Synthesis and biological activity of two pregnane derivatives with a triazole or imidazole ring at C-21

Steroidal 21-imidazolium salt derivatives: Synthesis and anticancer activity

Nitrogen-containing steroids are known as prostate cancer therapeutics. In this work, a series of pregnane derivatives bearing an imidazolium moiety were synthesized using Δ16-20-ketones as starting material. An improved approach for the construction of the 20-keto-21-heterocycle-substituted fragment involved the rearrangement of 16,17-epoxides with HCl, followed by reaction of the formed α-chloroketone with 1-substituted imidazoles. Binding affinity analysis of the imidazolium steroids and their synthetic intermediates to human CYP17A1 showed only type I (substrate-like) interactions. The strongest affinity was observed for 16α,17α-epoxy-5α-pregnan-20-on-3β-ol (Kd = 0.66 ± 0.05 µM). The steroid derivatives have been evaluated for antitumor activity against a range of prostate cancer cells as well as against various other solid tumor and hematologic cancer cell lines. All 21-imidazolium salts were active against the hormone-dependent prostate cancer line LNCaP. The most pronounced cytotoxicity in solid tumor and hematologic cancer cell lines was observed for intermediate product, 21-chloro-5α-pregn-16-en-20-on-3β-ol. Among the imidazolium salts, the derivatives with a single bond were more cytotoxic than their unsaturated congeners.

Secosteroid thiosemicarbazides and secosteroid-1,2,4-triazoles as antiproliferative agents targeting breast cancer cells: Synthesis and biological evaluation

A convenient and selective approach to 13,17-secoestra-1,3,5(10)-trien-17-oic acid [N'-arylcarbothioamido]hydrazides and hybrid molecules containing secosteroid and 1,2,4-triazole fragments was disclosed and these novel types of secosteroids were screened for cytotoxicity against hormone-dependent human breast cancer cell line MCF-7. Most of secosteroid-1,2,4-triazole hybrids showed significant cytotoxic effect comparable or superior to that of the reference drug cisplatin. Hit secosteroid-1,2,4-triazole hybrids 4b and 4h were characterized by high cytotoxicity and good selectivity towards MCF-7 breast cancer cells. PARP cleavage (marker of apoptosis) and ERα and cyclin D1 downregulation were discovered in MCF-7 cells treated with lead secosteroid-1,2,4-triazole hybrid 4b. The synthesized secosteroids may be considered as new promising anticancer agents.

Development of 1,3,4-Oxadiazole Derived Antifungal Agents and Their Application in Maize Diseases Control

Maize is an important food crop and its fungal disease has become a limiting factor to improve the yield and quality of maize. In the control of plant pathogens, commercial fungicides have no obvious effect on corn diseases due to the emergence of drug resistance. Therefore, it is of great significance to develop new fungicides with novel structure, high efficiency, and low toxicity to control maize diseases. In this paper, a series of 1,3,4-oxadiazole derivatives were designed and synthesized from benzoyl hydrazine and aromatic aldehydes through condensation and oxidation cyclization reaction. The antifungal activity of oxadiazole derivatives against three maize disease pathogens, such as Rhizoctonia solani (R. solani), Gibberella zeae (G. zeae), and Exserohilum turcicum (E. turcicum), were evaluated by mycelium growth rate method in vitro. The results indicated that most of the synthesized derivatives exhibited positive antifungal activities. Especially against E. turcicum, several compounds demonstrated significant antifungal activities and their EC ₅₀ values were lower than positive control carbendazim. The EC ₅₀ values of compounds 4k, 5e, and 5k were 50.48, 47.56, 32.25 μg/ml, respectively, and the carbendazim was 102.83 μg/ml. The effects of active compounds on E. turcicum microstructure were observed by scanning electron microscopy (SEM). The results showed that compounds 4k, 5e, and 5k could induce the hyphae of E. turcicum to shrink and collapse obviously. In order to elucidate the preliminary mechanism of oxadiazole derivatives, the target compounds 5e and 5k were docked with the theoretical active site of succinate dehydrogenase (SDH). Compounds 5e and 5k could bind to amino acid residues through hydrophobic contact and hydrogen bonds, which explained the possible mechanism of binding between the inhibitor and target protein. In addition, the compounds with antifungal activities had almost no cytotoxicity to MCF-7. This study showed that 1,3,4-oxadiazole derivatives were worthy for further attention as potential antifungal agents for the control of maize diseases.

Multiple strategies for the treatment of invasive breast carcinoma: A comprehensive prospective

In this review, we emphasize on evolving therapeutic strategies and advances in the treatment of breast cancer (BC). This includes small-molecule inhibitors under preclinical and clinical investigation, phytoconstituents with antiproliferative potential, targeted therapies as antibodies and antibody-drug conjugates (ADCs), vaccines as immunotherapeutic agents and peptides as a novel approach inhibiting the interaction of oncogenic proteins. We provide an update of molecules under different phases of clinical investigation which aid in the identification of loopholes or shortcomings that can be overcomed with future breast cancer research.

Anticancer potential of cardiac glycosides and steroid-azole hybrids

Steriods are well-known scaffolds that have a widespread occurrence in different compounds characterized by extensive biological properties including anticancer activity. Structural modifications on steroids always generate potential lead compounds with superior bioactivity, and creation of steroid hybrids by combining steroid with other anticancer pharmacophores in one molecule, which can exert the anticancer activity through different mechanisms, is one of the most promising strategies to enhance efficiency, overcome drug resistance and reduce side effects. Sugars and azoles, can act on diverse receptors, proteins and enzymes in cancer cells, are pharmacologically significant scaffolds in the development of novel anticancer agents. Therefore, steroid-sugar hybrids cardiac glycosides and steroid-azole hybrids are privileged scaffolds for the discovery of novel anticancer candidates. This review emphasized on the development, the structure-activity relationship and the mechanism of action of cardiac glycosides and steroid-azole hybrids with potential application for fighting against various cancers including drug-resistant forms to facilitate further rational design of novel drug candidates covering articles published between 2015 and 2020.

Design, synthesis, and biological activities of novel thiophene, pyrimidine, pyrazole, pyridine, coumarin and isoxazole: Dydrogesterone derivatives as antitumor agents

On the basis of our consideration to design and to develop antitumor activities of heterocyclic compound derivatives, especially in fused ring system, we refer to the possibility of the heterocyclic extension of one of the most important steroid compounds used as a medicinal drug. The reaction of dydrogesterone with each of the malononitrile or ethylcyanoacetate containing elemental sulfur afforded thiophene derivatives 1a,b. Also, dydrogesterone was reacted with a mixture of ethylcyanoacetate–hydrazine, ethylcyanoacetae–urea, or ethylcyanoacetate–thiourea to produce pyrazole derivative 4 and pyrimidine derivatives 5a,b. Thienopyrimidine derivatives 2a–d were introduced from the reaction of thiophene derivatives 1a,b with either phenylisothiocyanate or benzoylisothioyanate. Furthermore, compounds 1a,b were directed toward the reaction with ethylcyanoacetate to produce compounds 6a,b, and the last compounds 6a,b were directed toward cyclization to obtain thienopyridine derivatives 7a,b. In addition, compounds 6a,b were subjected to react with different carbonyl compounds, such as salicylaldehyde, cyclopentanone-elemental sulfur, malonaldehyde, and acetylacetone to produce coumarin derivatives 8a,b, fused thiophene derivatives 9a,b, and pyridine derivatives 10a–d. Isooxazole derivatives 12a,b were afforded through the reaction of compounds 6a,b with hydroxylamine hydrochloride. Finally, 2-pyridone derivatives 14a,b were obtained through the reaction of compounds 6a,b with benzoylacetonitrile. Conformation structure of the synthesized compounds was established by applying IR, 1H NMR, 13C NMR, and mass spectrometry, and their antitumor activity was examined. Some compounds showed promising growth inhibitory effects on the three different cell lines.

Biotransformation of Ethinylestradiol by Whole Cells of Brazilian Marine-Derived Fungus Penicillium oxalicum CBMAI 1996

In this study, we report our contribution to the application of whole cells of Brazilian marine-derived fungi in the biotransformation of ethinylestradiol 1. A preliminary screening with twelve marine-derived fungi strains revealed that the fungus Penicillium oxalicum CBMAI 1996 promoted the biotransformation of ethinylestradiol 1. Then, P. oxalicum CBMAI 1996 was employed in the reactions in decaplicate in order to purify and characterize the main biotransformation products of ethinylestradiol 1. Compounds 1b and 1c were characterized by NMR, HRMS, [α]_D and mp. Compound 1b was also characterized by single crystal X-ray diffraction. In addition, kinetic monitoring of the biotransformation of ethinylestradiol 1 by P. oxalicum CBMAI 1996 was evaluated in this study in order to obtain high yields of compounds 1b and 1c with a reduction of the reaction time. In this work, we proposed a biotransformation pathway of ethinylestradiol 1, which suggests the presence of several enzymes such as phenol oxidases, monooxygenases, and ene-reductases in the fungus P. oxalicum CBMAI 1996. In summary, the rapid biodegradation of ethinylestradiol 1 and compounds 1b and 1c also has an environmental relevance, since ethinylestradiol 1 and other steroidal compounds are improperly discarded in the environment, and part of these compounds are displaced into the oceans.

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.

Semi-synthesis of β-keto-1,2,3-triazole derivatives from ethinylestradiol and evaluation of the cytotoxic activity

In this study, we report our contribution to the application of the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction for the synthesis of β-keto-1,2,3-triazole derivatives 3a-f from ethinylestradiol and their application in the inhibition of two human cancer cells lines: human breast adenocarcinoma (MCF-7) and human hepatocellular carcinoma (HepG2). The β-keto-1,2,3-triazole derivates 3a-f exhibited moderate cytotoxic activity for the HepG2 cells with IC₅₀ values of 29.7 μM (3a), 16.4 μM (3b), 17.8 μM (3c), 20.4 μM (3d), 28.1 μM (3e) and 28.2 μM (3f). The semi-synthetic β-keto-1,2,3-triazoles derivatives 3a-f were all characterized by FT-IR, NMR, HRMS and [α]_D.

Synthesis and evaluation of novel D-ring substituted steroidal pyrazolines as potential anti-inflammatory agents

To identify new potential anti-inflammatory agents, a number of novel steroidal derivatives with nitrogen heterocyclic side chains 4a-4l were synthesized and evaluated for their anti-inflammatory effects in activated RAW 264.7 macrophage cells. The synthesis scheme involves two steps, Claisen-Schmidt condensation with the corresponding pregnenolone and aromatic aldehydes as the first step followed by nucleophilic addition of thiosemicarbazide across an α, β-unsaturated carbonyl as a later step. Compound structures were confirmed by ¹H NMR, ¹³C NMR, HRMS, and IR. The compounds were assayed to test their anti-inflammatory effects in activated RAW 264.7 cells. Compound 4g, 3β-hydroxy-pregn-5-en-17β-yl-5'-(m-fluorophenyl)-4', 5'-dihydro-1'-carbothioic acid amido pyrazole, was identified as the most potent anti-inflammatory agent of the analysed compounds, with an IC₅₀ value of 0.86 µM on nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 cells for 24 h compared to dexamethasone (IC₅₀ = 0.62 µM) and low cytotoxicity against RAW 264.7 cells. Compound 4g significantly inhibited NO produced by LPS-induced RAW 264.7 cells. Further studies showed that compound 4g markedly inhibited the expression of pro-inflammatory factors, including inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2) in LPS-induced RAW 264.7 cells. These results indicate that derivatives bearing pyrazoline structure might be considered for further research and scaffold optimization in designing anti-inflammatory drugs and compound 4g might be a promising therapeutic anti-inflammatory drug candidate.

Synthesis, Structural Analysis, and Biological Activities of Some Imidazolium Salts

Four newly synthesized imidazolium salts were characterized by nuclear magnetic resonance, vibrational spectra, and mass spectra. Then, the density functional theory calculations were performed to obtain the molecular configurations on which the theoretical nuclear magnetic resonance and infrared spectra were consequently obtained. The comparison of calculated spectra with the experimental spectra for each molecule leads to the conclusion that the theoretical results can be assumed to be a good approach to their molecular configurations. The in vitro biological activities of the salts on the selected bacteria and cancer cell lines were determined by using the broth dilution method according to Clinical and Laboratory Standards Institute guidelines. The 1,3-bis(2-hydroxyethyl) imidazolidinium bromide and 3-(2-ethoxy-2-oxoethly)-1-(3-aminopropyl)-1H-imidazol-3-ium bromide showed efficiency on Bacillus cereus ATCC 11778. The 3-bis(2-carboxyethyl)-4-methyl-1-H-imidazol-3-ium bromide was effective on HeLa while a similar effect was observed on Hep G2 with 3-(2-carboxyethyl)-1-(3-aminopropyl)-1H-imidazol-3-ium bromide.

Structure-activity relationship (SAR) study and design strategies of nitrogen-containing heterocyclic moieties for their anticancer activities

The present review article offers a detailed account of the design strategies employed for the synthesis of nitrogen-containing anticancer agents. The results of different studies describe the N-heterocyclic ring system is a core structure in many synthetic compounds exhibiting a broad range of biological activities. Benzimidazole, benzothiazole, indole, acridine, oxadiazole, imidazole, isoxazole, pyrazole, triazoles, quinolines and quinazolines including others drugs containing pyridazine, pyridine and pyrimidines are covered. The following studies of these compounds suggested that these compounds showed their antitumor activities through multiple mechanisms including inhibiting protein kinase (CDK, MK-2, PLK1, kinesin-like protein Eg5 and IKK), topoisomerase I and II, microtubule inhibition, and many others. Our concise representation exploits the design and anticancer potency of these compounds. The direct comparison of anticancer activities with the standard enables a systematic analysis of the structure-activity relationship among the series.