Analysis of bioactive peptides in protein hydrolysates from five microalgae

Spirulina and microalgae are sources of vitamins, proteins, and bioactive compounds that are beneficial as health supplements. This research studies the protein hydrolysates obtained by digesting proteins extracted from five microalgae: Spirulina platensis strain C1 and BP, Nannochloropsis sp., Isochrysis sp. and Chaetoceros muelleri through enzymatic digestion using pepsin. Peptide sequences of hydrolysates from the five algae were analyzed by using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). Then, bioactivity profiles of the peptides sequences were compared with a database of bioactive peptides by using the SmartBioPep platform. The results revealed that bioactive peptides of protein hydrolysates from five microalgae were found such as Angiotensin-Converting Enzyme (ACE) inhibitors, Dipeptidyl Peptidase IV (DPPIV) inhibitors, and Antioxidants, which are related to blood pressure reduction, associated with diabetes treatment, and exhibited antioxidant properties, respectively. Then, the bioactivity was tested by analyzing ACE inhibitory activity, DPPIV inhibitory activity, and Antioxidant activity. The analysis of ACE inhibitory activity, DPPIV inhibitory activity, and antioxidant activity revealed that bioactive peptides from protein hydrolysates of five microalgae inhibited ACE and DPPIV activity by 94–99% and 85–99% at a concentration of 0.225 mg/mL and 0.9 mg/mL, respectively, and exhibited a total antioxidant capacity (TAC) ranging from 0.23 to 0.93 mM UAE at a concentration of 0.9 mg/mL. The results indicate that peptides derived from the five microalgae exhibit potential efficacy for further development as nutraceuticals.