Yung-Hyo Koh

A Novel Nonnucleoside Analogue That Inhibits Human Immunodeficiency Virus Type 1 Isolates Resistant to Current Nonnucleoside Reverse Transcriptase Inhibitors

ABSTRACT Nonnucleoside reverse transcriptase (RT) inhibitors (NNRTIs) are important components of current combination therapies for human immunodeficiency virus type 1 (HIV-1) infection. However, their low genetic barriers against resistance development, cross-resistance, and serious side effects can compromise the benefits of the two current drugs in this class (efavirenz and nevirapine). In this study, we report a novel and potent NNRTI, VRX-480773, that inhibits viruses from efavirenz-resistant molecular clones and most NNRTI-resistant clinical HIV-1 isolates tested. In vitro mutation selection experiments revealed that longer times were required for viruses to develop resistance to VRX-480773 than to efavirenz. RT mutations selected by VRX-480773 after 3 months of cell culture in the presence of 1 nM VRX-480773 carried the Y181C mutation, resulting in a less-than-twofold increase in resistance to the compound. A virus containing the double mutation V106I-Y181C emerged after 4 months, causing a sixfold increase in resistance. Viruses containing additional mutations of D123G, F227L, and T369I emerged when the cultures were incubated with increasing concentrations of VRX-480773. Most of the resistant viruses selected by VRX-480773 are susceptible to efavirenz. Oral administration of VRX-480773 to dogs resulted in plasma concentrations that were significantly higher than those required for the inhibition of wild-type and mutant viruses. These results warrant further clinical development of VRX-480773 for the treatment of HIV infection in both NNRTI-naive and -experienced patients.

Synthesis of Nucleoside Libraries on Solid Support. II. 2,6,8‐Trisubstituted Purine Nucleosides Using 8‐Bromoguanosine as Precursor

A series of 2,6,8‐trisubstituted purine nucleoside libraries was prepared by parallel solid‐phase synthesis using 8‐bromoguanosine as a common synthetic precursor. Polystyrene‐methoxytrityl chloride resin was linked to the N2 or O5′ position of the guanosine analogues. 8‐Bromoguanosine was derivatized at the C8 position via carbon‐carbon bond formation. Nucleophilic aromatic substitution at C2 and/or C6 positions with various amines produced two series of purine nucleoside libraries with very diverse substitution. †In honor and celebration of the 70th birthday of Professor Leroy B. Townsend.