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Herbs with Antidepressant Effects
Published in Scott Mendelson, Herbal Treatment of Major Depression, 2019
Among the many phytochemical constituents of kava, known collectively as kavalactones or kavapyrones, are dihydrokawain, kawain, methysticin, yangonin, dihydromethysticin, desmethoxyyangonin, flavokawin A, pinostrobinchalcone, dihydrotectochrysin, alpinetinchalcone, alpinetin, dihydrooroxylin A, and others in lesser degrees of concentration.2 Six of these kavalactones, including kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin, are responsible for nearly all of the plant's pharmacological activity.
Catalog of Herbs
Published in James A. Duke, Handbook of Medicinal Herbs, 2018
Stimulant consumed with Polynesian religious rites, usually as a fermented liquor made from the upper portion of the rhizome. The natives believe it relaxes the mind and body, eases pain, and induces restful sleep. Kava prepared by chewing and fermenting is said to be narcotic. Unlike alcohol, the drug does not impair mental alertness.11 The deep dreamless sleep following kava ingestion is not followed by hangover.11 Tierra28 speaks not of dreamless sleep, but of “a deep restful sleep with clear, epic-length dreams.” According to Duve,266 the chemical constituents possess anaesthetic, analgesic, anticonvulsive, antifungal, sleep-inducing, and spasmolytic properties. Dihydrokawain and dihydromethysticin are both said to have sedative effects.
The sub-acute toxicity of kavalactone in rats: a study of the effect of oral doses and the mechanism of toxicity in combination with ethanol
Published in Drug and Chemical Toxicology, 2023
Mohammed Abdulabbas Hasan, Syam Mohan, Heshu Sulaiman Rahman, Hemn Hasan Othman, Shirwan Hamasalih Omer, Abdullah Farasani
The constituents of kava responsible for producing the desirable mood-altering effects, such as muscle relaxation and anxiety relief, are kavalactones or kava pyrones (Thomsen and Schmidt 2021). Kawain, dihydrokawain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangoninare obtained from the lipid-soluble fraction, and they are the six main lactones being responsible for the potency of kavalactones. Dihydro kawain and dihydro methysticin are considered pain-relieving chemicals, which are believed to be as effective as aspirin (Ebadi 2006, Tauchen 2020). Research suggests that KL has a synergistic effect, as laboratory experiments have shown that lactones administered alone seem to have a more negligible impact compared to when they are administered in combination (Clough 2003, Fu et al. 2008). Animal experiments have demonstrated that the mechanism whereby kava components may cause sedative and hypnotic effects are similar to the mechanisms employed by the benzodiazepine group of drugs (Jussofie et al. 1994, White 2018). Folk medicine suggests that kava also may help treat sleeplessness, anxiety, headaches, colds, rheumatism, menopausal symptoms, venereal diseases, menstrual, and genitourinary tract problems (Amorim et al. 2007, Salehi et al. 2019). Kavalactones have also been mixed in certain commercially available beverages such as chocolate, tea, and drink mixes (Dennehy et al. 2005, Clayton et al. 2007, Aporosa 2020).
Bioactivation of herbal constituents: mechanisms and toxicological relevance
Published in Drug Metabolism Reviews, 2019
Kava (Piper methysticum) is an effective herbal medicine for anxiety and insomnia and has been consumed in Polynesia as a ceremonial and cultural drink for centuries. However, upon introduction as a dietary supplement in Western countries, there have been multiple case reports of kava-induced hepatotoxicity requiring liver transplantation (Becker et al. 2019). The major constituents of kava extracts are bioactive kavalactones including kawain, 7,8-dihydrokawain, methysticin, 7,8-dihydromethysticin, yangonin, and desmethoxyyangonin (Olsen et al. 2011). The two MDP-bearing lactones, methysticin and 7,8-dihydromethysticin, were shown to produce reactive o-quinones via initial CYP-mediated O-demethylenation of the MDP moiety to a catechol followed by two-electron oxidation (Johnson et al. 2003) (Figure 9(a)). GSH or mercapturic acid conjugates were not identified in human urine presumably due to extensive conjugation of the catechols via glucuronidation and sulfation in vivo. Detection of mercapturic acid adducts of 6-phenyl-3-hexen-2-one in human urine suggested an alternative bioactivation pathway of kavalactones (Zou et al. 2005). Scission of the pyrone ring followed by decarboxylation and o-demethylation led to formation of 6-phenyl-3-hexen-2-one, an α, β-unsaturated ketone metabolite which reacts with GSH or mercapturic acid via Michael-type addition (Zou et al. 2005).