Entry Inhibitors Of HIV-1 Based On G-quadruplex

There are a lot of G-rich sequences in the human genome which can form G-quadruplex and play an important role in a number of important physiological processes. G-quadruplex can be not only as a therapeutic target for certain diseases, but also as therapeutic agents to bind to certain proteins specifically and inhibit specific protein functions. Oligonucleotide sequence 5'-d (TGGGAG) -3 ' can form stable G-quadruplex in the presence of K+, when substituted with a variety of aromatic groups at the 5'-end, were tested for anti-HIV-1 activity. In order to get a more stable and active compound based on this sequence, new chemical modifications on the bases and the composition of the sequence were conducted, and made the 5'-d (TGGGAG)-3'carrying DMTr at the 5'end as the positive control.Based on the structure-activity relationship, we introduced the bulky aromatic group TBDPS into the 5'end thymine and sugar group of the 5'-d (TGGGAG)-3'. Nine nucleoside analogues and their phosphoramidites were synthesized, of which the phosphoramidites LK-CW-712, 813, 1202, 1102, 1003, 1303 are new structures, and the others are synthesized by my colleagues in the research group.First, we introduced TBDPS into the base of dT at the 5'-end of the sequence under the premise of not affecting the formation of G-quadruplex, to optimize the position of aromatic groups. Methene, ethidene, propylidene were used as the connecting arms between the aromatic groups and the base. The results showed that the aromatic groups in the base could contribute to the inhibitory activity as those located at the sugar ring. It meant that the position of the aromatic groups hold flexibility at the 5'end. Furthermore, there were still some differences between three connecting arms. Second, the same or different aromatic groups were introduced to both the 5'-hydroxyl and the nucleotide base of 5'-dT, however, twice the amount of aromatic structure at the 5'- end of the Hotoda's sequence did not result in additive inhibitory effect. However the CD spectrum results showed that the stability of the modified sequences were improved. Third, there is no significant difference of inhibitory effect with the type of the aromatic groups, between TBDPS and DMTr. Fourth, the G-quadruplex formation was examined by incorporation of 7-deaza-2'-deoxyguanosine, the stable quadruplex was necessary for the activity. When 7-deaza-2'-deoxyguanosine was located at the 5'end of the sequence in its DMTr form, it contributed to the activity just like 5'-DMTr-dT. Fifth, the double helix of DNA was used instead of quadruplex, because both skeletons are characterized by negative ion aggregate, which are supposed to have a static interaction with the target protein gp120 and CD4. The active double helix DNA with 5'-end hydrophobic groups and the corresponding inactive single-stranded ODNs indicated that a rigid negatively-charged binding region is necessary for the activity. This kind of double helix as a molecular scaffold has never been reported before.CD spectroscopy confirmed the expected helix structure of the modified sequence under the conditions for evaluation of inhibitory activity.