Correlation of hyperforin content of Hypericum perforatum (St John's Wort) extracts with their effects on alcohol drinking in C57BL/6J mice: a preliminary study

Hyperforin: A natural lead compound with multiple pharmacological activities

Hypericum perforatum L. (Clusiaceae), commonly known as St. John's wort, has a rich historical background as one of the oldest and most widely studied herbal medicines. Hyperforin is the main antidepressant active ingredient of St. John's wort. In recent years, hyperforin has attached increasing attention due to its multiple pharmacological activities. In this review, the information on hyperforin was systematically summarized. Hyperforin is considered to be a lead compound with diverse pharmacological activities including anti-depression, anti-tumor, anti-dementia, anti-diabetes and others. It can be obtained by extraction and synthesis. Further pharmacological studies and more precise detection methods will help develop a value for hyperforin. In addition, structural modification and pharmaceutical preparation technology will be beneficial to promoting the research progress of hyperforin based innovative drugs. Although these works are full of known and unknown challenges, researchers are still expected to make hyperforin play a greater value.

Ethnopharmacological Applications Targeting Alcohol Abuse: Overview and Outlook

Excessive alcohol consumption is the cause of several diseases and thus is of a major concern for society. Worldwide alcohol consumption has increased by many folds over the past decades. This urgently calls for intervention and relapse counteract measures. Modern pharmacological solutions induce complete alcohol self-restraint and prevent relapse, but they have many side effects. Natural products are most promising as they cause fewer adverse effects. Here we discuss in detail the medicinal plants used in various traditional/folklore medicine systems for targeting alcohol abuse. We also comprehensively describe preclinical and clinical studies done on some of these plants along with the possible mechanisms of action.

Natural Products for the Prevention and Treatment of Hangover and Alcohol Use Disorder

Alcoholic beverages such as beer, wine and spirits are widely consumed around the world. However, alcohol and its metabolite acetaldehyde are toxic and harmful to human beings. Chronic alcohol use disorder or occasional binge drinking can cause a wide range of health problems, such as hangover, liver damage and cancer. Some natural products such as traditional herbs, fruits, and vegetables might be potential dietary supplements or medicinal products for the prevention and treatment of the problems caused by excessive alcohol consumption. The aim of this review is to provide an overview of effective natural products for the prevention and treatment of hangover and alcohol use disorder, and special emphasis is paid to the possible functional component(s) and related mechanism(s) of action.

Attenuation of ethanol withdrawal syndrome by extract of Hypericum perforatum in Wistar rats

The effects of Hypericum perforatum (St John's wort) on ethanol withdrawal syndrome have been investigated in ethanol-dependent rats. Adult male Wistar rats were subjects. Ethanol (7.2% v/v) was given to rats by a liquid diet for 15 days. Hypericum perforatum extract (HPE) (25-200 mg/kg) and saline were injected to rats intraperitoneally just before ethanol withdrawal. After second, fourth and sixth hour of ethanol withdrawal, rats were observed for 5 min, and withdrawal signs that included locomotor hyperactivity, stereotyped behavior and tremors were recorded or rated. A second series of injections was given at 6 h after the first one, and subjects were then tested for audiogenic seizures. HPE (25-200 mg/kg) produced some dose-dependent and significant inhibitory effects on locomotor hyperactivity at second and sixth hour of ethanol withdrawal. In addition, it significantly reduced the number of stereotyped behaviors at the same dose range. HPE (50 and 100 mg/kg) produced some significant inhibitory effects on tremor and audiogenic seizures during withdrawal period. These results suggest that HPE has some beneficial effects on ethanol withdrawal syndrome in rats.

Depressive-like behavior and high alcohol drinking co-occur in the FH/WJD rat but appear to be under independent genetic control

This review will consider the evidence supporting the view that a specific substrain of Fawn-Hooded rat (FH/Wjd) exhibits co-occurring depressive-like behavior and high alcohol intake independently. First, the FH/Wjd rat is compared with other Fawn-Hooded substrains (FH/Har, FHH/Eur, FHL/Eur) and it is concluded that only the FH/Wjd rat is both highly immobile in the forced swim test and drinks substantial amounts of 5-10% alcohol voluntarily. Next it is demonstrated that the FH/Wjd rat fulfils many of the criteria proposed for an animal model of alcoholism (becomes tolerant, becomes dependent and expresses withdrawal symptoms, bar-presses for alcohol). Other literature in addition to the high swim test immobility suggests that the FH/Wjd rat may also be an animal model of depression (high basal corticosterone levels, blunted hormonal responses to serotonergic agonists). To study the phenotypes more closely an inbred strain (ACI/N) of rat that drank little alcohol voluntarily and exhibited considerable swimming in the forced swim test (i.e., low immobility) was obtained. A systematic intercrossing of the parental strains and the resulting F1 progeny was carried out to generate more than 800 F2s. Swim test immobility, alcohol intake and preference and saccharin intake are four of the 7 variables assessed in each of these rats. Using classical quantitative genetics methods, it was determined that these four phenotypes exhibited modest heritability and were influenced by multiple genes. Correlation coefficients between immobility and the other measures were near zero, whereas alcohol intake and preference were highly correlated (r=0.9) and alcohol and saccharin intakes were modestly correlated (r=0.3). A final study showed that chronic fluoxetine treatment counteracted the high immobility but did not affect alcohol intake, similar to human studies. These findings suggest that although depressive-like behavior and high alcohol intake co-occur in the FH/Wjd rat, they are independently regulated.

Modulation of high alcohol drinking in the inbred Fawn-Hooded (FH/Wjd) rat strain: implications for treatment

The Fawn-Hooded rat (FH/Wjd) is an inbred alcohol-preferring rat strain, unlike most of the other strains that were selectively bred for high alcohol intake and preference. It was chosen for study some 16 years ago because of a reported mutation that disrupted platelet serotonin function. Although the FH/Wjd rat has high alcohol intake (>5 g/kg/day) and preference (>65%), interbreeding with an alcohol-non-preferring inbred strain suggested that these measures are unrelated to the serotonin abnormality. Similarly, the exaggerated immobility of the FH/Wjd rats in the forced swim test did not correlate with the high alcohol intake. Many compounds have been tested in the FH/Wjd rats after both acute and chronic treatment and a substantial number of them have proved effective. However, as the case with opiate antagonists, tolerance to the effects of the drug can develop. An up-regulation of opioid receptors accompanied the chronic treatment and this mechanism may account for the development of tolerance. Tolerance to opiate antagonists has also been demonstrated in two of the selectively bred alcohol-preferring rat lines, but it is unknown whether this process may contribute to the relapses seen in individuals being treated with naltrexone. Other drugs that reliably decrease alcohol intake in the FH/Wjd rats include the 5-hydroxytryptamine-2A receptor antagonist, amperozide, the mGlu5 receptor antagonist 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (MTEP) and herbal derivatives such as ibogaine, St. John's wort and kudzu extract. Thus, studies in the FH/Wjd rat have led to the discovery of a wide variety of targets for the development of novel agents to treat alcoholism. The fact that several of these drugs were shown to reduce alcohol intake in some of the selectively bred alcohol-preferring rat lines and/or alcohol-preferring vervet monkeys increases our confidence that they are good candidates for further development.

NMDA receptor-antagonistic properties of hyperforin, a constituent of St. John's Wort

Extracts of the medicinal plant St. John's wort (Hypericum perforatum) are widely used for the treatment of affective disorders. Hyperforin, a constituent of St. John's wort, is known to modulate the release and re-uptake of various neurotransmitters, an action that likely underlies its antidepressive activity. We now report that hyperforin also has N-methyl-D-aspartate (NMDA)-antagonistic effects. Hyperforin (10 microM) was found to inhibit the NMDA-induced calcium influx into cortical neurons. In rat hippocampal slices, hyperforin inhibited the NMDA-receptor-mediated release of choline from phospholipids. Hyperforin also antagonized the increase of water content in freshly isolated hippocampal slices, and it counteracted, at 3 and 10 microM, the increase of water content induced by NMDA. Hyperforin was inactive, however, in two in vivo models of brain edema formation, middle cerebral artery occlusion and water intoxication in mice. In conclusion, hyperforin has NMDA-receptor-antagonistic and potential neuroprotective effects in vitro. This effect may contribute to the therapeutic effectiveness of St. John's wort extracts in some situations, for example, for relapse prevention in alcoholism.

Identification of Miltirone as Active Ingredient of Salvia miltiorrhiza Responsible for the Reducing Effect of Root Extracts on Alcohol Intake in Rats

BACKGROUND

Previous work found that extracts from the roots of Salvia miltiorrhiza, a Chinese medicinal herb, reduced alcohol intake in selectively bred Sardinian alcohol-preferring (sP) rats. The present study was designed to evaluate whether miltirone, one of the possible active constituents of S. miltiorrhiza, might be responsible for the reducing effect of the extracts on alcohol intake.

METHODS

An initial experiment assessed the effect of 100 mg/kg (intragastric, i.g.) of 4 extracts of S. miltiorrhiza, differing in miltirone content (0, 2, 3, and 7%, respectively), on alcohol intake in alcohol-experienced sP rats exposed to the 2-bottle "alcohol (10%, volume in volume) versus water" choice regimen. Subsequently, the effect of pure miltirone (2.5-10 mg/kg, i.g., i.e., a dose range comparable to its content in the effective doses of the active extracts) on acquisition and maintenance of alcohol-drinking behavior was evaluated in alcohol-naive and alcohol-experienced sP rats exposed to the 2-bottle choice regimen. The effect of miltirone (10 mg/kg, i.g.) on blood alcohol levels was assessed after the i.g. and intraperitoneal (i.p.) administration of alcohol. Finally, the effect of miltirone (30-100 mg/kg, i.g.) on the severity of alcohol withdrawal syndrome was evaluated in Wistar rats made physically dependent on alcohol by the repeated administration of intoxicating doses of alcohol.

RESULTS

The reducing effect of 4 different extracts of S. miltiorrhiza on alcohol intake was positively and significantly correlated with their miltirone content. Pure miltirone reduced alcohol intake in alcohol-experienced rats and delayed acquisition of alcohol-drinking behavior in alcohol-naive rats. Similar to S. miltiorrhiza extracts, miltirone markedly reduced blood alcohol levels when alcohol was administered i.g. but not i.p., suggesting that miltirone hampered alcohol absorption from the gastrointestinal system. Finally, miltirone failed to affect the severity of alcohol withdrawal syndrome in alcohol-dependent rats.

CONCLUSIONS

The results of the present study suggest that miltirone is the likely active constituent of S. miltiorrhiza responsible for the reducing effect of its extracts on alcohol intake in different experimental models of excessive alcohol consumption.

Reduction of ethanol intake by chronic treatment with Hypericum perforatum, alone or combined with naltrexone in rats

Acute treatment with extracts of Hypericum perforatum, the common plant usually called St. John's Wort, reduces voluntary ethanol intake in Marchigian Sardinian alcohol-preferring (msP) rats and acts synergistically with opioid receptor antagonists to further attenuate ethanol consumption. The present study evaluated the effect of chronic (once a day for 12 days) intragastric administration of a CO2 Hypericum perforatum extract (HPCO2), given alone or combined with naltrexone (NTX), on ethanol intake offered 2h/day in msP rats. Chronic treatment with HPCO2 markedly reduced ethanol intake at the dose of 125, but not at 7 mg/kg; the effect of 125 mg/kg was observed since the first day of treatment and remained constant across the 12 days. The same dose of HPCO2 slightly reduced the simultaneous intake of food only on day 3 and day 11 of treatment. Treated rats promptly recovered baseline ethanol intake when treatment did not precede access to ethanol (on day 8) or after the end of treatment (day 13 and day 14), suggesting that HPCO2 administrations did not induce conditioned aversion to alcohol. Chronic intraperitoneal treatment with NTX reduced ethanol intake at 3, but not at 0.5mg/kg. The synergistic effect on ethanol intake of HPCO2 and NTX was evident also in conditions of chronic treatment. HPCO2, 7 mg/kg, and NTX, 0.5mg/kg, evoked a pronounced and statistically significant reduction of ethanol intake, while being inactive. The effect on ethanol intake of the combined treatment remained stable over the 12 days of treatment; food intake was slightly reduced only on day 3 and on day 7 in response to 125 mg/kg of HPCO2 combined with NTX 0.5mg/kg, but no difference in body weight between controls and treated rats was observed at the end of treatment. Following 12-day treatment with 125 mg/kg of HPCO2, no difference was observed in the responsivity of msP rats to the effect on ethanol intake of several doses of the extract. In conclusion, the present results provide evidence for a selective and pronounced effect of HPCO2, alone or combined with naltrexone, on ethanol intake in conditions of chronic treatment, without development of tolerance. These findings further support the view that clinical trials for extracts of Hypericum perforatum in the treatment of alcoholism should be considered.

Effect of Hypericum perforatum CO2 extract on the motivational properties of ethanol in alcohol-preferring rats

AIMS

Extracts of Hypericum perforatum (HPE) attenuate voluntary ethanol intake in different lines of alcohol-preferring rats. The present study evaluated the effect of the intragastric (IG) administration of a CO(2) Hypericum perforatum extract (HPCO(2)) on operant ethanol self-administration, as well as on voluntary ethanol intake, after a period of ethanol deprivation in genetically selected Marchigian Sardinian alcohol-preferring rats.

METHODS

HPCO2 was administered by means of an indwelling IG catheter, 1 h before the tests. For the self-administration experiments, the rats were trained to self-administer 10% (v/v) ethanol in 30-min daily sessions under a fixed ratio 1 schedule of reinforcement. HPCO2 was also tested on 0.2% w/v saccharin self-administration. For the ethanol deprivation experiments, rats that had a previous experience with voluntary ethanol drinking were deprived of ethanol for 9 days, whereas water and food were freely available; HPCO2 was given by IG injection 1 h before the ethanol re-presentation.

RESULTS

HPCO2 in doses of 31 or 125 mg/kg but not 7 mg/kg, significantly reduced ethanol self-administration, while it did not modify saccharin self-administration. The same doses of the extract abolished the increased ethanol intake following ethanol deprivation.

CONCLUSIONS

These findings provide evidence that HPCO2 markedly reduces the reinforcing properties of ethanol in the self-administration paradigm, as well as the increase of ethanol intake following ethanol deprivation. These findings further support the view that the use of HPE may represent an interesting pharmacological approach in the treatment of alcohol abuse and alcoholism.

Natural and complementary therapies for substance use disorders

PURPOSE OF REVIEW

To review recent studies that have examined the efficacy of natural and complementary therapies as treatments for substance use disorders and their complications.

RECENT FINDINGS

Despite increasing interest in natural and complementary therapies for substance use disorders, rigorous clinical studies in this area are few in number. Recent clinical studies, although preliminary, have reported potential therapeutic effects for hypericum in the treatment of smoking cessation, for prickly pear extract in the prevention of alcohol hangover and magnesium supplementation as an adjunct to methadone treatment. Other clinical studies have reported negative findings for ginkgo as an adjunctive treatment for cocaine dependence, for artichoke in prevention of alcohol hangover, and acupuncture for alcohol withdrawal. Relevant findings from animal studies are also discussed. Neither vitamin E nor Liv 52 had a useful effect in alcohol-related liver disease. A study of silymarin in baboons, which was undertaken in an attempt to untangle the conflicting findings of human studies, reported a potential for this compound to prevent liver injury. There is increasing awareness of safety issues associated with complementary therapies. Safety issues pertinent to substance use treatment are discussed in this review.

SUMMARY

Several pharmacological and psychosocial treatments for substance use disorders are solidly evidence-based and improve both individual and public health outcomes. At this stage, there remains insufficient evidence to support the use of natural and complementary therapies as a primary intervention for substance use disorders. Further clinical trials are required to clarify the potential role of particular agents.

Role of hyperforin in the pharmacological activities of St. John's Wort

The phloroglucinol derivative hyperforin has been recently shown to be a major antidepressant component in the extract of Hypericum perforatum. Experimental studies clearly demonstrated its activity in different behavioral models of depression. Moreover clinical studies linked the therapeutic efficacy of Hypericum extracts to their hyperforin content, in a dose-dependent manner. The molecular mechanism of action of hyperforin is still under investigation. Hyperforin has been shown to inhibit, like conventional antidepressants, the neuronal uptake of serotonin, norepinephrine and dopamine. However, hyperforin inhibits also the uptake of gamma-aminobutyric acid (GABA) and L-glutamate. The uptake inhibition by hyperforin does not involve specific binding sites at the transporter molecules; its mechanism of action seems to be related to sodium conductive pathways, leading to an elevation in intracellular Na(+) concentration. Other additional mechanisms of action of hyperforin, involving ionic conductances as well synaptosomal and vesicular function, have been suggested. In addition to its antidepressant activity, hyperforin has many other pharmacological effects in vivo (anxiolytic-like, cognition-enhancing effects) and in vitro (antioxidant, anticyclooxygenase-1, and anticarcinogenic effects). These effects could be of clinical importance. On the other hand, the role of hyperforin in the pharmacological interactions occurring during Hypericum extract therapy must be fully investigated. Hyperforin seems to be responsible for the induction of liver cytochrome oxidase enzymes and intestinal P-glycoprotein. Several pharmacokinetic studies performed in rats and humans demonstrated oral bioavailability of hyperforin from Hypericum extract. Only recently a new chromatographic method for detection of hyperforin in the brain tissue has been developed and validated. Taking into account the chemical instability of hyperforin, current efforts are directed to the synthesis of new neuroactive derivatives.