, Volume 235, Issue 1, pp 145–153 | Cite as

Hypericum perforatum extract modulates cortical plasticity in humans

  • Carmen Concerto
  • Hyunji Boo
  • Charles Hu
  • Priam Sandilya
  • Anita Krish
  • Eileen Chusid
  • Diego Coira
  • Eugenio Aguglia
  • Fortunato Battaglia
Original Investigation



Hypericum perforatum (HYP) extract is one of the most commonly used complementary alternative medicines (CAMs) for the treatment of mild-to-moderate depression. Non-invasive brain stimulation protocols can be used to investigate the effect of psychoactive substances on the human brain. In this study, we explored the effect of a single dose of HYP extract (WS 5570) intake on corticospinal excitability and plasticity in humans.


Twenty-eight healthy subjects were required to intake 900 mg of either HYP extract or placebo. Cortical excitability was assessed using single and paired transcranial magnetic stimulation (TMS). The electrophysiological parameters of motor threshold, recruitment of motor-evoked potentials (MEPs), cortical silent period (CSP), short interval intracortical inhibition (SICI), and intracortical facilitation (ICF) were tested before and 2 and 5 h after the oral intake. Spinal and neuromuscular excitability and peripheral nerve excitability were measured by F response and M-wave. Cortical plasticity was induced using transcranial direct current stimulation (tDCS). Subjects received either HYP extract or placebo before anodal and cathodal tDCS of the primary motor cortex. Plasticity was assessed by MEP amplitudes.


HYP extract reversed cathodal tDCS-induced long-term depression (LTD)-like plasticity into facilitation, as compared to placebo. HYP extract did not have a significant effect on anodal tDCS-induced plasticity and TMS measures of motor cortex and spinal/neuromuscular excitability.


Our findings suggest that a single oral dose of HYP extract modulates cortical plasticity in healthy subjects and provide new insight into its possible mechanism of action in humans.


Hypericum perforatum extract TMS tDCS Cortical plasticity 



We thank the volunteers that participated in this study.

Compliance with ethical standards

All participants provided their written informed consent. All the procedures were approved by the local ethics committee and complied with the Declaration of Helsinki.

Conflict of interest

The authors declare that they have no conflicts of interest.


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Copyright information

© Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  1. 1.Department of Interprofessional Health Sciences and Health Administration, School of Health and Medical SciencesSeton Hall UniversitySouth OrangeUSA
  2. 2.Pre-clinical sciencesNew York College of Podiatric MedicineNew YorkUSA
  3. 3.Department of Psychiatry and Behavioral MedicineHackensack-Meridian University Medical CenterHackensackUSA
  4. 4.Department of Clinical and Experimental Medicine, Psychiatry UnitUniversity of CataniaCataniaItaly

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