Intestinal filtration as a consequence of increased mucosal hydraulic permeability. A new concept for laxative action

Evolution of 3-(4-hydroxyphenyl)indoline-2-one as a scaffold for potent and selective anticancer activity

Development of targeted anticancer modalities has prompted a new era in cancer treatment that is notably different from the age of radical surgery and highly toxic chemotherapy. Behind each effective compound is a rich and complex history from first identification of chemical matter, detailed optimization, and mechanistic investigations, ultimately leading to exciting molecules for drug development. Herein we review the history and on-going journey of one such anticancer scaffold, the 3-(4-hydroxyphenyl)indoline-2-ones. With humble beginnings in 19th century Bavaria, we review this scaffold's synthetic history and anticancer optimization, including its recent demonstration of tumor eradication of drug-resistant, estrogen receptor-positive breast cancer. Compounds containing the 3-(4-hydroxyphenyl)indoline-2-one pharmacophore are emerging as intriguing candidates for the treatment of cancer.

Sennoside-induced secretion is not caused by changes in mucosal permeability or Na+,K(+)-ATPase activity

The effect of sennosides (50 mg kg-1) on the rat colon in-situ was studied 6 h after oral treatment when the laxative effect was maximal. In a second experiment, rhein (4 x 10(-3) M), an active sennoside metabolite, was administered into the lumen of the colon for 1 h. Both sennosides and rhein reduced net H2O and Na+ absorption or reversed it to net secretion. Paracellular permeability, as measured using erythritol as a small marker molecule, was increased 2- to 3-fold; permeability to a large molecule, PEG 1000, was unchanged. The activity of Na+,K(+)-ATPase in the colon mucosa was not affected. There was no damage of the epithelial cells as determined by lactic acid dehydrogenase release. These results indicate that neither inhibition of Na+,K(+)-ATPase nor damage of the colon epithelium are involved in the secretory effect of sennosides or rhein. The increased paracellular permeability of small molecules fits into the concept of stimulation of active chloride secretion by sennosides, which is electrochemically and osmotically balanced by an increase in Na+ and H2O flow via the paracellular pathway.

Differentiation of secretagogue drugs by chlorpromazine in rat intestine in vivo

The effect of chlorpromazine (CPZ) on passive epithelial permeability and net fluid movement induced by secretagogues was tested in the rat intestine in vivo. CPZ, in a dose of 20 mg/kg intramuscularly, did not alter colonic permeability either in control conditions or during increased permeability caused by deoxycholic acid (DOC) or bisacodyl. Fluid secretion induced by cholera toxin and theophylline was strongly reduced by CPZ. The effects of oxyphenisatin and bisacodyl were only slightly but significantly inhibited by CPZ, whereas the action of DOC was unaffected. It is concluded, that the increase of the epithelial permeability is the main reason for the augmented fluid secretion caused by DOC. Bisacodyl and oxyphenisatin seem to act partly via an increase in permeability and to some degree via an induction of an active secretory process.

Interaction between diphenolic laxatives and intestinal bacteria in vitro

The ability of the laxative diphenols desacetylbisacodyl, oxyphenisatin, and phenolphthalein to inhibit growth and cause leakage of potassium ion from microbial cells in vitro was studied with 25 aerobic and 25 anaerobic bacterial strains. None of the aerobes, but some of the anaerobes showed growth inhibition. Potassium release assayed by flame photometry was observed in strains which showed growth inhibition, but also in other strains including anaerobes and aerobes. The highest antibacterial activity among the diphenols was observed with phenolphthalein and the least with desacetylbisacodyl; this relationship as noted for both growth inhibition and potassium release. Enzymatic hydrolysis of picosulphate to the free diphenol desacetylbisacodyl carried out by three strains of anaerobic bacteria was indicated by high pressure liquid chromatography.

Studies on hydragogue drugs: effect of surfactants on cAMP levels in the rat jejunal mucosa in short time experiments in vivo

Theophylline and the surface active agents specified below were instilled into the jejunum of anaesthetized rats, and the cAMP levels in the mucosal tissue determined after 71/2 and 15 min. incubation in vivo. Most experiments were done in rats prepared with two tied intestinal loops; one of these served as the control loop and the other as the stimulated loop. The surfactants (mmol/l) included dodecylsulphate (17), dioctylsulphosuccinate (5.6), cetrimonium bromide (4.1), deoxycholic acid (2.4 and 3.6) and Lubrol WX (0.5% w/v). Theophylline (10 mmol/l) caused a substantial increase in cAMP (110% +/- 17, n = 7 and 60% +/- 8.9, n = 10, respectively) and dodecylsulphate a minor and transitory increase (28.1% +/- 3.8, n = 10 and 11.7% +/- 4.9, n = 8). The other agents were without stimulatory effect on cAMP, although like dodecylsulphate they may significantly affect normal intestinal cation and glucose transport under these conditions. The results, therefore, do not suggest that stimulation of cAMP and intestinal secretion induced thereby is any significant phenomenon in the overall hydragogue effect of these agents, at least not in short term jejunal experiments.

Net sodium and glucose transport in the jejunum, ileum and colon of anaesthetized rats in response to intraluminal theophylline and anionic surfactants

Osmotically balanced solutions of sodium chloride and glucose (5-150 mmol/l) were instilled into rats prepared with two tied intestinal loops (jej-col or il-col). Luminal accumulation or disappearance of Na and glucose after 15 min. was determined, and the parameters of the linear regression lines of net Na flux (y) with initial Na concentration (x) calculated. Control cation and glucose transport were changed by dioctylsulphosuccinate and dodecylsulphate in the way described by Sund & Matheson (1978). Theophylline (10-25 mmol/l) on the other hand did not alter glucose disappearance, and had a distinctly dissimilar effect on net Na transport compared to the surfactants. This could be described as a parallel displacement of the control regression lines to the right, without improvement in correlation. This effect of theophylline was greatest in the ileum, where mean luminal Na concentration corresponding to zero net transport was raised from about 70 mmol/l under control condition to values above 200 mmol/l. The results are consistent with the view that theophylline mainly affects transcellular and the surfactants mainly paracellular sodium transport, and do not support the theory that the effect of dioctylsulphosuccinate on intestinal transport is related to an activation of the mucosal adenylate cyclase/cAMP system, at least not in short term experiments.