Benzimidazole-Pyrimidine Hybrids: Synthesis and Medicinal Properties

Background: Heterocyclic compounds represent a key class of compounds in medicinal chemistry. Both benzimidazoles and pyrimidines are essential heterocycles in medicinal chemistry, with various therapeutic properties. Recent literature presents a series of hybrid heterocyclic compounds, as their medicinal properties are generally improved compared to those of single heterocyclic rings. Methods: A literature search was conducted across relevant scientific literature from peer-reviewed sources, using keywords, including "benzimidazole", "pyrimidine", "Biginelli", "benzimidazole-pyrimidine hybrids", "anticancer", "antiviral", "antimicrobial", and "anti-inflammatory". Results: In this review, benzimidazole-pyrimidine hybrids are reported as anticancer, antimicrobial, antiviral, anti-inflammatory, analgesic, antiulcer, antidepressant, anti-Alzheimer's, or antioxidant agents, with activities even better than those of existing drugs. The IC₅₀ values for these anticancer hybrids are in the nanomolar range, which signifies potent anticancer agents. It can be mentioned here that the anticancer hybrid Abemaciclib, as a CDK4/6 inhibitor for the treatment of certain types of breast cancer, was approved in 2017. The antimicrobial activity of these hybrids proved especially potent against a broad variety of infections, with MIC values in the range of µM or even nM. Moreover, these hybrids exhibited good antiviral properties against SARS-CoV-2, HIV-1, and the hepatitis C virus. The hybrids also functioned as JAK3 inhibitors, COX-1 inhibitors, and MAO-A inhibitors. Conclusions: This review presents synthesis methods of benzimidazole-pyrimidine hybrids, their medicinal properties, and SAR studies reported in the last 20 years. For almost every therapeutic activity, SAR studies have revealed the essential presence of a substituent on the aromatic rings or between the two benzimidazole and pyrimidine nuclei.