Hypericum perforatum

St. John's Wort (Hypericum Perforatum) is a herb which, through the active component Hypericin, works as a dopamine-related anti-depressant and is effective at doing so. This is also the prototypical 'adverse drug-interaction' herb

1. Sources and Composition

1.1. Composition

St. John's wort (SJW) refers to a plant by the botanical name of hypericum perforatum (of the family hypericaceae), with this species in particular being called Common St. John's wort or Perforate St. John's wort to distinguish it from other species in the plant genus of hypericum which all share the common name of St. John's wort.

Contains:

• Hypericin, initially thought to be the major psychoactive component of the plant
• Pseudohypericin
• Hyperforin, a phloroglucinol derivative currently thought to be the major psychoactive component of the plant
• Adhyperforin^[1]

1.2. Formulations and Variants

LI-160 refers to a standardized extract of hypericum perforatum which contains precisely 0.3% hypericin (250µg per 300mg) and approximately twice as much pseudohypericin (0.6% of the total extract) according to HPLC analysis.^[2][3]

2. Molecular Targets

2.1. Ion Channels

Hyperforin from St.John's Wort has been suggested to be the major neuroactive component of the plant, and it has been noted that hyperforin can activate nonselective cation channels (NSCCs) at 10μM although the EC₅₀ in neurons was found to be 720nM.^[4] This activation increases sodium uptake in the cell, and is dependent on NSCC1 and NSCC2,^[4] and this is thought to underlie the antidepressant effects as those two channels are present in neurons^[5] and the increase in sodium uptake correlates well with inhibition of serotonin uptake in vitro.^[4]

The NSCC that appears to be specifically implicated is TRPC6^[6][7] and it appears that the related molecule adhyperforin also possesses this reuptake property.^[1]

It was noted that hyperforin also elevated calcium ion concentrations in neurons (PC12) with an EC₅₀ of 1.16μM, only slightly less potent than its influence on sodium ions.^[4]

Hyperforin appears to be capable of causing an influx of ions (primarily sodium) into various cells such as neurons due to acting on channels which mediate their uptake

This is potentially related to the antidepressant effects of St.John's Wort since it is known to inhibit serotonin reuptake despite not influencing the serotonin transporter^[8] like SSRIs would; the reuptake has been tied into an increase in intracellular sodium ion concentrations.^[9] Reuptake inhibition has occurred with many other neurotransmitters as well including dopamine, noradrenaline, glutamate, and GABA^[10] although dopamine may be most sensitive (serotonin less sensitive and noradrenaline potentially unresponsive from standard doses^[11]).

This has been noted in the prefrontal cortex with oral supplementation in rats^[11] and in vitro in corticol neurons^[8] and hippocampal cells.^[7] Oral supplementation failed to influence neurotransmitters in the striatum.^[11]

The influx of ions seems to be related to the inhibition of neurotransmitter reuptake that is seen with hyperforin, and thus this mechanism may underlie the antidepressant effects of St.John's Wort (as it appears dopamine and serotonin are primarily affected, their reuptake inhibition leading to antidepressant effects)

3. Pharmacology

3.1. Absorption

The bioavailability of hypericin has been stated to be approximately 14%.^[12]

3.2. Transportation in Serum

Following oral administration of 300, 600, or 1,800mg hypericum perforatum containing 0.3% hypericin (250, 750, and 1,500µg), the T_max appeared to occur 4.6 hours later with the concentrations reached being dose-dependent between 1.5-14.2µg/L (median values).^[13] Similar numbers have been found elsewhere with a similar study design, where the same supplement reached a C_max of 1.3-16.6µg/L after 5.5-6.0 hours.^[3]

Steady state plasma concentrations of hypericin can be reached after four days supplementation of hypericum perforatum (300mg thrice daily) of approximately 8.5µg/L.^[13]

Oral ingestion of St.John's Wort at 300mg/kg (WS 5572) in rats has resulted in plasma hyperforin concentrations of 370ng/mL (690nM) at a T_max of three hours.^[14]

Ingestion of 300mg St.John's Wort (14.8mg hyperforin) in otherwise healthy subjects increases plasma hyperforin to 150ng/mL (280nM).^[14] Increasing the dose to 600mg increased the exposure to hyperforin while 900-1,200mg St.John's Wort had less exposure than the lower doses, and the estimated steady state exposure with the standard 300mg thrice daily dosing is 150nM.^[14]

3.3. Neurological Distribution

One review^[12] has stated (via referencing the 1997 American Herbal Pharmacopoeia) that brain concentrations of hypericin may only reach 5% of what is observed in plasma, although the half-life may be weeks.

3.4. Elimination

When looking at the elimination of hypericin, it seems that the alpha half-life (t_1/2α) is relatively rapid at 1.9 hours (250µg hypericin) or 5.8-6.0 hours (750-1,500µg hypericin) but the beta half-life (t_1/2β) is prolonged between 24.5 hours (250µg) or 43.1-48.2 hours (750-1,500µg);^[3] this suggests hypericin is being deposited/retained in bodily tissue. Pseudohypericin follows similar kinetics, and daily dosing of 750µg hypericin over 14 days does not appear to alter the kinetics of elimination.^[3]

3.5. Phase I Enzyme Interactions

^[12]

3.6. Known Drug Interactions

4. Neurology

4.1. Adrenergic Neurotransmission

When tested in vitro, both hyperforin and hyperoside have been noted to downregulate β1 adrenergic receptors when at a concentration of 1μM over three days incubation resulting in 10% less activity under basal conditions and under stimulation (assessed by cAMP production).^[15] These mechanisms also appear to apply to the high affinity β2 adrenergic receptor subsets^[16] and hypericin may also be active on adrenergic receptors although with a different time for efficacy than hyperforin.^[17] It is uncertain how this occurs with St. John's wort bioactives, although an oxidative component may exist since this process can be inhibited by Vitamin E in vitro.^[18]

Hyperforin appears to downregulate β-adrenergic receptors in the rat frontal cortex following subchronic exposure^[19] and appears to be similar to other antidepressants (imipramine and fluoxetine) where there is a mild decrease in β-adrenergic signalling in the prefrontal cortex after two weeks with a mild increase after eight weeks, although its efficacy differed based on the fractions used.^[17]

4.2. Dopaminergic Neurotransmission

A single high dose of hypericum perforatum (300mg/kg of 0.3% hypericin and 4.1% hyperforin) in otherwise normal rats appears capable of increasing extracellular dopamine in the prefrontal cortex by 40% after an hour;^[11] this was associated with reduced levels of dopamine's metabolites DOPAC (15% of baseline) and HVA (53%) while noradrenaline (NA) remained unchanged, and due to no overall changes in tissue dopamine concentration this was attributed to increased turnover.^[11]

This observation is in line with in vitro observations of hypericum perforatum inhibiting dopamine reuptake due to hyperforin,^[20] as while a methanolic extract of the plant inhibits dopamine reuptake to a potent degree (IC₅₀ of 0.85µg/mL^[20]) pure hyperforin is said to be more potent.^[21] This is thought to be unrelated to the dopamine transporter (DAT) itself, as a DAT inhibitor failed to replicate the effects^[11] (the effect on serotonin reuptake from hyperforin is also unrelated to its transporter^[8][9]) and although blockade of the NA transporter could also prevent dopamine reuptake^[22] NA concentrations were unaffected.^[11]

4.3. Serotonergic Neurotransmission

Subchronic administration of St.John's Wort has been noted to increase 5-HT₂ serotonin receptors in the frontal cortex of the rat brain.^[19]

Potential influence on serotonin receptors

Hypericum perfotatum is known to inhibit serotonin reuptake in a manner not associated with the serotonin transporter (SERT),^[8] which is the common mechanism of SRI/SSRI antidepressants. The active component is known to be hyperforin (amongst other possible components)^[20] and appears to work by increasing intracellular sodium concentrations.^[9] Unlike monensin, a chemical that can increase intracellular sodium concentrations unilaterally leading to toxicity,^[23] hyperforin appears to only do so to a certain degree before losing efficacy in vitro.^[9]

Mild elevations of serotonin have been noted in the prefrontal cortex of rats given 300mg/kg St.John's Wort (4.1% hyperforin).^[11]

Hyperforin is likely the component of St.John's Wort that increases serotonin activity overall, and this appears to be due to inhibiting serotonin reuptake in an atypical manner

4.4. Miscellaneous Mechanisms

Hypericin^[24] and the flavanol fraction of hypericum perforatum^[25] are known to inhibit monoamine oxidase (MAO), with hypericin being activate at 1mM.^[26] The extract of the plant itself seems more potent at inhibiting MAO (showing efficacy at 10µM^[26]) but it is uncertain if MAO inhibition plays a role in the effects seen with hypericum perforatum supplementation due to the high concentrations required (with one study noting that while 100µg/mL of the plant was effective on both MAO-A and MAO-B, more practical concentrations of 1-10µg/mL were not^[11]).

Catechol-O-methyltransferase (COMT) can also be inhibited by hypericum perforatum at 100µM while hypericin is inactive on this enzyme.^[26]

While the plant has been noted to have inhibitory actions on both MAO and COMT, which would normally confer some antidepressant properties, it is uncertain if these mechanisms are relevant to supplementation due to high concentrations needed at the level of the enzymes

4.5. Depression

A 2008 Cochrane Meta-Analysis^[27] of 29 trials (5489 patients) that were blinded and randomized in patients with major depression (DSM-IV criteria) noted that in the trials against placebo that St. John's Wort was associated with less depressive symptoms with an Odds Ratio of 1.28 (95% CI of 1.10-1.49) in larger trials and 1.87 (95% CI of 1.22 to 2.87) in the smaller trials.^[27] The studies in this meta-analysis were quite heterogeneous, lasting between 4-12 weeks but was comprised of high quality studies (assessed by Jadad; 5/5 median value); this meta-analysis restricted studies to those in Major Depression, rather than the previous Meta-Analysis looking at all depressive studies.^[28]

When St. John's Wort was compared to Tricyclic Antidepressants (TCAs) and SSRIs, the respective Odds ratio benefitting St. John's Wort were 1.02 and 1.00 respectively; suggesting that the was no practical difference between the pharmaceuticals and St. John's Wort.^[27] Additionally, dropouts associated with St. Johns wort were significantly less than both TCAs (OR of 0.24) and SSRIs (OR of 0.53) suggesting that St. John's wort has less side-effects.^[27]

The studies included in this meta-analysis that were against placebo are cited here,^{[29][30][31][32][33][34][35][36][37][38][39][40][41]} with those comparative in nature (against pharmaceuticals) cited here against SSRIs^{[42][43][44][45][31][46][47][48][49][50][32][51][52][53][54]} or TCAs.^[55]]^{[55][56][57][58]}

Non-response to St. John's Wort has been noted in some persons.^[29]

St. John's Wort, overall, appears to reduce depressive symptoms with a potency not significantly different than SSRIs and TCAs (Pharmaceutical anti-depressants); some non-responders to St. John's Wort have been noted, who then respond to regular therapy

References

1. Tian J1, et al Antidepressant-like activity of adhyperforin, a novel constituent of Hypericum perforatum L . Sci Rep. (2014)
2. Brockmöller J1, et al Hypericin and pseudohypericin: pharmacokinetics and effects on photosensitivity in humans . Pharmacopsychiatry. (1997)
3. Kerb R1, et al Single-dose and steady-state pharmacokinetics of hypericin and pseudohypericin . Antimicrob Agents Chemother. (1996)
4. Treiber K1, et al Hyperforin activates nonselective cation channels (NSCCs) . Br J Pharmacol. (2005)
5. Yang B1, Samson WK, Ferguson AV Excitatory effects of orexin-A on nucleus tractus solitarius neurons are mediated by phospholipase C and protein kinase C . J Neurosci. (2003)
6. Leuner K1, et al Hyperforin--a key constituent of St. John's wort specifically activates TRPC6 channels . FASEB J. (2007)
7. Leuner K1, et al Hyperforin modulates dendritic spine morphology in hippocampal pyramidal neurons by activating Ca(2+) -permeable TRPC6 channels . Hippocampus. (2013)
8. Gobbi M1, et al Hypericum perforatum L. extract does not inhibit 5-HT transporter in rat brain cortex . Naunyn Schmiedebergs Arch Pharmacol. (1999)
9. Singer A1, Wonnemann M, Müller WE Hyperforin, a major antidepressant constituent of St. John's Wort, inhibits serotonin uptake by elevating free intracellular Na+1 . J Pharmacol Exp Ther. (1999)
10. Chatterjee SS1, et al Hyperforin as a possible antidepressant component of hypericum extracts . Life Sci. (1998)
11. Yoshitake T1, et al Hypericum perforatum L (St John's wort) preferentially increases extracellular dopamine levels in the rat prefrontal cortex . Br J Pharmacol. (2004)
12. Russo E1, et al Hypericum perforatum: pharmacokinetic, mechanism of action, tolerability, and clinical drug-drug interactions . Phytother Res. (2014)
13. Staffeldt B1, et al Pharmacokinetics of hypericin and pseudohypericin after oral intake of the hypericum perforatum extract LI 160 in healthy volunteers . J Geriatr Psychiatry Neurol. (1994)
14. Biber A1, et al Oral bioavailability of hyperforin from hypericum extracts in rats and human volunteers . Pharmacopsychiatry. (1998)
15. Jakobs D1, et al Downregulation of β1 -adrenergic receptors in rat C6 glioblastoma cells by hyperforin and hyperoside from St John's wort . J Pharm Pharmacol. (2013)
16. Prenner L1, et al Reduction of high-affinity beta2-adrenergic receptor binding by hyperforin and hyperoside on rat C6 glioblastoma cells measured by fluorescence correlation spectroscopy . Biochemistry. (2007)
17. Simbrey K1, Winterhoff H, Butterweck V Extracts of St. John's wort and various constituents affect beta-adrenergic binding in rat frontal cortex . Life Sci. (2004)
18. De Marchis GM1, et al Vitamin E reduces antidepressant-related beta-adrenoceptor down-regulation in cultured cells. Comparable effects on St. John's wort and tricyclic antidepressant treatment . Planta Med. (2006)
19. Müller WE1, et al Effects of hypericum extract (LI 160) in biochemical models of antidepressant activity . Pharmacopsychiatry. (1997)
20. Müller WE1, et al Hyperforin represents the neurotransmitter reuptake inhibiting constituent of hypericum extract . Pharmacopsychiatry. (1998)
21. Müller WE Current St John's wort research from mode of action to clinical efficacy . Pharmacol Res. (2003)
22. Carboni E1, et al Blockade of the noradrenaline carrier increases extracellular dopamine concentrations in the prefrontal cortex: evidence that dopamine is taken up in vivo by noradrenergic terminals . J Neurochem. (1990)
23. Mollenhauer HH1, Morré DJ, Rowe LD Alteration of intracellular traffic by monensin; mechanism, specificity and relationship to toxicity . Biochim Biophys Acta. (1990)
24. Suzuki O, et al Inhibition of monoamine oxidase by hypericin . Planta Med. (1984)
25. Bladt S1, Wagner H Inhibition of MAO by fractions and constituents of hypericum extract . J Geriatr Psychiatry Neurol. (1994)
26. Thiede HM1, Walper A Inhibition of MAO and COMT by hypericum extracts and hypericin . J Geriatr Psychiatry Neurol. (1994)
27. Linde K, Berner MM, Kriston L St John's wort for major depression . Cochrane Database Syst Rev. (2008)
28. Linde K, et al St John's wort for depression: meta-analysis of randomised controlled trials . Br J Psychiatry. (2005)
29. Gelenberg AJ, et al The effectiveness of St. John's Wort in major depressive disorder: a naturalistic phase 2 follow-up in which nonresponders were provided alternate medication . J Clin Psychiatry. (2004)
30. Brenner R, Madhusoodanan S, Pawlowska M Efficacy of continuation treatment with hypericum perforatum in depression . J Clin Psychiatry. (2002)
31. Fava M, et al A Double-blind, randomized trial of St John's wort, fluoxetine, and placebo in major depressive disorder . J Clin Psychopharmacol. (2005)
32. Hypericum Depression Trial Study Group Effect of Hypericum perforatum (St John's wort) in major depressive disorder: a randomized controlled trial . JAMA. (2002)
33. Kasper S, et al Superior efficacy of St John's wort extract WS 5570 compared to placebo in patients with major depression: a randomized, double-blind, placebo-controlled, multi-center trial {ISRCTN77277298} . BMC Med. (2006)
34. Hypericum treatment of mild–moderate depression in a placebo–controlled study. A prospective, double–blind, randomized, placebo–controlled, multicentre study
35. Laakmann G, et al St. John's wort in mild to moderate depression: the relevance of hyperforin for the clinical efficacy . Pharmacopsychiatry. (1998)
36. Effectiveness of St John's Wort in Major Depression
37. Kalb R, Trautmann-Sponsel RD, Kieser M Efficacy and tolerability of hypericum extract WS 5572 versus placebo in mildly to moderately depressed patients. A randomized double-blind multicenter clinical trial . Pharmacopsychiatry. (2001)
38. Multicenter Double-Blind Study Examining the Antidepressant Effectiveness of the Hypericum Extract LI 160
39. The Ham D6 is more homogenous and as sensitive as the Ham D17
40. Lecrubier Y, et al Efficacy of St. John's wort extract WS 5570 in major depression: a double-blind, placebo-controlled trial . Am J Psychiatry. (2002)
41. Uebelhack R, et al Efficacy and tolerability of Hypericum extract STW 3-VI in patients with moderate depression: a double-blind, randomized, placebo-controlled clinical trial . Adv Ther. (2004)
42. Schrader E Equivalence of St John's wort extract (Ze 117) and fluoxetine: a randomized, controlled study in mild-moderate depression . Int Clin Psychopharmacol. (2000)
43. Behnke K, et al Hypericum perforatum versus fluoxetine in the treatment of mild to moderate depression . Adv Ther. (2002)
44. Bjerkenstedt L, et al Hypericum extract LI 160 and fluoxetine in mild to moderate depression: a randomized, placebo-controlled multi-center study in outpatients . Eur Arch Psychiatry Clin Neurosci. (2005)
45. Brenner R, et al Comparison of an extract of hypericum (LI 160) and sertraline in the treatment of depression: a double-blind, randomized pilot study . Clin Ther. (2000)
46. Gastpar M, Singer A, Zeller K Efficacy and tolerability of hypericum extract STW3 in long-term treatment with a once-daily dosage in comparison with sertraline . Pharmacopsychiatry. (2005)
47. Gastpar M, Singer A, Zeller K Comparative efficacy and safety of a once-daily dosage of hypericum extract STW3-VI and citalopram in patients with moderate depression: a double-blind, randomised, multicentre, placebo-controlled study . Pharmacopsychiatry. (2006)
48. St John's wort or sertraline? Randomized controlled trial in primary care
49. Harrer G, Hübner WD, Podzuweit H Effectiveness and tolerance of the hypericum extract LI 160 compared to maprotiline: a multicenter double-blind study . J Geriatr Psychiatry Neurol. (1994)
50. Harrer G, et al Comparison of equivalence between the St. John's wort extract LoHyp-57 and fluoxetine . Arzneimittelforschung. (1999)
51. Vitiello B, et al Hyperforin plasma level as a marker of treatment adherence in the National Institutes of Health Hypericum Depression Trial . J Clin Psychopharmacol. (2005)
52. Efficacy and tolerability of Hypericum perforatum in major depressive disorder in comparison with selective serotonin reuptake inhibitors: A meta-analysis
53. Moreno RA, et al Hypericum perforatum versus fluoxetine in the treatment of mild to moderate depression: a randomized double-blind trial in a Brazilian sample . Rev Bras Psiquiatr. (2006)
54. Anghelescu IG, et al Comparison of Hypericum extract WS 5570 and paroxetine in ongoing treatment after recovery from an episode of moderate to severe depression: results from a randomized multicenter study . Pharmacopsychiatry. (2006)
55. Philipp M, Kohnen R, Hiller KO Hypericum extract versus imipramine or placebo in patients with moderate depression: randomised multicentre study of treatment for eight weeks . BMJ. (1999)
56. Comparison of St John's wort and imipramine for treating depression: randomised controlled trial
57. Vorbach EU, Arnoldt KH, Hübner WD Efficacy and tolerability of St. John's wort extract LI 160 versus imipramine in patients with severe depressive episodes according to ICD-10 . Pharmacopsychiatry. (1997)
58. Wheatley D LI 160, an extract of St. John's wort, versus amitriptyline in mildly to moderately depressed outpatients--a controlled 6-week clinical trial . Pharmacopsychiatry. (1997)

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