The present invention is directed to novel natural product-derived ratjadone-based compounds useful as payloads (or toxins) in drug-conjugates constructs with cell target binding moieties (CTBM) and payload-linker compounds useful in connection with drug conjugates. The present invention further relates to new ratjadone compositions including the aforementioned payloads, payload-linkers and drug conjugates, and methods for using these payloads, payload-linkers and drug conjugates, to treat pathological conditions including cancer, inflammatory and infectious diseases.