8 research outputs found
Cytotoxicity of Triterpene Seco-Acids from Betula pubescens Buds
The present study investigated the magnitude and mechanism of the cytotoxic effect on selected cancer cell lines of 3,4-seco-urs-4(23),20(30)-dien-3-oic acid (1), 3,4-seco-olean-4(24)-en-19-oxo-3-oic acid (2), and 3,4-seco-urs-4(23),20(30)-dien-19-ol-3-oic acid (3) isolated from downy birch (Betula pubescens) buds by carbon dioxide supercritical fluid extraction and gradient column chromatography. Cell viability in six human cancer lines exposed to these compounds was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was quantified by annexin V/propidium iodide staining of gastric cancer AGS and colorectal cancer DLD-1 cells. To evaluate the mechanism of apoptosis, the expression of apoptosis-related proteins was analyzed by Western blot. Compound 1 exhibited non-specific toxicity, while compounds 2 and 3 were specifically toxic to colon and stomach cancer cells. The toxicity of compounds 2 and 3 against these two cell lines was greater than for compound 1. Cleavage of caspase-8, -9, and -3 was found in AGS and DLD-1 cells treated with all three seco-acids, indicating the induction of apoptosis via extrinsic and intrinsic pathways. Therefore, triterpene seco-acids (1–3) decreased cell viability by apoptosis induction. AGS and DLD-1 cells were more susceptible to seco-acids with an oxidized C19 than normal fibroblasts. Hence, it made them a new group of triterpenes with potential anticancer activity
Ferutinin as a Ca<sup>2+</sup> complexone: Lipid bilayers, conductometry, FT-IR, NMR studies and DFT-B3LYP calculations
Calcium ionophoretic properties of ferutinin were re-evaluated in solvent-containing bilayer lipid membranes. The slopes of conductance-concentration curves suggest that in the presence of a solvent in the membrane the majority of complexes appear to consist of a single terpenoid molecule bound to one Ca ion. By contrast, the stoichiometry of ferutinin-Ca2+ complexes in acetone determined using the conductometric method was 2 :1. While the cation-cation selectivity of ferutinin did not change, the cation-anion selectivity slightly decreased in solvent containing membranes. FT-IR and NMR data together with DFT calculations at the B3LYP/6-31G(d) level of theory indicate that in the absence of Ca ions ferutinin molecules are hydrogen-bonded at the phenol hydroxyl groups. The variations of absorption assigned to -OH and -C-O stretching mode suggest that ferutinin interacts strongly with Ca ions via the hydroxyl group of ferutinol and carboxyl oxygen of the complex ether bond. The coordination through the carbonyl group of ferutinin was demonstrated by theoretical calculations. Taken together, ferutinin molecules form H-bonded dimers, while complexation of Ca2+ by ferutinin ruptures this hydrogen bond due to spatial re-orientation of the ferutinin molecules from parallel to antiparallel alignment.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
PhSeZnCl in the Synthesis of Steroidal 尾-Hydroxy-Phenylselenides Having Antibacterial Activity
We report here the reaction of in situ prepared PhSeZnCl with steroid derivatives having an epoxide as an electrophilic functionalization. The corresponding ring-opening reaction resulted to be regio- and stereoselective affording to novel phenylselenium-substituted steroids. Assessment of their antibacterial properties against multidrug-resistant bacteria, such as Pseudomonas aeruginosa Xen 5 strain, indicates an interesting bactericidal activity and their ability to prevent bacterial biofilm formation
Photoinduced Isomerization of 23-Oxosapogenins: Conformational Analysis and Spectroscopic Characterization of 22-Isosapogenins
The first synthesis of 22-isospirostane derivatives is
described.
They were obtained by photochemical isomerization of 23-oxosapogenins.
The structure of 23-oxo-22-isotigogenin acetate (<b>12</b>)
was proved by a single crystal X-ray diffraction, while structures
of 23-oxo-22-isodiosgenin acetate (<b>13</b>) and 23-oxo-22-isosarsasapogenin
acetate (<b>14</b>) were elucidated by spectroscopic methods.
22-Isodiosgenin acetate (<b>17</b>) was obtained by NaBH<sub>4</sub> reduction of the 23-oxo derivative <b>13</b> followed
by the two-step Barton鈥揗cCombie deoxygenation procedure. Conformational
analysis of 22-iso compounds was carried out with CD and NMR, as well
as DFT calculations
Oxidation of Olefins with Benzeneseleninic Anhydride in the Presence of TMSOTf
A new
oxidizing system for olefins, consisting of benzeneseleninic
anhydride and trimethylsilyl triflate, was studied. The highly reactive
benzeneseleninyl cation is presumably formed under these conditions.
It has been shown that different products are formed with this species
depending on the specific structure of olefin. The 1,1-disubstituted
olefins afforded mostly 伪,尾-unsaturated carbonyl compounds.
The sterically encumbered tri- or tetrasubstituted olefins yielded
1,2- or 1,4-dihydroxylated products, presumably via four-membered
cyclic intermediates