Comparative in Vitro Evaluation of Garlic, Red Yeast Rice, Lemon, and Coconut Oil for HMG-CoA Reductase Inhibition and Antioxidant Activity

Original Article

Abstract

Objective: This study comparatively evaluated the in vitro lipid-modulating and antioxidant profiles of garlic (Allium sativum), red yeast rice (Monascus purpureus), lemon (Citrus limon), and coconut oil.

Methodology: We evaluated prepared samples using concentration-dependent HMG-CoA reductase inhibition and DPPH radical-scavenging assays, along with LDL- and HDL-related endpoints. Apparent IC₅₀ values were estimated where the concentration-response range permitted. We used Fourier-transform infrared spectroscopy for complementary characterization. Lovastatin served as a reference inhibitor.

Results: The dataset demonstrated distinct biochemical profiles. Red yeast rice showed the greatest apparent HMG-CoA reductase inhibition, reaching 72.4% at 100 µg/mL, with an apparent IC₅₀ of 57.3 µg/mL, whereas garlic demonstrated intermediate inhibition (55.2%; IC₅₀, 79.6 µg/mL). Lemon exhibited the strongest apparent DPPH radical-scavenging activity, reaching 82.1% at 100 µg/mL and an apparent IC₅₀ of 51.8 µg/mL. Red yeast rice produced the greatest apparent reduction in the LDL-related endpoint (30.8%), whereas coconut oil showed comparatively limited direct activity. Antioxidant and cholesterol-biosynthesis-related activities were not necessarily concordant.

Conclusion: The investigated natural products exhibited distinct in vitro biochemical profiles, with red yeast rice showing prominent HMG-CoA reductase-related activity and lemon showing prominent radical-scavenging activity. However, the thesis identifies the numerical datasets as assumed or simulated; therefore, quantitative findings require verification against original experimental records before presentation as definitive experimental results. These findings do not support conclusions about clinical efficacy.