Extraction of antioxidant and ACE inhibitory peptides from Thai traditional fermented shrimp pastes

Antioxidant and angiotensin converting enzyme (ACE) inhibitory peptides were extracted and isolated from two different types of Thai traditional fermented shrimp pastes, Kapi Ta Dam (Kp-B6) and Kapi Ta Deang (Kp-R6). Compounds with masses less than 500 Da were found to be predominantly presented in both extracts. Following fractionation with sequential anion exchange chromatography and solid phase extraction (C18 matrix), three dipeptides were identified. Ser-Val and Ile-Phe were shown to exhibit ACE inhibitory activity with IC₅₀ values of 60.68 ± 1.06 and 70.03 ± 1.45 μM, respectively. Trp-Pro was shown to have high 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) radical scavenging activity (EC₅₀ 17.52 ± 0.46 μM). These results indicate that Thai traditional fermented shrimp pastes are potential sources of bioactive peptides possessing ACE inhibitory and antioxidant activities.