Pyrrolobenzodiazepines

Pyrrolobenzodiazepines (PBDs) are sequence-selective DNA minor-groove binding agents that covalently attach to guanine bases and create durable DNA damage[1]. Mechanistically, PBD dimers form non-distorting interstrand cross-links, while SJG-136 reacts with guanine bases in the 5′-GATC-3′ sequence and shows higher cytotoxicity than melphalan in CHO repair models[2][3]. In cancer research, PBDs have progressed from natural products to synthetic monomers, hybrids, dimers, and antibody-drug conjugate (ADC) payloads[1][4]. Compared with related DNA-binding systems, PBD activity differs from duocarmycin or CC-1065 analogs that alkylate adenine-rich minor-groove sites, and PBDs show insignificant affinity for most DNA G-quadruplexes without large C8 substituents[5][6]. For experimental applications, linker length and guanine spacing shape PBD dimer adduct patterns, supporting rational design of sequence-selective DNA cross-linking agents and ADC payloads[7][8].
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