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PubMed2002

Characterization of essential oils from lamiaceae species by fourier transform Raman spectroscopy.

The Fourier transform Raman (FT-Raman) spectra of pure terpenes and essential oils obtained by hydrodistillation of some Lamiaceae species, are presented. This study shows that principal components of an essential oil can be recognized by FT-Raman. Components predicted by FT-Raman spectrum of an essential oil correlate well with those found as major constituents by GC-MS. In this way the basic chemical character of an essential oil can be recognized. The results demonstrate that certain Raman intensities can be correlated to specific terpenes and therefore FT-Raman can discriminate between the essential oils of which main components belong to different classes of compounds.

Acyclic Monoterpenes↗
PubMed2004

Anti-AIDS agents. 52. Synthesis and anti-HIV activity of hydroxymethyl (3'R,4'R)-3',4'-di-O-(S)-camphanoyl-(+)-cis-khellactone derivatives.

To enhance the water solubility and oral bioavailability of DCK analogues, 12 new mono- and disubstituted (3'R,4'R)-3',4'-di-O-(S)-camphanoyl-(+)-cis-khellactone (DCK) analogues were synthesized and evaluated for inhibition of HIV-1 replication in H9 lymphocytes. 3-Hydroxymethyl-4-methyl-DCK (4c) exhibited significant anti-HIV activity in H9 lymphocytes and primary peripheral blood mononuclear cells with EC(50) values of 0.004 and 0.024 microM, respectively. Although this compound was not as potent as 4-methyl-DCK (2) and 3-bromomethyl-4-methyl-DCK (4a), it provides increased water solubility and possible linkage to other moieties. Of particular note, 4c exhibits moderate oral bioavailability (15%) when administered as a carboxymethylcellulose suspension to rats, whereas 2 is not orally bioavailable in the same formulation. Further studies on mechanism of action suggest that 4c inhibits the production of double-stranded viral DNA from the single-stranded DNA intermediate. In addition, 4a is the most potent compound in this series of new analogues, with EC(50) and TI values of 0.00011 microM and 189,600, respectively. Thus, further modification at the 3-position of the coumarin ring can improve the potency of new DCK analogues.

Animals↗
PubMed2004

Anti-AIDS agents. 60. Substituted 3'R,4'R-di-O-(-)-camphanoyl-2',2'-dimethyldihydropyrano[2,3-f]chromone (DCP) analogues as potent anti-HIV agents.

Synthesis of positional isomers is a commonly used technique in drug design. Accordingly, based on prior SAR studies of 3'R,4'R-di-O-(S)-camphanoyl-(+)-cis-khellactone (DCK, 1) analogues, a series of mono- and disubstituted chromone derivatives of 3'R,4'R-di-O-(-)-camphanoyl-2',2'-dimethyldihydropyrano[2,3-f]chromone (DCP, 4) were designed and synthesized. Together with 1 and 4-methyl DCK (2), all newly synthesized DCP analogues (4-21) were screened for anti-HIV-1 activity against a non-drug-resistant strain in H9 lymphocytes and a multiple reverse transcriptase (RT) inhibitor-resistant strain in the MT4 cell line. Several DCP analogues (4, 5, 7, 8, 13, and 17) exhibited extremely high anti-HIV activity in the non-drug-resistant strain assay, with EC(50) values ranging from 0.00032 to 0.0057 microM and remarkable therapeutic indexes (TI) ranging from 5.6 x 10(3) to 1.16 x 10(5), which were similar to those of 2 (EC(50) 0.0059 microM, TI > 6.6 x 10(3)) and better than those of 1 (EC(50) 0.049 microM, TI > 328). Even more promisingly, some DCP analogues also showed activity against a multi-RT inhibitor-resistant strain, HIV-1 RTMDR1, whereas most DCK analogues did not. The most significant compound was 8, with an EC(50) value of 0.06 microM and TI of 718 against the multi-RT inhibitor-resistant HIV-1 strain. Compounds 9 and 10 also showed good activity with an EC(50) value of 0.14 microM, and TIs of 272 and >111, respectively. 2-Ethyl DCP (8) exhibited the best anti-HIV activity in both assays. Further development of 8-related compounds as clinical trial candidates is warranted.

Anti-HIV Agents↗
PubMed2005

Combined quantum mechanical/molecular mechanical study on the pentacoordinated ferric and ferrous cytochrome P450cam complexes.

The pentacoordinated ferric and ferrous cytochrome P450(cam) complexes have been investigated by combined quantum mechanical/molecular mechanical (QM/MM) calculations in the presence of a protein/solvent environment and by QM calculations on the isolated QM regions with use of density functional theory. The B3LYP functional has been found more reliable than the BLYP and BHLYP functionals for estimating the relative state energies. The B3LYP/CHARMM calculations with an all-electron basis set for iron give high-spin ground states for the title complexes, in agreement with experiment. The comparison of the B3LYP/CHARMM results of the entire protein system with the B3LYP calculations on the naked QM regions shows that the amount of stabilization by the protein environment is largest for the intermediate-spin states, followed by the high-spin states of the complexes. The calculation of Mössbauer parameters in the presence of the enzyme environment confirms the double occupation of the d(xz) orbital in the quintet spin state of the ferrous complex, consistent with the computed QM/MM energies in the enzyme environment, while the d(x)2(-)(y)2 orbital is doubly occupied in the gas-phase quintet state.

Camphor 5-Monooxygenase↗
PubMed2001

A virtual high throughput screen for high affinity cytochrome P450cam substrates. Implications for in silico prediction of drug metabolism.

Structure-based virtual screening techniques require reliable scoring functions to discriminate potential substrates effectively. In this study we compared the performance of GOLD, PMF, DOCK and FlexX scoring functions in FlexX flexible docking to cytochrome P450cam binding site. Crystal structures of protein-substrate complexes were most effectively reproduced by the FlexX/PMF method. On the other hand, the FlexX/GOLD approach provided the best correlation between experimental binding constants and predicted scores. Binding modes selected by the FlexX/PMF approach were rescored by GOLD to obtain a reliable measure of binding energetics. The effectiveness of the FlexX/PMF/GOLD method was demonstrated by the correct classification of 32 out of the 33 experimentally studied compounds and also in a virtual HTS test on a library of 10,000 compounds. Although almost all the available functions were developed to be general, our study on cytochrome P450cam substrates suggests that careful selection or even tailoring the scoring function might increase the prediction power of virtual screens significantly. The FlexX/PMF/GOLD methodology was tested on cytochrome P450 3A4 substrates and inhibitors. This preliminary study revealed that the combined function was able to recognise 334 out of the 345 compounds bound to 3A4.

Binding Sites↗
PubMed2000

A full-UV spectrum absorbing daily use cream protects human skin against biological changes occurring in photoaging.

BACKGROUND: There is overwhelming evidence that exposure of human skin to ultraviolet radiations (UVR) leads to the development of cutaneous photoaging and eventually to neoplasia. This study was designed to evaluate in humans the protection afforded by a daily use cream containing a photostable combination of UVB and UVA absorbers (Uvinul N539, Parsol 1789 and Mexoryl SX) providing a continuous absorption through the entire UV spectrum, against damages induced by repeated daily exposure to solar simulated radiation (SSR). METHODS: Buttock skin of 12 healthy volunteers was exposed 5 days per week for 6 weeks to one minimal erythema dose of solar simulated radiation per exposure. The following parameters in treated and untreated skin were evaluated: erythema, pigmentation, skin hydration, skin microtopography, histology and immunochemistry, and collagen and metalloproteinase (MMP) mRNA levels. RESULTS: In SSR exposed unprotected skin sites, we observed melanization and changes in the skin hydration and microtopography. The epidermis revealed a significant increase in stratum corneum and stratum granulosum thickness. In the dermis, an enhanced expression of tenascin and a reduced expression of type I pro-collagen were evidenced just below the dermal epidermal junction. Although we were unable to visualize any change in elastic fibers in exposed buttock skin, a slightly increased deposition of lysozyme and alpha 1 antitrypsin on these fibers was observed using immunofluorescence techniques. Furthermore, types I and III collagen mRNA were slightly increased and a significant enhancement (up to 2.8-fold) of MMP-2 mRNA level was observed. The daily use cream was shown to prevent all these biological changes. CONCLUSION: Our results show in vivo that an appropriate full-UV spectrum product significantly reduces the solar-UV-induced skin damage, demonstrating the benefit of daily photoprotection.

Acrylates↗
PubMed2002

Interface pattern formation in nonlinear dissipative systems.

The problem of interface pattern selection in nonlinear dissipative systems is critical in many fields of science, occurring in physical, chemical and biological systems. One of the simplest pattern formations is the Saffman-Taylor finger pattern that forms when a viscous fluid is displaced by a less viscous fluid. Such finger-shaped patterns have been observed in distinctly different fields of science (hydrodynamics, combustion and crystal growth) and this has led to a search for a unified concept of pattern formation, as first proposed by the classic work of D'arcy Thomson. Two-dimensional finger-shaped patterns, observed in flame fronts and the ensembled average shape of the diffusion-limited aggregation pattern, have been shown to be similar to Saffman-Taylor finger shapes. Here we present experimental studies that establish that the cell shapes formed during directional solidification of alloys can be described by the form of the Saffman-Taylor finger shape equation when a second phase is present in the intercellular region.

Alloys↗
PubMed1995

Structure of cytochrome P450eryF involved in erythromycin biosynthesis.

Cytochrome P450eryF catalyzes the 6S-hydroxylation of 6-deoxyerythronolide B, the initial reaction in a multistep pathway to convert 6-deoxyerythronolide B into the antibiotic, erythromycin. The overall structure of P450eryF is similar to that of P450cam but differs in the exact positioning of several alpha-helices. The largest difference occurs in the B' helix and results in the enlargement of the substrate-binding pocket of P450eryF. The substrate is positioned with the macrolide ring perpendicular to the haem plane and contacts seven hydrophobic residues and three solvent molecules. The substrate participates in a network of hydrogen bonds that may provide a proton shuttle pathway in the oxygen cleavage reaction.

Amino Acid Sequence↗
PubMed2000

A scanning tunnelling study of immobilised cytochrome P450cam.

A site-specifically engineered surface cysteine residue, located in a region where the haem moiety is closest to the surface, is used to anchor cytochrome P450cam enzyme molecules covalently to a gold electrode. More reproducibly ordered adsorption, at high coverage, occurs with this K344C mutant than with the wild-type enzyme. The subsequently formed close-packed monolayer arrays have been probed by scanning tunnelling microscopy under ambient conditions and under aqueous (buffered) solution at high resolution. Initial indications suggest that the immobilised enzyme is both electrochemically addressable and catalytically active.

Camphor 5-Monooxygenase↗