George Falkay

Khat - a controversial plant.

SummaryKhat (Catha edulis) is a shrub or tree whose leaves have been chewed for centuries by people who live in the Eastern part of Africa and the Arabian Peninsula. It has recently turned up in North America and Europe, particularly among emigrants and refugees from countries such as Somalia, Ethiopia and Yemen. Khat contains a number of chemicals, among which are two controlled substances, cathinone (Schedule I) and cathine (Schedule IV). Both chemicals are stimulant drugs with effects similar to amphetamine. Chewing the leaves makes people feel more alert and talkative, and suppresses appetite. Chewing khat leaves releases cathinone, a stimulant that produces the feeling of euphoria. When cathinone is broken down in the body, it produces chemicals including cathine and norephedrine, which have a similar structure to amphetamine and adrenaline (epinephrine). Regular khat use is associated with a rise in arterial blood pressure and pulse rate, corresponding with levels of cathinone in the plasma. Moreover, regular khat chewers have gingivitis and loose teeth, but there appears to be no convincing unusual incidence of oral cancer. Among khat users in Yemen there is, however, a higher incidence of esophageal cancer compared with gastric cancer. Long term use or abuse can cause insomnia, anorexia, gastric disorders, depression, liver damage and cardiac complications, including myocardial infarction. Manic and delusional behavior, violence, suicidal depression, hallucinations, paranoia and khat-induced psychosis have also been reported. On the basis of the scientific data it seems clear that khat use has negative consequences on the economic development of a country and on the health of the society.

Antiproliferative effect of flavonoids and sesquiterpenoids from Achillea millefolium s.l. on cultured human tumour cell lines

The antiproliferative activities of n‐hexane, chloroform, aqueous‐methanol and aqueous extracts of the aerial parts of the Achillea millefolium aggregate on three human tumour cell lines were investigated by means of MTT assays. The chloroform‐soluble extract exerted high tumour cell proliferation inhibitory activities on HeLa and MCF‐7 cells, and a moderate effect on A431 cells; accordingly, it was subjected to detailed bioactivity‐guided fractionation. As a result of the multistep chromatographic purifications (VLC, CPC, PLC, gel filtration), five flavonoids (apigenin, luteolin, centaureidin, casticin and artemetin) and five sesquiterpenoids (paulitin, isopaulitin, psilostachyin C, desacetylmatricarin and sintenin) were isolated and identified by spectroscopic methods. The antiproliferative assay demonstrated that centaureidin is the most effective constituent of the aerial parts of yarrow: high cell growth inhibitory activities were observed especially on HeLa (IC50 0.0819 µm) and MCF‐7 (IC50 0.1250 µm) cells. Casticin and paulitin were also highly effective against all three tumour cell lines (IC50 1.286–4.76 µm), while apigenin, luteolin and isopaulitin proved to be moderately active (IC50 6.95–32.88 µm). Artemetin, psilostachyin C, desacetylmatricarin and sintenin did not display antiproliferative effects against these cell lines. This is the first report on the occurrence of seco‐pseudoguaianolides (paulitin, isopaulitin and psilostachyin C) in the Achillea genus. Copyright

Pregnancy-induced alterations of GABAA receptor sensitivity in maternal brain: an antecedent of post-partum ‘blues’?

Pregnancy increases affinity of [3H]muscimol binding to GABAA receptors in the rat forebrain. Post-partum, the receptor affinity is further increased concomitantly with a reduction of the receptor density. These changes may result from an action of endogenous placental and adrenal steroids, tetrahydroprogesterone and tetrahydrodeoxycorticosterone, which in vitro behave as allosteric agonists of GABAA receptors. The alterations may contribute to the psychological phenomena associated with pregnancy and the puerperium.

Efficient approach to androstene-fused arylpyrazolines as potent antiproliferative agents. Experimental and theoretical studies of substituent effects on BF3-catalyzed intramolecular [3 + 2] cycloadditions of olefinic phenylhydrazones

Highly diastereoselective Lewis acid induced intramolecular 1,3-dipolar cycloadditions of alkenyl phenylhydrazones (containing various substituents on the aromatic ring) obtained from a d-secopregnene aldehyde were carried out under fairly mild conditions to furnish androst-5-ene-fused arylpyrazolines in good to excellent yields. The ability of phenylhydrazones to undergo cyclization was found to be affected significantly by the electronic features of the substituents on the aromatic moiety. The rates of the ring-closure reactions were observed to be increased by electron-donating and decreased by electron-withdrawing groups. The experimental findings on the BF(3)-catalyzed transformations were supported by calculations of the proposed mechanism at the BLYP/6-31G(d) level of theory, indicating a noteworthy dependence, mainly of the initial complexation step, and hence of the whole process, on the character of the substituent. The cycloaddition was estimated to occur via a zwitterionic intermediate rather than involving a pure concerted mechanism. The antiproliferative activities of the structurally related pyrazoline derivatives were tested in vitro on three malignant human cell lines (HeLa, MCF7, and A431): the microculture tetrazolium assay revealed that several compounds exerted marked cell growth-inhibitory effects. The highest cytotoxic activities, displayed by the p-methoxyphenylpyrazoline derivative 7d (IC(50) values: 2.01, 2.16, and 1.41 microM on HeLa, MCF7, and A341 cells, respectively), were better than those of cisplatin (IC(50) values: 12.43, 9.63, and 2.84 microM, respectively).

Antiproliferative activity of Hungarian Asteraceae species against human cancer cell lines. Part II

The antiproliferative activities of aqueous and organic extracts prepared from 26 Hungarian species of the tribes Cynereae and Lactuceae (Asteraceae) were tested in vitro against HeLa (cervix epithelial adenocarcinoma), A431 (skin epidermoid carcinoma) and MCF7 (breast epithelial adenocarcinoma) cells by using the MTT assay. Of the tested 200 extracts of different plant parts obtained with n‐hexane, chloroform, 50% methanol and water, 16 extracts displayed noteworthy cell growth inhibitory activity (>50% inhibition at a concentration of 10 µg/mL). The IC50 values of these extracts were determined, and their direct cytotoxic effects were measured. High differences between the antiproliferative and cytotoxic activities, demonstrating a real cell proliferation inhibitory activity rather than direct killing effects, were found for some Centaurea, Cirsium, Cichorium, Lactuca, Onopordum and Scorsonera extracts. Copyright

Synthesis and receptor-binding examinations of the normal and 13-epi-D-homoestrones and their 3-methyl ethers.

An effective epimerization of the normal estrone 3-methyl and 3-benzyl ethers by using o-phenylenediamine and AcOH made the possibility for facile entry into the 13alpha-estrone series. Combination of this synthetic methodology with an isolation step carried out by means of the Girard-P reagent, the corresponding ethers of 13-epi-estrone were obtained in excellent yields. The 3-hydroxy and 3-methoxy D-homoestrone derivatives in both the normal and the 13alpha-estrone series were then synthesized and tested in vitro in a radioligand-binding assay. The estrogen receptor recognizes these compounds, but their relative binding affinities (RBAs) are lower than that of the reference compound 3,17beta-estradiol. The progesterone receptor-binding affinities of the four D-homo derivatives were also tested showing low values for 13alpha-D-homoestrone and its 3-methyl ether. Pharmacologically, these 13alpha-D-homoestrone derivatives are estrogen receptor-selective molecules.

Functional and Histochemical Characterization of a Uterine Adrenergic Denervation Process in Pregnant Rats

Abstract The time course of pregnancy-induced changes in the contractile responses of isolated uterine rings and sympathetic innervation pattern were studied using electric field stimulation and histofluorescence techniques, respectively, in intact and 6-hydroxydopamine-treated rats. Neurally mediated contractions elicited by field stimulation (0.6 msec, 1–70 Hz, 40 V) were measured in uterine preparations obtained from nonpregnant, 6-hydroxydopamine-treated and 5-, 10-, 15-, 18-, and 22-day (term) pregnant rats. At all frequencies, the amplitudes of contractions were highest in nonpregnant uteri. Stimulation at 1–2.5 Hz evoked contractions in 10-day pregnant uteri but failed to cause contractions on Day 5 and from Day 15 onward. In uterine preparations obtained from term and from 6-hydroxydopamine-treated rats, contractions could not be evoked by stimulation at 1–20 Hz. Fluorescence histochemistry of uterine adrenergic nerves revealed rich perivascular and myometrial innervation in nonpregnant and in pregnant rats through Day 10. Degeneration and loss of adrenergic nerve fibers was apparent by Day 15, and fluorescent myometrial and perivascular nerves were practically absent by Day 22. These findings demonstrate a progressive, frequency-related reduction of nerve-mediated uterine contractions beginning in midterm pregnancy, in parallel with a gradual loss of adrenergic nerve fibers. Pregnancy-induced nerve degeneration may promote the development of nonsynaptic α-adrenergic uterine contractile activity towards term. The reduced responsiveness of uterine smooth muscle to electric field stimulation in early pregnancy appears to be unrelated to alterations in uterine innervation but may be related to changes associated with implantation.

Antiproliferative effect of normal and 13-epi-d-homoestrone and their 3-methyl ethers on human reproductive cancer cell lines

The possibility of the therapeutic use of estrogens emerged following the recognition that certain estradiol analogs, and particularly metabolites (e.g. the A-ring metabolite 2-hydroxyestrone, etc.) inhibit the differentiation of diverse tumor cell lines. Until recently, despite the investigation of numerous synthetic d-ring-substituted estrone derivatives, no analysis had been published on the effects of D-ring expansion of estrone on its tumor-suppressing activity. The aim of the present study was to characterize the antiproliferative effects of normal and 13-epi-D-homoestrone and their 3-methyl ethers (1-4) on human reproductive cancer cell lines. The antitumor activities of the two epimer pairs on HeLa, MCF-7 and Ishikawa cells were determined. Normal D-homoestrone exerted the greatest cytostatic effect on HeLa cells (IC(50)=5.5 μM) and was subjected to further investigations to elucidate its mechanism of action on apoptosis induction. Morphological changes detected by Hoechst 33258-propidium iodide double staining, the cell cycle arrest at phase G2/M and the subsequent increase in the proportion of the subG1 fraction determined by flow cytometric analysis and the significant increase in the activity of caspase-3 confirmed the induction of apoptosis in HeLa cells treated with D-homoestrone. D-Homoestrone was also tested on a non-cancerous human lung fibroblast cell line (MRC-5) to determine its selective toxicity. The concentration in which it inhibited cell proliferation by 50% was at least six times higher for the fibroblast cells than for cervical cancer cells. No significant in vivo estrogenic activity was observed as concerns the uterus weight of gonadectomized rats after a 7-day treatment with normal D-homoestrone. These results led to the conclusion that normal D-homoestrone is a novel antitumor compound with a similar activity on HeLa cells as that of the reference agent cisplatin, but its selectivity toward non-cancerous cells is significantly higher than that of cisplatin. It may be considered to be a basic lead molecule for the preclinical development of potential anticancer agents.

Synthesis and biological activity of a new progestogen, 16-methylene-17α-hydroxy-18-methyl-19-norpregn-4-ene-3,20-dione acetate

The progestational activity of second- and third-generation progestins in oral contraceptives were markedly increased by addition of an 18-methyl group. A new progestin, the 18-methyl analog of Nestorone, 16-methylene-17alpha-hydroxy-18-methyl-19-norpregn-4-ene-3,2 0-dione acetate (10), was synthesized. The relative binding affinity and biologic activity of 10 was compared with Nestorone, levonorgestrel, and progesterone using a binding assay for rat progesterone receptors, the Clauberg assay in the rabbit, and by assessing pregnancy maintenance in the rat. These studies, as summarized in Table 4, show that 10 is three to ten times more potent than Nestorone. The addition of the 18-methyl group to Nestorone markedly increased its potency as noted above, but is unlikely to change its rate of delivery from sustained release systems. 10 should be ideally suited for administration by implants or small skin patches.

Modulation of uterine GABAA receptors during gestation and by tetrahydroprogesterone.

Binding of a GABAA receptor agonist, [3H]muscimol, was studied in rat uterine membranes of non-pregnant rats and those at days 15 and 19 of pregnancy. Also, an interaction of the uterine GABAA receptors with tetrahydroprogesterone was examined. At day 15 of gestation [3H]muscimol binding was twice as high as in non-pregnant rats, but at day 19 it was reduced. These changes resulted from an increase of the receptor affinity and decrease of the receptor density, at days 15 and 19, respectively. Since tetrahydroprogesterone, in vitro, also increased [3H]muscimol binding, we propose that this steroid may participate in regulation of uterine function during pregnancy.