HIV envelope glycoprotein transmembrane subunit gp41 plays a critical rolein the fusion between viral and target cell membranes.Upon gp120 binding to CD4 and a coreceptor (CCR5 or CXCR4),gp41 changes its conformation by forming N-helix trimer between N-heptad repeats (NHRs) and then six-helix bundle between the N-trimer and the Cheptad repeats (CHRs).Peptides derived from the NHR and CHR of gp41 extracellular region have demonstrated potent inhibitory activity on the HIV mediated cell fusion.One of these peptides,T-20,became the first success of a new class of anti-HIV agents,named HIV entry inhibitors.However,a relatively long peptide such as T-20 suffers from several limitations including lack of oral bioavailability and high cost of production.