[1] Univ Santo Tomas, Grad Sch, Manila 1015, Philippines
[2] Angeles Univ Fdn, Coll Arts & Sci, Angeles City 2009, Philippines
[3] Angeles Univ Fdn, Grad Sch, Angeles City 2009, Philippines
[4] Univ Santo Tomas, Res Ctr Nat & Appl Sci, Phytochem Lab, Manila 1015, Philippines
[5] Univ Regensburg, Inst Organ Chem, D-93053 Regensburg, Germany
[6] Univ Angers, SONAS UPRES EA 921, UFR Sci Pharmaceut & Ingn Sante, F-49100 Angers, France
[7] Univ Paderborn, Dept Chem, D-33098 Paderborn, Germany
[8] Univ Illinois, Coll Pharm, Inst TB Res, Chicago, IL 60612 USA