Seasonal variation in toxic steroidal alkaloids of foothill death camas (Zigadenus paniculatus)

Death camas (Zigadenus spp.) is a common poisonous plant in North America with plants occurring in a wide variety of habitats with species of toxic concern occurring primarily in meadows, grasslands, shrublands, and mountains. The toxicity of Zigadenus species has been attributed to a series of steroidal alkaloids. The objective of this study was to evaluate zygacine and total steroidal alkaloid concentrations in different plant tissues of Zigadenus paniculatus as a function of plant maturity. Death camas plants were collected at two locations at different developmental growth stages representing vegetative, flower, seed pod, and shattered seed pod stages. Zygacine represented greater than 50% of the total steroidal alkaloids at all developmental stages. In bulbs, total steroidal alkaloid and zygacine concentrations did not change significantly as a function of plant phenology, and concentrations were lower than what were observed in above ground plant parts. Total steroidal alkaloid and zygacine concentrations in above ground parts were highest at early vegetative growth stages and decreased over the growing season. In plant reproductive parts, total steroidal alkaloid and zygacine concentrations increased until maturity and then decreased as the plant senesced. The concentrations of steroidal alkaloids reported here suggest that the toxic risk associated with death camas is greatest in the early vegetative growth stages followed by the flower and pod stages. There is a toxic risk to livestock as long as the plant is present, and caution should be taken when grazing livestock in areas with death camas until the plant senesces.     

Steroidal glycosides from the bulbs of Bessera elegans and their cytotoxic activities

Examination of the bulbs of Bessera elegans (Liliaceae) led to isolation of nine new and five known steroidal glycosides. The structures of the nine compounds were determined based on the results of spectroscopic analysis, including two-dimensional NMR, and hydrolysis followed by chromatographic and spectroscopic analysis. The isolated compounds and derivatives were evaluated for cytotoxicity against HL-60 human promyelocytic leukemia cells, A549 human lung adenocarcinoma cells, and TIG-3 normal human diploid fibroblasts. One compound, the pseudo-furostanol glycoside, induced apoptosis in HL-60 and A549 cells in a time-dependent manner and cell-cycle arrest at the G0/G1 phase in A549 cells.     

Liquid chromatography tandem mass spectrometry in study of the pharmacokinetics of six steroidal saponins in rats

A rapid, simple and sensitive high-performance liquid chromatography tandem mass spectrometry method was developed and validated for simultaneous determination of six main steroidal saponins in Paris polyphylla in rat plasma. Ginsenoside Rg3 was selected as the internal standard (IS). Plasma samples were pretreated with protein precipitation, and the separation was achieved on a reverse phase Agilent poroshell120 EC-C18 column using a gradient mobile phase system of acetonitrile–water containing 0.1% formic acid. The triple quadruple mass spectrometer was set in negative electrospray ionization mode and multiple reaction monitoring (MRM) was used for six steroidal saponins quantification. The precursors to produce ion transitions monitored for polyphyllin I, polyphyllin II, polyphyllin VI, polyphyllin VII, dioscin, gracillin and IS were m/z 899.5 > 853.4, 1059.5 > 1013.5, 783.4 > 737.4, 1075.5 > 1029.5, 913.5 > 867.4, 929.5 > 883.4 and 819.5 > 783.4, respectively. The intra- and inter-day precisions (RSD%) were less than 13% and the average extraction recoveries ranged from 85% to 97.0% for each analyte. Six steroidal saponins were proved to be stable during sample storage, preparation and analytical procedures. The established method was employed for simultaneous quantification and successfully used for the first time for the pharmacokinetics evaluation of the six main compounds after intragastric administration of P. polyphylla extract in Sprague–Dawley rats.     

Characteristic Steroids from the South China Sea Gorgonian Muricella sibogae and Their Cytotoxicities

Twenty‐four steroid‐based natural products, 9,10‐secosteroids ( 1 – 10 ), 1,4‐dien‐3‐one steroids ( 11 – 19 ), and 4‐en‐3‐one steroids ( 20 – 24 ), containing varying side‐chains, were isolated from the South China Sea gorgonian Muricella sibogae. The structures of one new 9,10‐secosteroid, sibogol D ( 1 ), and two new 1,4‐dien‐3‐one steroids, sibogols E and F ( 11 and 12 ), were elucidated by extensive spectroscopic analyses and by comparison with the literature data. Cytotoxicities for all the isolates were evaluated against four selected tumor cell lines, HL‐60, HCT116, K562, and P388. Compounds 3, 9 , and 13 exhibited potent cytotoxic activities against the HL‐60 cell line, with IC₅₀ values ranging from 1.27 to 10.05 μM , and compound 3 was also cytotoxic against HCT116 with an IC₅₀ value of 5.8 μM . The bioassay results also indicated a potential relationship between structural patterns and activity. The newly presented series of 1,4‐dien‐3‐one and 4‐en‐3‐one types of steroids relating to the unique 9,10‐secosteroids in biogenesis were found in this species for the first time, which is of considerable chemotaxonomic significance.     

New lipoxygenase-inhibiting constituents from Calligonum polygonoides

Calligonolides A (1) and B (2), two new butanolides, and a new steroidal ester, 3, have been isolated from the whole plant of Calligonum polygonoides, together with four known compounds, tetracosan-4-olide, beta-sitosterol and its glucoside, and ursolic acid. Their structures were elucidated by spectroscopic and mass-spectrometric studies. Compounds 1-3 showed moderate inhibitory potential against lipoxygenase from soybean.     

Tissue distribution of cholinesterases and anticholinesterases in native and transgenic tomato plants

Acetylcholinesterase, a major component of the central and peripheral nervous systems, is ubiquitous among multicellular animals, where its main function is to terminate synaptic transmission by hydrolyzing the neurotransmitter, acetylcholine. However, previous reports describe cholinesterase activities in several plant species and we present data for its presence in tomato plants. Ectopic expression of a recombinant form of the human enzyme and the expression pattern of the transgene and the accumulation of its product in transgenic tomato plants are described. Levels of acetylcholinesterase activity in different tissues are closely effected by and can be separated from -tomatine, an anticholinesterase steroidal glycoalkaloid. The recombinant enzyme can also be separated from the endogenous cholinesterase activity by its subcellular localization and distinct biochemical properties. Our results provide evidence for the co-existence in tomato plants of both acetylcholinesterase activity and a steroidal glycoalkaloid with anticholinesterase activity and suggest spatial mutual exclusivity of these antagonistic activities. Potential functions, including roles in plant-pathogen interactions are discussed.     

雀舌黄杨的甾体生物碱

从昆明植物园载培的南方常见的园艺植物雀舌黄杨（Buxus bodinieri Levl.)中得到了5个新甾体生物碱成分雀舌黄杨碱A－E（1－5）,通过波谱解析确定了化学结构。     

Two new glycosides and one new neolignan from the roots of Cynanchum stauntonii

Three new compounds including one C₂₁-steroidal glycoside, one methylglycoside, and one neolignan, named as Deoxyamplexicogenin A-3-O-yl-4-O-(4-O-α-l-cymaropyranosoyl-β-d-digitoxopyranosoyl)-β-d-canaropyranoside (1), Methyl-O-α-l-cymaropyranosoyl-(1 → 4)-β-D-digitoxopyranoside (2), and (+)-(7S, 8R, 7′E)-5-hydroxy-3, 5′-dimethoxy-4′, 7-epoxy-8, 3′-neolign-7′-ene-9, 9′-diol 9′-ethyl ether (3), respectively, were isolated from the roots of Cynanchum stauntonii. The structure elucidations were achieved by in-depth spectroscopic examination, mainly including the experiments and analyses of multiple 1D- and 2D-NMR and HRESIMS and CD analysis and qualitative chemical tests. Cytotoxicity activities of compounds 1–3 were evaluated against five tumor cell lines (HCT-8, Bel-7402, BGC-823, A549, and A2780) in cell based assays where they were found to be inactive.     

Steroidal saponins from Asparagus acutifolius

Six new steroidal saponins (1-6) were isolated from the roots of A. acutifolius L., together with a known spirostanol glycoside (7). Their structures were elucidated mainly by extensive spectroscopic analysis (1D and 2D NMR, FABMS and HRESIMS). Compounds 4-7 demonstrated antifungal activity against the human pathogenic yeasts C. albicans, C. glabrata and C. tropicalis with MICs values between 12.5 and 100 microg/ml.     

A new steroidal saponin from Allium ampeloprasum var. porrum with antiinflammatory and gastroprotective effects

A new steroidal saponin was isolated from the bulbs of Allium ampeloprasum var. porrum. On the basis of chemical conversions and detailed analyses of ¹H and ¹³C NMR spectra including 2D NMR spectroscopic techniques, its structure was established as 3-[(O-β-d-glucopyranosyl-(1 → 3)-β-d-glucopyranosyl-(1 → 2)-O-[O-β-d-glucopyranosyl-(1 → 3)]-O-β-d-glucopyranosyl-(1 → 4)-β-d-galactopyranosyl)oxy]-2,6-dihydroxy-(2α,3β,5α,6β,25R)-spirostane. Results of the present study indicated that the steroidal saponin showed haemolytic effects in the in vitro assays and demonstrated antiinflammatory activity and gastroprotective property using in vivo models.