Cyanobufalins: Cardioactive Toxins from Cyanobacterial Blooms (October 28, 2018) Abstract Cyanobufalins A–C (1–3), a new series of cardiotoxic steroids, have been discovered from cyanobacterial blooms in Buckeye Lake and Grand Lake St. Marys in Ohio. Compounds 1–3 contain distinctive structural features, including geminal methyl groups at C-4, a 7,8 double bond, and a C-16 chlorine substituent that distinguish them from