Intriguing Antiviral Modified Nucleosides: A Retrospective View into the Future Treatment of COVID-19.

Great pioneers of nucleic acid chemistry had elucidated nucleic acid functions and structures and developed various antiviral modified nucleoside drugs. It is possible in theory that antiviral modified nucleosides prevent viral replication by inhibiting viral polymerases. However, biological phenomena far exceed our predictions at times.

Combination of non-natural D-amino acid derivatives and allophenylnorstatine-dimethylthioproline scaffold in HIV protease inhibitors have high efficacy in mutant HIV.

Several non-natural D-amino acid derivatives were introduced as P2/P3 residues in allophenylnorstatine-containing (Apns; (2S,3S)-3-amino-2-hydroxy-4-phenylbutyric acid) HIV protease inhibitors. The synthetic analogues exhibited potent inhibitory activity against HIV-1 protease enzyme and HIV-1 replication in MT-4 cells. Structure-activity relationships revealed that D-cysteine or serine derivatives contributed to highly potent anti-HIV activities.

Synthesis and antiviral property of allophenylnorstatine-based HIV protease inhibitors incorporating D-cysteine derivatives as P2/P3 moieties.

We designed several HIV protease inhibitors with various d-cysteine derivatives as P(2)/P(3) moieties based on the structure of clinical drug candidate, KNI-764. Herein, we report their synthesis, HIV protease inhibitory activity, HIV IIIB cell inhibitory activity, cellular toxicity, and inhibitory activity against drug-resistant HIV strains. KNI-1931 showed distinct selectivity against HIV proteases and high potency against drug-resistant strains, surpassing those of Ritonavir and Nelfinavir.

An expedient synthesis of N(alpha)-protected-L-tetrahydrofuranylglycine and its application in the synthesis of novel substrate based inhibitors of HIV-1 protease.

Z- and Fmoc-L-tetrahydrofuranylglycines have been obtained from L-vinylglycine through dipolar cycloaddition reaction, and its Fmoc derivative has been applied in the synthesis of modified S9 and S10 substrates of HIV-1 protease. These compounds mostly acted as strong inhibitors, rather than substrates, of the protease, probably due to the favourable interactions of the tetrahydrofuranylglycine moiety at the S(2) site.