Date of Completion

2025

Document Type

Thesis

Degree Name

Bachelor of Science in Pharmacy

Keywords

Clitoria ternatea, ACE inhibition, Captopril, synergy, hypertension, combination therapy

Abstract

Hypertension remains a global health challenge, with many patients failing to achieve optimal blood pressure control through conventional monotherapy. This study investigated the potential synergistic antihypertensive effects of Clitoria ternatea Linn. flower ethanolic extract (CTEE) and the angiotensin-converting enzyme (ACE) inhibitor Captopril using an in vitro ACE inhibition assay. Fresh C. ternatea flowers were extracted with 70% ethanol, yielding a crude extract rich in phenolic (42.75 ± 6.49 mg GAE/g) and flavonoid (44.02 ± 2.89 mg QE/g) compounds. ACE was isolated from porcine lungs and characterized for enzymatic activity. The inhibitory effects of CTEE, Captopril, and their combination were evaluated through spectrophotometric measurement of hippuric acid production from the substrate hippuryl-histidyl-leucine (HHL). Results demonstrated dose-dependent ACE inhibition for both agents, with IC₅₀ values of 116.07 μg/mL for CTEE and 15.60 μg/mL for Captopril. The fixed-ratio combination (1:7.5, Captopril: CTEE) exhibited enhanced inhibition (IC₅₀ = 49.34 μg/mL). CompuSyn analysis revealed synergistic interaction (Combination Index = 0.780 at 50% inhibition) with favorable dose reduction indices (2.40 for Captopril, 2.11 for CTEE). These findings suggest that C. ternatea extract synergizes with Captopril's ACE inhibitory activity, potentially enabling dose reduction while maintaining therapeutic efficacy. This study is the first to show measurable evidence that C. ternatea and Captopril work better together than alone, suggesting that combining plant extracts with blood pressure medications could improve treatment. Next steps should include testing in live models, checking for safety, and eventually moving toward clinical trials to see if this approach could benefit patients.

First Advisor

Alicia P. Catabay, RPh, MSc., PhD

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