Synthesis of New Promising BNCT Agents Based on Conjugates of -Dodecaborate Anion and Aliphatic Diamino Acids.

In this work, a series of boronated amidines based on the -dodecaborate anion and amino acids containing an amino group in the side chain of the general formula [BHNHC(NH(CH)CH(NH)COOH)CH], where n = 2, 3, 4, were synthesized. These derivatives contain conserved α-amino and α-carboxyl groups recognized by the binding centers of the large neutral amino acid transporter (LAT) system, which serves as a target for the clinically applied BNCT agent para-boronophenylalanine (BPA). The paper describes several approaches to synthesizing the target compounds, their acute toxicity studies, and tumor uptake studies in vivo in two tumor models. The promising compound [BHNHC(NH(CH)CH(NH)COOH)CH]*3HO demonstrates low toxicity (LD in a range from 150 to 300 mg/kg) and excellent solubility and also shows selective uptake in experimental melanoma in laboratory mice (T/N ratio remained >3 up to 60 min post-injection, with a maximum T/N of 6.2 ± 2.8 at 45 min).