In Silico and In Vitro Analysis of Bacoside A Aglycones and Its Derivatives as the Constituents Responsible for the Cognitive Effects of Bacopa monnieri

PLoS One. 2015 May 12;10(5):e0126565. doi: 10.1371/journal.pone.0126565. eCollection 2015.

Abstract

Bacopa monnieri has been used in Ayurvedic medicine to improve memory and cognition. The active constituent responsible for its pharmacological effects is bacoside A, a mixture of dammarane-type triterpenoid saponins containing sugar chains linked to a steroid aglycone skeleton. Triterpenoid saponins have been reported to be transformed in vivo to metabolites that give better biological activity and pharmacokinetic characteristics. Thus, the activities of the parent compounds (bacosides), aglycones (jujubogenin and pseudojujubogenin) and their derivatives (ebelin lactone and bacogenin A1) were compared using a combination of in silico and in vitro screening methods. The compounds were docked into 5-HT1A, 5-HT2A, D1, D2, M1 receptors and acetylcholinesterase (AChE) using AutoDock and their central nervous system (CNS) drug-like properties were determined using Discovery Studio molecular properties and ADMET descriptors. The compounds were screened in vitro using radioligand receptor binding and AChE inhibition assays. In silico studies showed that the parent bacosides were not able to dock into the chosen CNS targets and had poor molecular properties as a CNS drug. In contrast, the aglycones and their derivatives showed better binding affinity and good CNS drug-like properties, were well absorbed through the intestines and had good blood brain barrier (BBB) penetration. Among the compounds tested in vitro, ebelin lactone showed binding affinity towards M1 (Ki = 0.45 μM) and 5-HT2A (4.21 μM) receptors. Bacoside A and bacopaside X (9.06 μM) showed binding affinity towards the D1 receptor. None of the compounds showed any inhibitory activity against AChE. Since the stimulation of M1 and 5-HT2A receptors has been implicated in memory and cognition and ebelin lactone was shown to have the strongest binding energy, highest BBB penetration and binding affinity towards M1 and 5-HT2A receptors, we suggest that B. monnieri constituents may be transformed in vivo to the active form before exerting their pharmacological activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacopa / chemistry
  • Central Nervous System / chemistry
  • Central Nervous System / drug effects
  • Cognition / drug effects
  • Cognition / physiology
  • Cognition Disorders / drug therapy*
  • Cognition Disorders / pathology
  • Cognitive Behavioral Therapy
  • Computer Simulation
  • Dammaranes
  • Humans
  • Medicine, Ayurvedic*
  • Molecular Docking Simulation
  • Receptor, Muscarinic M1 / chemistry
  • Receptor, Serotonin, 5-HT2A / chemistry
  • Saponins / chemistry*
  • Saponins / pharmacokinetics
  • Saponins / therapeutic use
  • Triterpenes / chemistry*
  • Triterpenes / pharmacokinetics
  • Triterpenes / therapeutic use

Substances

  • Receptor, Muscarinic M1
  • Receptor, Serotonin, 5-HT2A
  • Saponins
  • Triterpenes
  • bacoside A
  • jujubogenin

Grants and funding

The authors wish to acknowledge the grants RG032/10BIO provided by the University of Malaya, and High Impact Research Grants HIR-MOHE (UM.C/625/1/HIR/MOHE/MED/17 and UM.C/625/1/HIR/MOHE/MED/33) provided by the Ministry of Higher Education, Malaysia, for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.