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.

Introduction
Material and Methods
    1. Plant materials and reagents
    2. Extraction method
    3. Determination of total phenolic compound andflavonoid contents
    4. Amino acid analysis
    5. Determination of antioxidant capacity
    6. ACE inhibition assay
    7. Statistical analysis
Result and Discussion
    1. Functional compounds and antioxidant activities ingrains
    2. Amino acid composition and antihypertensive propertyof grains
    3. Antihypertensive property of amino acid standardcompounds
Conclusion
Acknowledgements
References

• Narae Han(Post-Doctor, Dept. of Central Area Crop Science, National Institute of Crop Science, Rural Development Administration, Suwon 16613, Korea)
• Koan Sik Woo(Senior Researcher, Bioenergy Crop Research Institute, National Institute of Crop Science, Rural Development Administration, Muan 58545, Korea)
• Jin Young Lee(Researcher, Dept. of Central Area Crop Science, National Institute of Crop Science, Rural Development Administration, Suwon 16613, Korea)
• Jiho Chu(Associate Researcher, Dept. of Southern Area Crop Science, National Institute of Crop Science, Rural Development Administration, Miryang 50424, Korea)
• Mihyang Kim(Researcher, Dept. of Central Area Crop Science, National Institute of Crop Science, Rural Development Administration, Suwon 16613, Korea)
• Yu-Young Lee(Senior Researcher, Dept. of Central Area Crop Science, National Institute of Crop Science, Rural Development Administration, Suwon 16613, Korea)
• Moon Seok Kang(Senior Researcher, Dept. of Central Area Crop Science, National Institute of Crop Science, Rural Development Administration, Suwon 16613, Korea)
• Hyun-Joo Kim(Researcher, Dept. of Central Area Crop Science, National Institute of Crop Science, Rural Development Administration, Suwon 16613, Korea) Corresponding author