Recent Advances in the Use of the Dimerization Strategy as a Means to Increase the Biological Potential of Natural or Synthetic Molecules

The design of C₂-symmetric biologically active molecules is a subject of interest to the scientific community. It provides the possibility of discovering medicine with higher biological potential than the parent drugs. Such molecules are generally produced by classic chemistry, considering the shortness of reaction sequence and the efficacy for each step. This review describes and analyzes recent advances in the field and emphasizes selected C₂-symmetric molecules (or axial symmetric molecules) made during the last 10 years. However, the description of the dimers is contextualized by prior work allowing its development, and they are categorized by their structure and/or by their properties. Hence, this review presents dimers composed of steroids, sugars, and nucleosides; known and synthetic anticancer agents; polyphenol compounds; terpenes, known and synthetic antibacterial agents; and natural products. A special focus on the anticancer potential of the dimers transpires throughout the review, notwithstanding their structure and/or primary biological properties.

[Synthetic Studies on Developments for Bioactive New Leads of Oligovalent Symmetrical Molecules]

Interactions between carbohydrate-containing glycoproteins, proteoglycans, and glycolipids on the cell surface are important biological stages for the processes of bacterial or viral infection and tumor metastasis. Moreover, supramolecular interaction by macromolecules with two-fold (C₂) or three-fold (C₃) geometry is one of the common interactions in many important biological responses. To develop new multivalent symmetrical bioactive compounds or leads, we designed and synthesized several new molecules with these geometries and evaluated their bioactivities in an attempt to find new types of bioactive leads that may interfere with the sugar recognition process. We evaluated bioactivities including antibacterial, antiviral, and anticancer activities of targeted molecules in vitro using biological assay systems. Among the synthesized target derivatives examined, some bivalent symmetrical derivatives showed high levels of bioactivities. In this review, the author describes the results of synthesis of oligovalent symmetrical target compounds and some interesting guiding results of evaluation of their biological activities and structure-activity relationships.

Anti-proliferative Activities of Some Bivalent Symmetrical 5-Substituted Hydantoin Derivatives towards Human Brain Glioma U251 Cells (U251) and Human Carcinoma Cells (KB3-1)

Novel bivalent twin-drug type hydantoin derivatives were evaluated in vitro using a human brain glioma cell line (U251) and a human carcinoma cell line (KB3-1). Among the 5-substituted hydantoin derivatives (1a-b and 2a-d) examined in this study, bivalent symmetrical 5-substituted hydantoin derivative 1b showed the highest anti-proliferative activity towards both U251 and KB3-1 cells. The values of anti-proliferative activity (IC₅₀) of this hydantoin derivative against the two cell lines (U251 and KB3-1) were 0.46 and 5.21 µM, respectively. The anti-proliferative activity of all of the compounds except for compounds 2a and 2d against U251 cells was higher than that of cisplatin. Bivalent symmetrical compound 1b had a biphenylmethane linker in the molecule. All of the tested bivalent hydantoin derivatives showed higher activity against U251 cells than against KB3-1 cells. For twin-drug type hydantoin derivatives 2a-d, which have a linear methylene linker in the molecules, it was found that methylene linker length in these molecules have an effect on the anti-proliferative activity against U251 and KB3-1 cells.

Anti-proliferative Activities towards Human Brain Glioma U251 Cells and Human Carcinoma Cells (KB3-1) of Some Twin-Drug Type Bivalent C2-Symmetrical Phenylboronic Acid Derivatives

Derivatives of C₂-symmetrical bivalent phenylboronic acid exhibit several remarkable biological activities such as anti-herpes simplex virus (HSV)-1 and cytotoxic activities against Vero cells and they can reverse the effect of anticancer drugs. Novel symmetrical bivalent molecules were synthesized and their biological activities were evaluated in vitro using a human brain glioma cell line (U251) and a human carcinoma cell line (KB3-1). Among the tested compounds (1a-i), bivalent C₂-symmetrical phenylboronic acid derivative 1g showed the highest anti-proliferative activity towards both U251 and KB3-1 cells. The values of 50% anti-proliferative activity (IC₅₀) of this compound against the two cell lines (U251 and KB3-1) were 19.0 and 3.78 µM, respectively. The anti-proliferative activity of compound 1g towards KB3-1 cells was higher than that of cisplatin. The bivalent C₂-symmetrical compound 1g had a linear methylene linker in the molecule.