Angioteinsin I-converting enzyme (ACE) inhibitory peptide was isolated from marine sponge (Stylotella aurantium) hydrolysate prepared by various hydrolysis enzymes. The peptic hydrolysate exhibited highest ACE inhibitory activity among them and was fractionated into three ranges of molecular weight. The below 5 kDa fraction showed the highest ACE inhibitory activity and was used for subsequent purification steps. The amino acid sequences of the purified peptides were identified to be Tyr-Arg (337.2 Da), and Ile-Arg (287.2 Da). The purified peptides from marine sponge had an IC50 value of 237.2 mu M and 306.4 mu M, respectively. The molecular docking study revealed that ACE inhibitory activity of the purified peptides was mainly attributed to the hydrogen bond interactions and Pi interaction between the dipeptides and ACE. The results suggest that marine sponge, S. aurantium would be an attractive raw material for the manufacture of anti-hypertensive nutraceutical ingredients. (C) 2016 Elsevier Ltd. All rights reserved.