Haralambos E. Katerinopoulos

COMPOSITION AND INSECT ATTRACTING ACTIVITY OF THE ESSENTIAL OIL OF Rosmarinus officinalis

The essential oil and a number of extracts of Rosmarinus officinalisL. in solvents of increasing polarity were isolated, and their components identified and tested as pest control agents. Ethanol and acetone extracts attract grape berry moth Lobesia botrana. However, none of the extracts had a significant effect on western flower thrips Frankliniella occidentalis, which is attracted by 1,8-cineole, a major essential oil component.

The development of a new family of intracellular calcium probes

Four new potential fluorescent probes for Ca2+ using the coumarin moiety as a fluorophore have been synthesized and their spectral properties and binding affinities for Ca2+ determined. The most promising derivative for intracellular use, BTC, exhibits an excitation wavelength shift from 462 nm to 401 nm on binding Ca2+, with an emission wavelength of 530 nm. The quantum yield of this probe increases from 0.07 as the free indicator to 0.12 on binding Ca2+. BTC, loaded as its tetraacetoxymethyl ester (AM ester) into mouse myeloma P3X cells, responded only when cytoplasmic Ca2+ exceeded typical intracellular calcium concentrations. The dye, therefore, appears to be useful in excitatory cells or extracellular spaces with intracellular calcium concentrations high enough to saturate typical excitation ratio Ca2+ indicators such as Fura-2.

Coumarin-based ratiometric fluorescent indicators with high specificity for lead ions

Total syntheses and spectral properties of fluorescent Pb(2+) indicators are reported.

Composition and antimicrobial activity of the essential oil of Cistus creticus L

ABSTRACT The chemical composition of the essential oil of the leaves of Cistus creticus L., (Fam. Cistaceae), was investigated by GC/MS. Among the 49 components identified, (representing 76.56% of the oil composition) diterpenes (59.59%) predominated. The major components were manoyl oxide (19.61%) and 13-epi-manoyl oxide (13.44%). The oil of C. creticus was found to exhibit a strong antibacterial activity against Gram + bacteria.

Near-membrane iminocoumarin-based low affinity fluorescent Ca2+ indicators

Two new potential near-membrane iminocoumarin-based fluorescent Ca(2+) indicators were synthesized and the spectral profiles of their free and Ca(2+) bound forms were studied. The probes incorporate in their BAPTA-related structures, the 3-(benzimidazolyl)iminocoumarin or the 3-(benzothiazolyl)iminocoumarin moiety, substituted at the imino nitrogen with an n-dodecyl lipophilic chain. The compounds are excited with visible light and have Ca(2+) dissociation constant values of 5.50 and 4.49 microM, respectively, the highest reported to date in the literature. Fluorescence spectra studies indicated a clear shift in their excitation wavelength maxima upon Ca(2+) binding along with changes in fluorescence intensity that enable the compounds to be used as ratiometric near-membrane, low Ca(2+) affinity probes.

Anti-inflammatory and antioxidant activity of coumarins designed as potential fluorescent zinc sensors

A series of coumarin analogs, designed and synthesised as potential fluorescent zinc probes were evaluated for their biological activity as anti-inflammatory and antioxidant agents. The effect of the synthesised compounds on inflammation, using the carrageenin-induced rat paw oedema model, was studied. In general, the compounds were found to be potent anti-inflammatory agents (26.5–64%). Compound 5 was found to interact significantly with 1,1-diphenyl-2-picryl-hydrazyl stable free radical (DPPH) whereas the remainder were inactive in this assay. The compounds inhibit in general the soybean lipoxygenase and scavenge superoxide anion radicals. The anti-inflammatory activity seems to be connected with their reducing activity. Their RM values were determined as an expression of their lipophilicity. Theoretical calculations of their lipophilicity as clog P were performed indicating that only a poor relationship exists between their lipophilicity and anti-inflammatory activity.

A novel method for the preparation of monomethine cyanine dyes

A novel method for the preparation of symmetric and asymmetric monomethine cyanine dyes was developed. Quaternary salts of a heterocyclic 2- or 4-methyl compound and N-heterocyclic 2- or 4-sulfobetainic compounds were reacted by simple melting or by boiling in diAerent solvents in the absence of a basic compound. The preparation is fast and the yields are good to high, exceeding in some cases those by other methods. The novel method is environmentally more friendly. # 1999 Elsevier Science Ltd. All rights reserved.

A “turn-on”–turning-to-ratiometric sensor for zinc(II) ions in aqueous media

A potential fluorescent zinc(II) sensor was synthesized and its spectral profile was studied in aqueous solutions of increasing zinc(II) concentrations. Due to the inherent properties of its chromophore, the sensor exhibits a “turn on” response in solutions of nanomolar zinc(II) concentrations that turns to ratiometric, as zinc(II) ion concentrations reach micro/millimolar levels.

A cyclam-type “turn on” fluorescent sensor selective for mercury ions in aqueous media

The synthesis and spectral profile of a cyclam-type “turn on” fluorescent sensor selective for Hg2+ ions in aqueous media is described. Its properties are compared to those of a second probe with an N-deprotected cyclam system. The vast difference in ion selectivity between the two sensors reveals the influence of functional group modifications on the selectivity of fluorescent ion probes.

Fullerene–Coumarin Dyad as a Selective Metal Receptor: Synthesis, Photophysical Properties, Electrochemistry and Ion Binding Studies

A coumarin derivative with a malonate unit has been synthesized and used for the preparation of a fullerene-coumarin dyad through the Bingel cyclopropanation method. The newly synthesized dyad is soluble in organic solvents and has been fully characterized with traditional spectroscopic techniques. Electronic interactions between the two components of the dyad were probed with the aid of UV/Vis spectroscopy, fluorescence emission, and electrochemistry measurements. Our studies clearly show the presence of electronic interactions between C(60) and modified coumarin in the ground state; efficient electron-transfer quenching of the singlet excited state of the coumarin moiety by the appended fullerene sphere was also observed. Time-resolved fluorescence measurements revealed lifetimes for the coumarin-C(60) dyad at a maximum of 50 ps, while the quantum yield was reaching unity. Additionally, the redox potentials of the C(60)-coumarin dyad were determined and the energetics of the electron-transfer processes were evaluated. Finally, after alkaline treatment of C(60)-coumarin, which resulted in the deprotection of carboxylate units, the dyad was tested as a metal receptor for divalent metal cations; ion competition studies and fluorescence experiments showed binding selectivity for lead ions.