Milos Budesinsky

Platinum(II) complexes with steroidal esters of l-methionine and l-histidine: Synthesis, characterization and cytotoxic activity

Twelve steroidal platinum(II) complexes were synthesized by reaction of potassium tetrachloroplatinate with steroidal esters of L-methionine and L-histidine. The steroidal esters coordinated as bidentate ligands via S and N donor atoms of L-methionine and via two N donor atoms of L-histidine. Cholesterol, cholestanol, diosgenine, pregnenolone, dehydroepiandrosterone, testosterone, estrone, and estradiol were used as the steroidal compounds. The esters and complexes prepared were characterized by infrared, mass, and (1)H NMR spectroscopy and elemental analysis. Platinum complexes were tested for in vitro cytotoxicity against several cancer cell lines: T-lymphoblastic leukemia CEM, breast carcinoma MCF-7, lung carcinoma A-549, multiple myeloma RPMI 8226, and one normal cell line human fibroblast BJ.

The complete Consensus V3 loop peptide of the envelope protein gp120 of HIV-1 shows pronounced helical character in solution

The disulfide bridge closed cyclic peptide corresponding to the whole Consensus V3 loop of the envelope protein gp120 of HIV‐1 was examined by proton 2D‐NMR spectroscopy in water and in a 20% trifluoroethanol/water solution. In water, NOE data support a β‐turn conformation for the central conservative GPGR region and point towards partial formation of a helix in the C‐terminal part. Upon addition of trifluoroethanol, a C‐terminal helix is formed. This is evidenced by NOE data, α‐proton chemical shift changes and changes in the J Nα vicinal coupling constants. The C‐terminal helix is amphipathic and also occurs in other examined strains. It could therefore be an important feature for the functioning of the V3 loop.

Brassinosteroids: synthesis and activity of some fluoro analogues.

Three types of 5alpha-androstane and ergostane analogues of brassinolide, containing a fluorine atom in either the 3alpha or the 5alpha positions or in 3alpha and 5alpha positions, were prepared using standard operations (reaction of 3beta-alcohols with (diethylamino)sulfur trifluoride, cleavage of epoxide with HF in py or BF 3.Et 2O). The 5alpha-fluorine was found to affect chemical reactivity (e.g., electrophilic addition to the Delta (2)-double bond) as well as physical properties (e.g., NMR, chromatographic behavior) of the products. Cytotoxicity of the products was studied using human normal and cancer cell lines with 28-homocastasterone as positive control and their brassinolide type activity was established using the bean second-internode test with 24-epibrassinolide as standard. The equivalence of F and OH groups was observed in some of the active compounds. The anticancer and the brassinolide-type activity do not correlate with each other: ergostane derivatives were most active in the former test while androstane derivatives were best in the latter.

Regioselective synthesis of polysubstituted 3,3′-bi-1H-pyrazole derivatives via 1,3-dipolar cycloaddition reactions

Abstract N,N′-Diarylbisnitrile imides 2 add regioselectively to α-(benzothiazol-2-yl)cinnamonitriles 3 and α-(1-methylbenzimidazol-2-yl)cinnamonitriles 7 to yield exclusively the cycloadducts 5,5′-dicyano-4,4′,5,5′-tetrahydro[3,3′-bi-1H-pyrazoles] 4 and 8, respectively. Compounds 4 and 8 undergo aromatization via thermal elimination of hydrogen cyanide under basic conditions to afford the corresponding 3,3′-bi-1H-pyrazole derivatives 6 and 10, respectively. The regiochemistry of the cycloadducts is discussed.

Norsesquiterpene hydrocarbon, chemical composition and antimicrobial activity of Rhaponticum carthamoides root essential oil

A detailed analysis of Rhaponticum carthamoides (Willd.) Iljin root essential oil was carried out by GC, GC-MS and GC-FTIR techniques. In total, 30 components were identified, accounting for 98.0% of total volatiles. A norsesquiterpene 13-norcypera-1(5),11(12)-diene (22.6%), followed by aplotaxene (21.2%) and cyperene (17.9%), were isolated and their structures confirmed by 1D and 2D-NMR spectra (COSY, ROESY, HSQC, HMBC and INADEQUATE). Selinene type sesquiterpenes and aliphatic hydrocarbons were among minor constituents of the essential oil. The oil exhibited antimicrobial activity against 5 of 9 strains of bacteria and yeast, when tested using broth micro-dilution method. Minimum inhibitory concentrations ranged between 32 and 256 microg/ml.

Physicochemical and biological properties of novel amide-based steroidal inhibitors of NMDA receptors

Graphical abstract Figure. No Caption available. HighlightsSynthesis of new amide‐based inhibitors of NMDA receptors.Strong inhibitors of NMDA currents.The Caco‐2 assay was used to evaluate permeability of new compounds.Compounds with minimal or no adverse hepatic effect.Amide‐based inhibitors of NMDA receptors are able to cross blood‐brain‐barrier. Abstract Herein, we report a new class of amide‐based inhibitors (1–4) of N‐methyl‐d‐aspartate receptors (NMDARs) that were prepared as analogues of pregnanolone sulfate (PAS) and pregnanolone glutamate (PAG) – the steroidal neuroprotective NMDAR inhibitors. A series of experiments were conducted to evaluate their physicochemical and biological properties: (i) the inhibitory effect of compounds 3 and 4 on NMDARs was significantly improved (IC50 = 1.0 and 1.4 &mgr;M, respectively) as compared with endogenous inhibitor – pregnanolone sulfate (IC50 = 24.6 &mgr;M) and pregnanolone glutamate (IC50 = 51.7 &mgr;M); (ii) physicochemical properties (logP and logD) were calculated; (iii) Caco‐2 assay revealed that the permeability properties of compounds 2 and 4 are comparable with pregnanolone glutamate; (iv) compounds 1–4 have minimal or no adverse hepatic effect; (v) compounds 1–4 cross blood‐brain‐barrier.

Etienic etienate as synthon for the synthesis of steroid oligoester gelators

Linear oligoesters based on etienic acid (3beta-hydroxyandrost-5-ene-17beta-carboxylic acid) containing four steroid units were prepared using a 2+2 synthetic strategy in a successful synthesis of 3beta-{[3beta-({3beta-[(3beta-hydroxyandrost-5-ene-17beta-carbonyl)oxy]androst-5-ene-17beta-carbonyl}oxy)androst-5-ene-17beta-carbonyl]oxy}androst-5-ene-17beta-carboxylic acid. The main problems with deprotection were overcome by using orthogonal groups as O-nitrates and 2-(trimethylsilyl)ethyl ethers.

A New Class of Potent N-Methyl-d-Aspartate Receptor Inhibitors: Sulfated Neuroactive Steroids with Lipophilic D-Ring Modifications

N-Methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels that play a crucial role in excitatory synaptic transmission. However, the overactivation of NMDARs can lead to excitotoxic cell damage/death, and as such, they play a role in numerous neuropathological conditions. The activity of NMDARs is known to be influenced by a wide variety of allosteric modulators, including neurosteroids, which in turn makes them promising therapeutic targets. In this study, we describe a new class of neurosteroid analogues which possess structural modifications in the steroid D-ring region. These analogues were tested on recombinant GluN1/GluN2B receptors to evaluate the structure-activity relationship. Our results demonstrate that there is a strong correlation between this new structural feature and the in vitro activity, as all tested compounds were evaluated as more potent inhibitors of NMDA-induced currents (IC50 values varying from 90 nM to 5.4 μM) than the known endogeneous neurosteroid-pregnanolone sulfate (IC50 = 24.6 μM).

Synthesis and cytotoxic activities of estrone and estradiol cis-dichloroplatinum(II) complexes.

Sixteen platinum(II) complexes of estrone and estradiol were synthesized in this work to evaluate their cytotoxic activity against several cancer cell lines including estrogen dependent and independent ones. The synthesis of all the complexes was done in three steps. The reaction of steroids with dibromoalkanes was followed by a reaction of the bromoalkyl steroids with 2-(aminomethyl)pyridine or 2-(2-aminoethyl)pyridine. The last step was a reaction of steroidal diamino ligands with potassium tetrachloroplatinate to obtain the desired platinum(II) complexes. Cytotoxicity assays showed that most of the complexes prepared are active against the cancer cell lines used-CEM, U-2 OS, MCF7, MCF7 AL, MDA-MB-468, BT-474, BT-549, and BJ fibroblasts. The six-membered platinum complexes are more active than five-membered ones.

Allopregnanolone (3α-Hydroxy-5α-pregnan-20-one) Derivatives with a Polar Chain in Position 16α: Synthesis and Activity

The lipophilic nature of allopregnanolone prevents its user-friendly application in human medicine. On inspiration by previously prepared allopregnanolone with a 16alpha-bound tetraethylammonium salt, an attempt was made to produce allopregnanolone analogues with polar groups introduced into position 16alpha with the goal of increasing water solubility, brain accessibility, and potency of neuroactive steroids. The Michael addition to derivatives of pregn-16-en-20-one was the key reaction step. The link between the steroid skeleton and the new side chain was either a methylene group (when diethyl malonate was added) or an oxygen atom (when a hydroxy derivative was added). [(35)S]TBPS displacement was used to evaluate the products. Several carbamates (but not their parent alcohols) displaced TBPS from the picrotoxin binding site on GABA(A) receptors. Although none of them was more potent than the above ammonium salt, which stimulated this study, their nonionic nature should not prevent their passage into the brain.