Phenolic compounds from sandpaper (ficus exasperata) leaf inhibits angiotensin 1 converting enzyme in high cholesterol diet fed rats

Ethnopharmacological relevance: Sandpaper [Ficus exasperata Vahl (Moraceae)] leaf has been reportedly used in folklore for the management/treatment of cardiovascular diseases with little/or no scientific basis for their action. This study sought to investigate the effect of dietary supplementation of sandpaper leaf on angiotensin-I converting enzyme (ACE) activity in hypercholesterolemia as well as the effect of their phenolic extract on this enzyme in vitro. Materials and methods: The phenolic extract was prepared, then, the inhibitory effect of the leaf extract on ACE was determined in vitro. Thereafter, the effect of dietary supplementation of sandpaper leaf on angiotensin-I converting enzyme (ACE) activity in high cholesterol diet fed rats for 14 days was evaluated as well as some biochemical parameters. Results: The result revealed that under in vitro condition, the phenolic extract inhibited ACE (IC50 = 14.7 mu g/mL) in a dose-dependent manner (0-10 mu g/mL). Feeding high cholesterol diets to rats caused a significant (P < 0.05) increase in the ACE activity. However, there was a significant (P < 0.05) decrease in the ACE activity as a result of supplementation with the sand paper leaves. Furthermore, there was a significant (P < 0.05) increase in the plasma lipid profile with a concomitant increase in malondialdehyde (MDA) content in rat liver and heart tissues. However, supplementing the diet with sandpaper leaf (either 10% or 20%) caused a significant (P < 0.05) decrease in the plasma total cholesterol (TC), triglyceride (TG), very low density lipoprotein-cholesterol (VLDL-C), and low-density lipoprotein-cholesterol levels (LDL-C), and in MDA content in the tissues. Conversely, supplementation caused a significant (P<0.05) increase in plasma high-density lipoprotein-cholesterol level when compared with the control diet. Reversed phase HPLC analysis of the extract revealed Quercitrin (43.7 mg/g), chlorogenic acid (42.8 mg/g) and caffeic acid (33.9 mg/g) as the major phenolics in the leaf. Conclusion: The inhibition of ACE activity and prevention of hypercholesterolemia by sandpaper leaf could be part of the possible mechanism underlying its anti-hypertensive property which could lay credence to its use in folk medicine. However, these activities may be directly/indirectly attributed to the polyphenolics present. (C) 2014 Elsevier Ireland Ltd. All rights reserved.