Heterocyclic ring extension of androstenedione: synthesis and cytotoxicity of fused pyran, pyrimidine and thiazole derivatives

Formation of nitrogen-containing six-membered heterocycles on steroidal ring system: A review

Steroidal heterocyclic compounds constitute interesting and promising scaffolds for drug discovery as they have displayed diverse chemical reactivity and several types of biological activities. This study is a concise report on the most recent advancements in the chemistry of the steroid skeleton, including reactions at the A, B, and D ring systems. The modern synthetic methods for the steroidal nitrogen-containing six-membered heterocyclic derivatives from 3-keto-, 6-keto-, 17-keto-, and 20-keto-steroids, as well as 2-Aldo-, 4-Aldo-, 6-Aldo-, and 16-Aldo-steroids, are discussed. However, some other methods for the synthesis of steroidal N-containing 6-membered heterocyclic derivatives are also included. These compounds have shown therapeutic potential as cytotoxic agents against various cell lines and have also shown antiproliferative, anti-inflammatory, and antioxidant activities. Therefore, they could be used as prospective candidates for the development of various medications. This paper not only describes synthetic details involved in creating N-containing 6-membered heterocyclic steroid derivatives, but also provides a brief overview of the medicinal applications of these compounds. This information will be highly useful for the medicinal chemists conducting research in this field.

Design, Synthesis, and Biological Evaluation of Two Series of Novel A-Ring Fused Steroidal Pyrazines as Potential Anticancer Agents

BACKGROUND

Increasingly, different heterocyclic systems have been introduced into the steroid nucleus to significantly enhance the antitumor activities of steroid molecules. However, in this study, few literature precedents describing the pyrazine heterocyclic-condensed modification to an A-ring of steroid monomers were found, although the pyrazine group is thought to be essential for the potent anticancer activity of clinically relevant drugs and natural steroid dimers.

METHODS AND RESULTS

Two series of novel A-ring fused steroidal pyrazines were designed and efficiently synthesized from commercially available progesterone via key α-ketoenol intermediates. Through a cell counting kit-8 cytotoxic assay of 36 derivatives for three tumor cells, 14 compounds displayed significant antiproliferative activity compared to 5-fluorouracil, especially for human prostatic tumor cells (PC-3) in vitro. Further mechanistic studies indicated that the most active compound, 12n (IC₅₀, 0.93 μM; SI, 28.71), could induce the cell apoptosis of PC-3 cells in a dose-dependent manner and cause cell cycle arrest in the G2/M phase. The molecular docking study suggested that compound 12n fitted the active sites of cytochrome P450 17A1 (6CIZ) well.

CONCLUSIONS

12n might serve as a promising lead compound for the development of novel anticancer drugs. This facile ring-closing strategy may provide a novel and promising avenue for the cycloaddition reaction of the steroidal skeleton through α-ketoenol intermediates.

Heterocyclic steroids: Efficient routes for annulation of pentacyclic steroidal pyrimidines

Steroids are components of cell membranes, signaling molecules and are a type of secondary metabolites as a result of their high impact of biological significance. The present review described the literature reports of pentacyclic steroidal pyrimidines as a type of heterocyclic steroids. The main sections included the synthesis of the investigated steroids fused at rings-A or B or D of steroid skeleton, synthesis of binary or linked-type pyrimidines, pyrimidine oxides, macromolecules and mono- or di- or tri-peptides linked-steroidal pyrimidines. Besides, the present research highlighted the biological significance of steroidal pyrimidines, in which the compounds revealed potent anticancer, antioxidant, antibacterial, and anti-Alzheimer agents. In addition, some hetero-steroids were screened for binding DNA assay and gene expression analysis. It was settled that the incorporation of pyrimidine scaffold into steroid basic skeleton is crucial for better biological results.

A Review on Synthesis, Anticancer and Antiviral Potentials of Pyrimidine Derivatives

Background:

Pyrimidine is the six membered heterocyclic aromatic compound similar to benzene and pyridine containing two nitrogen atoms at 1st and 3rd positions. Pyrimidine is present throughout nature in various forms and is the building blocks of numerous natural compounds from antibiotics to vitamins and liposacharides. The most commonly recognized pyrimidines are the bases of RNA and DNA, the most abundant being cytosine, thymine or uracil.

Results:

Pyrimidine is a core structure in a wide variety of compounds that exhibits significant biological activity and also plays an important role in the drug discovery process. Various synthetic aspects indicated that pyrimidine derivatives are easy to synthesize and has diverse biological and chemical applications. The present review article aims to review the work reported on synthesis, anticancer and antiviral potentials of pyrimidine derivatives during new millennium.

Conclusion:

It may be concluded that the fused pyrimidine derivatives enhanced the anticancer potential against different human cancer cell lines and antiviral potential against different human immunodeficiency virus (HIV), herpes simplex virus (HSV-1) etc, which created interest among the medicinal chemists in the pyrimidine skeleton in medicinal chemistry. Thus, a tremendous scope for research is present in this direction for investigating pyrimidine derivatives as lead molecules.

Therapeutic potential of heterocyclic pyrimidine scaffolds

Heterocyclic compounds offer a high degree of structural diversity and have proven to be broadly and economically useful as therapeutic agents. Comprehensive research on diverse therapeutic potentials of heterocycles compounds has confirmed their immense significance in the pathophysiology of diseases. Heterocyclic pyrimidine nucleus, which is an essential base component of the genetic material of deoxyribonucleic acid, demonstrated various biological activities. The present review article aims to review the work reported on therapeutic potentials of pyrimidine scaffolds which are valuable for medical applications during new generation.

Synthesis and Characterisation of Novel 4-Chloro-16E-Benzylidene Steroidal Derivatives

Using androstenedione as the starting material, we have synthesised 11 novel 4-chloro-16-( E)-benzylidene androst-1,4-diene-3,17-dione derivatives. All the final products are novel and were identified by 1H NMR, 13C NMR and HRMS spectrometry.

Multicomponent access to androstano-arylpyrimidines under microwave conditions and evaluation of their anti-cancer activity in vitro

Novel ring D- and A-fused pyrimidines in the androstane series were efficiently synthesized within 10-15min in polar protic solvents under microwave irradiation via two kinds of multicomponent heterocyclization reactions followed by spontaneous or promoted oxidation. The rates of the one-pot catalyst-free transformations of steroidal β-ketoaldehydes, ammonium acetate and substituted benzaldehydes in EtOH were found to be affected slightly by the steric and electronic feature of the substituents on the aromatic ring of the arylaldehyde component and the different reactivities of rings D and A of the sterane core. At the same time, the acid-catalyzed Biginelli-type reaction of dihydrotestosterone acetate, urea and arylaldehydes, and subsequent Jones oxidation of the primarily formed dihydropyrimidinones led to the corresponding ring A-fused 1H-pyrimidin-2-ones in moderate yields independently of the substituents on the aromatic moiety. The synthesized compounds were tested in vitro on human cancer cell lines as well as on non-cancerous fibroblast cells by the MTT assay in order to investigate their biological effects. As a result of the pharmacological screen, a remarkable structure-function relationship has been observed as the acetylated Biginelli products exhibited higher toxicity compared to the deacetylated version of each compound. Furthermore, in case of three 2'-arylpyrimidine derivatives a strong prostate cancer cell specific activity has been identified.

Synthesis of Novel Heterocyclic Compounds Incorporate 4,5,6,7-Tetrahydrobenzo[b]thiophene Together with Their Cytotoxic Evaluations

The 2-amino-3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene was the key starting compound used to synthesize new thiazole, pyrimidine, pyran, pyridine and thiazine derivatives. The cytotoxicity of the synthesized compounds was studied towards the three cancer cell lines namely MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and SF-268 (central nervous system (CNS) cancer) in addition to the normal cell line (WI-38) using doxorubicin as the reference drug. The study showed that compounds 5, 9a, 15b, 17c, 18 and 21b were the most potent compounds.

The binding properties of metandienone and human serum albumin by comparing with other five similar compounds

Metandienone (MET) is an exogenous anabolic androgenic steroid. The interaction between MET and human serum albumin (HSA) was investigated by molecular modeling and different optical techniques. There was no possibility of energy transfer, and the fluorescence quenching of HSA induced by MET was mainly due to the complex formation. The differences of binding ability between MET and compounds 1-5 were significantly caused by space steric hindrance. The single crystallographic data of two steroids (compounds 4 and 5) were obtained in the methanol at the first time. In addition, the binding ability was slightly affected by -OH, -CH₃ , and -COCH₃ . The results of displacement experiment demonstrated that the MET binding site was mainly located in site 1 of HSA. H-bonding and van der Waals forces were significant in the MET-HSA binding. MET played an insignificant role on the local conformation change in HSA.

Synthesis and Cytotoxic Evaluation of Pyran, Dihydropyridine and Thiophene Derivatives of 3-Acetylcoumarin

A series of coumarin analogues bearing 4H-pyran rings 2a-d, 11a-d and 1,4-dihydropyridine rings 3a-d, 12a-d at position 3 were synthesized starting from either 3-acetyl coumarin (1) or the coumarin acetohydrazide derivative 4. Condensation of 3-acetylcoumarin (1) with 2-cyanoacetohydrazide afforded 2-cyano-N'-{1-[2-oxo-2H-chromen-3-yl]ethylidene}acetohydrazide (4). Reaction of compound 4 with elemental sulfur and either malononitrile or ethyl cyanoacetate afforded the thiophene derivatives 8 and 9, respectively. The structures of the newly synthesized compounds were confirmed on the basis of their spectral data and elemental analyses. All synthesized compounds were screened for their in vitro anticancer activity against six human cancer cell lines and normal fibroblasts. Several compounds showed potent inhibition with an IC50 value of ˂870 nM. Compound 3d exhibited equivalent cytotoxic effect as the standard CHS 828 against a breast cancer cell line (IC50 value=18 nM). Normal fibroblast cells (WI38) were affected to a much lesser extent (IC50 value >10000 nM).

The Knoevenagel reaction of cyanoacetylhydrazine with pregnenolone: Synthesis of thiophene, thieno[2,3-d]pyrimidine, 1,2,4-triazole, pyran and pyridine derivatives with anti-inflammatory and anti-ulcer activities

The reaction of pregnenolone with cyanoacetylhydrazine and ammonium acetate at 120°C gave the Knoevenagel condensation product 3. The latter reacted with different reagents to give thiophene, thieno[2,3-d]pyrimidine, 1,2,4-triazole and pyran derivatives. The anti-inflammatory and anti-ulcer evaluations of the newly synthesized products were evaluated and the results showed that compounds 4, 8c, 10, 11, 13c, 15a, 15c, 17a, 17b, 17e, 18a and 18f possessed higher activity compared to the rest of the compounds. In addition to this, the toxicity of these active compounds was studied against shrimp larvae where compounds 15a, 15c and 18a showed non-toxicity against the tested organisms.

Synthesis, anti-inflammatory and anti-ulcer evaluations of thiazole, thiophene, pyridine and pyran derivatives derived from androstenedione

The reaction of androstenedione with bromine gave the 16-bromo derivative 2. The latter reacted with either cyanothioacetamide or thiourea to give the 2-cyanomethylthiazole derivative 4 and the 2-aminothiazole derivative 13. Compound 4 and 13 were used underwent some condensation, coupling and heterocyclization reactions to give thiophene, pyridine and pyran derivatives. The anti-inflammatory and anti-ulcer evaluations of the newly synthesized products were evaluated and the results showed that 23f showed the maximum antiulcer activity. In addition, toxicity of the most active compounds was studied against shrimp larvae and showed that compounds 2, 23c and 23f showed non-toxicity against the tested organisms.