6-N-Acyltriciribine analogues: structure-activity relationship between acyl carbon chain length and activity against HIV-1.

Triciribine (TCN) and triciribine-5'-monophosphate (TCN-P) are active against HIV-1 at submicromolar concentrations. In an effort to improve and better understand this activity, we have conducted a structure-activity relationship study to explore the tolerance of TCN to structural modifications at the 6-position. A number of 6-N-acyltriciribine analogues were synthesized and evaluated for antiviral activity and cytotoxicity. The cytotoxicity of these compounds was minimal in three human cell lines (KB, CEM-SS cells, and human foreskin fibroblasts (HFF)). The compounds were marginally active or inactive against herpes simplex virus type 1 (HSV-1) and human cytomegalovirus (HCMV). In contrast, most of the compounds exhibited moderate to high activity against human immunodeficiency virus type 1 (HIV-1), IC 50 's = 0.03 to 1 μM. This structure-activity relationship study identified the N-heptanoyl group as having the optimal carbon chain length. This compound was as active against HIV-1 as TCN and TCN-P. Reverse phase HPLC of extracts from uninfected cells treated with 6-N-acyltriciribines detected sufficient TCN-P to account for anti-HIV activity thereby suggesting a prodrug effect. Studies in an adenosine kinase deficient cell line showed that the 6-N-acyl derivative was not phosphorylated directly but first was metabolized to triciribine which then was converted to TCN-P.