Pharmacological profile of apigenin, a flavonoid isolated from Matricaria chamomilla.

Dried flowers of Matricaria chamomilla L. are largely used to provide sedative as well as spasmolytic effects. In the present study, we examined in particular the pharmacological property of a fraction isolated from a methanolic extract of M. chamomilla, which was identified by HPLC-MS-MS analysis as apigenin. By radioreceptor binding assays, we demonstrated the ability of the flavone to displace a specific radioligand, [(3)H]Ro 15-1788, from the central benzodiazepine binding site. Electrophysiological studies performed on cultured cerebellar granule cells showed that apigenin reduced GABA (gamma-aminobutyric acid)-activated Cl(-) currents in a dose-dependent fashion. The effect was blocked by co-application of Ro 15-1788, a specific benzodiazepine receptor antagonist. Accordingly, apigenin reduced the latency in the onset of picrotoxin-induced convulsions. Moreover, apigenin injected i.p. in rats reduced locomotor activity, but did not demonstrate anxiolytic, myorelaxant, or anticonvulsant activities. The present results seem to suggest that the inhibitory activity of apigenin on locomotor behaviour in rats cannot be ascribed to an interaction with GABA(A)-benzodiazepine receptor but to other neurotransmission systems, since it is not blocked by Ro 15-1788.

Determination of 1,4-benzodiazepines by high-performance liquid chromatography-electrospray tandem mass spectrometry.

A sensitive and selective method to determine diazepam, N-desmethyldiazepam, nitrazepam, flunitrazepam and medazepam in human serum and urine was established employing solid-phase extraction and high-performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS-MS) with the selected reaction monitoring (SRM) mode. Using diazepam-d5 and N-desmethyldiazepam-d5 as internal standards, recoveries between 90.4 and 109.7% were determined. The routine quantification limit was set at 2 ng/ml for serum and urine at a signal-to-noise ratio of 10:1.

Naturally occurring benzodiazepines may codetermine chronotypes.

Determinants of individual differences in sleep-wake cycles and vigilance are being recognized as major factors of influence in both physical and mental health. Alterations of an accustomed circadian sleep-wake rhythm are commonly seen in the early stages of the majority of psychiatric disorders and, by themselves, predispose to significant morbidity even in the absence of an underlying illness. While it is well known that disruptions of sleep respond favourably to benzodiazepines, agents which have been prescribed for insomnia since their industrial synthesis in the early 1960s, little attention has been paid to putative central nervous system effects of naturally occurring benzodiazepines. These molecules were found in various nutritive plants and have been quantified in human brain and peripheral blood of drug-naive individuals at trace amounts. There is agreement that elevated concentrations of naturally occurring benzodiazepines participate in the complex pathophysiology of hepatic encephalopathy, a condition asssociated with progressive impairment of consciousness and, ultimately, coma. In the present study, we address the relationship between naturally occurring benzodiazepines and time-of-day effects on the behavior of healthy subjects.

Naturally occurring benzodiazepines: current status of research and clinical implications.

Naturally occurring benzodiazepines (BZDs) were first detected in mammalian tissues in 1986. They comprise a variety of 1,4-benzodiazepines corresponding to drugs commercially available for the treatment of anxiety disorders, sleep disturbances and epileptic seizures. Several biosynthetic pathways leading to the formation of BZDs are currently being discussed and have led to the proposition of possible precursor molecules. For years, the identification of naturally occurring BZDs in mammalian organisms was mostly confined to post mortem CNS material for sensitivity reasons. While radioimmunoassay and radioreceptor assay techniques have been tentatively applied to quantitations of genuine BZDs from human milk and cerebrospinal fluid, accurate measurements in peripheral blood have only recently become accessible, e. g., by gas chromatography/selected ion monitoring-mass spectrometry (GC/SIM-MS). This review summarizes existing evidence of benzodiazepines' occurrence in nature and discusses implications for neuropsychiatric disorders.

Benzodiazepine-like compounds in the plasma of patients with fulminant hepatic failure.

BACKGROUND: Benzodiazepine-like compounds have been implicated in the pathogenesis of encephalopathy after fulminant hepatic failure. METHODS: The levels and the nature of benzodiazepine-like compounds were determined in six cases of fulminant hepatic failure during the course of the disease. Blood samples were collected on admission and a few days later, when the neurologic status had improved in five cases and immediately before death in one case. The compounds were measured in sera with a binding technique after high-performance liquid chromatography purification and analyzed with mass spectrometry. RESULTS: Their levels were highly variable in those with severe encephalopathy and were still increased on awakening in some cases. Diazepam and N-desmethyldiazepam were inconsistently present. CONCLUSIONS: The inconsistent presence of benzodiazepine-like compounds in encephalopathy after fulminant hepatic failure and their persistence, in some cases, at high levels on awakening from coma seem to indicate that the encephalopathy is not strictly dependent on the levels of these compounds.

Endogenous benzodiazepine-like compounds and diazepam binding inhibitor in serum of patients with liver cirrhosis with and without overt encephalopathy.

BACKGROUND/AIM: Despite some controversy, it has been suggested that endogenous benzodiazepine plays a role in the pathogenesis of hepatic encephalopathy. The aim of the present study was to evaluate the concentrations of endogenous benzodiazepines and the peptide, diazepam binding inhibitor, in the blood of patients with liver cirrhosis with and without overt encephalopathy, and to compare these levels with those of consumers of commercial benzodiazepines. SUBJECTS: Normal subjects (90), benzodiazepine consumers (14), and cirrhotic patients (113) were studied. METHODS: Endogenous benzodiazepines were measured by the radioligand binding technique after high performance liquid chromatography (HPLC) purification. The presence of diazepam and N-desmethyldiazepam was assayed by HPLC-electrospray tandem mass spectrometry. Diazepam binding inhibitor was studied in serum by radioimmunoassay. RESULTS: Endogenous benzodiazepines were below the limit of detection in 7% of patients with encephalopathy. When detectable, their levels were at least comparable with those of benzodiazepine consumers and correlated with the liver dysfunction but not the stage of encephalopathy. Serum levels of diazepam binding inhibitor tended to decrease when endogenous benzodiazepines levels increased. CONCLUSIONS: Endogenous benzodiazepines may accumulate in patients with liver cirrhosis during the course of the disease, and the phenomenon appears to be independent of the presence or absence of encephalopathy.