ACE Inhibitory Activity of Hydrolysates of Phycobiliproteins from Spirulina

ACE inhibitory peptides were prepared from Spirulina phycobiliproteins by pepsin or trypsin-catalyzed hydrolysis and the ACE inhibitory activities were determined by in vitro spectrophotometric assay so as to optimize the hydrolysis conditions by orthogonal factorial design. The results showed the conditions for pepsin-catalyzed hydrolysis were as follows: enzyme/substrate ratio 1:50, pH 3.0 and substrate concentration 5% (m/V), and hydrolysis temperature 37 ℃ for a hydrolysis duration of 120 min, and these conditions resulted in 82.16% of the ACE inhibition rate and the IC50 reached 0.104 mg/ml; the optimal conditions for trypsin-catalyzed hydrolysis were as follows: enzyme/substrate ratio 1:50, pH 8.0 and substrate concentration 6% (m/V), and hydrolysis temperature 42 ℃ for a hydrolysis duration of 160 min; and the IC50 of trypsin-catalyzed hydrolysates of Spirulina phycobiliproteins by pepsin (both under the optimized conditions) reached 0.087 mg/ml.