The present invention relates to production of polyketides and other natural products and to libraries of compounds and individual novel compounds. Therefore in aspect the present invention provides 17-desmethylrapamycin and analogues thereof, methods for their production, including recombinant strains, and isolation and uses of the compounds of the invention. In a further aspect the present invention provides for the use of 17-desmethylrapamycin and analogues thereof in the induction or maintenance of immunosuppression, the stimulation of neuronal regeneration or the treatment of cancer, B-cell malignancies, fungal infections, transplantation rejection, graft vs. host disease, autoimmune disorders, diseases of inflammation vascular disease and fibrotic diseases, and in the regulation of wound healing.