• Journal of Photoscience
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• v.10 no.1
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• pp.149-155
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• 2003

The absorption, fluorescence and fluorescence-excitation spectra of concentrated toluene solutions of selected para substituted trans-stilbene derivatives provide strong evidence for aggregation. A red-shifted fluorescence spectrum peaking at 420 nm gains in intensity as the stilbene concentration is increased. The excitation spectrum of this new emission is well to the red of the normal stilbene absorption spectrum, consistent with the appearance of a red shifted shoulder in the UV spectrum. Formation of a fluorescent ground state dimer (or higher aggregate) is proposed to account for these observations. The presence of polar substituents is crucial to the formation of this ground state complex.

• Preventive Nutrition and Food Science
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• v.7 no.4
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• pp.447-450
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• 2002

Previously, a methanol extract from seeds of Paeonia lactiflora was shown to have a potent inhibitory activities against tyrosinase and soybean lipoxygenase (SLO). Seven stilbenes, trans-resveratrol-4-Ο-$\beta$-D-glucoside, trans resveratrol, trans-$\varepsilon$-viniferin, cis-$\varepsilon$-viniferin, gnetin H, suffruticosol A and B were isolated from the seeds as active principles for inhibition of the enzymatic activity. Among them, the resveratrol trimer, gnetin H exhibited the most potent inhibitory activities against tyrosinase and SLO, respectively. Additionally, the resveratrol dimers, trans-$\varepsilon$-viniferin and cis-$\varepsilon$-viniferin exhibited significant inhibitory activity against the two oxidative enzymes. Meanwhile, three other stilbene derivatives, such as trans-resveratrol, suffruticosol A and suffruticosol B had also weak inhibition activity. The least inhibitory activity was observed in transresveratrol-4-Ο-$\beta$-D-glucoside. These results suggest that resveratrol dimers and trimer in the seeds of Paeonia lactiflora are potentially useful therapeutic agents against pathological disorders such as hyperpigmentation and inflammation.

• Horticultural Science & Technology
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• v.29 no.4
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• pp.374-381
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• 2011

Stilbenes are polyphenolic natural products, which have antioxidative and antifungal activities. In some plants, including grapevine, the stilbene compounds, as resveratrol derivatives, exist in very diverse forms. Experiments to identify the individual stilbene compounds were carried out first to quantify them in UV-irradiated grapevine leaves. For this, stilbene glycosides were extracted from grapevine leaves which irradiated intensively with UV light. The glycoside samples were hydrolyzed by ${\beta}$-glucosidase, before analyzed by HPLC-mass spectrometer at each m/z corresponding to the mass of specific stilbenes. As results, in chromatograms, the enzymatic hydrolysis resulted in decrease and increase of the peaks expected for glycosides and aglycones, respectively. The samples were also exposed to sunlight in order to photo-isomerize the stilbene compounds. The light exposure resulted in disappearance and appearance of peaks expected for trans- and cis-isomers of stilbenes, respectively. Such a change of the peaks in chromatograms provided information needed for the inference to peak components. In this way, it was possible to identify 16 kinds of stilbene compounds from grapevine leaves. The identified stilbenes were quantified from grapevine leaves irradiated mildly by UV light. The UV-irradiation increased markedly in the content of stilbene compounds, especially trans-resveratrol by several hundredfold. In addition, piceatannol, which is a mere minor component of stilbenes in control leaves and a more active radical scavenger than resveratrol, was also increased by several tenfold by the treatment. The increase in stilbene contents as influenced by UV irradiation seems to be one of the stress coping responses of grapevine as a hormesis phenomenon.

• Bulletin of the Korean Chemical Society
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• v.9 no.3
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• pp.167-171
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• 1988

Formation of intermolecular charge-transfer complexes between 7,7,8,8-tetracyanoquinodimethane (TCNQ) and two different series of stilbene derivatives has been studied spectroscopically at $25^{\circ}$C in 1,2-dichloroethane. The compounds of Series I include stilbene and derivatives which have fused phenyl rings on one end of the central ethylene structure and a phenyl ring on the other end. The other Series, II, is comprised of stilbenes which have various para substituents on one of the two phenyl rings. The equilibrium constant, $K_c^{AD}$ and the molar extinction coefficient, ${\varepsilon}_{\lambda}^{AD}$, were determined using the Scott equation. The values of the charge-transfer transition frequency, ${\vu}_AD$ and $K_c{AD}$ correlated well respectively with the ionization potentials of the fused rings of Series Ⅰ or of the compounds of Series II and with the values of ${\sigma}_p$, the Hammett constants of the Series II substituents. trans-4-N,N-Dimethylaminostilbene and trans-4-nitrostilbene were found to be able to participate in electron transfer reaction with TCNQ forming the corresponding anion radical, TCNQ$^-$:

• Bulletin of the Korean Chemical Society
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• v.31 no.8
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• pp.2175-2179
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• 2010

Quantum mechanical properties of unsymmetrical and unfunctionalized trans-stilbene derivatives 1-3, which had been prepared by solid-phase parallel syntheses, were characterized using mPW1PW91/6-311G(d,p) (hybrid HF-DF) calculations. The total electronic energies, normal vibrational modes, Gibbs free energies, and HOMOs and LUMOs of sixteen different structures from three different groups were analyzed. The energy differences between the HOMOs and LUMOs of the various unsymmetrical trans-stilbenes are in accord with the maximum absorption peaks of the experimental UV spectra of 1-3. The calculated normal vibrational modes of 21 were comparable with its experimental IR spectrum. The $\pi$-conjugation in the para-connected biphenyl group of 2 is better than the one in the metaconnected biphenyl group on the shorter side of 3.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.971-975
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• 2010

Eight hydroxylated stilbene derivatives including resveratrol, desoxyrhapontigenin and piceatannol as potential radical scavenger and tyrosinase inhibitor are synthesized using optimized Wittig-Horner reaction for excellent trans-selectivity in good yields. Antioxidant activity was tested against ABTS radical and tyrosinase inhibitory activity was performed with L-tyrosine as the substrate based on previous procedure with some modification. In general, catecholic stilbenes showed stronger activity against ABTS radical and resorcinolic moiety showed stronger tyrosinase inhibitory activity. Synthetic piceatannol which containing both catecholic and resorcinolic moieties showed the strongest activity in both as ABTS radical scavenger and tyrosinase inhibitor with $IC_{50}$ values of 4.1 and $8.6\;{\mu}M$, respectively.

• Proceedings of the PSK Conference
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• 2003.10a
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• pp.88-88
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• 2003

The syntheses of different types of stilbenoid libraries have been studied recently. In these courses, the screening of the generated natural product-mimic focused libraries led to the identification of the novel lead compounds for human cytochrome P450 (CYP) lAs, melanin production, and sortase A. A library of trans-stilbene derivatives was prepared through a new efficient solution pahse synthetic pathway and their inhibitory activities were evaluated on human cytochrome P450s(CYP) 1A1, 1A2, and 1B1 to find a potent and selective CYP1 inhibitor. (omitted)

• Journal of the Korean Wood Science and Technology
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• v.37 no.5
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• pp.474-479
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• 2009

Pinus koraiensis inner bark was collected and extracted with 95% ethanol. The extracts were concentrated and then sequentially fractionated using n-hexane, $CH_2Cl_2$, EtOAc, and $H_2O$ to be freeze dried. A portion of EtOAc fraction (6.6 g) was chromatographed on a Sephadex LH-20 column using aqueous methanol to isolate (+)-catechin (1), (-)-epicatechin (2), and trans-pinostilbenoside (3). Resveratrol (4) and trans-pinostilbene (5) were isolated by column chromatography using EtOH-hexane mixture after purification with aqueous methanol. The structures of these stilbenosides and flavans were characterized by spectroscopic tools using NMR and MS.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.05a
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• pp.92-92
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• 2002

Recently we have reported that various hydroxystilbenes show strong inhibition of human P450 1 activity. A series of synthetic trans-stilbene derivatives were prepared and their inhibitory potentials were evaluated with the bacterial membrane of recombinant human P450 1A1, 1A2 or 1B1 coexpressed with human P450/NADPH-450 reductase to find new candidates for cancer chemoprevention.(omitted)

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.148.2-149
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• 2003

Recently we have reported that various hydroxystilbenes show strong inhibition of human cytochrome P450 1 enzyme activities. A series of syntheic trans-stilbene derivatives were prepared and their inhibitory potentials were evaluated with the bacterial membrane of recombinant human cytochrome P450 1A1, 1A2 and 1B1 coexpressed with hyman NADPH-P450 reductase to find a new inhibitor of cytochrome P450 enzymes. Of the compounds tested, SY-081 exhibited a potent inhibition of human cytochrome P450 1B1 with an $IC_50$ value of 2.6 nM. (omitted)