Preparation of Nicotinoyl Amino Acid Derivatives by Fmoc-solid Phase Synthesis and Preliminary Studies on the Dna-binding Properties of Nicotinoyl Derivatives

Three types of nicotinoyl amino acids, i.e., nicotinoyl leucine (NA-Leu), NA-Leu-His, and NA-Tyr-Tyr, were synthesized by Fmoc solid-phase peptide synthesis, purified by reversed-phase HPLC, and characterized by 1H, 13C NMR and ESI-MS. The interactions of nicotinic acid and nicotinoyl derivatives with ctDNA were investigated by fluorescence spectroscopy. NA-Leu-His and NA-Tyr-Tyr exhibited higher affinity for ctDNA compared with free NA, indicating that the imidazolyl of histidine and the phenol group of tyrosine can enhance the embedding interaction of nicotinoyl derivatives into ctDNA. In addition, leucine in the derivatives helped form a special surrounding and spatial structure to interact with ctDNA. The stronger interaction of NA-Tyr-Tyr and NA-Leu-His with ctDNA suggested that the modified nicotinic acid probably erhaps had significant practical value and should be further studied. INTRODUCTION Nicotinic acid (NA) is one of thirteen necessary vitamins, and also is known as vitamin PP (pellegra preventive factor) because it has been identified as the cause of pellegra disease. Niacinamide cannot be directly converted from NA in the body, but both compounds are important components of the co-factors NAD and NADP.1 At present, NA and niacinamide are mainly used as peripheral vasodilators in the 252 HETEROCYCLES, Vol. 92, No. 2, 2016