(À)-Lemonomycin (1) belongs to a large family of tetrahydroisoquinoline (THIQ) alkaloids,[1] and was isolated from the fermentation broth of Streptomyces candidus (LLAP191) in 1964.[2] In 2000, researchers at Wyeth–Ayerst discovered that 1 shows antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VREF),[3] as well as cytotoxicity to a human colon-tumor cell line ( ...