Five new manzamine alkaloids (1-5) and new salt forms of two known manzamines (6 and 7), along with seven known compounds (8-14) of the same structural class, were isolated from an Indonesian Acanthostrongylophora sp. sponge. On the basis of the results of combined spectroscopic analyses, the structure of kepulauamine A (1) was determined to possess an unprecedented pyrrolizine moiety, while others were functional group variants of known manzamines. These compounds exhibited weak cytotoxicity, moderate antibacterial activity, and mild inhibition against the enzyme isocitrate lyase.