30C-2 |
Purification of an angiotensin converting enzyme inhibitor from Ixeris dentata Nakai |
K. B. SONG, Food Science and Technology, College of Agriculture, Chungnam National University, 220 Gungdong, Yusungku, Taejon, 305764, South Korea and H. Jung. Angiotensin converting enzyme (ACE) converts angiotensin I into angiotensin II by cleaving C-terminal dipeptide of angiotensin I and inactivates bradykinin. ACE inhibitor acts on the inhibition of ACE and causes to result in decrease of blood pressure and was screened from protein hydrolysates of various food sources. Ixeris dentate Nakai has been known as an oriental medicine for treatment of patients having hypertension. Our objective was to isolate an ACE inhibitor from Ixeris dentate Nakai, which is known to be a medicinal plant in Korea, and to develop a new functional food ingredient. Crude water extracts of Ixeris dentate Nakai were obtained after treating at 60 oC for 2 hr, followed by centrifugation at 8000 x g for 30 min. Crude extracts were filtered using YM-3 and YM-1 membranes. The membrane-filtered solution was loaded onto FPLC with Resource RPC column (6.5mm x 100mm) on the condition of eluent A (0.1% trifluroacetic acid, TFA) and eluent B (acetonitrile containing 0.1% TFA), having gradient of B to 50%. The highest inhibitory fraction from FPLC was further purified using anion exchange chromatography with Resource Q column (6.4mm x 30mm) and the reverse phase HPLC with a C18 column. ACE inhibitory activity was measured by the method of Cushman and Cheung. An ACE inhibitor was isolated from crude water extracts of Ixeris dentate Nakai using the consecutive chromatographic methods including Resource RPC FPLC, ion exchange chromatography, and reverse phase HPLC. The ACE inhibitor purified from Ixeris dentate Nakai was unambiguously identified as a dipeptide having IC50 of 38 mM, composed of Glu and Gly by mass spectrometry and amino acid analysis. These results showed that crude extracts of Ixeris dentate Nakai can be used as a functional food ingredient having antihypertensive property. Especially, it can be used as an additive in nutraceutical drink products.
Session 30C, Food Chemistry: Proteins
|