One Sentence Summary: Biologically active concentrations of resveratrol can be generated intracellularly following uptake of the major human sulfate metabolites by selected cells; at doses considered safe in humans, resveratrol produced via this route may be of greater importance than unmetabolised resveratrol for eliciting beneficial effects. Abstract:The phytochemical resveratrol is thought to exert numerous health benefits. Its rapid phase II metabolism and resulting poor bioavailability may limit translation of these effects to humans. It is conceivable, but unproven, that metabolites contribute to activity in vivo, perhaps via hydrolysis of conjugates regenerating the parent. We present the first accurate quantitation of resveratrol sulfate and glucuronide conjugates in human plasma and tissue following repeated ingestion of resveratrol. Pharmacokinetic characterisation of a mixture of resveratrol-3-and 4′-O-sulfates in mice demonstrates that these metabolites are orally absorbed, but have low bioavailability at ~14 and 3%, respectively. Sulfate hydrolysis in vivo, liberates free resveratrol, which accounts for ~2% of the total resveratrol species present in plasma. Monosulfate metabolites were also converted to the parent in human colorectal cells. The extent of cellular uptake was dependent on specific membrane transporters and dictated anti-proliferative activity. Sulfate metabolites induced autophagy and senescence in cancer cells.These effects were abrogated by inclusion of a sulfatase inhibitor, which reduced intracellular resveratrol, suggesting the parent compound elicits this activity. These findings demonstrate that resveratrol sulfates may contribute to efficacy in vivo, by delivering resveratrol to target tissues in a stable conjugated form enabling gradual regeneration of the parent within selected cells. At doses considered safe in humans resveratrol generated via this route may be of greater importance than unmetabolised resveratrol.

Resveratrol (trans-3,5,4 0 -trihydroxystilbene) is a naturally occurring polyphenol with cancer chemopreventive properties in preclinical models of carcinogenesis, including those of colorectal cancer. Recently, a variety of analogues of resveratrol have been synthesised and investigated in in vitro assays. One analogue, 3,4,5,4 0 -tetramethoxystilbene (DMU 212), showed preferential growth-inhibitory and proapoptotic properties in transformed cells, when compared with their untransformed counterparts. As part of a chemoprevention drug development programme, the pharmacokinetic properties of DMU 212 were compared with those of resveratrol in the plasma, liver, kidney, lung, heart, brain and small intestinal and colonic mucosa of mice. DMU 212 or resveratrol (240 mg kg À1 ) were administered intragastrically, and drug concentrations were measured by HPLC. Metabolites were characterised by cochromatography with authentic reference compounds and were identified by mass spectrometry. The ratios of area of plasma or tissue concentration vs time curves of resveratrol over DMU 212 (AUC res /AUC DMU212 ) for the plasma, liver, small intestinal and colonic mucosa were 3.5, 5, 0.1 and 0.15, respectively. Thus, resveratrol afforded significantly higher levels than DMU 212 in the plasma and liver, while DMU 212 exhibited superior availability compared to resveratrol in the small intestine and colon. Resveratrol was metabolised to its sulphate or glucuronate conjugates, while DMU 212 underwent metabolic hydroxylation or single and double O-demethylation. DMU 212 and resveratrol inhibited the growth of human-derived colon cancer cells HCA-7 and HT-29 in vitro with IC 50 values of between 6 and 26 mM. In the light of the superior levels achieved in the gastrointestinal tract after the administration of DMU 212, when compared to resveratrol, the results provide a good rationale to evaluate DMU 212 as a colorectal cancer chemopreventive agent.

Naturally occurring molecules with putative cancer chemopreventive properties such as the phytoalexin resveratrol (3,5,4 0 -trihydroxystilbene) are lead molecules that guide the design of novel agents with improved pharmacologic properties. The synthetic resveratrol analog 3,4,5,4 0 -tetramethoxystilbene (DMU-212) has been shown to possess stronger antiproliferative properties in human colon cancer cells than resveratrol. We tested the hypothesis that DMU-212 is also a more potent inhibitor of adenoma development in the ApcMinþ mouse, a model of human intestinal carcinogenesis. Apc Minþ mice received either stilbene derivative with the diet (0.2%), and adenomas were counted after experiments were terminated. Resveratrol and DMU-212 decreased adenoma load by 27% and 24%, respectively, compared to untreated controls. Cyclooxygenase (COX) enzymes are important mechanistic targets of resveratrol, and we investigated whether DMU-212 interferes with the expression and activity of COX in human colon cells. Incubation of HCA-7 cancer cells for 24-96 hr with either stilbene derivative (1-50 µM) decreased prostaglandin E-2 (PGE-2) production, but only resveratrol decreased COX-2 protein expression. In mice, which received either stilbene derivative (0.2%) for 3 weeks with their diet, PGE-2 levels in the intestinal mucosa were reduced by between 45% and 62% compared to mice on control diet. While resveratrol inhibited enzyme activity in purified COX preparations, DMU-212 failed to do so. The PGE-2 decrease seen with DMU-212 in cells and in vivo is probably mediated via its metabolites. The results suggest that alteration of the resveratrol molecule to generate DMU-212 does not abrogate its ability to decrease adenoma number in Apc Minþ mice or to interfere with PGE-2 generation in cells. ' 2005 Wiley-Liss, Inc.

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Curcumin, the main constituent of turmeric, is suspected to possess cancer chemopreventive properties. Pharmacokinetic and pharmacodynamic parameters have been reported, but few data exist describing whether methodologies are suitably robust for curcuminoid detection in colonic biopsy specimens. Information on the acceptability of prolonged administration of daily curcumin is not available. This is of vital importance to implement chemoprevention strategies. This study aimed to quantify levels of curcuminoids in colorectal mucosa of patients undergoing colorectal endoscopy or surgical resection and to obtain information on the acceptability and compliance with daily curcumin. Curcumin C3 complex (2.35 g) was administered to patients once daily for 14 days before endoscopic biopsy or colonic resection. Safety and tolerance were monitored. Analysis of curcuminoids in plasma, urine, and colonic mucosa was conducted by ultraperformance liquid chromatography (UPLC)-UV with characterization by liquid chromatography/tandem mass spectrometry (LC/MS-MS). Twenty-four of 26 patients commencing curcumin completed the course. Six patients reported mild gastrointestinal adverse events. Curcuminoids were detectable in nine of 24 plasma samples, 24 of 24 urine samples, and in the colonic mucosa of all 23 biopsied participants. Mean tissue levels were 48.4 mg/g (127.8 nmol/g) of parent curcuminoids. The major conjugate, curcumin glucuronide, was detectable in 29 of 35 biopsies. High levels of topical curcumin persisted in the mucosa for up to 40 hours postadministration. Sixteen participants (67%) stated that they would take curcumin long-term should it be of proven benefit. In summary, pharmacologically active levels of curcumin were recovered from colonic mucosa. The regimen used here seems safe, and patients support its use in long-term trials. Cancer Prev Res; 6(2); 119-28. Ó2012 AACR.