A high throughput screen performed to identify catalytic inhibitors of the oncogenic fusion form of cAMP-dependent protein kinase A catalytic subunit alpha (J-PKAc alpha) found an individual fraction from an organic extract of the marine soft coral Acrozoanthus australiae as active. Bioassay-guided isolation led to the identification of a 2-amino adenine alkaloid acroamine A (1), the first secondary metabolite discovered from this genus and previously reported as a synthetic product. As a naturally occurring protein kinase inhibitor, to unambiguously assign its chemical structure using modern spectroscopic and spectrometric techniques, five N-methylated derivatives acroamines A(1)-A(5) (2-6) were semisynthesized. Three additional brominated congeners A(6)-A(8) (7-9) were also semisynthesized to investigate the structure-activity relationship of the nine compounds as J-PKAc alpha inhibitors. Compounds 1-9 were tested for J-PKAc alpha and wild-type PKA inhibitory activities, which were observed exclusively in acroamine A (1) and its brominated analogs (7-9) achieving moderate potency (IC50 2-50 mu M) while none of the N-methylated analogs exhibited kinase inhibition.