In vitro 3‑Hydroxy‑3‑methylglutaryl‑coenzyme: A Reductase Inhibition Assay of Triphala Ayurvedic Formulation

Background: Triphala, the Ayurvedic herbal formulation composed of Terminalia chebula Retz. (Combretaceae), Terminalia bellirica Roxb. (Combretaceae), and Phyllanthus emblica L. (Euphorbiaceae) fruits. It has been reported the cholesterol‑lowering effect that the reduction of 3‑hydroxy‑3‑methylglutaryl‑coenzyme A (HMG‑CoA) reductase activity was proposed as a key mechanism of action. Since, triphala formulations in equal proportion (1:1:1) and different ratios of its three fruit constituents (vata, pitta, and kapha) have been prescribed by the traditional practitioners due to the patient’s body conditions. The biological activities of each formulation are needed to evaluate. Objectives: The objective of the study was to investigate phytochemicals, HMG‑CoA reductase inhibitory effect, and HMG‑CoA reductase molecular modeling of triphala extracts. Materials and Methods: Four triphala extracts were prepared by decoction and determined the contents of gallic acid, ellagic acid, chebulagic acid, and chebulinic acid as markers using high‑pressure liquid chromatography analysis. The in vitro HMG CoA reductase assay was performed based on ultraviolet spectrophotometry, and molecular modeling was simulated using Autodock 1.5.6 to characterize the binding energy, ligand efficacy, and H‑bond interaction. Results: All extracts contained gallic acid and chebulagic acid in the high contents, whereas ellagic acid and chebulinic acid were found in a small amount. The enzyme assay revealed pitta extract (at 10 μg/mL) was the most potent enzyme inhibition of 58.4% ± 0.40% (P ≤ 0.05). Moreover, the modeling results indicated that these four markers can interact the enzyme with different configurations and binding affinities. Conclusion: Pitta extract appeared to be a potent HMG‑CoA reductase inhibitor. It was a potential natural product as an alternative treatment for hypercholesterolemia.