml of oleandrin, we observed 127.7 ng/ml of digitoxin equivalent but only 2.4 ng/ml of digoxin equivalent concentration. Digibind neutralized all cardiac toxins studied as evidenced by significant fall of free concentrations. When aliquots of serum pool containing 50.0 microg/ml of oleandrin were supplemented with 0, 10.0, 25.0, 50.0, 100, and 200 microg/ml of digibind, the mean free concentrations were 30.6, 23.3, 16.0, 10.7, 7.8 and 5.5 microg/ml respectively. Similarly, with 50.0 microg/ml of oleandrigenin (total concentration: 36.2 ng/ml), the free concentration was 14.5 ng/ml digitoxin equivalent in the absence of digibind and 5.4 ng/ml in the presence of 200 microg/ml of digibind. In another specimen containing 500 ng/ml bufalin (total concentration: 156.9 ng/ml), the free concentration was 8.6 ng/ml in the absence of digibind and none detected in the presence of 100.0 microg/ml digibind. Because such neutralization may also occur in vivo, digibind may be useful in treating patients exposed to these toxins.

[Effect of scald processing on the content of recibufogenin in Pellis sicci Bufonis]

OBJECTIVE

To investigate the effect of scald processing on the content of recibufogenin in Pellis Sicci Bufonis.

METHOD

Samples were analyzed by high performance liquid chromatography.

RESULT

The content of recibufogenin in the scald processed product was 25.7% higher than that in the unprocessed one. The average recovery was 98.34% and RSD 1.28%.

CONCLUSION

The results indicate that the content of recibufogenin in scald processed Pellis Sicci Bufonis is higher than that in the unprocessed drug.

Rapid detection of cardioactive bufalin toxicity using fluorescence polarization immunoassay for digitoxin

Intoxication caused by digitalis-like substances after ingestion of cooked toad soup has been reported. Bufalin, a cardioactive compound, is found in toad. Bufalin is also found in many Chinese medicines. Earlier reports demonstrated cross reactivity of bufalin with fluorescence polarization immunoassay for digoxin. In this report, the authors demonstrated a significantly higher cross reactivity of bufalin with the fluorescence polarization assay for digitoxin. They supplemented aliquots of normal plasma that had various concentrations of bufalin (1 to 50 micrograms/ml) from a local blood bank and measured apparent digitoxin concentrations using fluorescence polarization immunoassay and chemiluminescent assays (ACS digitoxin) for digitoxin. They measured apparent digoxin and digitoxin concentrations using fluorescence polarization, microparticle enzyme immunoassay, and chemiluminescent assays for digitoxin. They observed apparent digitoxin or digoxin concentrations in sera supplemented with bufalin only with the fluorescence polarization assays. For example, the apparent digitoxin concentration observed in a serum supplemented with 25 ng/ml of bufalin was 24.3 ng/ml of digitoxin equivalent. The apparent digoxin concentration observed in the same specimen was 1.33 ng/ml digoxin equivalent. Bufalin caused positive interference in serum digoxin or digitoxin measurements in specimens containing digoxin or digitoxin when concentrations were measured by fluorescence polarization assays. In contrast, bufalin lowered the measured digoxin concentrations in serum pools containing digoxin when digoxin concentrations were measured by the microparticle enzyme immunoassay. The authors conclude that bufalin toxicity can be rapidly detected by the fluorescence polarization assay for digitoxin.

Absence of tetrodotoxins in a captive-raised riparian frog, Atelopus varius

Bufonid frogs of the genus Atelopus contain two classes of skin toxins, namely the steroidal bufadienolides and the water-soluble tetrodotoxins. Frogs of the Panamanian species Atelopus varius have now been raised in captivity and levels in skin extracts of bufadienolides and of tetrodotoxin-like compounds assessed, using inhibition of [3H]ouabain binding and inhibition of [3H]saxitoxin binding, respectively. Levels of ouabain equivalents, corresponding to bufadienolides, were comparable to those found in wild-caught frogs from the same population in Panama, while tetrodotoxin-like activity was undetectable. The results strongly implicate environmental factors, perhaps symbiotic microorganisms, in the genesis of tetrodotoxins in the skin of frogs of the genus Atelopus, while indicating that the frog itself produces the skin bufadienolides.

Treatment of toad venom poisoning with digoxin-specific Fab fragments

Toxicity from toad venom poisoning is similar to digoxin toxicity and carries a high mortality rate. We report on six previously healthy men who developed vomiting and bradycardia after ingesting a purported topical aphrodisiac. Each patient had positive apparent digoxin levels and the first four patients died of cardiac dysrhythmias. The last two patients recovered following treatment with digoxin Fab fragments. We analyzed samples of the purported aphrodisiac and found that it was identical to Chan Su, a Chinese medication made from toad venom. To our knowledge, this is the first reported use of digoxin Fab fragments to treat toad venom poisoning.

Endogenous marinobufagenin-like immunoreactive substance. A possible endogenous Na, K-ATPase inhibitor with vasoconstrictor activity

Vasoconstrictor and Na/K pump inhibitory properties of a bufodienolide Na/K-ATPase inhibitor, marinobufagenin, were studied in isolated rings of 2 to 3 order branches of human pulmonary arteries respectively. Marinobufagenin displayed concentration-dependent vasoconstrictor activity (0.01 to 10 mmol/L). In sarcolemma membranes prepared from pulmonary artery marinobufagenin inhibited Na/K-ATPase (IC50 = 50 nmol/L). In eight healthy male Caucasians, concentrations of marinobufagenin-like immunoreactive material in C-18 extracted plasma were 1.38 +/- 0.60 nmol/L. Twenty-four-hour urinary release of marinobufagenin-like immunoreactive material in eight healthy males was 1.20 +/- 0.95 nmol/day. Chloroform extract of human urine was fractionated using reverse-phase high-performance liquid chromatography (32% acetonitrile, Deltapak). The HPLC fraction coeluting with marinobufagenin in 7 min, cross reacted with antimarinobufagenin and antidigoxin, but not antiouabain antibody. These results demonstrate that human plasma and urine contains a bufodienolide vasoconstrictor EDLF, marinobufagenin-like immunoreactive Na,K pump inhibitor.

Deaths associated with a purported aphrodisiac--New York City, February 1993-May 1995

During February 1993-May 1995, the New York City Poison Control Center (NYCPCC) was informed about onset of illness in five previously healthy men after they ingested a substance marketed as a topical aphrodisiac; four of the men died. These cases were investigated by the New York City Department of Health, the New York City Department of Environmental Protection, and the Food and Drug Administration (FDA). Four cases were referred to the NYCPCC and one case to the New York City medical examiner's office. The decedents died from cardiac dysrhythmias, and all five patients had measurable levels of digoxin* detected in their serum. Digoxin had not been prescribed for therapeutic purposes for any of these patients, and none had medical conditions associated with endogenous digoxin-like immunoreactive substances. The purported aphrodisiac contains bufadienolides, naturally occurring cardioactive steroids that have digoxin-like effects. This report describes three of the five case reports, summarizes the investigations of the five cases, and underscores the health risks associated with inappropriate use of preparations containing digoxin-like substances.

Structures of novel bufadienolides in the eggs of a toad, Bufo marinus

In this paper, we report chemical structures of five compounds including four novel polyhydroxylated cardiac steroids in the eggs of a toad, Bufo marinus. These cardiac steroids were purified by high-performance liquid chromatography, and their structures were determined to be 11 alpha,19-dihydroxy-telocinobufagin (I), 11 alpha-hydroxytelocinobufagin (II), 11 alpha,19-dihydroxymarinobufagin (III), 11 alpha-hydroxymarinobufagin (IV) and 19-hydroxytelocinobufagin (V) on the basis of spectral data of nuclear magnetic resonance and mass spectroscopy. All the five compounds showed biological activity, as tested by inhibition of Na+,K(+)-ATPase activity and of [3H]ouabain binding to the receptor on Na+,K(+)-ATPase. This is the first finding of bufadienolides as cardiac steroids in animal eggs.

Identification of digitalis-like compounds in human cataractous lenses

Human cataractous lens nuclei extract inhibited, in a dose-dependent fashion, [3H]ouabain binding to rat brain synaptosomes and microsomal Na(+)- and K(+)-dependent adenosine triphosphate (Na+, K(+)-ATPase) activity and interacted with anti-digoxin antibodies. The compounds responsible for these activities, termed digitalis-like compounds (DLC), were also detected in bovine, rat, cat and rabbit, normal, transparent lenses, but the levels were only 0.7-5.4% of the average levels in the cataractous human lenses. DLC from the human cataractous lenses were purified by a procedure consisting of organic extractions and batch chromatography followed by filtration through a 3000 Da cut-off filter and subsequent separations using reverse-phase high-performance liquid chromatography. The presence of DLC in the different fractions obtained in the chromatograms was monitored by their ability to inhibit [3H]ouabain binding and Na+, K(+)-ATPase activity. Based on chemical ionization mass spectrometry together with ultraviolet spectrometry and biological characterization, it is suggested that new bufodienolides, 19-norbufalin and 19-norbufalin peptide derivatives are responsible for the endogenous DLC activity. It is proposed that these compounds may regulate Na+, K(+)-ATPase activity in the lens under some physiological and pathological conditions.

Experimental evidence that the active principle of the poisonous plant Thesium lineatum L.f. (Santalaceae) is a bufadienolide

The toxicity of Thesium lineatum is confirmed in sheep. A toxic crystalline bufadienolide, with the suggested trivial name thesiuside, has been isolated from it. This is the first cardiac glycoside to be isolated from a member of the Santalaceae. The toxin appears to have no cumulative effect and the symptoms of intoxication and pathology in sheep are similar to that expected from acute cardiac glycoside intoxication.

The toxicity to cattle and bufadienolide content of six Bryophyllum species

Cardiac glycoside poisoning was produced in calves given (in descending order of toxicity) flower heads of the hybrid Bryophyllum (Kalanchoe) daigremontianum x B. tubiflorum, of B. pinnatum, of B. tubiflorum (from previous work), whole plant of B. fedtschenkoi, flower heads of B. daigremontianum and whole plant of B. proliferum. For each plant (except B. tubiflorum), 2 calves were each given a single dose of 20 g wet weight per kg bodyweight. By using high performance liquid chromatography, the bufadienolides (cardiac glycosides) bryotoxin A, B and C were detected and assayed in the flower heads and leaf plus stem of B. tubiflorum and in the roots of B. tubiflorum, the hybrid and B. pinnatum. Only bryotoxins B and C were detected and assayed in the flower heads and leaf plus stem of the hybrid, B. daigremontianum and B. pinnatum. No bryotoxins were detected in B. fedtschenkoi. Bryotoxin A and a mixture of bryotoxins B and C from B. tubiflorum flowers were used as standards in the chromatographic assay. Comparing the results of the calf toxicity experiment with the amounts of bufadienolide measured in the plants suggests that bryotoxins A, B and C probably account for the observed disease, but that B. pinnatum and B. fedtschenkoi contain at least one other cardiac glycoside.