[1] Univ Texas, Coll Pharm, Div Med Chem, Austin, TX 78712 USA
[2] Univ Texas, Dept Chem & Biochem, Austin, TX 78712 USA
[3] Univ Wisconsin, Lab Biosynth Chem, Madison, WI 53705 USA
[4] Univ Wisconsin, Sch Pharm, Pharmaceut Sci Div, Natl Cooperat Drug Discovery Grp, Madison, WI 53705 USA