Synthesis and Biological Evaluation of Triazolyl 13α-Estrone-Nucleoside Bioconjugates

Steroid-triazole conjugates: A brief overview of synthesis and their application as anticancer agents

Steroids are biomolecules that play pivotal roles in various physiological and drug discovery processes. Abundant research has been fuelled towards steroid-heterocycles conjugates over the last few decades as potential therapeutic agents against various diseases especially as anticancer agents. In this context various steroid-triazole conjugates have been synthesized and studied for their anticancer potential against various cancer cell lines. A thorough search of the literatures revealed that a concise review pertaining the present topic is not compiled. Therefore, in thus review we summarize the synthesis, anticancer activity against various cancer cell lines and structure activity relationship (SAR) of various steroid-triazole conjugates. This review can lay down the path towards the development of various steroid-heterocycles conjugates with lesser side effects and profound efficacy.

A Comprehensive Review on Steroidal Bioconjugates as Promising Leads in Drug Discovery

Ever increasing unmet medical requirements of the human race and the continuous fight for survival against variety of diseases give birth to novel molecules through research. As diseases evolve, different strategies are employed to counter the new challenges and to discover safer, more effective, and target-specific therapeutic agents. Among several novel approaches, bioconjugation, in which two chemical moieties are joined together to achieve noticeable results, has emerged as a simple and convenient technique for a medicinal chemist to obtain potent molecules. The steroid system has been extensively used as a privileged scaffold gifted with significantly diversified medicinal properties in the drug discovery and development process. Steroidal molecules are preferred for their rigidness and good ability to penetrate biological membranes. Slight alteration in the basic ring structure results in the formation of steroidal derivatives with a wide range of therapeutic activities. Steroids are not only active as such, conjugating them with various biologically active moieties results in increased lipophilicity, stability, and target specificity with decreased adverse effects. Thus, the steroid nucleus prominently behaves as a biological carrier for small molecules. The steroid bioconjugates offer several advantages such as synergistic activity with fewer side effects due to reduced dose and selective therapy. The steroidal bioconjugates have been widely explored for their usefulness against various disorders and have shown significant utility as anticancer, anti-inflammatory, anticoagulant, antimicrobial, insecticidal/pesticidal, antioxidant, and antiviral agents along with several other miscellaneous activities. This work provides a comprehensive review on the therapeutic progression of steroidal bioconjugates as medicinally active molecules. The review covers potential biological applications of steroidal bioconjugates and would benefit the wider scientific community in their drug discovery endeavors.

HFIP in Organic Synthesis

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) is a polar, strongly hydrogen bond-donating solvent that has found numerous uses in organic synthesis due to its ability to stabilize ionic species, transfer protons, and engage in a range of other intermolecular interactions. The use of this solvent has exponentially increased in the past decade and has become a solvent of choice in some areas, such as C-H functionalization chemistry. In this review, following a brief history of HFIP in organic synthesis and an overview of its physical properties, literature examples of organic reactions using HFIP as a solvent or an additive are presented, emphasizing the effect of solvent of each reaction.

Green synthesis of triazolo-nucleoside conjugates via azide–alkyne C–N bond formation

Modified nucleosides are the core precursors for the synthesis of artificial nucleic acids, and are important in the field of synthetic and medicinal chemistry. In order to synthesize various triazolo-compounds, copper and ruthenium catalysed azide–alkyne 1,3-dipolar cycloaddition reactions also known as click reaction have emerged as a facile and efficient tool due to its simplicity and convenient conditions. Introduction of a triazole ring in nucleosides enhances their therapeutic value and various photophysical properties. This review primarily focuses on the plethora of synthetic methodologies being employed to synthesize sugar modified triazolyl nucleosides, their therapeutic importance and various other applications.

Modified Nucleosides, Nucleotides and Nucleic Acids via Click Azide-Alkyne Cycloaddition for Pharmacological Applications

The click azide = alkyne 1,3-dipolar cycloaddition (click chemistry) has become the approach of choice for bioconjugations in medicinal chemistry, providing facile reaction conditions amenable to both small and biological molecules. Many nucleoside analogs are known for their marked impact in cancer therapy and for the treatment of virus diseases and new targeted oligonucleotides have been developed for different purposes. The click chemistry allowing the tolerated union between units with a wide diversity of functional groups represents a robust means of designing new hybrid compounds with an extraordinary diversity of applications. This review provides an overview of the most recent works related to the use of click chemistry methodology in the field of nucleosides, nucleotides and nucleic acids for pharmacological applications.

Promising applications of steroid сonjugates for cancer research and treatment

The conjugation of biologically active molecules is a powerful tool for drug discovery used to target a variety of multifunctional diseases including cancer. Conjugated drugs can provide combination therapies in a single multi-functional agent and, by doing so, be more specific and powerful than conventional classic treatments. Steroids are widely used for conjugation with other biological active molecules. This review refers to investigations of steroid conjugates as potential anticancer agents carried out mostly over the past decade. It consists of five parts in which the data concerning structure and anticancer activity of steroid conjugates with DNA alkylating agents, metallocomplexes, approved drugs, some biological active molecules, some natural compounds and related synthetic analogs are described.

Homogeneous Catalysis: A Powerful Technology for the Modification of Important Biomolecules

Homogeneous catalysis plays an important and ubiquitous role in the synthesis of simple and complex molecules, including drug compounds, natural products, and agrochemicals. In recent years, the wide-reaching importance of homogeneous catalysis has made it an indispensable tool for the modification of biomolecules, such as carbohydrates (sugars), amino acids, peptides, nucleosides, nucleotides, and steroids. Such a synthetic strategy offers several advantages, which have led to the development of new molecules of biological relevance at a rapid rate relative to the number of available synthetic methods. Given the powerful nature of homogeneous catalysis in effecting these synthetic transformations, this Focus Review has been compiled to highlight these important developments.

Antiproliferative and antimetastatic properties of 3-benzyloxy-16-hydroxymethylene-estradiol analogs against breast cancer cell lines

Despite emerging new therapeutic opportunities, cancer is still a major health problem and a leading cause of death worldwide. Breast tumors are the most frequently diagnosed female malignancies, and the triple-negative subtype is associated with poorer prognosis and lower survival rates than other breast cancer types. The aims of the present study were to determine the anticancer potency of a set of C-3 and C-16 modified estradiol-derivatives against a panel of breast cancer cell lines, and to characterize the mechanism of action of two selected compounds (1 and 5) against the MDA-MB-231 triple-negative breast cancer cell line. Growth-inhibitory properties were investigated by an MTT-assay. Cell cycle analysis by flow cytometry has revealed G1 phase accumulation and indicated the proapoptotic effect of 1 and 5 through the elevation of the apoptotic subG1 phase on MDA-MB-231 cells after 24 h treatment. The antimetastatic activities of these compounds were examined by wound healing and Boyden chamber assays, and both compounds were shown to significantly inhibit the migration and invasion of MDA-MB-231 cells at sub-antiproliferative concentrations. Gelatin zymography assay has indicated that matrix metalloproteinase-2 and -9 are not involved in the antimetastatic action of the molecules. Western blot analysis was performed with 24 h incubation to examine the possible changes in the level of focal adhesion kinase (FAK), and both compounds were found to inhibit the phosphorylation of FAK in a concentration-dependent manner in MDA-MB-231 cells. The results of this study demonstrate that C-3 and C-16 modified estradiol derivatives are potent antiproliferative and antimetastatic compounds against a triple-negative breast cancer cell line with a mechanism of action involving the inhibition of FAK, a novel anticancer therapeutic target. Therefore, these findings can be utilized in the development of promising anticancer agents with steroid skeleton.

Synthesis of Novel C-2- or C-15-Labeled BODIPY-Estrone Conjugates

Novel BODIPY-estrone conjugates were synthesized via Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC). Estrone-alkynes or an estrone-azide as starting compounds were synthesized via Michael addition or Sonogashira reaction as key steps. Fluorescent dyes based on BODIPY-core were provided by azide or alkyne functional groups. Fluorescent labeling of estrone was efficiently achieved at the C-2 or C-15 position. The newly-elaborated coupling procedures might have a broad applicability in the synthesis of fluorescent-labeled estrone conjugates suitable for biological assays.

Design, Modeling and Synthesis of 1,2,3-Triazole-Linked Nucleoside-Amino Acid Conjugates as Potential Antibacterial Agents

Copper-catalyzed azide-alkyne cycloadditions (CuAAC or click chemistry) are convenient methods to easily couple various pharmacophores or bioactive molecules. A new series of 1,2,3-triazole-linked nucleoside-amino acid conjugates have been designed and synthesized in 57–76% yields using CuAAC. The azido group was introduced on the 5′-position of uridine or the acyclic analogue using the tosyl-azide exchange method and alkylated serine or proparylglycine was the alkyne. Modeling studies of the conjugates in the active site of LpxC indicate they have promise as antibacterial agents.