[1] Univ Calif San Francisco, Dept Pharmaceut Chem, San Francisco, CA 94158 USA
[2] NIBS, Beijing 102206, Peoples R China
[3] Univ Bologna, Dipartimento Sci Farmaceut, I-40126 Bologna, Italy
[4] Univ Calif Riverside, Dept Comp Sci & Engn, Riverside, CA 92521 USA