Enhanced efficacy and reduced side effects of diazepam by kava combination

Safety Aspects of Herb Interactions: Current Understanding and Future Prospects

BACKGROUND

The use of herbal medicines is on the rise throughout the world due to their perceived safety profile. However, incidences of herb-drug, herb-herb and herb-food interactions considering safety aspects have opened new arenas for discussion.

OBJECTIVE

The current study aims to provide comprehensive insights into the various types of herb interactions, the mechanisms involved, their assessment, and historical developments, keeping herbal safety at the central point of discussion.

METHODS

The authors undertook a focused/targeted literature review and collected data from various databases, including Science Direct, Wiley Online Library, Springer, PubMed, and Google Scholar. Conventional literature on herbal remedies, such as those by the WHO and other international or national organizations.

RESULTS

The article considered reviewing the regulations, interaction mechanisms, and detection of herb-herb, herb-drug and herb-food interactions in commonly used yet vital plants, including Glycyrrhiza glabra, Mentha piperita, Aloe barbadensis, Zingiber officinale, Gingko biloba, Withania somnifera, etc. The study found that healthcare professionals worry about patients not informing them about their herbal prescriptions (primarily used with conventional treatment), which can cause herb-drug/herb-food/herb-herb interactions. These interactions were caused by altered pharmacodynamic and pharmacokinetic processes, which might be explained using in-vivo, in-vitro, in-silico, pharmacogenomics, and pharmacogenetics. Nutrivigilance may be the greatest method to monitor herb-food interactions, but its adoption is limited worldwide.

CONCLUSION

This article can serve as a lead for clinicians, guiding them regarding herb-drug, herb-food, and herb-herb interactions induced by commonly consumed plant species. Patients may also be counseled to avoid conventional drugs, botanicals, and foods with a restricted therapeutic window.

An Updated Review on the Psychoactive, Toxic and Anticancer Properties of Kava

Kava (Piper methysticum) has been widely consumed for many years in the South Pacific Islands and displays psychoactive properties, especially soothing and calming effects. This plant has been used in Western countries as a natural anxiolytic in recent decades. Kava has also been used to treat symptoms associated with depression, menopause, insomnia, and convulsions, among others. Along with its putative beneficial health effects, kava has been associated with liver injury and other toxic effects, including skin toxicity in heavy consumers, possibly related to its metabolic profile or interference in the metabolism of other xenobiotics. Kava extracts and kavalactones generally displayed negative results in genetic toxicology assays although there is sufficient evidence for carcinogenicity in experimental animals, most likely through a non-genotoxic mode of action. Nevertheless, the chemotherapeutic/chemopreventive potential of kava against cancer has also been suggested. Both in vitro and in vivo studies have evaluated the effects of flavokavains, kavalactones and/or kava extracts in different cancer models, showing the induction of apoptosis, cell cycle arrest and other antiproliferative effects in several types of cancer, including breast, prostate, bladder, and lung. Overall, in this scoping review, several aspects of kava efficacy and safety are discussed and some pertinent issues related to kava consumption are identified.

Evaluation of Anti-Convulsive Properties of Aqueous Kava Extract on Zebrafish Using the PTZ-Induced Seizure Model

Kava roots have been extensively studied in clinical trials as potential candidate anti-anxiety drugs. However, anti-convulsive properties of various tissues of stems of Kava have not been reported to date. The objective of the study was to evaluate the anti-convulsive potential of aqueous extracts prepared from specific tissues of Kava (Piper methysticum) stems in zebrafish, using the PTZ-induced seizure model. The potency of each extract was compared in terms of the intensity of seizure scores and onset time after pre-treating the zebrafish before the PTZ challenge. The results indicate that aqueous extract of Kava stems without peel after 45 min of pre-treatment exhibited anti-convulsive potential at the dose of 50 mg/L. This study provides evidence to the anti-convulsive properties of peeled Kava stems and its potential for investigation and design of candidate anti-convulsive drugs.

Kavalactones from Kava (Piper methysticum) root extract as modulators of recombinant human glycine receptors

Roots of kava (Piper methysticum) plant are used in almost all Pacific Ocean cultures to prepare a drink with sedative, anesthetic and euphoric properties. One of the main active ingredients of the extract are kava lactones. Here, kava root CO2 extract and three kavalactones, DL-kavain, dihydrokavain and yangonin (isolated from whole extract by column chromatography) were tested for their inhibitory action on recombinant homomeric human α1 glycine receptors expressed in HEK293 cells. Kava CO2 root extract, as well as the individual components DL-kavain, dihydrokavain and yangonin inhibited glycine receptor activity in a dose-dependent manner. DL-kavain was the most potent inhibitor (IC50 = 0.077 ± 0.002 mm), followed by yangonin (IC50 = 0.31 ± 0.04 mm) and dihydrokavain (IC50 = 3.23 ± 0.10 mm) which were 4- and 40-fold less active than DL-kavain, respectively. Application of kava root extract did not reduce maximum currents, but increased EC50 of glycine. Simultaneous application of kava extract and strychnine showed additive inhibition, suggesting that binding of kavalactones and strychnine on the receptor is mutually exclusive. Overall, kavalactones exert a moderate inhibitory effect on the human α1 glycine receptor with DL-kavain being the most potent constituent.