Nodulisporic acid B, B1, and B2: a series of 1′-deoxy-nodulisporic acids from Nodulisporium sp.

Abstract During the re-isolation of the lead compound nodulisporic acid A ( 1a ) and targeted chemical screening for related compounds, we discovered a series of 1′-deoxy congeners named herein nodulisporic acids B ( 1b ), B 1 ( 2b ), and B 2 ( 3b ). In comparison with nodulisporic acid A, these compounds were less active and were chemically unstable resulting into formation of Δ 23 dehydro derivatives. Therefore, these compounds were stabilized and isolated as sodium salts and methyl ester. Nodulisporic acid B is 100-fold less active than nodulisporic acid A against fleas. The isolation, structure elucidation, and biological activities of these compounds are described.