Steroid Skeleton Research Articles

Predicting the Binding Mode of 2-Hydroxypropyl-β-cyclodextrin to Cholesterol by Means of the MD Simulation and the 3D-RISM-KH Theory.

It has been found that a cyclodextrin derivative, 2-hydroxypropyl-β-cyclodextrin (HPβCD), has reasonable therapeutic effect on Niemann-Pick disease type C, which is caused by abnormal accumulation of unesterified cholesterol and glycolipids in the lysosomes and shortage of esterified cholesterol in other cellular compartments. We study the binding affinity and mode of HPβCD with cholesterol to elucidate the possible mechanism of HPβCD for removing cholesterol from the lysosomes. The dominant binding mode of HPβCD with cholesterol is found based on the molecular dynamics simulation and a statistical mechanics theory of liquids, or the three-dimensional reference interaction site model theory with Kovalenko-Hirata closure relation. We examine the two types of complexes between HPβCD and cholesterol, namely, one-to-one (1:1) and two-to-one (2:1). It is predicted that the 1:1 complex makes two or three types of stable binding mode in solution, in which the βCD ring tends to be located at the edge of the steroid skeleton. For the 2:1 complex, there are four different types of the complex conceivable, depending on the orientation between the two HPβCDs: head-to-head (HH), head-to-tail (HT), tail-to-head (TH), and tail-to-tail (TT). The HT and HH cyclodextrin dimers show higher affinity to cholesterol compared to the other dimers and to all the binding modes of 1:1 complexes. The physical reason why the HT and HH dimers have higher affinity compared to the other complexes is discussed based on the consistency with the 1:1 complex. On the one hand, in case of the HT and HH dimers, the position of each CD in the dimer along the cholesterol chain comes right on or close to one of the positions where a single CD makes a stable complex. On the other hand, one of the CD molecules is located on unstable region along the cholesterol chain, for the case of TH and TT dimers.

Micellisation of Binary Mixtures of Surfactants Na-Deoxycholate–Na-Decyl Sulfate and Na-Hyodeoxycholate–Na-Decyl Sulfate in Water Solutions: Rational Development of the Thermodynamic Model for the Excess Gibbs Energy (GE)

Micellisation of two binary mixtures, sodium decyl sulfate (NaDS)–sodium deoxycholate (NaDC) and sodium decyl sulfate (NaDS)–sodium hyodeoxychlolate (NaHDC), is examined, in consideration with the different molar fractions of the monomers (x = 0.1–0.9). In bile acids, the OH groups attached to steroid skeletons are spatially ecraned, while the sulfate group of NaDS is not ecraned. Thus, NaDC and NaHDC in relation to NaDS have different coordination numbers in the micelle pseudophase. On the basis of stereochemical analysis, rational design shows that the excess Gibbs energy (GE) of formation of the binary mixed micelle throughout the whole composition range can be described with a two-parameter Margules function, while the GE function from the regular solution theories is applicable only in the narrow interval of the bile salts molar fractions (x = 0.5– 0.8). Coefficient of activity (hypothetical) of the infinitely diluted mixed micelle of NaDS in the presence of NaDC shows significant thermodynamic stabi...

Skeleton-Controlled pDNA Delivery of Renewable Steroid-Based Cationic Lipids, the Endocytosis Pathway Analysis and Intracellular Localization.

Using renewable and biocompatible natural-based resources to construct functional biomaterials has attracted great attention in recent years. In this work, we successfully prepared a series of steroid-based cationic lipids by integrating various steroid skeletons/hydrophobes with (l-)-arginine headgroups via facile and efficient synthetic approach. The plasmid DNA (pDNA) binding affinity of the steroid-based cationic lipids, average particle sizes, surface potentials, morphologies and stability of the steroid-based cationic lipids/pDNA lipoplexes were disclosed to depend largely on the steroid skeletons. Cellular evaluation results revealed that cytotoxicity and gene transfection efficiency of the steroid-based cationic lipids in H1299 and HeLa cells strongly relied on the steroid hydrophobes. Interestingly, the steroid lipids/pDNA lipoplexes inclined to enter H1299 cells mainly through caveolae and lipid-raft mediated endocytosis pathways, and an intracellular trafficking route of “lipid-raft-mediated endocytosis→lysosome→cell nucleic localization” was accordingly proposed. The study provided possible approach for developing high-performance steroid-based lipid gene carriers, in which the cytotoxicity, gene transfection capability, endocytosis pathways, and intracellular trafficking/localization manners could be tuned/controlled by introducing proper steroid skeletons/hydrophobes. Noteworthy, among the lipids, Cho-Arg showed remarkably high gene transfection efficacy, even under high serum concentration (50% fetal bovine serum), making it an efficient gene transfection agent for practical application.

Matched Coupling of Propargylic Carbonates with Cyclopropanols.

The ring opening-coupling reaction of cyclopropanols with propargylic carbonates affording synthetically attractive allenyl ketones has been developed. The mechanism involves the ligand-exchange reaction of in situ formed allenyl palladium methoxide with cyclopropanols followed by carbon-carbon bond cleavage and reductive elimination. The reactions proceeded smoothly under mild reaction conditions with Pd(0)/XPhos catalysis in the absence of any external base and displayed a wide scope and application to a steroidal skeleton. The efficiency of chirality transfer and synthetic utility of the allene products have also been demonstrated.

Sterol Sulfates and Sulfotransferases in Marine Diatoms.

Sterol sulfates are widely occurring molecules in marine organisms. Their importance has been so far underestimated although many of these compounds are crucial mediators of physiological and ecological functions in other organisms. Biosynthesis of sterol sulfates is controlled by cytosolic sulfotransferases (SULTs), a varied family of enzymes that catalyze the transfer of a sulfo residue (-SO3H) from the universal donor 3'-phosphoadenosine-5'-phosphosulfate to the hydroxyl function at C-3 of the steroid skeleton. The absence of molecular tools has been the main impediment to the development of a biosynthetic study of this class of compounds in marine organisms. In fact, there is very limited information about these enzymes in marine environments. SULT activity has, however, been reported in several marine species, and, recently, the production of sterol sulfates has been linked to the control of growth in marine diatoms. In this chapter, we describe methods for the study of sterol sulfates in this lineage of marine microalgae. The main aim is to provide the tools useful to deal with the biosynthesis and regulation of these compounds and to circumvent the bottleneck of the lack of molecular information. The protocols have been designed for marine diatoms, but most of the procedures can be used for other marine organisms.

Synthesis and antitumor activity of alkylated bile acids and oxazolines

Bile acid derivatives with a free carboxylic group or an oxazoline ring in the side chain and with different lengths of alkyl chains on steroid skeleton were synthetized and their antitumor activity against six human cancer cell lines was investigated. Methyl, ethyl, butyl or octyl chains were introduced stereoselectively by Grignard reaction at C-7 of acid and oxazoline, and at C-12 of oxazoline. Carbonyl group at C-12 of acid compound gave addition product only with methyl Grignard reagent, and complex mixture of products with other used reagents. Due to enolization, the C-3 carbonyl group did not participate in the Grignard reaction. Steric reasons are a main cause of this chemical behavior. Compounds with a butyl chain at the C-7 position showed very good antitumor activity with IC50 < 5 μM.

A homologues prediction strategy for comprehensive screening and characterization of C21 steroids from Xiao-ai-ping injection by using ultra high performance liquid chromatography coupled with high resolution hybrid quadrupole-orbitrap mass spectrometry

Because of the complicated chemical composition of Traditional Chinese Medicines, their chemical profile study has been a great challenge. In the present work, a homologues prediction strategy for rapid screening and identification of C21 steroids in Xiao-ai-ping injection was developed by using an ultra high performance liquid chromatography coupled with high resolution hybrid quadrupole-orbitrap mass spectrometry. This strategy was characterized by the design of C21 steroidal skeleton, substituent group and glycan chain in an orderly way, which could quickly and efficiently screen the interested precursor ions. As a result, a total of 95C21 steroids including 47 potential new ones were identified or tentatively identified, which greatly expanded our knowledge of C21 steroids in Xiao-ai-ping injection. The results indicated that the homologues prediction strategy not only provided an efficient technique to screen and identify target constituents, but also offered a new perspective for discovery new components in Traditional Chinese Medicines.

Structure-Property Relationships in Sodium Muricholate Derivative (Bile Salts) Micellization: The Effect of Conformation of Steroid Skeleton on Hydrophobicity and Micelle Formation-Pattern Recognition and Potential Membranoprotective Properties.

It is known that β-muricholic acid anions prevent membrane toxicity of hydrophobic bile acids, which are being used in therapy for solubilization of the cholesterol type bile stone. Better knowledge of these derivative micelles is very important for understanding their physiological and pharmacological effects. β-Axial (a) oriented hydroxyl group from the steroid skeleton decreases the hydrophobic surface of the convex side of the steroid skeleton. Therefore, the critical micellization concentration (CMC) for steroid surfactants with β-a-OH group should increase, but in the case of OH groups of different orientations forming H-bonds in the hydrophobic phase of the micelle, it has the opposite effect; the CMC decreses, and aggregation is more favored. The set of muricholic acids (MCs) is composed by α-MC, β-MC, γ-MC, and ω-MC, where α-MC and β-MC have β-axial-OH groups. The aggregation numbers (n) are determined using the Moroi-Matsuoka-Sugioka thermodynamic method. CMC, enthalpy of demicellization, and ΔCp are determined by isothermal titration calorimetry (ITC). This report pioneers in the study of MC derivatives micellization. Micelles of β-MC and γ-MC belong to the linear congeneric group (LCG) and their micelles above 85 mM have constant aggregation numbers n = 4-5. Micelles of α-MC and ω-MC are outliers in relation to the LCG, their aggregation number constantly increases; at 85 mM n = 6.8 (α-MC) and 6.5 (ω-MC). In micelles of derivatives β-MC and γ-MC, there is a low probability for the existence of hydrogen bonds. A micelle of α-MC probably has hydrogen bonds in its hydrophobic domain.

Twisted nanoribbons from a RGD-bearing cholic acid derivative

In light of the biomedical interest for self-assembling amphiphiles bearing the tripeptide Arg-Gly-Gly (RGD), a cholic acid derivative was synthesized by introducing an aromatic moiety on the steroidal skeleton and the RGD sequence on the carboxylic function of its chain 17–24, thus forming a peptide amphiphile with the unconventional rigid amphiphilic structure of bile salts. In aqueous solution, the compound self-assembled into long twisted ribbons characterized by a very low degree of polydispersity in terms of width (≈25nm), thickness (≈4.5nm) and pitch (≈145nm). It was proposed that in the ribbon the molecules are arranged in a bilayer structure with the aromatic moieties in the interior, strongly involved in the intermolecular interaction, whereas the RGD residues are located at the bilayer-water interface. The nanostructure is significantly different from those generally provided by RGD-containing amphiphiles with the conventional peptide-tail structure, for which fibers with a circular cross-section were observed, and successfully tested as scaffolds for tissue regeneration. From previous work on the use of this kind of nanostructures, it is known that features like morphology, rigidity, epitope spacing and periodicity are important factors that dramatically affect cell adhesion and signaling. Within this context, the reported results demonstrate that bile salt-based peptide surfactants are promising building blocks in the preparation of non-trivial RGD-decorated nanoaggregates with well-defined morphologies and epitope distributions.

Synthesis and antiproliferative activity of novel A-homo-B-norsteroid thiadiazole derivatives

Abstract Using cholesterol as a starting material, two novel steroidal thiadiazole derivatives possessing a structure of A-homo lactam and a B-nor steroidal skeleton were designed and synthesized by six steps of reactions, and their antiproliferative activities were assayed against various cancer cell lines. The result shows that compound 7b displays an excellent selective inhibition to A-549 (human lung carcinoma) cancer cell lines with an IC50 value of 8.0 μM.

Synthesis of androstene oxime-nitrogen mustard bioconjugates as potent antineoplastic agents

In the present study, synthesis and antineoplastic activity of phenylacetic acid and benzoic acid nitrogen mustard conjugates of various steroidal oximes are reported for the first time. The conjugation was achieved through a more stable oxime-ester linkage and the resulting newly synthesized conjugates were evaluated in vitro on various human cancer cell lines for cytotoxicity. The extent of their alkylating activity was investigated by the in vitro colorimetric 4-(p-nitrobenzyl)pyridine (NBP) assay. The 17E-steroidal oxime-benzoic acid mustard ester 3β-acetoxy-17E-[p-(N,N-bis(2-chloroethyl)amino)]benzoyloxyimino-androst-5-ene (8) emerged as the most potent conjugate having significant cytotoxicity on most of the NCI 60-cell lines. Outstanding growth inhibition was observed on the IGROV1 ovarian cancer cell line with GI50=0.937µM. In general, the D-ring derived androstene oxime-nitrogen mustard conjugates were found to possess better antineoplastic activity over a variety of cancer cells in comparison to those derived from other rings of the steroid skeleton.

Quest for steroidomimetics: Amino acids derived steroidal and nonsteroidal architectures

The chiral pool amino acids have been utilized for the construction of steroidal and non-steroidal architectures in the quest for steroidomimetics. Chirality derived from amino acid-based architectures provides new and easy to incorporate chiral chemical space, which is otherwise very difficult to introduce and comprised of several synthetic steps for asymmetric steroids. The different and exciting ligand-receptor interactions may arise from the use of each amino acid enantiomer that was introduced into the chiral steroidal backbone. The A and D rings of steroidal architectures can be mimicked by the phenyl group of the amino acid tyrosine. The Mitsunobu reaction, nucleophilic substitution and elimination, etc. were utilized for constructing diverse tri- and tetracyclic steroidal skeletons as well as benzofused seco-steroids from amino acids. These benzofused, amino acid-derived steroidal and nonsteroidal molecules had promising biological activity in hormonal related disorders.

Efficient synthesis of a multi-substituted diphenylmethane skeleton as a steroid mimetic

Steroids are important components of cell membranes and are involved in several physiological functions. A diphenylmethane (DPM) skeleton has recently been suggested to act as a mimetic of the steroid skeleton. However, difficulties are associated with efficiently introducing different substituents between two phenyl rings of the DPM skeleton, and, thus, further structural development based on the DPM skeleton has been limited. We herein developed an efficient synthetic method for introducing different substituents into two phenyl rings of the DPM skeleton. We also synthesized DPM-based estrogen receptor (ER) modulators using our synthetic method and evaluated their ER transcriptional activities.

Stille and Suzuki Cross‐Coupling Reactions as Versatile Tools for Modifications at C‐17 of Steroidal Skeletons – A Comprehensive Study

AbstractHerein, we report on a comparative Stille and Suzuki cross‐coupling study of steroidal vinyl (pseudo)halides with different boronic acids and tributyltin organyls. Furthermore, we have investigated the “inverse” case of those cross‐coupling reactions, i.e., the reaction of a steroidal vinylpinacolatoborane or a tributyltin steroid with various bromides. The development of both methods allows the introduction of different residues at C‐17 of steroid skeletons providing access to a broad variety of steroid analogues which are of high interest for biological screenings or natural product synthesis.magnified image

Antitumor activity of newly synthesized oxo and ethylidene derivatives of bile acids and their amides and oxazolines

Bile acid derivatives with modifications in side chain and modifications on steroid skeleton were synthetized and their antitumor activity against five human cancer cell lines was investigated. Modifications in side chain include amid group, formed in reaction with 2-amino-2-methylpropanol, and 4,4-dimethyloxazoline group, obtained after cyclization of amides. In the steroid skeleton oxo groups were introduced in position 7 (2, 2a, 2b) and 7,12 (3, 3a, 3b). Ethylidene groups were introduced regio- and stereoselectively on C-7, and/or without stereoselectivity on C-3 by Wittig reaction. By combination of these modifications, a series of 19 bile acid derivatives were synthesized. Compounds containing both C-7 ethylidene and C-12 carbonyl groups (6, 6a, 6b) shown very good antitumor activity with IC50<5µM. Altering carboxylic group to amide or oxazoline group has positive effect on cytotoxicity. Different molecular descriptors were determined in silico and after principal component analysis was found that molecular descriptor BLTF96 can be used for fast assessment of experimental cytotoxicity of bile acid derivatives.

Biological Activity of Brassinosteroids – Direct Comparison of Known and New Analogs in planta

A systematic investigation of structural modifications of brassinosteroids is presented. We describe in detail their synthetic preparation, which includes significant improvements of previously reported protocols as well as access to new analogs with functional modifications of the steroid skeleton and of the C(17)‐attached side chain. We report the biological potency of the prepared brassinosteroid analogs as plant hormones, which were carefully established in the French bean second internode elongation assay and discuss our observations in light of the recently reported structural data detailing the molecular interactions between brassinolide in the trimeric complex with the protein receptors kinases BRASSINOSTEROID INSENSITIVE 1 (BRI1) and SOMATIC EMBRYOGENESIS RECEPTOR KINASE 1 (SERK1). In a further part of this work we describe the preparation of H2O‐soluble pro‐forms of 24‐epicastasterone and we discuss their physical properties, hydrolytic stabilities and biological activity.

Synthesis of new derivatives of 21-imidazolyl-16-dehydropregnenolone as inhibitors of 5α-reductase 2 and with cytotoxic activity in cancer cells

The aim of this study was to synthesize several 16-dehydropregnenolone derivatives containing an imidazole ring at C-21 and a different ester moiety at C-3 as inhibitors of 5α-reductase 1 and 2 isoenzymes. Their binding capacity to the androgen receptor (AR) was also studied.Additionally, we evaluated their pharmacological effect in a castrated hamster model and their cytotoxic activity on a panel of cancer cells (PC-3, MCF7, SK-LU-1).The results showed that only the derivatives with an alicyclic ester at C-3 showed 5α-R2 enzyme inhibition activity, the most potent of them being 21-(1H-imidazol-1-yl)-20-oxopregna-5,16-dien-3β-yl-cyclohexanecarboxylate with an IC50 of 29nM. This is important because prostatic benign hyperplasia is directly associated with the presence of 5α-R2. However, all the derivatives failed to inhibit 5α-R1 or bind to the AR. These alicyclic ester derivatives decreased the weight and size of androgen-dependent glands in the hamster, indicating they are very active in vivo and are not toxic. In addition, the 21-(1H-imidazol-1-yl)-20-oxopregna-5,16-dien-3β-yl-acetate derivative showed the highest cytotoxic activity on the three cancer cell lines studied.It is therefore important in the synthesis of steroidal compounds to consider the size of the ester moiety at C-3 of the steroid skeleton, which is key in obtaining biological activity, as observed in this experiment.

Isolation and Structural Elucidation of 20 Hydroxyecdystone from Vitex doniana Sweet Stem bark (Black plum) Mustapha

Vitex doniana Sweet, a plant commonly known black plum, in English, Prunier noir in French, dinya in Hausa, ucha koro in Igbo, oori-nla in yoruba and ngarmi in Kanuri is a medium-sized deciduous tree, 8-18 m high, with a heavy rounded crown and a clear bole up to 5 m. V. doniana is from Verbenaceae family and abundantly occurring in savannah regions. It can be found throughout tropical Africa. The ethanolic extract of Vitex doniana stem bark (11.9 g) was subjected to a silica gel accelerated column chromatography and eluents fractions (150 ml aliquots) obtained were collected and monitored with thin layer chromatography (TLC). Fractions with similar Rf values from same solvents system were poled together. Phytochemical test of all the fractions were perform. Complete elution yielded 48 fractions (150 ml/fraction) which were pooled to 24 fractions and finally to eight (8) eight fractions and coded. Fraction Vd8-a (56 mg) has gave a single spot a white crystal compound coded V1 on checking with TLC and observed under Ultraviolet lamp. The Rf values was calculated to be 0.433 and melting point was found to be 241-243°C uncorrected. The infrared spectrum of compound V1 shows prominent peaks that corresponds to OHstr (3365 cm-1) and C=0 (1652 cm-1). The 1H NMR (400 MHZ) spectrum of compound V1 in DMSO-d6 displayed five singlet signals. It further showed a broad singlet at δ 5.58 integrated for 1 H is due to an olefinic H-atom adjacent to the carbonyl carbon atom. Three signals at δ 3.10` (d, J = 9.0 Hz, H-22), 3.59 (m, 1H, 2H-a) and 3.72 (m, 1H, 3H-e) each integrating for one proton is due to an oxymethine protons indicating that three oxymethine H-atoms were present in the compound. The 13C-NMR spectrum showed the presence of 27 Carbon atoms, suggesting that may be steroid skeleton and the DEPT-135 spectra showed the presence of five CH3, eight CH2, and seven CH groups, and seven quaternary C-atoms. The Molecular formula was established as C27H44O7 by HRES-MS positive ion mode m/z 481.3179. Based on the spectral analysis, the compound V1 is thus concluded to have ecdysteriod skeleton and conclusively conforms with 2β, 3β 14α, 20R, 22R, 25- hexahydroxy-5 β cholest- 7-ene-6- one, commonly known as 20-hydroxyecdysone. This is the first time this compound was isolated from Vitex doniana sweet.

An unexplored pathway for degradation of cholate requires a 7α-hydroxysteroid dehydratase and contributes to a broad metabolic repertoire for the utilization of bile salts in Novosphingobium sp. strain Chol11.

Bile salts such as cholate are surface-active steroid compounds with functions for digestion and signaling in vertebrates. Upon excretion into soil and water bile salts are an electron- and carbon-rich growth substrate for environmental bacteria. Degradation of bile salts proceeds via intermediates with a 3-keto-Δ1,4 -diene structure of the steroid skeleton as shown for e.g. Pseudomonas spp. Recently, we isolated bacteria degrading cholate via intermediates with a 3-keto-7-deoxy-Δ4,6 -structure of the steroid skeleton suggesting the existence of a second pathway for cholate degradation. This potential new pathway was investigated with Novosphingobium sp. strain Chol11. A 7α-hydroxysteroid dehydratase encoded by hsh2 was identified, which was required for the formation of 3-keto-7-deoxy-Δ4,6 -metabolites. A hsh2 deletion mutant could still grow with cholate but showed impaired growth. Cholate degradation of this mutant proceeded via 3-keto-Δ1,4 -diene metabolites. Heterologous expression of Hsh2 in the bile salt-degrading Pseudomonas sp. strain Chol1 led to the formation of a dead-end steroid with a 3-keto-7-deoxy-Δ4,6 -diene structure. Hsh2 is the first steroid dehydratase with an important function in a metabolic pathway of bacteria that use bile salts as growth substrates. This pathway contributes to a broad metabolic repertoire of Novosphingobium strain Chol11 that may be advantageous in competition with other bile salt-degrading bacteria.

Parameters of micellization and hydrophobicity of sodium salts of 7-buthyl (butylidene) and 7-octyl (octylidene) derivatives of the cholic and the deoxycholic acid in a water solution: Pattern recognition — Linear hydrophobic congeneric groups

In this paper the influence of hydrophobicity is analysed (expressed with the reversed phase HPLC capacity factor, k) of the steroid skeleton anion derivatives with next groups placed in a position C7 of the steroid skeleton: octyl, octylidene, butyl, and butylidene group; the influence on their micellization parameters: aggregation number (n) and critical micelle concentration (CMC). If the examined derivative is more hydrophobic (higher values of k), CMC values are lower. Examined molecules have the same length of C7 hydrocarbon chain but different position of a double bond in the ring B (endocyclic between C6 and C7, and exocyclic on the C7) and have a different hydrophobicity as well as different CMC values. This can be explained using conformation analysis according to which conformation of the B ring of the steroid skeleton determines conformation of the C7 hydrocarbon chain, i.e. the degree of their departuring from steroid skeleton mean plane and approaching to convex surface of the molecule. In the plane lnk–n new derivatives with octyl/octylidene i.e. buthyl/butylidene group form two linear congeneric group: GE-LCC and H-LCC. Bile acid anions that form the H-LCC group, due the steric reasons, have a low possibility for formation of hydrogen bonds between different building units of a micelle. In the plane lnk–lnCMC only one linear hydrophobic congeneric group is formed which suggests that in micelles, on CMC, hydrogen bonds between building units are not present. Values of partition coefficients of nitrazepan for analysed derivatives micelles suggest that, in formation of mixed micelles of nitrazepan C7 alkyl chain from twisted conformation switches to elongated conformation and takes part in ecraning of the guest molecule.