Methysticin

Phytother Res. 2011 Mar;25(3):417-23.

Kavalactones Yangonin and Methysticin induce apoptosis in human hepatocytes (HepG2) in vitro.[Pubmed: 20734326]

While cases of severe kava hepatotoxicity have been reported, studies examining the toxicity of individual kavalactones are limited. The present study examined the in vitro hepatotoxicity of kavain, Methysticin and yangonin on human hepatocytes (HepG2) and the possible mechanism(s) involved.
METHODS AND RESULTS:
Cytotoxicity was assessed using lactate dehydrogenase (LDH) and ethidium bromide (EB) assays. The mode of cell death was analysed with acridine orange/ethidium bromide dual staining with fluorescence microscopy. Glutathione oxidation was measured using the ortho-phthalaldehyde (OPT) fluorescence assay. Kavain had minimal cytotoxicity, Methysticin showed moderate concentration-dependent toxicity and yangonin displayed marked toxicity with ~ 40% reduction in viability in the EB assay. Acridine orange/ethidium bromide staining showed the predominant mode of cell death was apoptosis rather than necrosis. No significant changes were observed in glutathione levels, excluding this as the primary mechanism of cell death in this model. Further studies may elucidate the precise apoptotic pathways responsible and whether toxic kavalactone metabolites are involved.

Naunyn Schmiedebergs Arch Pharmacol. 1995 Apr;351(4):348-55.

Effects of methysticin on three different models of seizure like events studied in rat hippocampal and entorhinal cortex slices.[Pubmed: 7630425]

Methysticin is one of the constituents of Piper methysticum which possesses anticonvulsant and neuroprotective properties.
METHODS AND RESULTS:
Its effects on different in vitro seizure models were tested using extracellular recordings in rat temporal cortex slices containing the hippocampus and the entorhinal cortex. Elevating [K+]0 induced seizure-like events with tonic and clonic electrographic phases in area CA1. Lowering [Ca2+]0 caused recurrent seizure like episodes with large negative field potential shifts. Lowering Mg2+ induced short recurrent discharges in area CA3 and CA1 while ictaform events lasting for many seconds were induced in the subiculum, entorhinal and temporal neocortex. In the hippocampus the activity stayed stable over a number of hours. In contrast, the ictaform events in the subiculum, entorhinal and temporal cortex changed their characteristics after one to two hours to late recurrent discharges. In a concentration-range from 10 to 100 microM Methysticin reversibly blocked all these types of epileptiform activity. Decreases in [Ca2+]0 and associated slow field potentials evoked by repetitive stimulation of the stratum radiatum or the alveus remained almost unaffected by Methysticin. A paired pulse stimulus paradigm used to test for effects of Methysticin on synaptically evoked transient field potentials in normal medium revealed interference with mechanisms involved in frequency potentiation. While responses to alvear stimulation were largely unaffected, the responses to a paired pulse stimulus to stratum radiatum were depressed over the whole range of tested stimulus intervals.
CONCLUSIONS:
The findings suggest that Methysticin has effects on different patterns of epileptiform activity possibly by interfering with processes responsible for frequency potentiation.

Toxicol Sci. 2011 Dec;124(2):388-99.

Methysticin and 7,8-dihydromethysticin are two major kavalactones in kava extract to induce CYP1A1.[Pubmed: 21908763]

Kava is a plant traditionally used for making beverages in Pacific Basin countries and has been used for the treatment of nervous disorders in the United States. The pharmacological activity of kava is achieved through kavalactones in kava extract, which include kawain, 7,8-dihydrokawain, yangonin, 5,6-dehydrokawain, Methysticin, and 7,8-dihydroMethysticin.
METHODS AND RESULTS:
Recent studies have shown that kava extract induces hepatic CYP1A1 enzyme; however, the mechanisms of CYP1A1 induction have not been elucidated, and the kavalactones responsible for CYP1A1 induction have not yet been identified. Using a combination of biochemical assays and molecular docking tools, we determined the functions of kava extract and kavalactones and delineated the underlying mechanisms involved in CYP1A1 induction. The results showed that kava extract displayed a concentration-dependent effect on CYP1A1 induction. Among the six major kavalactones, Methysticin triggered the most profound inducing effect on CYP1A1 followed by 7,8-dihydroMethysticin. The other four kavalactones (yangonin, 5,6-dehydrokawain, kawain, and 7,8-dihydrokawain) did not show significant effects on CYP1A1. Consistent with the experimental results, in silico molecular docking studies based on the aryl hydrocarbon receptor (AhR)-ligand binding domain homology model also revealed favorable binding to AhR for Methysticin and 7,8-dihydroMethysticin compared with the remaining kavalactones. Additionally, results from a luciferase gene reporter assay suggested that kava extract, Methysticin, and 7,8-dihydroMethysticin were able to activate the AhR signaling pathway. Moreover, kava extract-, Methysticin-, and 7,8-dihydroMethysticin-mediated CYP1A1 induction was blocked by an AhR antagonist and abolished in AhR-deficient cells.
CONCLUSIONS:
These findings suggest that kava extract induces the expression of CYP1A1 via an AhR-dependent mechanism and that Methysticin and 7,8-dihydroMethysticin contribute to CYP1A1 induction. The induction of CYP1A1 indicates a potential interaction between kava or kavalactones and CYP1A1-mediated chemical carcinogenesis.

Bioorg Med Chem Lett. 2009 Oct 1;19(19):5732-6.

Identification of methysticin as a potent and non-toxic NF-kappaB inhibitor from kava, potentially responsible for kava's chemopreventive activity.[Pubmed: 19716299]

Nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays an essential role in cancer development.
METHODS AND RESULTS:
The results of our recent chemopreventive study demonstrate that kava, a beverage in the South Pacific Islands, suppresses NF-kappaB activation in lung adenoma tissues, potentially a mechanism responsible for kava's chemopreventive activity.
CONCLUSIONS:
Methysticin is identified as a potent NF-kappaB inhibitor in kava with minimum toxicity. Other kava constituents, including four kavalactones of similar structures to Methysticin, demonstrate minimum activities in inhibiting NF-kappaB.