Structure–Activity Relationship Analysis of Bufadienolide-Induced in Vitro Growth Inhibitory Effects on Mouse and Human Cancer Cells

The in vitro growth inhibitory effects of 27 bufadienolides and eight degradation products, with two cardenolides (ouabain and digoxin) chosen as reference compounds, were analyzed by means of an MTT colorimetric assay in six human and two mouse cancer cell lines. A structure–activity analysis was then performed to highlight the most important substituents relating to the in vitro growth inhibitory activity of bufadienolides in cancer cells. Thus, the current study revealed that various bufadienolides, including gamabufotalin rhamnoside (<b>1a</b>), bufotalin (<b>2a</b>), and hellebrin (<b>3a</b>), displayed higher growth inhibitory activities for various human cancer cell lines when compared to ouabain and digoxin. Gamabufotalin rhamnoside (<b>1a</b>) was the only compound that displayed growth inhibitory effects of <1 μM in mouse cancer cells that expressed mutated forms of the Na⁺,K⁺-ATPase α-1 subunit. In addition, all genins and degradation products displayed weaker (if any) in vitro growth inhibitory effects on cancer cells when compared to their respective glycosylated homologue, with the exception of hellebrigenin (<b>3b</b>), which was as active as hellebrin (<b>3a</b>)

Characterization of Glucocerebrosides and the Active Metabolite 4,8-Sphingadienine from <i>Arisaema amurense</i> and <i>Pinellia ternata</i> by NMR and CD Spectroscopy and ESI-MS/CID-MS

Sphingolipid metabolites regulate cellular processes such as cell proliferation, differentiation, and apoptosis. In this study, glucocerebrosides (GluCer) from rhizomes of <i>Arisaema amurense</i> and <i>Pinellia ternata</i> were fully characterized using 1- and 2-dimensional nuclear magnetic spin resonance (NMR) and circular dichroism (CD) spectroscopy and tandem collision-induced dissociation mass spectrometry (ESI-MS/CID-MS). Three new acylated and seven known GluCer were elucidated with 4,8-sphingadienine (4,8-SD, d18:2) as backbone. 4,8-SD is a metabolite after enzymatical hydrolysis of GluCer in the gut lumen. In this study, 4,8-SD was hydrolyzed from GluCer and chromatographically purified on silica gel. In contrast to the GluCer, 4,8-SD showed cytotoxic effects in the WST-1 assay. GluCer with 4,8-SD as sphingoid backbone are present in plants consumed as food, such as spinach, soy, and eggplant

Characterization of Glucocerebrosides and the Active Metabolite 4,8-Sphingadienine from <i>Arisaema amurense</i> and <i>Pinellia ternata</i> by NMR and CD Spectroscopy and ESI-MS/CID-MS

Sphingolipid metabolites regulate cellular processes such as cell proliferation, differentiation, and apoptosis. In this study, glucocerebrosides (GluCer) from rhizomes of <i>Arisaema amurense</i> and <i>Pinellia ternata</i> were fully characterized using 1- and 2-dimensional nuclear magnetic spin resonance (NMR) and circular dichroism (CD) spectroscopy and tandem collision-induced dissociation mass spectrometry (ESI-MS/CID-MS). Three new acylated and seven known GluCer were elucidated with 4,8-sphingadienine (4,8-SD, d18:2) as backbone. 4,8-SD is a metabolite after enzymatical hydrolysis of GluCer in the gut lumen. In this study, 4,8-SD was hydrolyzed from GluCer and chromatographically purified on silica gel. In contrast to the GluCer, 4,8-SD showed cytotoxic effects in the WST-1 assay. GluCer with 4,8-SD as sphingoid backbone are present in plants consumed as food, such as spinach, soy, and eggplant

Triterpenoic Acids from Apple Pomace Enhance the Activity of the Endothelial Nitric Oxide Synthase (eNOS)

Pomace is an easy-accessible raw material for the isolation of fruit-derived compounds. Fruit consumption is associated with health-promoting effects, such as the prevention of cardiovascular disease. Increased vascular nitric oxide (NO) bioavailability, for example, due to an enhanced endothelial nitric oxide synthase (eNOS) activity, could be one molecular mechanism mediating this effect. To identify compounds from apple (Malus domestica Borkh.) pomace that have the potential to amplify NO bioavailability via eNOS activation, a bioassay-guided fractionation of the methanol/water (70:30) extract has been performed using the ¹⁴C-l-arginine to ¹⁴C-l-citrulline conversion assay (ACCA) in the human endothelium-derived cell line EA.hy926. Phytochemical characterization of the active fractions was performed using the spectrophotometric assessment of the total phenolic content, as well as TLC, HPLC-DAD-ELSD, and HPLC-MS analyses. Eleven triterpenoic acids, of which one is a newly discovered compound, were identified as the main constituents in the most active fraction, accompanied by only minor contents of phenolic compounds. When tested individually, none of the tested compounds exhibited significant eNOS activation. Nevertheless, cell stimulation with the reconstituted compound mixture restored eNOS activation, validating the potential of apple pomace as a source of bioactive components

Cytotoxic Constituents from <i>Lobaria scrobiculata</i> and a Comparison of Two Bioassays for Their Evaluation

Lichens are resilient organisms, known for their unique profiles of secondary metabolites and for exhibiting antioxidative, antibacterial, and cytotoxic effects. Analyzing the cytotoxic potential of <i>Lobaria scrobiculata</i>, a bioassay-guided fractionation strategy yielded seven known metabolites, with two of these compounds, <b>2</b> and <b>3</b>, exhibiting cytotoxicity against HL-60 cells. In order to verify the potential impact of degradation on observed bioactivity, a purity and stability evaluation was conducted. The consistency of results obtained by the water-soluble tetrazolium salt-1 assay and trypan blue cytotoxicity assay was evaluated for selected compounds

Identification of Ostruthin from <i>Peucedanum ostruthium</i> Rhizomes as an Inhibitor of Vascular Smooth Muscle Cell Proliferation

Inhibition of vascular smooth muscle cell (VSMC) proliferation is of substantial interest in combating cardiovascular disease. A dichloromethane extract from the rhizomes of <i>Peucedanum ostruthium</i>, a traditionally used Austrian medicinal plant with anti-inflammatory properties, was examined for a putative antiproliferative activity in rat aortic VSMC. This extract inhibited serum (10%)-induced VSMC proliferation concentration dependently. Further identification and biological testing of its major constituents revealed that the coumarin ostruthin (<b>7</b>) is the major antiproliferative substance. In summary, a new bioactivity of <i>P. ostruthium</i> rhizomes is described, and <b>7</b> has been identified as the responsible compound