3D scaffold fabricated with composite material for cell culture and its derived platform for safety evaluation of drugs.

In order to overcome the weakness of conventional approaches for cell culture, and provide cells with more in vivo-like microenvironment for studying hepatotoxicity of drugs, "multiple-in-one" strategy was adopted to fabricate a 3D scaffold of silk fibroin/hydroxyapatite/poly lacticco-glycolic acid (SF/HA/PLGA), where HepG2 cells were cultivated and the toxicity of drugs to the cells was investigated. The prepared 3D scaffold proves to bear proper porosity, excellent mechanical property, steady pH environment and good biocompatibility for cell culture. Furthermore, the validity of the developed 3D-SF/HA/PLGA-scaffold based platform was verified by probing the toxicity of a known drug-induced liver injury (DILI) concern acetaminophen (APAP) to HepG2 cells. Eventually, an application of the platform to dioscin (a medicinal plant extract) reveals the hepatotoxicity of dioscin, which involves the inhibition of the expression of CYP3A4 mRNA in the cells. The developed 3D-SF/HA/PLGA-scaffold platform may become a universal avenue for safety evaluation of drugs.

Twin drug design, synthesis and evaluation of diosgenin derivatives as multitargeted agents for the treatment of vascular dementia.

A novel series of multitargeted molecules were designed and synthesized by combining the pharmacological role of cholinesterase inhibitor and antioxidant of steroid as potential ligands for the treatment of Vascular Dementia (VD). The oxygen-glucose deprivation (OGD) model was used to evaluate these molecules, among which the most potent compound ML5 showed the highest activity. Firstly, ML5 showed appropriate inhibition of cholinesterases (ChEs) at orally 15 mg/kg in vivo. The further test revealed that ML5 promoted the nuclear translocation of Nrf2. Furthermore, ML5 has significant neuroprotective effect in vivo model of bilateral common carotid artery occlusion (BCCAO), significantly increasing the expression of Nrf2 protein in the cerebral cortex. In the molecular docking research, we predicted the ML5 combined with hAChE and Keap1. Finally, compound ML5 displayed normal oral absorption and it was nontoxic at 500 mg/kg, po, dose. We can draw the conclusion that ML5 could be considered as a new potential compound for VD treatment.

Diosgenin induces genotoxic and mutagenic effects on HepG2 cells.

Yam roots and other plants from Dioscorea genus have cultural, nutritional and economic importance to tropical and subtropical regions and have a great amount of diosgenin in its composition. In the present study the cytotoxic, genotoxic and mutagenic potential of diosgenin on HepG2 cells was investigated. Cytotoxicity was assessed using MTT and clonogenic assay. Genotoxic and mutagenic effects were performed using single cell gel electrophoresis and cytokinesis-block micronucleus assay, respectively. A reduction on cell viability was observed due to diosgenin treatment at concentrations higher than 30 µM. A genotoxic effect was shown by comet assay and CBMN. Besides, an increase in micronucleus frequency along with a significant cytostatic effect were observed. Diosgenin elicited DNA damage on HepG2 cells which could not be efficiently repaired contributing to the mutagenic effect observed. Those results suggest that diosgenin deleterious effect could take place through genetic instability, fact that affects the normal cell cycle, leading to cell's death.

Can treatment of Brachiaria decumbens (signal grass) improve its utilisation in the diet in small ruminants?-a review.

Brachiaria decumbens is an extremely productive tropical grass due to its aggressive growth habit and its adaptation to a varied range of soil types and environments. As a result of the vast availability, treated B. decumbens demonstrates as a promising local material that could be utilised as an improved diet for sheep and goats. Despite the fact that the grass significantly increases weight gains in grazing farm animals, there were many reports of general ill-thrift and sporadic outbreaks of photosensitivity in livestock due to the toxic compound of steroidal saponin found in B. decumbens. Ensiling and haymaking were found to be effective in removing toxin and undesirable compounds in the grass. Biological treatments using urea, activated charcoal, polyethylene glycol, and effective microorganisms were found to be useful in anti-nutritional factor deactivation and improving the nutritive values of feedstuffs. Besides, oral administration of phenobarbitone showed some degree of protection in sheep that fed on B. decumbens pasture. In this review, we aim to determine the effect of B. decumbens toxicity and possible treatment methods on the grass to be used as an improved diet for small ruminant.

Activity of Diosgenyl 2-amino-2-deoxy-ß-D-glucopyranoside, its Hydrochloride, and N,N-dialkyl Derivatives Against Non-albicans Candida Isolates.

BACKGROUND: Candida albicans belongs to the most common fungal pathogens in humans, but recently an increased proliferation of strains called non-albicans Candida has been reported. Species belonging to this group are often characterised by a reduced susceptibility to antifungal agents. OBJECTIVE: In view of the emergence of non-albicans Candida and their resistance to available antifungals, an attempt has been made to develop novel effective agents. Biological activities of the N,N-dialkyl diosgenyl glycosides, which were previously synthesized, were determined. METHOD: Minimum inhibitory concentration (MIC) was determined for group of clinical nonalbicans Candida isolates by serial dilution method in Sabouraud liquid medium. In order to assess the toxicity towards human cells the minimum haemolytic concentration (MHC) was determined on human erythrocytes by serial dilution method in phosphoric buffer. RESULTS: The saponins exhibited a strong activity towards clinical isolates of C. glabrata and C. parapsilosis comparable or even stronger than that of conventional antimicrobials. A high rate of resistance to fluconazole was shown among C. glabrata isolates. Among clinical strains of C. krusei and C. tropicalis, isolates with a decreased susceptibility to saponins were identified. All the tested C. krusei isolates showed resistance to fluconazole, while among C. tropicalis numerous strains were resistant to all tested azoles. The saponins did not show haemolytic activities at their microbiologically active concentrations. CONCLUSION: Results of the present work encourage to continue the study on steroidal saponins and their potential application for the treatment of candidemia.

Exploration in the cascade working mechanisms of liver injury induced by total saponins extracted from Rhizoma Dioscorea bulbifera.

Rhizoma Dioscorea bulbifera, the tuber of Dioscorea bulbifera L., has been used to treat various diseases. However, the clinical application has been limited for its hepatotoxicity. In this study, we explored the cascade working mechanisms of time-dependent hepatotoxicity induced by total saponins extracted from Rhizoma Dioscorea bulbifera (TSRD). Animals were orally administered with TSRD for indicated time period. The adverse effects were determined by histopathology and biochemistry. Similar hepatic index was analyzed in L-O2 cells exposed to dioscin for different durations. We found that TSRD could initially cause cell damage and cholestasis in rats. With the treatment going on, oxidative stress injury and up-regulation of Cytochromes P450 (CYPs) were observed both in vitro and in vivo. Eventually, TSRD induced mitochondrial permeability results in apoptosis or necrosis. Taken together, we provided evidence for the time-dependent hepatotoxicity of TSRD and created a 3-step injury model to clarify its cascade working mechanisms.

Ultrahigh-Performance Liquid Chromatography-High-Resolution Quadrupole Time-of-Flight Mass Spectrometry Based Metabolomics Reveals Key Differences between Brachiaria decumbens and B. brizantha, Two Similar Pastures with Different Toxicities.

Several species of Brachiaria (Poaceae) currently cover extensive grazing areas in Brazil, providing valuable source of feed for a large cattle population. However, numerous cases of toxicity outbreaks in livestock have raised concerns on safety of using these plants, especially B. decumbens. In this study, chemometric analysis of ultrahigh-performance liquid chromatography-high-resolution quadrupole time-of-flight mass spectrometry (UHPLC-HR-QTOF-MS) data has for the first time uncovered qualitative and quantitative differences between metabolomes of toxic B. decumbens and nontoxic B. brizantha. The steroidal saponin protoneodioscin was established as the main biomarker for B. decumbens when compared to B. brizantha, and therefore the key explanation for their phytochemical differentiation. Quantification of protodioscin in both plants showed no significant differences; consequently, the idea that this compound is solely responsible for toxicity outbreaks must be discarded. Instead, we propose that the added occurrence of its stereoisomer, protoneodioscin, in B. decumbens, can be considered as the probable cause of these events. Interestingly, the greatest concentrations of saponins for both species were reached during winter (B. decumbens = 53.6 ± 5.1 mg·g(-1) dry weight (D.W.); B. brizantha = 25.0 ± 1.9 mg·g(-1) D.W.) and spring (B. decumbens = 49.4 ± 5.0 mg·g(-1) D.W.; B. brizantha = 27.9 ± 1.4 mg·g(-1) D.W.), although in the case of B. decumbens these values do not vary significantly among seasons.

[Preliminary study on hepatotoxicity induced by dioscin and its possible mechanism].

Dioscin has a wide range of biological effects and broad application prospects. However the studies concerning the toxicology and mechanism of dioscin is small. This article is to study the hepatotoxicity of dioscin and the effect of dioscin treatment on expression of aryl hydrocarbon receptor (AhR) mRNA and CYP1A mRNA and protein in HepG2 cells in vitro. Dioscin 0.5-32 µmol · L(-1) exposed to HepG2 cells for 12 h, cell viability was examined by CCK-8 assay and the release rate of lactate dehydrogenase (LDH) was to evaluate cell membrane damage. HepG2 cells morphologic changes were quantified by inverted Microscope, and the effect on production of reactive oxygen species (ROS) was detected by flow cytometry. The mRNA expression of CYP1A and AhR was evaluated by RT-RCR. The protein expression of CYP1A1 was detected by western blot. The cell viability was significantly inhibited after HepG2 cells were exposed to dioscin 0.5-32 µmol · L(-1). Compared with the control, the LDH release rate and ROS were significantly increased. The expression of CYPlA and AhR mRNA was increased. The expression of CYP1Al protein was increased after dioscin treatment, and resveratrol, an AhR antagonist, could downregulate the expression of CYP1A1. It follows that large doses dioscin has potential hepatotoxicity. The possible mechanism may be dioscin can active aryl hydrocarbon receptor (AhR) and induce the expression of CYP1A.

Quantitative detection of eryptosis in human erythrocytes using tunable resistive pulse sensing and annexin-V-beads.

Toxicological assessments of human red blood cells (RBCs) are important in human health because RBCs are the most abundant cell type in our body. Erythrotoxicology testing guidelines using hemolysis have been established as a standard (e.g. by the ASTM International). However, many xenobiotics promote eryptosis (apoptosis in human RBCs) without causing hemolysis. Based on the major features of eryptosis, i.e. cell shrinkage and translocation of phosphatidylserine (PS) to the outer lipid bilayer of the plasma membrane, we report here a novel approach utilizing the quantitative tunable resistive pulse sensing (TRPS) technology, a widely adopted technique for characterizing nanoparticles in the field of nanotechnology, to measure the degree of eryptosis in a non-optical manner. With the TRPS system, we were able to determine PS externalization with microbeads functionalized with annexin-V for PS binding, cell swelling and shrinkage in physiological buffers (cell volume: 86 ± 12 fL) and solutions of different osmolarities with or without apoptotic trigger. After setting these standards, we then evaluated the toxicity of Polyphyllin D (PD), a potential anti-cancer drug that kills more liver cancer cells with multi-drug resistance, in erythrocytes to prove our concept. Data revealed that PD induced PS externalization and shrinkage in RBCs in a dose-dependent manner. Moreover, another feature of eryptosis, as small as 5 fL, was detected thus showing the PD-induced erythrotoxicity in human cells. Taken together, our results indicate that our approach using annexin-V-beads and TRPS is simple, safe and convenient, using only a small volume (35 µL) to evaluate the erythrotoxicity of xenobiotics.

Synthesis of novel anticancer agents through opening of spiroacetal ring of diosgenin.

Diosgenin has been modified to furostane derivatives after opening the F-spiroacetal ring. The aldehyde group at C26 in derivative 8 was unexpectedly transformed to the ketone 9. The structure of ketone 9 was confirmed by spectroscopy and finally by X-ray crystallography. Five of the diosgenin derivatives showed significant anticancer activity against human cancer cell lines. The most potent molecule of this series i.e. compound 7, inhibited cellular growth by arresting the population at G0/G1 phase of cell division cycle. Cells undergo apoptosis after exposure to the derivative 7 which was evident by increase in sub G0 population in cell cycle analysis. Docking experiments showed caspase-3 and caspase-9 as possible molecular targets for these compounds. This was further validated by cleavage of PARP, a caspase target in apoptotic pathway. Compound 7 was found non-toxic up to 1000mg/kg dose in acute oral toxicity in Swiss albino mice.

Dioscin enhances methotrexate absorption by down-regulating MDR1 in vitro and in vivo.

The purpose of this study was to investigate the enhancing effect of dioscin on the absorption of methotrexate (MTX) and clarify the molecular mechanism involved in vivo and in vitro. Dioscin increased MTX chemosensitivity and transepithelial flux in the absorptive direction, significantly inhibiting multidrug resistance 1 (MDR1) mRNA and protein expression and MDR1 promoter and nuclear factor κ-B (NF-κB) activities in Caco-2 cells. Moreover, inhibitor κB-α (IκB-α) degradation was inhibited by dioscin. Dioscin enhanced the intracellular concentration of MTX by down-regulating MDR1 expression through a mechanism that involves NF-κB signaling pathway inhibition in Caco-2 cells. Dioscin strengthened MTX absorption by inhibiting MDR1 expression in rat intestine. In addition, even though MTX is absorbed into the enterocytes, there was no increase in toxicity observed, and that, in fact, decreased toxicity was seen.

Identification of compounds from Paris polyphylla (ChongLou) active against Dactylogyrus intermedius.

The present study was designated to ascertain the anthelmintic activity of the rhizomes of Paris polyphylla and to isolate and characterize the active constituents. The methanol extract from rhizomes of P. polyphylla showed significant anthelmintic activity against Dactylogyrus intermedius with the median effective concentration (EC50) 22.5 mg L(-1). Based on this finding, the methanol extract was fractionated by silica gel column chromatography in a bioassay-guided fractionation yielding 2 bioactive compounds, the structures of these compounds were elucidated as formosanin C and polyphyllin VII. The in vivo tests revealed that formosanin C and polyphyllin VII were significantly effective against D. intermedius with EC50 values of 0.6 and 1.2 mg L(-1), respectively. The acute toxicities (LC50) of formosanin C and polyphyllin VII for grass carp were 2.8 and 2.9 mg L(-1), respectively. The overall results provide important information for the potential application of formosanin C and polyphyllin VII in the therapy of serious infection caused by D. intermedius.

A 90-day subchronic toxicological assessment of dioscin, a natural steroid saponin, in Sprague-Dawley rats.

Dioscin is the major active compound in many traditional Chinese medicines (TCMs), while safety evaluation of this natural product has not yet been investigated. Therefore, the aim of this study was to evaluate the 90-day subchronic toxicity of dioscin in rats. The rats were divided into four groups and dioscin was administered orally at doses of 0, 75, 150 and 300 mg/kg/day, respectively. The toxicity of dioscin was evaluated based on clinical observations, ophthalmic examination, body weight, food and water consumption, urinalysis, hematology, clinical biochemistry and pathology. The results showed that dioscin had no subchronic toxicity in female rats and had slight subchronic toxicity in male rats. However, male rats in the 300 mg/kg/day group showed slight gastro-intestinal tract distension during the treatment period and hemolytic anemia in the hematology assessment. Compared with the control group, body weight gain was significantly decreased in male rats. Other significant changes were not associated with dioscin in the male and female groups. In conclusion, the no-observed-adverse-effect level (NOAEL) and the lowest-observed-adverse-effect level (LOAEL) of dioscin are estimated to be 300 mg/kg/day for female and male rats, respectively. Our work provides useful data for further research and new drug exploration of dioscin.

Polyphyllin D induces apoptosis in human erythrocytes through Ca²âº rise and membrane permeabilization.

Polyphyllin D (PD) is a potent anticancer agent isolated from a traditional medicinal herb Paris polyphylla that has been used in China for many years to treat cancer. PD is not a substrate of p-glycoprotein, and it can bypass the multi-drug resistance in cancer cell line R-HepG2. However, the effect of PD on the induction of cell death in human erythrocytes remains unknown. Given that PD is a small molecule that can depolarize the mitochondrial membrane potential and release apoptosis-inducing factor (AIF) in isolated mitochondria, we hypothesized that the apoptogenic effect of PD in human erythrocytes devoid of mitochondria would be minimal. This study therefore tried to evaluate the in vitro effect of PD on hemolysis and apoptosis in human erythrocytes. Apoptosis in human red blood cells (RBCs), also known as eryptosis or erythroptosis, after PD treatment was determined by flow cytometry and confocal microscopy for the phosphatidyl-serine externalization and other apoptosis feature events. False to our prediction, PD caused hemolysis and eryptosis/erythroptosis in human RBCs. Mechanistically, elevation in the cytosolic Ca²âº ion level seems to be a key but not the only mediator in the PD-mediated eryptosis/erythroptosis because depletion of the external Ca²âº could not eliminate the PD effect. Also, PD was able to permeabilize the membrane of RBC ghosts in a way similar to digitonin. Taken together, we report here for the first time the toxicity of PD in human RBCs as well as its underlying mechanism for the hemolysis and eryptosis/erythroptosis.

Synthesis, antiproliferative activity, acute toxicity and assessment of the antiandrogenic activities of new androstane derivatives.

A number of 17-oxo-5-androsten-3ß-yl esters (9a-9f) and 3ß-alkoxy-5-androsten-17-ones (11a-11e) were synthesized from commercially available (25R)-5-spirosten-3ß-ol (Diosgenin) (4) as starting material. The synthesized compounds were evaluated for their antiproliferative activity against the prostate-specific cancer cell line DU-145, acute toxicity and effect on serum androgen levels, and compared with finasteride as positive control. Some of the compounds exhibited better cytotoxicity and antiandrogenic activity than the reference control. The detailed synthesis, spectroscopic data and biological activity of the synthesized compounds are reported.

Synthesis, cytotoxicity, and hemolytic activity of 6'-O-substituted dioscin derivatives.

Dioscin derivatives (1-12) with a variety of substitutions at the 6'-OH of the chacotriosyl residue and the 3',6'-anhydrosaponin derivatives (26, 30, and 32) were synthesized. All these derivatives showed much lower cytotoxicity than that of the parent dioscin, while their hemolytic activities were partially retained depending on the various 6'-O-substitutions.

Identification and characterization of several dietary alkaloids as weak inhibitors of hedgehog signaling.

The Hedgehog (Hh) signaling pathway plays an integral role in the patterning and development of diverse structures in the vertebrate embryo. Aberrations in Hh signaling are associated with a range of developmental defects including failure of interhemispheric division of the embryonic forebrain as well as midline facial dysmorphia including cleft lip/palate and cyclopia, collectively termed holoprosencephaly (HPE). Postnatally, Hh signaling has been postulated to play a pivotal role in healing and repair processes and inappropriate Hh pathway activation has been implicated in several types of cancers. The Veratrum alkaloid cyclopamine is a potent inhibitor of Hh signaling and causes HPE-like defects in diverse species including sheep, hamster, mouse, and zebra fish. Using murine cell-based assays, we have determined that a number of dietary alkaloids similar in structure to cyclopamine also inhibit Hh signaling but with significantly lower potency. We found that these dietary compounds act additively through a mechanism similar to cyclopamine, downstream of Ptc1 and upstream of Gli1. Using an embryonic zebra fish developmental assay, we found that while cyclopamine exposure caused HPE-like defects, exposure to one of these dietary compounds, solanidine, did not.

Synthesis and cytotoxicities of dioscin derivatives with decorated chacotriosyl residues.

Two series of dioscin derivatives (4a-o and 5a-o) with selected modifications at the 6' and 4''' positions of the chacotriosyl residue, respectively, were synthesized. All the 6'-N-acyl-dioscin derivatives did not show considerable inhibitory activities at 10 microM, while most of the 4'''-O-(2-N-acyl)ethyl-dioscin derivatives behaved as potent as dioscin, against the growth of tumor cells.

Microbial metabolism of methyl protodioscin by Aspergillus niger culture--a new androstenedione producing way from steroid.

Methyl protodioscin (1), a natural furostanol biglycoside steroid, was a preclinical anticancer drug, which showed potent activity against most cell lines from leukemia and solid tumors in the National Cancer Institute's (NCI) human cancer panel. Metabolism of methyl protodioscin by Aspergillus niger was investigated. Seven metabolites were isolated and identified. Two main metabolites were pregnane glycosides and four were furostanol glycosides, together with the aglycone. It was found that steroidal saponin skeleton could be converted to pregnenolone skeleton only using microbial methods, which must have chemical procedures in the reported literatures. The proposed biosynthetic pathways of the microbial conversion products of methyl protodioscin were drawn. The found enriched the reaction types of microbial bioconversion and provided a new producing way of androstenedione from steroid. Most metabolites showed strong cytotoxic activities against HepG2, NCI-H460, HeLa, and MCF-7 cell lines.

Proteomic approach to study the cytotoxicity of dioscin (saponin).

Dioscin, extracted from the root of Polygonatum zanlanscianense pamp, exhibits cytotoxicity towards human myeloblast leukemia HL-60 cells. Proteomic analysis revealed that the expression of mitochondrial associated proteins was substantially altered in HL-60 cells corresponding to the dioscin treatment, suggesting that mitochondria are the major cellular target of dioscin. Mitochondrial functional studies validated that mitochondrial apoptotic pathway was initiated by dioscin treatment. Changes in proteome other than mitochondrial related proteins implicate that other mechanisms were also involved in dioscin-induced apoptosis in HL-60 cells, including the activity impairment in protein synthesis, alterations of phosphatases in cell signaling, and deregulation of oxidative stress and cell proliferation. Current study of protein alterations in dioscin-treated HL-60 cells suggested that dioscin exerts cytotoxicity through multiple apoptosis-inducing pathways.