The stilbenoids E-resveratrol (E-3,5,4Ј-trihydroxystilbene, 1), E-3,5,4Ј-trimethoxystilbene (2), E-3,4,4Ј-trimethoxystilbene (3) and E-3,4Ј-dimethoxy-5-hydroxystilbene (4) were converted by photoisomerization to their corresponding Z-isomers 5Ð8. Compounds 1Ð8 were subjected to antiproliferative activity bioassays towards a set of four different human cancer cell lines, namely DU-145 (androgen not responsive human prostate tumor), LNCaP (androgen responsive human prostate tumor), M-14 (human melanoma) and KB (human mouth epidermoid carcinoma). The methylated analogues of 1 are more active than the natural lead in the majority of bioassays. The most active compound was Z-3,5,4Ј-trimethoxystilbene (6), which showed against DU-145 and LNCaP cells GI 50 values close to those of the anticancer drug vinorelbine; 6 resulted more active than its E-isomer 2 towards DU-145, LNCaP and especially KB cell lines. A number of methylated Z-isomers displayed a higher activity than their E-isomers, but E-resveratrol (1) was more active than Z-resveratrol (5) towards all the tested cell lines.

Six new polyhydroxy‐p‐terphenyl pyrazinediol dioxide conjugates (4−9) related to sarcodonin (3) have been isolated from the EtOAc extract of the fruiting bodies of the basidiomycete Sarcodon leucopus and we established their structures by spectral analysis and chemical conversions. Three of them, named sarcodonins α (4), β (5), and γ (6), afforded the same peracetate 12 upon acetylation. Compounds 7, 8, and 9 gave peracetate 13 and were characterized as the N‐oxide epimers of 3−5, respectively, and are named, accordingly, episarcodonin, episarcodonin α, and episarcodonin β. From the EtOH extract, we obtained a mixture of two violet pigments. Chemical and spectroscopic data allowed their structures to be established as the p‐terphenyl ortho‐quinones related to the sarcodonins, namely sarcoviolin α (10) and episarcoviolin α (11). Compounds 3, 4, 6, and 7 and the mixture of 10 and 11 were found to be active in assays against tumor cell cultures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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The biomimetic synthesis of a small library of dihydrobenzofuran neolignanamides (the natural trans-grossamide (4) and the related compounds 21-28) has been carried out through an eco-friendly oxidative coupling reaction mediated by Trametes versicolor laccase. These products, after complete spectroscopic characterization, were evaluated for their antiproliferative activity against Caco-2 (colon carcinoma), MCF-7 (mammary adenocarcinoma), and PC-3 (prostate cancer) human cells, using an MTT bioassay. The racemic neolignamides (±)-21 and (±)-27, in being the most lipophilic in the series, were potently active, with GI50 values comparable to or even lower than that of the positive control 5-FU. The racemates were resolved through chiral HPLC, and the pure enantiomers were subjected to ECD measurements to establish their absolute configurations at C-2 and C-3. All enantiomers showed potent antiproliferative activity, with, in particular, a GI50 value of 1.1 μM obtained for (2R,3R)-21. The effect of (±)-21 on the Caco-2 cell cycle was evaluated by flow cytometry, and it was demonstrated that (±)-21 exerts its antiproliferative activity by inducing cell cycle arrest and apoptosis.

The fractionation, guided by cell-growth inhibition assay, of the EtOAc crude extract from grape stems of the Sicilian Vitis vinifera variety 'Nerello Mascalese' allowed identification of ten constituents, isolated either as pure compounds (1, 3-5, 7-10) or inseparable mixtures (2a-d and 6a-e). The pure constituents were: two triterpenoid acids, oleanolic (1) and betulinic acids (5); daucosterol (7); a stilbenoid, E-resveratrol (3) and its dimer E-ε-viniferin (4); the simple phenol gallic acid (8); and the flavanols catechin (9) and gallocatechin (10). Four 6'-O-acyldaucosterols (2a-d) and five 1,2-di-O-acyl-3-O-β-Dgalactopyranosyl glycerols (6a-e) were also identified as inseparable mixtures. All the isolated compounds were subjected to spectroscopic analysis and MTT bioassay on MCF-7 human breast cancer cells. The majority showed growth-inhibitory activity, 5 being the most active (GI 50 = 0.57 μM). Compounds 3-5 were also tested on HT-29, U-87-MG and U-373-MG cell lines.