3-3--4-5--tetramethoxy-trans-stilbene and 3-3--4-5--tetrahydroxystilbene

Human glyoxalase I (GLO I), a rate-limiting enzyme for detoxification of methylglyoxal (MG), a by-product of glycolysis, is known to be a potential therapeutic target for cancer. Here, we searched new scaffolds from natural compounds for designing novel GLO I inhibitors and found trans-stilbene scaffold. We examined the inhibitory abilities to human GLO I of commercially available trans-stilbene compounds. Among them, piceatannol was found to have the most potent inhibitory activity against human GLO I. Piceatannol could inhibit the proliferation of human lung cancer NCI-H522 cells, which are dependent on GLO I for survival, in a dose- and time-dependent manner. In addition, piceatannol more significantly inhibited the proliferation of NCI-H522 cells than that of NCI-H460 cells, which are less dependent on GLO I. Importantly, overexpression of GLO I in NCI-H522 cells resulted in less sensitive to the antiproliferative activity of piceatannol. Taken together, this is the first report demonstrating that piceatannol inhibits GLO I activity and the GLO I-dependent proliferation of cancer cells. Furthermore, we determined a pharmacophore for novel inhibitors of human GLO I by computational simulation analyses of the binding mode of piceatannol to the enzyme hot spot in the active site. We suggest that piceatannol is a possible lead compound for the development of novel GLO I inhibitory anticancer drugs.

Topics: Cell Line, Tumor; Cell Proliferation; Enzyme Inhibitors; Humans; Lactoylglutathione Lyase; Lung Neoplasms; Stilbenes

Bioassay-guided fractionation of the leaves of Eugenia rigida yielded three stilbenes, (Z)-3,4,3',5'-tetramethoxystilbene (1), (E)-3,4,3',5'-tetramethoxystilbene (2), and (E)-3,5,4'-trimethoxystilbene (3). Their structures were determined using 1D- and 2D-NMR spectroscopy and HRESIMS. The sterically hindered Z-stereoisomer 1, a new natural product, was prepared by time-dependent photoisomerization of the E-isomer (2) under UV irradiation at λ254 nm, while 2,3,5,7-tetramethoxyphenanthrene (5) was identified at λ365 nm by UHPLC/APCI-MS and NMR spectroscopy. Compounds 1-3 were tested against a panel of luciferase reporter gene assays that assess the activity of many cancer-related signaling pathways, and the Z-isomer (1) was found to be more potent than the E-isomer (2) in inhibiting the activation of Stat3, Smad3/4, myc, Ets, Notch, and Wnt signaling, with IC50 values between 40 and 80 μM. However, both compounds showed similar inhibition against Ap-1 and NF-κB signaling. In addition, 1 demonstrated cytotoxic activity toward human leukemia cells, solid tumor cells of epidermal, breast, and cervical carcinomas, and skin melanoma, with IC50 values between 3.6 and 4.3 μM, while 2 was weakly active against leukemia, cervical carcinoma, and skin melanoma cells. Interestingly, 2 showed antioxidant activity by inhibition of ROS generation to 50% at 33.3 μM in PMA-induced HL-60 cells, while 1 was inactive at 100 μM (vs Trolox 1.4 μM).

Topics: Antineoplastic Agents, Phytogenic; Antioxidants; Drug Screening Assays, Antitumor; Female; HL-60 Cells; Humans; Inhibitory Concentration 50; Molecular Structure; NF-kappa B; Nitric Oxide Synthase Type II; Nuclear Magnetic Resonance, Biomolecular; Plant Leaves; Puerto Rico; Reactive Oxygen Species; Signal Transduction; Stereoisomerism; Stilbenes; Syzygium