Angiotensin-converting enzyme (ACE) inhibitory potential of standardized Mucuna pruriens seed extract

Context: Mucuna pruriens Linn. (Fabaceae) is a tropical legume, traditionally used for controlling blood pressure. Inhibition of angiotensin-converting enzyme (ACE) is one of the successful strategies for controlling hypertension. Objective: The present study evaluated the ACE inhibition potential of the standardized extract of M. pruriens seeds. Materials and methods: Standardization of the extract and its fractions were carried out by RPHPLC method [methanol and 1% v/v acetic acid in water (5: 95 v/v)] using levodopa as a marker. The ACE inhibition activity of the extract and fractions was evaluated at different concentrations (20, 40, 60, 80, and 100 mu g/mL) using the HPLC-DAD and the UV spectrophotometric method. The liberation of hippuric acid (HA) from hippuryl-L-histidyl-L-leucine (HHL) was estimated in the spectrophotometric method and RP-HPLC assay at 228 nm. Results: Methanol extract and aqueous fraction showed a maximum activity with IC50 values of 38.44 +/- 0.90 and 57.07 +/- 2.90 mu g/mL (RP-HPLC), and 52.68 +/- 2.02 and 67.65 +/- 2.40 mu g/mL (spectrophotometry), respectively. Discussion: The study revealed that the aqueous extract contains the highest amount of levodopa. Eventually the methanol extract showed highest ACE inhibition activity except levodopa alone. It was further observed that the inhibition was altered with respect to the change in the content of levodopa in the extract. Thus, it can be assumed that levodopa may be responsible for the ACE inhibition activity of M. pruriens seeds. Conclusion: It can be concluded that M. pruriens seed is a potential ACE inhibitor can be explored further as an effective antihypertensive agent.