Anti-vancomycin-resistant Enterococcus faecium and E. faecalis activities of (-)-gossypol and derivatives from Thespesia garckeana - Masila, VM; Midiwo, JO; Zhang, J; Gisacho, BM; Munayi, R; Omosa, LK; Wiggers, FT; Jacob, MR; Ibrahim, MA; Walker, LA; Muhammad, I (Planta Medica, 2015)