Efficient access to novel androsteno-17-(1',3',4')-oxadiazoles and 17β-(1',3',4')-thiadiazoles via N-substituted hydrazone and N,N'-disubstituted hydrazine intermediates, and their pharmacological evaluation in vitro

Oxazolinyl derivatives of androst-16-ene as inhibitors of CYP17A1 activity and prostate carcinoma cells proliferation: Effects of substituents in oxazolinyl moiety

Steroid derivatives modified with nitrogen containing heterocycles are known to inhibit activity of steroidogenic enzymes, decrease proliferation of cancer cells and attract attention as promising anticancer agents. Specifically, 2'-(3β-hydroxyandrosta-5,16-dien-17-yl)-4',5'-dihydro-1',3'-oxazole 1a potently inhibited proliferation of prostate carcinoma cells. In this study we synthesized and investigated five new derivatives of 3β-hydroxyandrosta-5,16-diene comprising 4'-methyl or 4'-phenyl substituted oxazolinyl cycle 1 (b-f). Docking of compounds 1 (a-f) to CYP17A1 active site revealed that the presence of substitutents at C4' atom in oxazoline cycle, as well as C4' atom configuration, significantly affect docking poses of compounds in the complexes with enzyme. Testing of compounds 1 (a-f) as CYP17A1 inhibitors revealed that the only compound 1a, comprising unsubstituted oxazolinyl moiety, demonstrated strong inhibitory activity, while other compounds 1 (b-f) were slightly active or non active. Compounds 1 (a-f) efficiently decreased growth and proliferation of prostate carcinoma LNCaP and PC-3 cells at 96 h incubation; the effect of compound 1a was the most powerful. Compound 1a efficiently stimulated apoptosis and caused PC-3 cells death, that was demonstrated by a direct comparison of pro-apoptotic effects of compound 1a and abiraterone.

Electrochemical Sensors Based on Au Nanoparticles Decorated Pyrene-Reduced Graphene Oxide for Hydrazine, 4-Nitrophenol and Hg2+ Detection in Water

Monitoring hazardous chemical compounds such as hydrazine (N2H4), 4-nitrophenol (4-NP) and Hg2+ in natural water resources is a crucial issue due to their toxic effects on human health and catastrophic impact on the environment. Electrochemical nanostructured platforms integrating hybrid nanocomposites based on graphene derivatives and inorganic nanoparticles (NPs) are of great interest for such a purpose. In this work, disposable screen-printed carbon electrodes (SPCEs) have been modified with a hybrid nanocomposite formed by reduced graphene oxide (RGO), functionalized by 1-pyrene carboxylic acid (PCA), and decorated by colloidal Au NPs. These hybrid platforms have been tested for the electrocatalytic detection of N2H4 and 4-NP by differential pulse voltammetry and have been modified with an electropolymerized film of Hg2+ ions imprinted polycurcumin for the electroanalytical detection of Hg2+ by DPV. LODs, lower and in line with the lowest ones reported for state-of-the-art electrochemical sensors, integrating similar Au-graphene < nanocomposites, have been estimated. Additionally, good repeatability, reproducibility, and storage stability have been assessed, as well as a high selectivity in the presence of a 100-fold higher concentration of interfering species. The applicability of the proposed platforms for the detection of the compounds in real complex matrices, such as tap and river water samples, has been effectively demonstrated.

Recent advances on synthesis and biological activities of C-17 aza-heterocycle derived steroids

Steroids modification for improving their biological activities is one of the most efficient and fruitful methods to develop novel medicines. Steroids with aza-heterocycles attaching to the C-17 owing various biological activities have received great attentions and some of the compounds are developed successfully as drugs. In this review, the research of the syntheses and biological activities of steroids bearing various aza-heterocycles published in the last 8 years is assembled, and some important structure-activity relationships (SARs) of active compounds are presented. According to the analysis of the literatures and our experiences in this field, the potential of aza-heterocyclic steroids as medicinal drugs is proposed.

Synthesis of dihydrotestosterone derivatives modified in the A-ring with (hetero)arylidene, pyrazolo[1,5-a]pyrimidine and triazolo[1,5-a]pyrimidine moieties and their targeting of the androgen receptor in prostate cancer

One of the main directions of steroid research is the preparation of modified derivatives in which, in addition to changes in physicochemical properties, receptor binding is significantly altered, thus a bioactivity different from that of the parent compound predominates. In the frame of this work, 2-arylidene derivatives were first synthesized by regioselective modification of the A-ring of natural sex hormone, 5α-dihydrotestosterone (DHT). After Claisen-Schmidt condensations of DHT with (hetero)aromatic aldehydes in alkaline EtOH, heterocyclizations of the α,β-enones were performed with 3-amino-1,2,4-triazole, 3-aminopyrazole and 3-amino-5-methylpyrazole in the presence of t-BuOK in DMF to afford 7'-epimeric mixtures of A-ring-fused azolo-dihydropyrimidines, respectively. Depending on the electronic demand of the substituents of the arylidene moiety, spontaneous or 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ)-induced oxidation of the heteroring led to triazolo[1,5-a]pyrimidines and pyrazolo[1,5-a]pyrimidines in good yields, while, using the Jones reagent as a strong oxidant, 17-oxidation also occurred. The crystal structures of an arylidene and a triazolopyrimidine product have been determined by single crystal X-ray diffraction and both were found to crystallize in the monoclinic crystal system at P2₁ space group. Most derivatives were found to diminish the transcriptional activity of androgen receptor (AR) in reporter cell line. The candidate compound (17β-hydroxy-2-(4-chloro)benzylidene-5α-androstan-3-one, 2f) showed to suppress androgen-mediated AR transactivation in a dose-dependent manner. We confirmed the cellular interaction of 2f with AR, described the binding in AR-binding cavity by the flexible docking and showed the ability of the compound to suppress the expression of AR-regulated genes in two prostate cancer cell lines.

A review on synthesis and biological activities of D-ring modified pregnenolone

Steroids are polycyclic compounds and are broadly exist in the natural world and display various biological activities. Many steroidal compounds have been used as traditional medicines, for example, antibacterial and few as hormone like medication. The introduction of heterocycle or heteroatom in the steroidal moiety has a significant biological impact. These derivatives have widespread biological activities such as anticancer, anti-inflammatory, anti-ulcer and antimicrobial. The present article is a brief review of the recent development of synthesis and biological activities of pregnenolone derivatives.

Antiproliferative and antimetastatic characterization of an exo-heterocyclic androstane derivative against human breast cancer cell lines

Cancer in general, and specifically gynaecological neoplasms, represents a major public health issue worldwide. Based on the effect of sex hormones on breast tumorigenesis and prognosis, as well as on the development of breast cancer metastases, modification of the steroid skeleton is a hotspot of research for novel anticancer agents. Numerous recent studies support that minor modifications of the androstane skeleton yield potent antiproliferative and antimetastatic drug candidates. The aim of the present study was to assess the antitumor and antimetastatic properties, as well as the mechanism of action of a D-ring-modified exo-heterocyclic androstadiene derivative named 17APAD. The test compound was found to be highly selective towards human breast cancer-derived cell lines (MCF-7, T47D, MDA-MB-361, MDA-MB-231) compared to non-cancerous fibroblast cells (NIH/3T3), and exerted superior effect compared to the clinically applied reference drug cisplatin. Changes in MCF-7- and MDA-MB-231 cell morphology and membrane integrity induced by the test substance were assessed by fluorescent double staining. Cell cycle disturbances were analyzed by flow cytometry, and concentration-dependent alterations were detected on breast cancer cell lines. Mitochondrial apoptosis induced by the test compound was demonstrated by JC-1 staining. Inhibitory effects on metastasis formation, including the inhibition of migration, invasion and intravasation were investigated in 2D and 3D models. Significant anti-migratory and anti-invasive effects on MCF-7 and MDA-MB-231 cells were detected after 24 h exposure in 2D wound healing and Boyden-chamber assays. The anti-intravasative properties of 17APAD were evident after 4 h of incubation in a co-culture 3D circular chemorepellent-induced defects (CCID) assay, and the level of inhibition at concentrations ≥2 µM was comparable to that exerted by the focal adhesion kinase inhibitor defactinib. Single cell mass cytometry revealed that chemosensitive subpopulations of MDA-MB-231 cells engaged to apoptosis were less positive for EGFR, CD274, and CD326, while the percentage of cells positive for GLUT1, MCT4, Pan-Keratin, CD66(a,c,e), Galectin-3 and TMEM45A increased in response to 17APAD treatment. Finally, the novel androstane analogue 17APAD had an outstanding inhibitory effect on tumour growth in the 4T1 orthotopic murine breast cancer model in vivo after 2 weeks of intraperitoneal administration. These findings support that substitution of the androsta-5,16-diene framework with a N-containing heterocyclic moiety at C17 position yields a molecular entity rational to be considered for design and synthesis of novel, effective antitumor agents, and 17APAD is worth further investigation as a promising anticancer drug candidate.

Recent developments in electrochemical sensors for detecting hydrazine with different modified electrodes

The detection of hydrazine (HZ) is an important application in analytical chemistry. There have been recent advancements in using electrochemical detection for HZ. Electrochemical detection for HZ offers many advantages, e.g., high sensitivity, selectivity, speed, low investment and running cost, and low laboriousness. In addition, these methods are robust, reproducible, user-friendly, and compatible with the concept of green analytical chemistry. This review is devoted to the critical comparison of electrochemical sensors and measuring protocols used for the voltammetric and amperometric detection of the most frequently used HZ in water resources with desirable recovery. Attention is focused on the working electrode and its possible modification which is crucial for further development.

Synthesis of cytotoxic urs-12-ene- and 28-norurs-12-ene- type conjugates with amino- and mercapto-1,3,4-oxadiazoles and mercapto-1,2,4-triazoles

A small library of 2-mercapto-1,3,4-oxadiazoles, 2-amino-1,3,4-oxadiazoles, and 3-mercapto-1,2,4-triazoles attached to the urs-12-ene- and 28-nor-urs-12-ene skeleton has been obtained. Ursolic acid derived hydrazides have been identified as useful starting materials for the developed synthesis. Ursolic acid hydrazide provided access to oxadiazoles attached directly to C-17 of the ursane core, but synthesis of structurally related 3-mercapto-1,2,4-triazoles was not possible in this way due to steric hindrance of the triterpenoid. Ester- and amide-linked hydrazides arising from ethoxycarbonylmethyl ursolate and ursolic acid amide with methyl β-alaninate served as key starting materials for the remotely connected mercapto-and amino-azoles. Antioxidant activities (DPPH method) of the newly obtained compounds are mediocre. However, excellent cytotoxicity and selectivity against MCF7 cell line were found for 28-nor-urs-12-ene 2-amino-1,3,4-oxadiazole conjugate. Also some other library members exceeded the cytotoxicity values of natural ursolic acid. The novel hybrid heterocycles with amino and mercapto substituents possess a great potential for further derivatization and are prospective scaffolds for the synthesis of triterpenoid analogs with chemopreventive and cytotoxic properties.

A ratiometric fluorescent probe for hydrazine detection with large fluorescence change ratio and its application for fluorescence imaging in living cells

Hydrazine and its derivatives are one of the most important raw chemical materials that have extensive utilization in many areas. It is also widely applied as pharmaceutical derivatives, such as the antipsychotic drug, anti-infective drug, and antitumor drug. However, hydrazine is a highly toxic reagent which can bring severe damage to human and animals. Herein, we have reported a new benzothiazole substituted naphthalene based probe for hydrazine with huge fluorescence change ratio. The fluorescence change ratio at F₃₉₀/F₅₀₉ is up to 200-fold in the presence of hydrazine in 60 min. The probe exhibited negligible cytotoxicity toward HeLa cells and was applied for hydrazine detection successfully in HeLa cells.

A Review Exploring Therapeutic Worth of 1,3,4-Oxadiazole Tailored Compounds

1,3,4-Oxadiazole, a five-membered aromatic ring can be seen in a number of synthetic molecules. The peculiar structural feature of 1,3,4-oxadiazole ring with pyridine type of nitrogen atom is beneficial for 1,3,4-oxadiazole derivatives to have effective binding with different enzymes and receptors in biological systems through numerous weak interactions, thereby eliciting an array of bioactivities. Research in the area of development of 1,3,4-oxadiazole-based derivatives has become an interesting topic for the scientists. A number of 1,3,4-oxadiazole based compounds with high therapeutic potency are being extensively used for the treatment of different ailments, contributing to enormous development value. This work provides a systematic and comprehensive review highlighting current developments of 1,3,4-oxadiazole based compounds in the entire range of medicinal chemistry such as anticancer, antifungal, antibacterial, antitubercular, anti-inflammatory, antineuropathic, antihypertensive, antihistaminic, antiparasitic, antiobesity, antiviral, and other medicinal agents. It is believed that this review will be of great help for new thoughts in the pursuit for rational designs for the development of more active and less toxic 1,3,4-oxadiazole based medicinal agents.

Microwave-assisted synthesis of biologically relevant steroidal 17-exo-pyrazol-5'-ones from a norpregnene precursor by a side-chain elongation/heterocyclization sequence

Multistep syntheses of novel 17β-pyrazol-5'-ones in the Δ⁵-androstane series were efficiently carried out from pregnenolone acetate. A steroidal 17-carboxylic acid was first synthesized as a norpregnene precursor by the bromoform reaction and subsequent acetylation. Its CDI-activated acylimidazole derivative was then converted to a β-ketoester containing a two carbon atom-elongated side chain than that of the starting material. A Knorr cyclization of the bifunctional 1,3-dicarbonyl compound with hydrazine and its monosubstituted derivatives in AcOH under microwave heating conditions led to the regioselective formation of 17-exo-heterocycles in good to excellent yields. The suppression of an acid-catalyzed thermal decarboxylation of the β-ketoester and thus a significant improvement in the yield of the desired heterocyclic products could be achieved by the preliminary liberation of the arylhydrazines from their hydrochloride salts in EtOH in the presence of NaOAc. The reaction rates were found to depend on the electronic character of the substituent present in the phenylhydrazine applied. The antiproliferative activities of the structurally related steroidal pyrazol-5'-ones and their deacetylated analogs were screened on three human adherent breast cancer cell lines (MCF7, T47D and MDA-MB-231): the microculture tetrazolium assay revealed that some of the presented derivatives exerted cell growth inhibitory effects on some of these cell lines comparable to those of the reference compound, cisplatin.

Stereoselective Synthesis, Synthetic and Pharmacological Application of Monoterpene-Based 1,2,4- and 1,3,4-Oxadiazoles

Stereoselective synthesis of monoterpene-based 1,2,4- and 1,3,4-oxadiazole derivatives was accomplished starting from α,β-unsaturated carboxylic acids, obtained by the oxidation of (−)-2-carene-3-aldehyde and commercially available (−)-myrtenal. 1,2,4-Oxadiazoles were prepared in two steps via the corresponding O-acylamidoxime intermediates, which then underwent cyclisation induced by tetrabutylammonium fluoride (TBAF) under mild reaction conditions. Stereoselective dihydroxylation in highly stereospecific reactions with the OsO₄/NMO (N-methylmorpholine N-oxide) system produced α,β-dihydroxy 1,2,4-oxadiazoles. Pinane-based 1,3,4-oxadiazoles were obtained similarly from acids by coupling with acyl hydrazines followed by POCl₃-mediated dehydrative ring closure. In the case of the arane counterpart, the rearrangement of the constrained carane system occurred with the loss of chirality under the same conditions. Stereoselective dihydroxylation with OsO₄/NMO produced α,β-dihydroxy 1,3,4-oxadiazoles. The prepared diols were applied as chiral catalysts in the enantioselective addition of diethylzinc to aldehydes. All compounds were screened in vitro for their antiproliferative effects against four malignant human adherent cell lines by means of the MTT assay with the O-acylated amidoxime intermediates exerting remarkable antiproliferative action.

Synthesis and Pharmacological Evaluation of New 3,4-Dihydroisoquinolin Derivatives Containing Heterocycle as Potential Anticonvulsant Agents

Two novel series of 3,4-dihydroisoquinolin with heterocycle derivatives (4a–t and 9a–e) were synthesized and evaluated for their anticonvulsant activity using maximal electroshock (MES) test and pentylenetetrazole (PTZ)-induced seizure test. All compounds were characterized by IR, ¹H-NMR, ¹³C-NMR, and mass spectral data. Among them, 9-(exyloxy)-5,6-dihydro-[1,2,4]triazolo[3,4-a]isoquinolin-3(2H)-one (9a) showed significant anticonvulsant activity in MES tests with an ED₅₀ value of 63.31 mg/kg and it showed wide margins of safety with protective index (PI > 7.9). It showed much higher anticonvulsant activity than that of valproate. It also demonstrated potent activity against PTZ-induced seizures. A docking study of compound 9a in the benzodiazepine (BZD)-binding site of γ-aminobutyric acid_A (GABA_A) receptor confirmed possible binding of compound 9a with the BZD receptors.