UVA photoprotective properties of an artificial carotenylflavonoid hybrid molecule.

Carotenoids and flavonoids represent two classes of natural antioxidants, a biological activity, which is determined by their chemical structure. To combine their antioxidant properties, a dual functional carotenylflavonoid hybrid molecule was synthesized. The antioxidant activity of this compound was tested in human dermal fibroblasts exposed to UVA irradiation. Test parameters were hemeoxygenase-1 (HO-1) expression, malondialdehyde (MDA), and reactive oxygen species (ROS) formation and cell viability. For comparison, the substructure components of the carotenylflavonoid, 4-hydroxyflavone and 11'-apo-ß-carotenylbenzene, were also tested. Incubation of cells with the carotenylflavonoid and 11'-apo-ß-carotenylbenzene attenuated UVA-induced HO-1 expression. In the MDA assay, the carotenylflavonoid and 11'-apo-ß-carotenylbenzene were moderately effective at low concentrations. At higher concentrations, the compound provoked an increase of MDA, which was confirmed by the H(2)DCF-DA assay measuring ROS formation. 4-Hydroxyflavone moderately inhibited the formation of MDA at all levels that were tested. The study showed that the carotenylflavonoid counteracts UVA-induced HO-1 expression. However, a photoprotection against lipid oxidation, ROS formation, and cell toxicity could not be proven in the experimental setting.

Novel indeno[1,2-b]indoloquinones as inhibitors of the human protein kinase CK2 with antiproliferative activity towards a broad panel of cancer cell lines.

We previously reported indeno[1,2-b]indoles as a novel class of potent inhibitors of the human protein kinase CK2. In the present study we prepared two novel quinoid derivatives, the indeno[1,2-b]indoloquinones 6b and 6c, and demonstrated inhibition of the human CK2 by the compounds. Furthermore, we showed substantial antiproliferative activity of both compounds towards a broad panel of human cancer cell lines in the low micromolar range. Whereas the earlier indeno[1,2-b]indoles have been shown to be selective for CK2, the indeno[1,2-b]indoloquinones 6b and 6c also inhibited the AMPK activated protein kinase ARK5, potentially contributing to the anti-cancer effects of the compounds. In addition, with compound 6b we found a very potent inhibitor of the leukemia-associated receptor tyrosine kinase FLT3, with an IC(50) of 0.18 µM.

Indeno[1,2-b]indole derivatives as a novel class of potent human protein kinase CK2 inhibitors.

Herein we describe the synthesis and properties of indeno[1,2-b]indole derivatives as a novel class of potent inhibitors of the human protein kinase CK2. A set of 19 compounds was obtained using a convenient and straightforward synthesis protocol. The compounds were tested for inhibition of human protein kinase CK2, which was recombinantly expressed in Escherichia coli. New inhibitors with IC(50) in the micro- and sub-micromolar range were identified. Compound 4b (5-isopropyl-7,8-dihydroindeno[1,2-b]indole-9,10(5H,6H)-dione) inhibited human CK2 with an IC(50) of 0.11 µM and did not significantly inhibit 22 other human protein kinases, suggesting selectivity towards CK2. ATP-competitive inhibition by compound 4b was shown and a K(i) of 0.06 µM was determined. Our findings indicate that indeno[1,2-b]indoles are a promising starting point for further development and optimization of human protein kinase CK2 inhibitors.

Circulating microparticles carry a functional endothelial nitric oxide synthase that is decreased in patients with endothelial dysfunction.

BACKGROUND: Microparticles (MPs) are circulating membrane particles of less than a micrometer in diameter shed from endothelial and blood cells. Recent literature suggests that MPs are not just functionally inert cell debris but may possess biological functions and mediate the communication between vascular cells. As a significant proportion of MPs originate from platelets and endothelial cells, we hypothesized that MPs may harbor functional enzymes including an endothelial NO synthase (eNOS). METHODS AND RESULTS: Using immunoprecipitation and Western blot analysis, we found that human circulating MPs carry an eNOS. Ca(2+) and l-arginine-dependent NOS activity of crude enzyme extract from MPs was determined by measuring the conversion of [(3)H]-L-arginine to [(3)H]-citrulline and NOS-dependent nitrite production. NOS-dependent NO production in intact MPs was assessed by the NO-specific fluorescent probe MNIP-Cu. In patients with cardiovascular disease, endothelial dysfunction was associated with an increase in the total number of circulating MPs as well as a significant decrease in the expression and activity of eNOS in MPs. No difference in reactive oxygen species was noted in MPs isolated from either group. CONCLUSIONS: Our data further support the concept that circulating MPs may not only retain phenotypic markers but also preserve the functionality of enzymes of the cells they originate from, including eNOS.

Direct evidence that (-)-epicatechin increases nitric oxide levels in human endothelial cells.

BACKGROUND: The dietary flavanol (-)-epicatechin has been suggested to mediate its vasodilatory effect by increasing nitric oxide levels in endothelial cells. AIM OF THE STUDY: To directly prove the formation of nitric oxide (NO) in human endothelial cells (HUVEC) in vitro by trapping NO to yield a fluorescent nitrosamine. METHODS: HUVEC were treated with (-)-epicatechin; nitrite and NO formation were determined by reductive chemiluminescence detection and the NO-sensitive fluorophore 5-methoxy-2-(1H-naphthol[2,3-d]imidazol-2-yl)-phenol copper complex (MNIP-Cu), respectively. MNIP was synthesized in a rapid and convenient one-step microwave reaction. Endothelial nitric oxide synthase (eNOS) mRNA levels and mRNA stability were measured. RESULTS: Incubation with (-)-epicatechin (0.3-10 µM) led to elevated NO levels in HUVEC measured via reductive chemiluminescence detection and visualized as the fluorescent NO derivative of MNIP. Expression of eNOS mRNA and mRNA stability were not affected by (-)-epicatechin treatment within the time frame studied. CONCLUSION: (-)-Epicatechin augments the level of NO in endothelial cells, a process suggested to be responsible for the vasodilatory properties of the compound.

Spectroscopic properties of phenolic and quinoid carotenoids: a combined theoretical and experimental study.

For the natural carotenoid 3,3'-dihydroxyisorenieratene (DHIR) and two synthetic derivatives, 3,3'-dihydroxy-16,17,18,16',17',18'-hexanor-Phi,Phi-carotene (DHHC) and Phi,Phi-carotene-3,3'-dione (DHIRQ, isorenieratene-3,3'-dione), steady state absorption experiments and combined density functional and multi-reference configuration interaction calculations were carried out. In addition, femtosecond transient absorption spectra were recorded for DHIR. Due to their marked out-of-plane distortion in DHIR, the phenolic end groups participate only partially in the conjugation system. In the low-energy regime its absorption spectrum with the maximum at 21 700 cm(-1) in acetone solution therefore closely resembles that of beta-carotene, the same as for the T1 energy. Further similarities are also found for the decay kinetics of the optically bright 1(1)Bu+ state of these compounds. After femtosecond excitation, the 1(1)Bu+ population of DHIR decays with a lifetime of 110 fs to the vibrationally hot 2(1)Ag-,v state which in turn relaxes to the 2(1)Ag-,0 state within 500 fs. Decay of the 2(1)Ag-,0 state to the S0 state occurs at a time scale of 12 ps. Demethylation of the phenolic end groups alleviates the steric repulsion by the polyene chain and causes a small red shift (1000 cm(-1)) comparing the absorption spectra of DHHC and DHIR. Oxidation of DHIR leads to drastic changes of the electronic and geometric properties. The quinoid end groups of DHIRQ are fully integrated into the conjugation system, shifting the absorption maximum to 17 800 cm(-1) in acetone solution which thus takes a blue color. The results of the quantum chemical calculations indicate that, in addition to the 2(1)Ag-(S1) state, two dark internal charge-transfer singlet states and the 1(1)Bu- state might be located energetically below the optically bright 1(1)Bu+ (S5) state of DHIRQ.