DNA N7 of guanine (N7-G) (N7-G)

The N7 position of guanine is the most nucleophilic site within the DNA double helix, making it the primary target for numerous electrophilic chemotherapeutic agents (Hemminki, 1993). Drugs such as cisplatin, carboplatin, and various nitrogen mustards (e.g., cyclophosphamide) form stable covalent bonds with this nitrogen atom, resulting in the formation of DNA adducts (Dasari & Bernard, 2014). These adducts can further evolve into intrastrand or interstrand cross-links, which physically obstruct the progression of DNA and RNA polymerases (StatPearls, 2023). This obstruction inhibits critical cellular processes, including DNA replication and transcription, effectively halting the cell cycle. If the damage is not repaired by cellular pathways such as base excision repair (BER) or nucleotide excision repair (NER), the cell undergoes programmed cell death or apoptosis (Fu et al., 2012). While these agents are highly effective against rapidly proliferating cancer cells, their lack of genomic specificity leads to significant damage in healthy tissues. This results in common clinical toxicities such as myelosuppression, nephrotoxicity, and an increased risk of therapy-induced secondary malignancies (Pai & Nahata, 2000).

Other names

N7-guanineGuanine N7N7 position of guanine7-guanineN7-G

Drugs targeting the N7 position of guanine function by forming covalent DNA adducts through alkylation or platination. This chemical modification often leads to the formation of interstrand or intrastrand cross-links that distort the DNA helix, thereby preventing strand separation and blocking the enzymatic machinery required for DNA replication and RNA transcription, which ultimately triggers apoptosis (Dasari & Bernard, 2014; StatPearls, 2023).