Hypericum Extract and Hyperforin: Memory-Enhancing Properties in Rodents

Abstract

Effects of a Hypericum extract in therapeutic use and hyperforin sodium salt were evaluated in rat and mouse avoidance tests. In a conditioned avoidance response (CAR) test on the rat, oral daily administration of hyperforin (1.25 mg/kg/day) or of the extract (50 mg/kg/day) before the training sessions considerably improved learning ability from the second day onwards until the day 7. In addition, the memory of the learned responses acquired during 7 consecutive days of administration and training was largely retained even after 9 days without further treatment or training. The observations made using different doses indicate that these learning-facilitating and/or memory-consolidating effects by the agents follow inverse U-shaped dose-response curves in dose ranges lower than (for hyperforin) or equal to (for Hypericum extract) their effective dose in the behavioral despair test for antidepressants. In a passive avoidance response test on the mouse, a single oral dose (1.25 mg/kg) of hyperforin not only improved memory acquisition and consolidation, but also almost completely reversed scopolamine-induced amnesia. The single Hypericum extract dose tested (25 mg/kg) did not reveal any significant effects in the passive avoidance response (PAR) test on the mouse. These observations suggest that the Hypericum extract could be a novel type of antidepressant with memory enhancing properties, and indicate that hyperforin is involved in its cognitive effects. Pure hyperforin seems to be a more potent antidementia agent than an antidepressant.

Hyperforin, a new lead compound against the progression of cancer and leukemia?

“…29 Avoidance tests suggest that Hypericum extract exhibits memory-enhancing properties, indicating that HF is involved in its cognitive effects, acting more as an antidementia agent than an antidepressant. 30 HF also increases the release of acetylcholine from rat hippocampus in vivo in a calciumdependent way, suggesting its potential therapeutic efficacy in central cholinergic dysfunction. 31 HF stimulates the processing of the amyloid precursor protein (APP) in rat pheochromocytoma PC12 cells transfected with human wild-type APP, with a transiently increased release of secretory APP fragments and a strong reduction of intracellular APP.…”

Hyperforin prevents β-amyloid neurotoxicity and spatial memory impairments by disaggregation of Alzheimer's amyloid-β-deposits

“…17 Besides its antidepressive activity, it has been suggested that HYP possesses memory-enhancing properties in rodents. 18 These antecedents drove us to investigate whether hyperforin derivatives would be able to reduce both the b-amyloid deposition and improve spatial learning acquisition. We used a rat model consisting of an intrahippocampal stereotaxic bilateral injection of preformed Ab fibrils.…”

Dual Modulation of Striatal Acetylcholine Release by Hyperforin, a Constituent of St. John's Wort

“…Nevertheless, a severe overdosage of St. John's wort extracts may have effects on motility and should be avoided, particularly in patients with disorders of the motor systems (e.g., Parkinson's disease). On the other hand, if the facilitatory action of hyperforin on ACh release is also present in other brain areas such as hippocampus or cortex, it may explain beneficial effects of hyperforin in learning and memory tests (e.g., scopolamine-induced amnesia; Klusa et al, 2001) and may form a basis for the use of hyperforin (and St. John's wort) in cognitive disorders . This possibility is currently under investigation in our laboratory.…”