Hypertension is characterized by excessive renin-angiotensin system activity, leading to blood vessel constriction. Several synthetic compounds have been developed to inhibit renin and angiotensin-converting enzyme (ACE). These drugs often have adverse side effects, driving the exploration of plant protein-derived peptides as alternative or supplementary treatments. This study assessed the phenolic compound and amino acid content and the antioxidant and antihypertensive activity of 5 South Korean staple crops. Sorghum had the highest phenolic compound content and exhibited the highest antioxidant activity. Millet grains, particularly finger millet (38.86%), showed higher antihypertensive activity than red beans (14.42%) and sorghum (17.16%). Finger millet was found to contain a large proportion of branched-chain, aromatic, and sulfur-containing amino acids, which are associated with ACE inhibition. In particular, cysteine content was positively correlated with ACE inhibition in the crops tested (r=0.696, p<0.01). This study confirmed that the amino acid composition was more correlated with the antihypertensive activity of grains than the phenolic compound content. Finger millet mainly contained amino acids, which have higher ACE inhibitory activity, resulting in the strongest antihypertensive activity. These findings underscore the antihypertensive potential of select crops as plant-based food ingredients, offering insight into their biological functions.

재래유자(C. junos I), 개량종 I(C. junos I+Poncirus trifoliata), 개량종 II(Citrus junos I+C. junos II) 세 가지 유자의 종류별 수확시기에 따른 유리당, 헤스페리딘, 나린진, 플라보노이드 함량과 항고혈압 활성을 알아보고자 실험을 수행하였다. 수확시기가 늦을수록 산도는 감소하고 당도는 증가하여 당산비는 증가하였고, 포도당, 서당은 수확시기에 따른 변화가 크지 않았으나, 과당은 유자가 충분히 익는 11월에 급격히 증가함을 보여주었다. 개량종 II는 10월 수확한 과피에서, 재래종은 10월 수확한 과즙에서 다른 품종보다 총 플라보노이드가 높았으며, 유자 과피의 hesperidin과 naringin은 유자가 미성숙했을 시기인 7월에 가장 높았고, 급격히 감소하고 있었다. 총 플라보노이드 중에서 hesperidin과 naringin이 차지하는 비율도 미숙과인 7월보다 11월에 현저히 감소하는 것으로 나타났다. ACE 저해 효과는 과즙과 과피에서 모든 수확시기에서 높게 나타났다. 과즙보다 과피에서 높게 나타났으며 품종별, 수확 시기별 차이는 관찰되지 않았으나 제철 11월에 수확한 재래종 과피에서 ACE 저해 효과가 가장 높았다. 따라서 hesperidin과 naringin을 이용하고자 할때는 미숙과를, 당도나 ACE 저해 효과를 이용하고자 할 때는 완숙과를 이용하는 것이 타당할 것으로 보인다.

Styela clava tunic is generated in large amounts as a waste from S. clava processing plants and leads to environmental problems. It destroys the beach scenery and causes a bad smell and pollution by trashing on the seashore. Therefore, purpose of this study was to investigate antioxidant and antihypertensive activities of different solvent extracts from S. clava tunic for recycling of fishery waste. Antioxidant and antihypertensive activities of all extracts were concentration-dependent. Of extracts, hot water extract showed the highest DPPH radical scavenging activity with the lowest effective concentration (EC50) value (0.733 mg/ml). Chloroform extract exhibited the highest metal chelation activity with the lowest EC50 value (2.696 mg/ml). Autoclaved water extract showed the highest NO radical scavenging activity with the lowest EC50 value (0.491 mg/ml) and n-hexane extract showed the highest reducing power (A700=1.897 at 100 mg/ml). And n-butanol extract showed the highest SOD-like activity with the lowest EC50 value (19.116 mg/ml) and ACE inhibition activity with the lowest inhibitory concentration(IC50) value (0.149 mg/ml). These results indicate that extracts obtained from S. clava tunic may potential candidate to reduce diseases caused by various oxidative stresses and hypertension.