Trihydroxy-3.5,4 -stilben

This protocol could be extended to a range of different ,/i-unsaturated carbonyl compounds and either activated or deactivated aryl iodides [22], An application of related Heck chemistry to the synthesis of methylated resveratrol (3,4, 5-trihydroxy-( )-stilbene) is shown in Scheme 6.4 [23]. The phytoalexin resveratrol exhibits a variety of interesting biological and therapeutic properties, among them activity against several human cancer cell lines. Botella and Najera have shown that the trimethyl ether of resveratrol (Scheme 6.4) can be rapidly prepared by microwave-assisted Heck reaction of the appropriate aryl iodide and styrene derivatives, using the same oxime-derived palladacycle as indicated in Scheme 6.3. 

Aside from being UV-protectants, in a number of species certain stilbenes act as phytoalexins. Resveratrol (6.24 trans-3,5,4 -trihydroxy-stilbene), its cA-isomer, as well as their glucosides and dehydrodimer mm-e- iniferin (6.25) are present in grape leaves and berries and play a role in the defense against gray rot caused by the fungal pathogen Botrytis cinerea. 

In 1975 Keen (21) reported that native microflora stimulated production of two antifungal compounds by peanut seeds that were soaked in water, sliced into sections, and incubated for 3-5 days. These compounds were judged to be phytoalexins and were subsequently identified as cis- and trans-isomers of 4-(3-methyl-but-2-enyl)-3,5,4 -trihydroxystilbene [1)(5)(Figure 1). Simultaneously, Ingham (6) reported the isolation of cis- and trans-resveratrol(3,5,4 trihydroxy stilbene[2] ) from peanut hypocotyls. Additional stilbenes have been shown to be produced by peanut seeds in response to wounding, and these include 4- (3-methyl-but-1-enyl) -3,5,3, 4 -tetra-hydroxystilbene [3](7), 4-(3-methyl-but-l-enyl)-3,5,4 -trihydroxy-... 

CClsOO reacts with phenols forming phenoxyl radicals (Neta et al. 1989, Alfassi et al. 1993). The reactions of CCI3OO with fra s-3,5,4 -trihydroxy-stilbene (trans-resveratrol) and its analogues showed that the p ra-hydroxyl group of trans-resveratrol scavenges free radicals more effectively than its meta-hydroxyl groups (Stojanovic et al. 2001). 

Amino-l,2,4-benzotriazine 1,2-dioxide Thin layer chromatography Thymidine-5 -phosphate iV,iV,iV, iV -Telramclhylphcnylcncdiamine Tetranitromethane 3,5,4 -Trihydroxy-frans-stilbene 2-Amino-2-hydroxy-l, 3-propanediol Time-resolved light-scattering p-[meso-5-5,10,15,20-Tetra(pyridyl)porphyrin]tetra kis[ (ns-(bipyridine) chloride ruthenium(II)]... 

Resveratrol [2], 3,4 ,5-trihydroxy-rra/ A-stilbene, is a phytoalexin found in grapes and other plants, that exhibits a variety of biological activities, including antileukemic, antibacterial, antifungal, anti antiplatelet aggregation, coronary vasodilator. Recently, it has been shown to induce apoptosis and decrease expression of Bcl-2 in the human leukaemia HL-60 cell line. 

Incubation of rat embryonic mesencephalic tissue, rich in dopaminergic neurones, with 0.2 mM tert-butyl hydroperoxide in the presence of the spin trap 5,5-dimethyl-1-pyrroline N-oxide for 20 min resulted in the trapping of radicals (Karlsson et al. 2000). The main radicals detected in cell suspensions were the tert-butoxyl radical and the methyl radical, indicating the one-electron reduction of the peroxide followed by a P-scission reaction. The appearance of electron paramagnetic resonance signals from the trapped radicals preceded the onset of cytotoxicity, which was almost exclusively necrotic in nature. The inclusion of resveratrol (3,5,4 -trihydroxy-fra s-stilbene) in incubations resulted in the marked protection of cells from ferf-butyl hydroperoxide. 

Resveratrol (3,4[5-trihydroxy-P-an5-stilbene) (Fig. 3), a common phytoalexin found in grape skins, peanuts, and red wine, has been speculated to... 

A natural benzil derivative, which appears to be biogenetically related to the stilbenes, has been isolated from the Leguminosae species, Zollernia paraensis which contains 2,4,2 -trihydroxy-4 -methoxybenzil (45). 

Hydroxysubstituted stilbenes are often methylated. Examples of such compounds are (E)-pallidol (10-148), which occurs in Riesling wine as 3-0-glucopyranoside and 3,3"-di-0-glucopyranoside. Another example is 3,3, 5-trihydroxy-4 -methoxystilbene, which... 

Resveratrol (3,5,4 -trihydroxy-trans-stilbene), a natural polyphenolic phytoalexin, found in high to moderate quantities in various foods including... 

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