The effect of ginger (Zingiber officinalis) and artichoke (Cynara cardunculus) extract supplementation on gastric motility: a pilot randomized study in healthy volunteers

OBJECTIVE

Prodigest® is the standardized combination of artichoke and ginger extracts. This combination was safe and effective in the treatment of functional dyspepsia. However, further evidence could be useful to shed new lights on the effect of Prodigest® on gastric motility. This pilot randomized study on healthy volunteers investigates the prokinetic activity of Prodigest®.

SUBJECTS AND METHODS

This was a randomized, cross-over study in healthy volunteers comparing Prodigest® versus placebo. Eleven healthy volunteers were enrolled. Each participant underwent two evaluations, at a 7-day interval. Ten minutes before the main meal, the baseline area of gastric volume was determined by ultrasonography. The subject was then given one Prodigest® or placebo capsule and, then consumed a standardized meal. One hour after the meal, the gastric volume was measured again. Two weeks after the second evaluation, three subjects repeated the above-mentioned procedures taking two capsules of Prodigest®.

RESULTS

The mean gastric area at baseline was 3.2 ± 0.5 cm(2); after the meal, this figure was 8.4 ± 0.7 cm(2) with Prodigest® and 11.0 ± 1.5 cm2 with placebo (p<0.001). The after-meal gastric area was significantly smaller, with a -24% difference, following the combination of extracts, as compared with placebo (p<0.001). The effect of two capsules of Prodigest® seems to be more evident but due to the very small number of the patients sample further clinical data are necessary before confirming the dose-related effects.

CONCLUSIONS

This pilot study shows that Prodigest®, a standardized extract of ginger and artichoke, significantly promotes gastric emptying in healthy volunteers without being associated with notable adverse effects.

Can nausea and vomiting be treated with ginger extract?

Ginger (Zingiber officinale) is a spice traditionally used to treat indigestion, nausea and vomiting. Ginger extracts accelerate gastric emptying and stimulate gastric antral contractions. These effects are mainly due to the presence of gingerols and shogaols and their activity on cholinergic M receptors and serotonergic 5-HT and 5-HT receptors. Various researches on this subject have led to controversial results, due to the chemical instability of ginger extracts and particularly of gingerols, which are readily-oxidizable substances. A systematic review of double-blind, placebo-controlled, randomized studies highlighted the potential efficacy of ginger on the prevention and treatment of nausea and vomiting of various origins, even though additional controlled studies are needed. This review focuses on pregnancy-induced nausea and vomiting and on chemotherapy induced nausea, and hypothesizes a therapeutic role for ginger extracts in case of side effects, as an alternative to traditional prokinetic drugs such as domperidone, levosulpiride or metoclopramide.

SAMITAL® improves chemo/radiotherapy-induced oral mucositis in patients with head and neck cancer: results of a randomized, placebo-controlled, single-blind Phase II study

PURPOSE

This randomised, placebo-controlled single-blind trial investigated the safety and efficacy of SAMITAL®, a formulation of highly standardised botanical extracts, in the treatment of chemo/radiotherapy-induced oral mucositis (OM) in patients with head and neck cancer.

METHODS

Patients received SAMITAL® or placebo four times daily for up to 50 days during scheduled chemo/radiotherapy. Severity of OM was monitored according to a modified WHO severity scale, and pain and quality-of-life assessments were based on the effect of symptoms of OM on relevant daily activities, according to a visual analogue scale.

RESULTS

Mean scores for the severity of OM were significantly (p < 0.05 versus baseline) reduced from day 31 until the end of treatment in patients treated with SAMITAL® (n = 20). No significant improvement was observed in the placebo group (n = 10). Pain reduction was significant from day 4 till end of treatment with SAMITAL® and from days 7 to 21 in placebo patients. SAMITAL® also significantly improved quality of life, as shown by improvements in scores for relevant daily activities including eating, drinking and sleeping. All SAMITAL® patients completed the treatment period, but no placebo recipients completed treatment. No severe adverse events were observed with SAMITAL®, and systemic absorption of relevant active ingredients was undetectable.

CONCLUSIONS

SAMITAL® significantly decreased the severity of chemo/radiotherapy-induced OM in patients with head and neck cancer, with no treatment-related adverse events. Pain relief lasted through the treatment period, and improvements in quality of life were reflected by the significant benefits of SAMITAL® on activities like drinking, eating and speaking.

A randomized, double-blind, placebo-controlled trial to evaluate efficacy and tolerability of an optimized botanical combination in the management of patients with primary hypercholesterolemia and mixed dyslipidemia

This study compared the efficacy and tolerability of an optimized botanical combination containing policosanol, tomato extract, orally bioavailable grape procyanidins and Oenothera biennis oil against placebo in the management of patients with primary hypercholesterolemia and mixed dyslipidemia. Such a combination is endowed with biological properties targeted to cholesterol control and vasoprotection. This randomized, double-blind, parallel-group trial consisted of a 6 week treatment period following 4 week baseline period, and a 2 week post-treatment follow-up. At baseline, both the groups were comparable to each other. Both the active treatment and the placebo group included 30 patients (active treatment: mean age 46.80 ± 7.43 years, nine males; placebo: mean age 45.50 ± 6.76 years, eight males). Significant reductions in the LDL-cholesterol (LDL-C; -17.33% from baseline, p < 0.001) and total cholesterol (TC; -13.38% from baseline, p < 0.0001) values over the treatment period were observed with the tested product. The treatment also resulted in reductions in C-reactive protein (CRP), malondialdehyde (MDA) and superoxide dismutase (SOD) values, which are indices of oxidative stress. This rational combination of different compounds is effective and safe in lowering the elevated LDL-C and TC values. It is also effective in the modulation of the oxidation indices values; however, a further long term study in a larger population would be needed in order to confirm these preliminary findings.

The hyperforin derivative IDN5706 occludes spatial memory impairments and neuropathological changes in a double transgenic Alzheimer's mouse model

The use of natural compounds is an interesting stratagem in the search of drugs with therapeutic potential for the treatment of Alzheimer's disease (AD). We report here the effect of the hyperforin derivative (IDN5706, tetrahydrohyperforin), a semi-synthetic derivative of the St. John's Wort, on the brain neuropathology, learning and memory in a double transgenic (APPswe, PS-1dE9) mouse model of AD. Results indicate that, IDN5706 alleviates memory decline induced by amyloid-beta (Abeta) deposits as indicated by the Morris water maze paradigm. Moreover, the analysis of Abeta deposits by immunodetection and thioflavin-S staining of brain sections, only reveals a decrease in the frequency of the larger-size Abeta deposits, suggesting that IDN5706 affected the turnover of amyloid plaques. Immunohistochemical analysis, using GFAP and n-Tyrosine indicated that the hyperforin derivative prevents the inflammatory astrocytic reaction and the oxidative damage triggered by high Abeta deposit levels. We conclude that the hyperforin derivative, IDN5706, has therapeutic potential for prevention and treatment of AD.

Molecular Biology and the Staging of Prostate Cancer

Cancer of the prostate is still controlled or cured by surgery, radiotherapy, and hormone therapy. The present criteria of complication and prediction are criticized more and more for not being sufficiently reliable, due to the high heterogeneity of prostatic cells. The continuing discoveries of intra- and extracellular mechanisms of the molecular informational network, which allow the continuity or discontinuity of the cell's life, are also related to prostate cancer. The role of androgen receptors is now under close scrutiny, in the light of the knowledge of regulatory genes and their molecular expression. In the near future, a complete study of prostate cancer's DNA is certainly envisaged. Looking forward to the extraordinary applications of molecular biology in this field, this article is aimed at establishing a clear link between the conventional ways of interpreting the clinical expression of prostate cancer and the oncoming applications of genomics and proteomics.

Antitumour activity of the silybin-phosphatidylcholine complex, IdB 1016, against human ovarian cancer

This study aimed to assess, in an in vivo experimental model, the growth inhibitory effects of IdB 1016 (Silipide, a complex of silybin/phosphatidylcholine) when used as a single agent against human ovarian cancer. We also wanted to investigate the mechanism of the antiangiogenic action by assessing Vascular Endothelial Growth Factor (VEGF) levels and by using macroarray technology to evaluate the regulation of a panel of genes involved in angiogenesis. We also aimed to establish the plasma and tumour bioavailability of silybin after repeated administration of IdB 1016. Female nude mice bearing human ovarian cancer xenografts (A2780) received 450 mg/kg/day IdB 1016 daily by oral gavage until the end of the study. At sacrifice, blood and tumour specimens were collected and subsequently processed for the determination of silybin levels, VEGF levels or a gene expression profile. IdB 1016 was significantly active in inhibiting ovarian tumour growth. Treatment with 450 mg/kg/day for a total of 20 administrations produced a tumour weight inhibition (TWI%) of 78% and a Log10 Cell Kill (LCK) of 1.1. Free silybin levels were found to be 7.0+/-5.3 microg/ml and 183.5+/-85.9 ng/g tissue (mean+/-standard deviation (S.D.)) in the plasma and tumour samples, respectively. No significant differences were found in the concentration of human VEGF in xenografts from control and IdB 1016-treated mice. The array analysis suggested the downregulation of the VEGR receptor 3 and the upregulation of angiopoietin-2 as potential mechanisms for the antiangiogenic activity. In conclusion, these findings suggest IdB 1016 is a good candidate, with a relevant clinical potential, for use in the management of recurrent ovarian cancer. A phase II, non-randomised clinical study is now ongoing in our Institute aimed at evaluating the efficacy of daily administrations of IdB 1016 in the serological recurrence of ovarian cancer.

IDN 5390: an oral taxane candidate for protracted treatment schedules

The recognition of the antiangiogenic properties of taxanes provides a basis for novel therapeutic approaches. A prolonged exposure to low drug concentrations has been proposed to be the most suitable approach to exploit the antiangiogenic potential of cytotoxic agents. Such schedule is required to target preferentially slowly dividing endothelial cells. The protracted use of taxanes could benefit from the availability of a taxane endowed with a favourable tolerability profile. Among compounds of a novel series of C-seco taxanes, IDN 5390 was originally selected on the basis of its potent antimotility activity and poor cytotoxicity on endothelial cells. The aim of the study was to investigate the preclinical pharmacologic profile of IDN 5390 in a variety of human tumour xenografts, including ovarian and colon carcinoma and a glioblastoma. IDN 5390, delivered by s.c. injection, daily for 5 days per week, exhibited a high activity against all tumours investigated (tumour growth inhibition was always >85%) in the range of well-tolerated doses. The maximum tolerated dose/injection (MTD), with no signs of systemic or local vesicant toxicity, was 120 mg kg(-1). In contrast, paclitaxel, delivered according to the same schedule, exhibited a variable antitumour efficacy associated with a substantial local toxicity (MTD=10 mg kg(-1)). Considering the remarkable efficacy of IDN 5390 delivered s.c. by protracted treatment schedule, the oral route of administration was further investigated, as the most suitable for daily treatment. Indeed, a good bioavailability of oral IDN 5390 was found. Oral IDN 5390 maintained a substantial efficacy against human tumour xenografts, including paclitaxel-resistant tumours, without loss of potency with respect to s.c. administration. In conclusion, the therapeutic advantages of IDN 5390, over paclitaxel, in protracted daily treatment schedules are represented by the oral efficacy and the high tolerability, which are favourable features to exploit the antiangiogenic potential and to design combinations with other effective agents.

High-performance liquid chromatographic assay for the determination of the novel C-Seco-taxane derivative (IDN 5390) in mouse plasma

A HPLC assay was developed to determine IDN 5390, a new paclitaxel analogue, in mouse plasma. The method involves solid-phase extraction from cyano cartridges (recovery >80%), HPLC separation on Symmetry C(18) (4.6 x 150 mm), on isocratic mobile phase of water-acetonitrile-acetic acid (49:50:1) and detection at 227 nm. Retention times of IDN 5390 and IDN 5517 (internal standard, I.S.) were 9.1 and 10.5 min, respectively. The assay was linear from 0.05 to 5 micro g/ml (r(2)>or=0.995), showed intra- and inter-day precision within 1.0 and 6.2%, and accuracy of 94.7-106.8%. LOQ was 0.050 micro g/ml. Using this method IDN 5390 pharmacokinetics was determined in mice.

A novel taxane active against an orthotopically growing human glioma xenograft

BACKGROUND

The development of effective chemotherapy for central nervous system tumors is hampered by the blood-brain barrier and by limited drug diffusion in the brain tissue. BAY 59-8862 is a new taxane analog that was selected and developed for its activity against tumors with a P-glycoprotein-mediated, multidrug-resistant phenotype. Because P-glycoprotein is implicated in limiting the access of drugs to central nervous system tumor targets, the objective of this study was to evaluate the ability of intravenously administered BAY 59-8862 to affect the growth of central nervous system tumors.

METHODS

The U-87 MG human glioma cell line was xenografted orthotopically (intracranially) in nude mice. Paclitaxel or BAY 59-8862 was delivered intravenously four times every fourth day, and antitumor efficacy was assessed by examining the effects on mouse survival time and by histologic examination of mouse brain. Drug levels in plasma and brain were determined according to a high-performance liquid chromatography method.

RESULTS

The analog was as potent as paclitaxel in inhibiting the proliferation of three human glioma cell lines (U-87 MG, SW1783, and GBM) and was as effective as paclitaxel in inhibiting the heterotopic (subcutaneous) tumor growth in nude mice of U-87 MG cells (tumor weight inhibition, approximately 60%). In contrast, BAY 59-8862 was more active than paclitaxel (P < 0.05 in two of three experiments) in increasing the survival time of mice that were injected orthotopically with U-87 MG cells. The results were supported by the pharmacokinetic data, which indicated a much higher (about 15-fold) brain:plasma level ratio in BAY 59-8862-treated animals compared with paclitaxel-treated animals.

CONCLUSIONS

The study provides evidence of an additional pharmacologic advantage of BAY 59-8862, i.e., the ability to affect the growth of intracranial tumors, probably due to the lack of recognition by the P-glycoprotein-mediated transport systems. The favorable behavior of BAY 59-8862 supports the potential interest in the analog for clinical studies in patients with brain tumors or metastases.

Chemoprevention of DMBA-induced mammary cancer in rats by dietary soy

This study was designed to assess the potential chemopreventive effect of the administration of a standardized soy extract, SOYSELECT, on 7,12-Dimethylbenz[a]anthracene (DMBA)-induced mammary tumors in rats. Three groups, 24 females each, were used. Animals were fed either a phytoestrogen-free diet alone (control) or the same diet supplemented with 0.35% or 0.7% of soy extract. Treatment started at weaning and continued to the end of the study (24 weeks after DMBA administration). At day 50 of age all animals received via oral gavage 80 mg/kg DMBA. Only tumors subsequently classified as adenocarcinomas were considered for data evaluation. In rats on the soy diet, mammary tumors took a longer period of time to develop as compared to control rats. However, at the end of the study, no relevant difference in tumor incidence and multiplicity was observed among the groups. The most significant changes were seen between control and soy-treated groups when tumor dimension and results from histopathologic examination were considered. The latter, in fact, showed a dose-dependent reduction in the percentage of poorly differentiated tumors in treated animals. This change was statistically significant in animals receiving 0.7% soy. In addition, assessment of estrogen and progesterone receptor (ERalpha, PR) levels, revealed a significant reduction in the percentage of ERalpha and PR positive tumors in animals receiving 0.7% dietary soy, when compared to controls. Interestingly, genistein and daidzein plasma levels determined at the end of the study were within the range of those detected in people consuming large amounts of soyfoods.

Synthesis and biosynthesis of isocordoin

In the search of a convenient synthesis for isocordoin (1), a potential anticancer natural product, 2',4'-dihydroxychalcone was inoculated in cell suspension cultures of Morus nigra, which were expected to contain an active prenyltransferase. After 24 hours the target compound was easily isolated from the metabolite extract. Optimization of the biotransformation resulted in a 85% yield of the prenyl derivative.

Synthesis and NMR-driven conformational analysis of taxol analogues conformationally constrained on the C13 side chain

Analogues of Taxol (paclitaxel) with the side chain conformationally restricted by insertion of a carbon linker between the 2'-carbon and the ortho-position of the 3'-phenyl ring were synthesized. Biological evaluation of these new taxoids showed that activity was dependent on the length of the linker and the configuration at C2' and C3'. Two analogues in the homo series, 9a and 24a, showed tubulin binding and cytotoxicity comparable to that of Taxol. NAMFIS (NMR analysis of molecular flexibility in solution) deconvolution of the averaged 2-D NMR spectra for 9a yields seven conformations. Within the latter set, the hydrophobically collapsed "nonpolar" and "polar" classes are represented by one conformation each with predicted populations of 12-15%. The five remaining conformers, however, are extended, two of which correspond to the T-conformation (47% of the total population). The latter superimpose well with the recently proposed T-Taxol binding conformer in beta-tubulin. The results provide evidence for the existence of two previously unrecognized structural features that support Taxol-like activity: (1) a reduced torsion angle between C2' and C3' and (2) an orthogonal arrangement of the mean plane through C1', C2' and the 2'-hydroxyl and the 3'-phenyl plane, the latter ring bisected by the former plane. By contrast, epimerization at 2',3' and homologation of the tether to CH2-CH2 were both detrimental for activity. The decreased activity of these analogues is apparently due to configurational and steric factors, respectively.

In vitro evaluation of newly developed chalcone analogues in human cancer cells

PURPOSE

Among flavonoids, chalcones have been identified as interesting compounds having chemopreventive and antitumor properties. We studied a panel of newly developed chalcone analogues (S1-S10) using MDA-MB 231 and MCF-7 ADRr breast cancer cells and the T-leukemic Jurkat cell line. Quercetin was used as the reference compound.

METHODS

Antiproliferative activity was evaluated by cell counts performed after 72 h of exposure to the drugs. DNA analysis and redox activity were evaluated using flow cytometry. Apoptosis was assessed by morphological analysis, using YOYO-1 as DNA dye; p-glycoprotein function was ascertained by quantitating the efflux of rhodamine 123.

RESULTS

All cells were sensitive to chalcone analogues yielding IC50 in micromolar concentrations with the following order regardless of the multidrug resistance (MDR) status: S1 > S2 > quercetin. S1 and S2, the most active compounds, were selected to evaluate their effect on the cell cycle, apoptosis, redox activity, and modulation of the p-glycoprotein function. No significant perturbation in cell cycle was seen with concentration up to 1 microM after 24 h. After 72 h a slight increase in G2/M block and DNA fragmentation occurred at 10 microM. Morphological analysis of apoptosis showed that chalcone analogues induced apoptosis to a higher extent than quercetin. Redox analysis demonstrated that all substances were able to increase intracellular thiol levels, which returned to baseline value after 24 h for all drugs except quercetin. Production of reactive oxygen species was essentially unaffected by all compounds. Finally, in MDR-positive MCF-7 ADRr cells chalcone analogues were unable to modulate p-glycoprotein function while quercetin was able to.

CONCLUSIONS

Newly developed S1 and S2 chalcones have a different but higher antitumor activity than quercetin and could be considered as potential new anticancer drugs.

Liquid chromatography/atmospheric pressure chemical ionization mass spectrometry of terpene lactones in plasma of volunteers dosed with Ginkgo biloba L. extracts

Liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-ITMS) was applied to evaluate the levels of ginkgolides A and B and bilobalide in plasma of volunteers after administration of Ginkgo biloba extracts in free (Ginkgoselect) or phospholipid complex (Ginkgoselect Phytosome) forms, providing 9.6 mg of total terpene lactones. The maximum plasma concentrations, C(max), of total ginkgolides A, B and bilobalide were 85.0 and 181.8 microg/mL for Ginkgoselect and Ginkgoselect Phytosome, respectively. The C(max) values were reached at 120 min for the free form and at 180--240 min for the phospholipid complex form. In both cases, the mean elimination half-life of each terpene lactone was in the range 120--180 min. Due to its sensitivity (about 1 ng/mL) and specificity, LC/APCI-ITMS proved to be a very powerful tool for pharmacokinetic studies of these phytochemicals.

Antitumour activity of novel taxanes that act at the same time as cytotoxic agents and P-glycoprotein inhibitors

Taxanes antitumour agents such as paclitaxel and docetaxel represent a successful family of chemotherapeutic drugs. Unfortunately, acquired and innate resistance represents a clinical problem for these drugs. We investigated, on a panel of 7 human cancer cell lines, the growth inhibition effect of 3 newly developed taxanes (SB-T-1213, SB-T-1250 and SB-T-101187) with modification at the C10 and C3' positions of the taxane framework. These positions have been previously characterized as critical to make taxanes highly active against cells overexpressing the efflux pump P-glycoprotein (P-gp). Paclitaxel and docetaxel were used as reference compounds. Results unambiguously indicate the exceptional activity of the novel taxanes toward P-gp positive cells (up to >400 fold higher potency than that of paclitaxel). SB-T-1213 and SB-T-1250 are also substantially more active than the reference compounds against P-gp negative cells. To better understand the mechanisms underlying the enhanced activity of the newly developed taxanes, we performed cell cycle and apoptosis analysis. This study demonstrates that the striking growth inhibition effect exhibited by the novel taxanes is ascribed to their increased ability in inducing apoptosis and G(2)/M cell cycle block. SB-T-1213 and SB-T-1250 are also more active than reference compounds in inducing intracellular accumulation of the beta-tubulin subunits. Finally, it is revealed that these novel taxanes have ability to inhibit the function of the P-gp efflux pump on the basis of the Rhodamine 123 assay. These findings strongly suggest that SB-T-1213, SB-T-1250 and SB-T-101187 represent a new tool to overcome innate or acquired P-gp mediated taxane-resistance.

UVB-induced hemolysis of rat erythrocytes: protective effect of procyanidins from grape seeds

Besides erythema and sunburn reactions, UVB stress can promote erythrocyte extravasation from skin capillaries and hemolysis, and photosensitized hemoglobin can in turn lead to an overload of free radicals in dermis which exacerbates photodamage. The objective of this study was to investigate in rat erythrocytes (RBC) the pattern of events leading to membrane peroxidation and hemolysis following UVB insult (1.5-8.5 J/cm2), and the protective action of grape seed procyanidins. UVB causes a dramatic dose-dependent decrease of intracellular glutathione (paralleled by the formation of pro-oxidant ferryl-hemoglobin), of intramembrane vitamin E and of membrane fluidity, then a rise of conjugated dienes (CD), and thiobarbituric acid-reactive substances (TBARS) and finally a strong hemolytic effect. Procyanidins prevent membrane peroxidation (but not intracellular GSH depletion nor ferryl-hemoglobin formation), with a minimal effective concentration of 0.1 microM (IC50 for TBARS and CD after 120 min UVB exposure: 0.71 microM and 0.56 microM) and dose-dependently delay the onset of hemolysis, by 30 min at 0.1 mciroM, by 90 and 120 min at 0.5 and 1.0 microM. Epigallocatechin-3-O-gallate (EGCG) and catechin, typical constituents of the fraction, were significantly less potent. This since procyanidins (1 microM) inhibit the formation of phospholipid hydroperoxides of the inner (phosphatidylserine, phosphatidylethanolamine) and outer (phosphatidylcholine) layers of the RBC membrane (HPLC analysis), suppress the decrease in membrane fluidity due to lipid and protein thiol oxidation and spare vitamin E from consumption in a dose-dependent manner (0.1-1 microM). Hence procyanidins, preserving membrane phospholipids, since their strong antilipoperoxidant activity, may maintain in vivo the integrity of RBC in sub-epidermal capillaries and effectively counteract in dermis the onset/exacerbation of the UVB-induced skin photodamage.

Botanical derivatives for the prostate

The prostate, after the age of 45 years, may undergo benign hyperplasia (BPH). Its etiology has not yet been completely explained, but different factors play a major role in its occurrence, among them, the sexual hormones (with a fundamental role of 5 alpha reductase). The 5-alpha reductase activity and inflammatory aspects in the prostate tissue can be effectively controlled with the use of highly standardized plant extracts (Pygeum africanum, Serenoa repens, etc.), which yield excellent results in the prophylaxis and treatment of the symptoms linked to prostate hypertrophy. The prostate tissue is not affected only by benign diseases but may also be subject to neoplastic transformation. From an epidemiological point of view, a vegetable derivative, lycopene, was linked with a lower occurrence of prostate carcinoma. A recent clinical study demonstrated that lycopene might not only prevent prostate cancer but also have therapeutic effects.

Potential use of medicinal plants in the treatment of alcoholism

The present paper briefly reviews the most relevant experimental data on the reducing effect of some medicinal herbs on voluntary alcohol intake in animal models of alcoholism. Pueraria lobata, Tabernanthe iboga, Panax ginseng, Salvia miltiorrhiza and Hypericum perforatum proved to be effective in decreasing alcohol consumption. Reduction of alcohol absorption from the gastrointestinal system appears to be a common feature among most of the above plants. These data suggest that medicinal plants may constitute novel and effective pharmacotherapies for alcoholism.

Cytotoxic effects toward human hematopoietic progenitor cells and tumor cell lines of paclitaxel, docetaxel, and newly developed analogues IDN5109, IDN5111, and IDN5127

The growth inhibitory effect of paclitaxel, docetaxel, and newly developed taxanes IDN5109, IDN5111, and IDN5127 was assessed on peripheral blood (PB) CD34+ maintained in liquid culture and on three human cancer cell lines (MDA-MB231, MCF-7 ADRr, CEM VBLr). Concomitantly, DNA analysis was also performed. For unfractionated peripheral blood progenitor cells (PBPC) toxicity was also assessed by clonogenic assay. The cytotoxic effects induced by taxanes toward PBPC as measured by clonogenic assay were correlated with those found for multidrug resistance (MDR)-positive cell lines (IDN5109 > IDN5111 > IDN5127 > docetaxel > paclitaxel). We established a therapeutic index (TI) between the antitumor activity in MDR-positive cells and the toxicity toward PBPC. Paclitaxel and IDN5109, as determined by TI, showed the best value in MDR-negative and MDR-positive cells, respectively. The ranking of the cytotoxic effects observed in PB CD34+ was not correlated with that obtained in clonogenic assay and in cancer cells (IDN5127 > IDN5109 > docetaxel > IDN5111). Remarkably, in DNA analysis docetaxel induced the maximal cell cycle blocking activity. Newly developed taxanes IDN5109 and IDN5111 are endowed of a profile of anticancer activity in MDR-bearing cells and toxicity toward hematopoietic progenitors better than that of docetaxel. However, mechanism(s) underlying toxicity toward hematopoietic progenitors could be, at least in part, different from that of docetaxel and likely dependent on the interaction with P-glycoprotein function in PB CD34+ cells.

Oral efficacy and bioavailability of a novel taxane

A novel taxane (IDN 5109), originally selected for its ability to overcome P-glycoprotein-mediated drug resistance, is characterized by an improved preclinical profile in terms of efficacy and tolerability. Because P-glycoprotein may critically influence intestinal absorption and oral bioavailability of taxanes, the purpose of the study was to evaluate the bioavailability, the pharmacokinetic behavior, and the antitumor activity of the new taxane after oral administration. A comparative study of antitumor activity of Taxol and IDN 5109 given orally was performed in a human breast carcinoma model, MX-1, which is highly responsive to i.v. treatment with both of the taxanes. In contrast to Taxol, which was completely ineffective after administration to MX-1-bearing mice, oral IDN 5109 exhibited an activity comparable with that of i.v. treatment (ie., 100% cures). Again, the maximal tolerated doses were comparable (90 mg/kg, every 4 days for four doses) after i.v. and oral treatment. Three other tumor models (LoVo, IGROV/DDP, and U87) with a variable sensitivity to the drug were used to compare the antitumor effects of i.v. and oral treatment with IDN 5109. The efficacy after oral administration was only slightly lower than that found after i.v. treatment at equivalent doses; but optimal effects were comparable likely as a consequence of the long (>6 h) terminal half-life of oral IDN 5109. The bioavailability of IDN 5109 assessed by comparing area-under-the-curve values after oral and i.v. administrations was approximately 50%. The oral efficacy of the novel taxane, likely related to the inability of the P-glycoprotein to recognize the drug, which allowed an adequate intestinal absorption, is a unique feature among the taxanes and may represent a pharmacological breakthrough in their clinical use.

Clinical effects of a standardized soy extract in postmenopausal women: a pilot study

OBJECTIVE

This double-blind, randomized study was aimed at evaluating comparatively, in postmenopausal women, the activity of a standardized soy extract (SOYSELECT) and placebo when given alone or in combination with conjugated equine estrogens (CEE) on early climacteric symptoms. Lipid profile, pituitary hormones, osteocalcin and endothelin levels, and vaginal and endometrial parameters were also evaluated.

DESIGN

Participants in the control group were given placebo, and participants in the treated group were given 400 mg/day of a standardized soy extract, corresponding to 50 mg/daily of isoflavones. After 6 weeks of treatment, CEE was also then given to each participant at a dose of 0.625 mg/day for 4 weeks. At the end of this period, soy and placebo treatment were suspended, and, until the end of the study (week 12), participants were administered 10 mg/day of medroxyprogesterone acetate in association with CEE (0.625 mg/day).

RESULTS

When compared with pretreatment data, on week 6 of the study, a significant (p < 0.01) reduction in the mean number of hot flushes per week was observed in participants who were receiving the standardized soy extract, whereas a more marked relief was observed in both soy and placebo groups during CEE administration. Concurrently, the severity of hot flushes, assessed by means of the Greene climacteric scale, was also reduced in the soy group participants (p < 0.001, by paired t-test). No soy-related changes were observed on vaginal cytology, endometrial thickness, uterine artery pulsatility index, or metabolic and hormonal parameters tested. Finally, CEE-related changes on genital tract, uterine vascular compartment, and pituitary hormones were not modified by soy treatment.

CONCLUSIONS

SOYSELECT may be a safe and efficacious therapy for relief of hot flushes in women who refuse or have contraindications for hormone replacement therapy.

Hyperforin analogues from St. John's wort (Hypericum perforatum)

Three oxygenated analogues of the prenylated phloroglucinol hyperforin (3-5) were isolated from the aerial parts of Hypericum perforatum and their structures elucidated by spectroscopic methods.

Anti-tumour activity of a panel of taxanes toward a cellular model of human cervical cancer

Using a model of human cervical cancer (ME-180 cells), the anti-tumour activity of paclitaxel was compared to that of docetaxel and IDN5109, a newly developed taxane. The growth inhibition effect of taxanes was assessed after 3 days of exposure. DNA analysis, the taxane-dependent modulation of the expression of the alpha and beta subunits of tubulin and DNA fragmentation were assessed by flow cytometry. The presence of apoptosis was confirmed by morphological analysis using a laser scan cytometer. For the evaluation of "in vivo" anti-tumour activity, taxanes were administered to nude mice intravenously once daily, according to a q3/4d x 4 schedule. Docetaxel, IDN5109 and paclitaxel obtained "in vitro" IC(50) values of 0.86, 1.4 and 2.4 nM, respectively. DNA analysis demonstrated a transient block at the G(2)/M phase of the cell cycle only after 12 h of culture in the presence of taxanes and an increase of nuclear fragmentation suggestive for apoptosis after additional 12 and 60 h of exposure. Morphological analysis confirmed the presence of apoptosis. Taxanes induced a down-modulation of the alpha subunit of tubulin in the G(0/1) phase of the cell cycle, and an overexpression of the beta subunit in the G(2)/M phase. A strong anti-tumour activity was obtained "in vivo" for nude mice xenografted using ME-180 cells (T/C=0% for all drugs). These data indicate that the three taxanes are strongly active both "in vitro" and "in vivo" toward ME-180 cells. Clinical studies are now needed to ascertain if the higher anti-tumour activity observed "in vitro" using docetaxel and IDN5109 yields a better clinical response in advanced cervical carcinoma with respect to paclitaxel.

IDN5109, a taxane with oral bioavailability and potent antitumor activity

IDN5109 is a new taxane, derived from 14beta-hydroxy-10-deacetylbaccatin III, selected for its lack of cross-resistance in tumor cell lines expressing the multidrug resistant phenotype. Because, unlike paclitaxel, IDN5109 is a poor substrate for P-glycoprotein, we hypothesized that IDN5109 given p.o. could improve bioavailability compared with paclitaxel. Here, we studied the p.o. and i.v. pharmacokinetics of IDN5109 together with its antitumor activity. Using a high-performance liquid chromatography method, the bioavailability of IDN5109 was determined to be 48% after oral delivery. IDN5109 given p.o. was highly active against the two human ovarian carcinoma xenografts 1A9 and HOC18 (90-100% tumor regressions) and showed significant activity on the paclitaxel-resistant MNB-PTX1 xenograft (10% tumor regressions). The p.o. administration was as active as the i.v. route at doses reflecting the pharmacokinetic data. IDN5109 is the first taxane with good oral bioavailability and potent antitumor activity and represents a potential candidate for clinical investigation.

High-performance liquid chromatographic assay for the determination of the novel taxane derivative IDN5109 in mouse plasma

An HPLC assay was developed to determine the paclitaxel analogue 13-(N-tert.-butoxycarbonyl-beta-isobutylisoserinyl)-14-hydroxyb accatin-1,14-carbonate (IDN5109) and its epimer in mouse plasma. The method involves solid-phase extraction on cyano cartridges (recovery >75%), HPLC separation on symmetry shield column, a mobile phase of NaH2PO4 (10 mM) pH 5.2, acetonitrile (47:53) and detection at 227 nm. Retention times of IDN5109, its epiform and internal standard were 15, 24 and 25.5 min, respectively. The assay was linear from 0.10 to 10 microg/ml (r2 = 0.999), with a C.V. <5% and accuracy in the range of 95-107%. LOQ was 50 ng/ml for both compounds. Using this method IDN5109 pharmacokinetic was determined in mice.

N-deacetyl-N-aminoacylthiocolchicine derivatives: synthesis and biological evaluation on MDR-positive and MDR-negative human cancer cell lines

A new series of N-deacetyl-N-(N-trifluoroacetylaminoacyl)thiocolchicine derivatives 9-15 have been synthesized starting from the corresponding N-deacetylthiocolchicine (3) and the N-trifluoroacetylamino acids 5-8 which were used as a racemic mixture. The trifluoroacetyl protecting group has been removed easily, giving the corresponding N-deacetyl-N-aminoacylthiocolchicines 16-22. Optical pure compounds 9-22 were isolated from the diastereoisomeric mixture or were prepared starting from compound 3 and an optical pure amino acid derivative; the configuration of each compound was assigned unequivocally. The diastereoisomeric couples of amino acids synthesized were tested, and their antiproliferative activity on MDR-positive and MDR-negative human cancer cell lines was evaluated.

Biological evaluation on different human cancer cell lines of novel colchicine analogs

Three new 7-0-substituted deacetamidothiocolchicine derivatives have been evaluated for their antitumor activity against various human tumor cell lines, some of which express the multidrug resistance (MDR) phenotype, for their impact on the cell cycle and their binding to tubulin. Colchicine and thiocolchicine were used as reference compounds. Thiocolchicine was the most active agent on MDR-negative cells in terms of growth inhibition, whereas for multidrug-resistant cells, thiocolchicone was the most active compound (IC50 = 14 nM). As indicated by statistical analysis, a perfect agreement for the potency order (IC50 values) of the compounds between all the MDR-negative cancer cells (k = 1.00), a poor agreement between MDR-positive and MDR-negative cancer lines, and a moderate agreement (k = 0.50) between the two resistant cancer cells MCF-7 ADRr and CEM VBL were observed. To gain further insight into the mechanism of the antitumor activity of colchicinoids, the most active compounds, colchicone and thiocolchicone, were selected to evaluate their effect on cell cycle, apoptosis, and tubulin interaction. The highest recruitment activity into the G21/M phase of the cell cycle was detected in thiocolchicone-treated breast cancer cells. Interestingly, after 72 h of culture, when the cell cycle block subsided, a consistent amount of DNA fragmentation, a hallmark of apoptosis, was evident. Morphological analysis of MCF-7 ADRr cells confirmed this hypothesis and revealed that thiocolchicone was able to induce apoptosis in this MDR-bearing model. We also demonstrated, using flow cytometry, that thiocolchicone interacts with alpha- and beta-tubulin, thereby affecting the expression of both subunits.

Efficacy of an Hypericum perforatum (St. John's wort) extract in preventing and reverting a condition of escape deficit in rats

The treatment of unselected depressed patients with an hydro-alcoholic extract of Hypericum perforatum has been reported to have an efficacy similar to that of classical antidepressants. In the present report, the effects of H. perforatum were studied on three animal models of depression: (i) an acute form of escape deficit (ED) induced by an unavoidable stress; (ii) a chronic model of ED, which can be maintained by the administration of mild stressors on alternate days; (iii) a model of anhedonia based on the finding that repeated stressors prevent the development of an appetitive behavior induced by vanilla sugar in satiated rats fed ad libitum. H. perforatum acutely protected animals from the sequelae of unavoidable stress; such an effect was partially prevented by the administration of SCH 23390 or (-)-pindolol. Moreover, H. perforatum reverted the ED maintained by repeated stressors and preserved the animal's capacity to learn to operate for earning a positive reinforcer. It was concluded that H. perforatum contains some active principle(s) endowed with antidepressant activity.

Furohyperforin, a prenylated phloroglucinol from st. John's wort (Hypericumperforatum)

Furohyperforin, an oxygenated analogue of the prenylated phloroglucinol hyperforin, was isolated from the aerial parts of Hypericum perforatum. Its structure was elucidated as 2 on the basis of extensive NMR investigations.

Salvia miltiorrhiza extract inhibits alcohol absorption, preference, and discrimination in sP rats

Experiment 1 of the present study investigated the ability of a standardized extract of Salvia miltiorrhiza in reducing voluntary ethanol intake in ethanol-preferring rats of the sP line. Ethanol intake occurred under the two-bottle free-choice regimen between 10% (v/v) ethanol and water in daily 4-h scheduled access periods; water was present 24 h/day. Intragastric administration of 200 mg/kg Salvia miltiorrhiza extract resulted in approximately 40% reduction in ethanol intake and preference throughout the 4-day treatment. This effect of Salvia miltiorrhiza extract was likely due to its ability of altering ethanol absorption from the gastrointestinal tract. Indeed, Experiments 2 and 3 of this study demonstrated that 200 mg/kg Salvia miltiorrhiza extract reduced blood ethanol levels (BELs) up to 60% in comparison to control rats, when ethanol was given IG, whereas it failed to modify BELs when ethanol was injected IP. The reducing effect of Salvia miltiorrhiza extract on ethanol absorption may have therefore resulted in an attenuated perception of the psychoactive effects of ethanol sought by ethanol-drinking rats. Consistently, the results of Experiment 4 of the present study demonstrated that a combination of 200 mg/kg Salvia miltiorrhiza extract IG and 1 or 2 g/kg ethanol IG resulted in a partial blockade of the discriminative stimulus effects of ethanol in sP rats trained to discriminate these doses of ethanol from water in a drug discrimination procedure. Collectively, the results are discussed as being suggestive that drugs curbing ethanol absorption from the gastrointestinal tract may constitute a novel strategy for controlling excessive alcohol consumption in human alcoholics.

Reproductive effects of dietary soy in female Wistar rats

This study was designed to assess the effects of administration of dietary soy on reproductive function and fertility of female Wistar rats. Four groups, each of 20 females, were used. Control animals were fed a standard cereal-based diet for rats. Treated animals were fed a standard diet supplemented with 0.7%, 1.2% or 2.4% of a soy extract. Treatment started at weaning and continued until day 7 post-partum (day of sacrifice). Growth depression was seen in the 2.4% soy group. Vaginal opening occurred earlier in females receiving soy supplemented feed when compared with controls. Analysis of vaginal smears revealed that all animals were cycling, although an increase in the mean duration of each cycle was seen in the 2.4% soy group. Uterine effects were observed in high-dose females and included increases in weight, oedema, endothelial hyperplasia and leucocytic infiltration. Vaginal modifications (i.e. inflammation, hyperkeratosis and dyskeratosis) and alterations in the distribution of follicular size in the ovaries were also observed among treated animals. These data suggest that long-term exposure to high doses of phytoestrogens can produce significant agonistic actions in several oestrogen-dependent tissues and parameters, even though in this model no clear influence on reproductive processes was observed.

Diet enriched with procyanidins enhances antioxidant activity and reduces myocardial post-ischaemic damage in rats

Aim of this work was to study the efficacy of procyanidins from Vitis vinifera seeds, a standardized mixture of polyphenol antioxidants, on cardiac mechanics following ischemia/reperfusion stunning in the rat, after 3 weeks supplementation. Young and aged male rats were fed a diet enriched with procyanidins complexed (1:3 w/w) with soybean lecithin (2.4%); control animals (CTR-young and CTR-aged) received an equal amount of lecithin and 2 additional groups of animals the standard diet. At the end of the treatment, the total plasma antioxidant defense (TRAP), vitamin E, ascorbic acid and uric acid were determined in plasma and the hearts from all groups of animals subjected to moderate ischemia (flow reduction to 1 ml/min for 20 min) and reperfusion (15 ml/min for 30 min). In both young and aged rats supplemented with procyanidins the recovery of left ventricular developed pressure (LVDP) at the end of reperfusion was 93% (p < 0.01) and 74% (p < 0.01) of the preischemic values and the values of coronary perfusion pressure (CPP) were maintained close to those of the preischemic period. Also creatine kinase (CK) outflow was restrained to baseline levels, while a 2-fold increase in prostacyclin (6-keto-PGF1alpha) in the perfusate from hearts of young and aged rats was elicited during both ischemia and reperfusion. In parallel, procyanidins significantly increased the total antioxidant plasma capacity (by 40% in young and by 30% in aged rats) and the plasma levels of ascorbic acid, while tend to reduce vitamin E levels; no significant differences were observed in uric acid levels. The results of this study demonstrate that procyanidins supplementation in the rat (young and aged) makes the heart less susceptible to ischemia/reperfusion damage and that this is positively associated to an increase in plasma antioxidant activity.

A novel taxane with improved tolerability and therapeutic activity in a panel of human tumor xenografts

Clinically available taxanes represent one of the most promising class of antitumor agents, despite several problems with their solubility and toxicity. In an attempt to improve the pharmacological profile of taxanes, a new series of analogues was synthesized from 14beta-hydroxy-10-deacetylbaccatin III and tested in a panel of human tumor cell lines. On the basis of the pattern of cytotoxicity and lack of cross-resistance in tumor cell lines expressing the typical multidrug-resistant phenotype, a compound (IDN5109) was selected for preclinical development. A comparative efficacy study of IDN5109 and paclitaxel was performed using a large panel of human tumor xenografts, characterized by intrinsic (seven tumors) or acquired (four tumors) resistance to cisplatin or doxorubicin, including four ovarian, one breast, one cervical, three lung, one colon, and one prostatic carcinoma. Drugs were delivered i.v. according to the same schedule (four times every 4th day). IDN5109 achieved a very high level of activity (percentage tumor weight inhibition >70%; log10 cell kill >1) in all but one of the tested tumors. Compared to paclitaxel, IDN5109 exhibited a significantly superior activity in six tumors (including the four tumors that were resistant to paclitaxel) and a comparable activity against the other five paclitaxel-responsive tumors. Additional advantages of IDN5109 over paclitaxel were also suggested by its toxicity profile. IDN5109 was not only less toxic (maximal tolerated doses were 90 and 54 mg/kg for IDN5109 and paclitaxel, respectively), but it also appeared to be endowed with a reduced neurotoxic potential and an improved profile of tolerability compared to the parent drug. Furthermore, the best antitumor efficacy was often already reached with doses lower than the maximal tolerated dose, suggesting an improved therapeutic index for the new drug. In conclusion, the results support the preclinical interest of IDN5109 in terms of the toxicity profile and of the efficacy with particular reference to the ability to overcome multiple mechanisms of drug resistance.

Relationship between rate and extent of catechin absorption and plasma antioxidant status

Flavonoids are described to exert a large array of biological activities, which are mostly ascribed to their radical-scavenging, metal chelating and enzyme modulation ability. Most of these evidences have been obtained by in vitro studies on individual compounds and at doses largely exceeding those dietary. Little is known about a possible relationship between rate and extent of the absorption and modifications of plasma antioxidants. To elucidate this aspect, human volunteers were supplemented with single doses of green tea catechins in free (Greenselect) or phospholipid complex form (Greenselect Phytosome) equivalent to 400 mg epigallocatechingallate (EGCg). EGCg was chosen as biomarker for green tea catechin absorption, and its time course plasma concentration was correlated to the subsequent percent variations of plasma ascorbate, total glutathione, alpha-tocopherol, beta-carotene and Total Radical Antioxidant Parameter (TRAP). Green tea catechins were absorbed more extensively when administered as phospholipid complex rather than as free catechins. Single dose intake of both forms of catechins produced a transient decrease (10-20%) of plasma ascorbate and total glutathione and an increase of plasma TRAP (16-19%). These variations were consistent with the plasmatic levels of EGCg, ascorbate and total glutathione.

An evaluation of the antioxidant activity of a standardized grape seed extract, Leucoselect

Coronary Artery Disease (CAD) remains the major cause of mortality and morbidity in the Western World. The oxidation of low-density lipoproteins (LDLs) by free radicals is associated with initiation of atherosclerosis and therefore, development of CAD. LDLs are protected from oxidation by antioxidants and in times of antioxidant deficiency are more likely to be oxidized. Hypercholesterolaemic patients are at a higher cardiovascular risk and may, therefore, require more antioxidant protection. Increased consumption of red wine containing antioxidants is thought to account for the lower incidence of CAD in Mediterranean countries. Red wine, although rich in antioxidants, is not suitable as routine therapy for prevention of CAD.

OBJECTIVE

To evaluate the effects of a capsule formulation of an antioxidant polyphenolic extract of grapes on serum total antioxidant activity and vitamin C and E levels.

METHOD

A single-blinded randomised, placebo-controlled cross-over study was undertaken in 20 young volunteers. Subjects were given two capsules containing 300 mg of grape procyanidin extracts (Leucoselect-phytosome) or placebo daily for 5 days. Blood samples were taken at the start of the study and end of the study and assayed for antioxidant activity and vitamins C and E levels. After a washout period of at least 2 weeks, the study was repeated with the second treatment.

RESULTS

The extract had no effect on serum vitamins C and E levels but increased serum total antioxidant activity (TAC). On day 5, TAC increased from 408.1+/-22.9 to 453.3+/-453.3 micromol/l trolox equivalents 1 hour postdose.

CONCLUSION

The capsules increased serum antioxidant activity but the longer-term clinical implications need to be assessed in further randomised clinical trials.

Antitumor activity of paclitaxel (taxol) analogues on MDR-positive human cancer cells

A series of newly developed paclitaxel analogues have been tested for their growth inhibitory activity on two human breast cancer cell lines, one of which expresses the MDR (multidrug resistance) phenotype. Paclitaxel (taxol) was used as a reference compound. Three new classes of taxanes were analyzed: the cephalomannine compounds, the pyrazoline derivatives and the seco-derivatives. Our results demonstrated an increased antiproliferative activity of pyrazoline derivatives on drug-resistant cancer cells with respect to paclitaxel. These compounds were able to block MDR-bearing MCF-7 ADRr cells in the G2/M phase of cell cycle and, consequently, induce programmed cell death. In keeping with the antiproliferative effects, cells treated with paclitaxel derivatives showed a more pronounced cell cycle arrest than the parent compound paclitaxel. Also, apoptotic cell death, calculated as a percent of DNA fragmentation, occurred to a greater extent in cells exposed to pyrazoline derivatives. The development of new paclitaxel analogues with greater antitumour activity on MDR-positive cells may be useful in selecting new taxanes effective on resistant tumors.

Sparing effect of procyanidins from Vitis vinifera on vitamin E: in vitro studies

The sparing/recycling effect of a highly purified, high molecular weight fraction of catechin oligomers (procyanidins) from Vitis vinifera seeds on alpha-tocopherol was studied in both homogeneous solution and in heterogeneous phase (phosphatidylcholine liposomes and red blood cells). By HPLC and electron spin resonance (ESR) spectroscopy we evidenced that tocopheroxyl radical, induced by reaction of alpha-tocopherol with the stable radical DPPH (2,2-diphenyl-1-picrylhydrazyl) is recycled by procyanidins. In addition procyanidins significantly and dose-dependently spare vitamin E from consumption (HPLC monitoring) during the autooxidation phase of the HO-induced peroxidation of phosphatidylcholine, by 23% at the lowest concentration (0.5 microM) and by 65.5% at 3 microM. In this membrane model the combination of 0.5 microM procyanidins and 2 microM alpha-tocopherol results in a marked delay in the appearance of conjugated dienes in respect to the single antioxidants (synergistic interaction), while catechin showed to be active only at 5 microM. In red blood cells oxidatively stressed by UVB exposure, procyanidins at 0.1-1.0 microM prevent vitamin E loss, markedly decrease membrane lipid peroxidation, linearly related to the concentration of vitamin E in the membranes, and significantly delay the onset of hemolysis (catechin protects between 5 and 10 microM).

Differential effects of paclitaxel and derivatives on guinea pig isolated heart and papillary muscle

Paclitaxel (Taxol) is an anticancer agent with clinical activity against various human cancer types. Paclitaxel blocks cell division by stabilizing microtubules, a mechanism that also underlies its major side effects (neutropenia and neurotoxicity). Paclitaxel can also alter cardiac function, and to elucidate the mechanism of this activity, we tested the mechanical and electrical effects of paclitaxel and a series of analogs (docetaxel, taxol B, taxol C and N-methyltaxol C; 5-20 microM) on two different cardiac preparations, the isolated coronary perfused heart and the papillary muscle of the guinea pig. Paclitaxel and N-methyltaxol C induced conduction arrhythmias and reduced coronary flow and left ventricular systolic pressure in the isolated heart, whereas the other taxol derivatives tested had no significant effect. Moreover, paclitaxel blocked the vasodilator effect of bradykinin in the isolated heart. Paclitaxel and N-methyltaxol C produced a positive inotropic effect in papillary muscle, without alterations in the action potential. In the latter preparation, no significant variations were observed after treatment with the other taxol derivatives. The in vitro cardiodepressant and arrhythmogenic activity of paclitaxel is similar to that reported after its clinical administration and might be due to coronary vasoconstriction. The precise role of microtubules as modulators of intracellular calcium in cardiac and smooth muscle cells is at present unclear, because docetaxel and other taxol analogs, though they exhibited similar activity on tubulin, lacked cardiac effects.

Antiproliferative activity of colchicine analogues on MDR-positive and MDR-negative human cancer cell lines

In this study the in vitro antitumor activity of a series of 20 colchicine analogues was tested and compared with colchicine and thiocolchicine on three different human cancer cell lines, two of which express the multidrug-resistance (MDR) phenotype. At concentrations from 1 nM to 100 microM, all compounds tested inhibited cancer cell proliferation. The IC50 values indicate that the three fluorinated analogues were the most active compounds, with a similar decreasing order of potency (IDN 5005 > IDN 5079 > IDN 5080) on the two MDR-expressing cell lines, whereas thiocolchicine was the most effective compound on the MDR-negative MDA-MB 231 cells. A strong correlation (r = 0.94; P = 0.004) was found between IC50 values obtained using the two MDR-positive cell lines. Conversely, IC50 values obtained in MDA-MB 231 cells did not show a significant correlation with MDR-positive cell lines, thereby suggesting some difference in the antiproliferative mechanism(s) of colchicine analogues. Cell cycle analysis of the most active analogues in breast cancer cells showed a relationship between cell cycle blocking activity and growth inhibition. The most active agents on the MDR-positive MCF7 ADRr cell line, after 24 h of culture, in terms of cell cycle blocking activity were the three fluorinated analogues. Interestingly, after 72 h, when the cell cycle block subsided, a consistent amount of DNA fragmentation was evident. The extent of cell cycle block, measured as the G2/G1 ratio, was significantly correlated with the apoptosis rate expressed as a percentage of DNA fragmentation on both cell lines, thereby suggesting that a large number of blocked cells underwent the apoptotic pathway.