Showing papers on "Lanosterol published in 2006"
TL;DR: The relationship between membrane hydrophobic thickness and elastic properties is explored and it is demonstrated that membrane properties are affected to different degrees by these structurally distinct sterols, yet nonetheless exhibit universal behavior.
255 citations
TL;DR: It is shown that plants also have the ability to synthesize lanosterol directly from 2,3-oxidosqualene, which may lead to a new pathway to plant sterols.
Abstract: ;Sterols are important as structural components of plasma membranes and precursors of steroidal hormones in both animals and plants. Plant sterols show a wide structural variety and significant structural differences from those of animals. To elucidate the origin of structural diversity in plant sterols, their biosynthesis has been extensively studied [Benveniste (2004) Annu. Rev. Plant. Biol. 55: 429, Schaller (2004) Plant Physiol. Biochem. 42: 465]. The differences in the biosynthesis of sterols between plants and animals begin at the step of cyclization of 2,3-oxidosqualene, which is cyclized to lanosterol in animals and to cycloartenol in plants. However, here we show that plants also have the ability to synthesize lanosterol directly from 2,3oxidosqualene, which may lead to a new pathway to plant sterols. The Arabidopsis gene At3g45130, designated LAS1, encodes a functional lanosterol synthase in plants. A phylogenetic tree showed that LAS1 belongs to the previously uncharacterized branch of oxidosqualene cyclases, which differs from the cycloartenol synthase branch. Panax PNZ on the same branch was also shown to be a lanosterol synthase in a yeast heterologous expression system. The higher diversity of plant sterols may require two biosynthetic routes in steroidal backbone formation.
109 citations
TL;DR: Phylogenetic reconstructions reveal that lanosterol synthases are broadly distributed in eudicots but evolved independently from those in animals and fungi, and novel catalytic motifs establish that plant lanosterl synthases comprise a third catalytically distinct class of lanosterols synthase.
82 citations
TL;DR: Comparative DSC and Fourier transform infrared spectroscopic studies indicate that lanosterol is less miscible in DPPC bilayers than is cholesterol, but perturbs their organization to a greater extent, probably due primarily to the rougher faces and larger cross-sectional area of the Lanosterol molecule.
79 citations
TL;DR: The data indicate that fungicide residues in food are unlikely to exert a relevant inhibition of CYP51 in humans whereas systemic use of some antimycotic drugs, e.g. ketoconazole or miconazole, should be carefully considered regarding disturbance of human steroid biosynthesis.
75 citations
TL;DR: Clinical and experimental evidence indicates that garlic ingestion lowers blood cholesterol levels, and treatment of cells in culture with garlic and garlic-derived compounds inhibits cholesterol synthesis, which indicates that compounds containing an allyl-disulfide orallyl-sulfhydryl group are most likely responsible for the inhibition of cholesterol synthesis by garlic.
Abstract: Clinical and experimental evidence indicates that garlic ingestion lowers blood cholesterol levels, and treatment of cells in culture with garlic and garlic-derived compounds inhibits cholesterol synthesis. To identify the principal site of inhibition in the cholesterolgenic pathway and the active components of garlic, cultured hepatoma cells were treated with aqueous garlic extract or its chemical derivatives, and radiolabeled cholesterol and intermediates were identified and quantified. Garlic extract reduced cholesterol synthesis by up to 75% without evidence of cellular toxicity. Levels of squalene and 2,3-oxidosqualene were not altered by garlic, indicating that the site of inhibition was downstream of lanosterol synthesis, and identical results were obtained with 14 C-acetate and 14 C-mevalonate, confirming that 3-hydroxy-3-methylglutaryl-CoA reductase activity was not affected in these short-term studies. Several methylsterols that accumulated in the presence of garlic were identified by coupled gas chromatography-mass spectrometry as 4,4'-dimethylzymosterol and a possible metabolite of 4-methylzymosterol; both are substrates for sterol 4a-methyl oxidase, pointing to this enzyme as the principal site of inhibition in the cholesterolgenic pathway by garlic. Of 9 garlic-derived compounds tested for their ability to inhibit cholesterol synthesis, only diallyl disulfide, diallyl trisulfide, and allyl mercaptan proved inhibitory, each yielding a pattern of sterol accumulation identical with that obtained with garlic extract. These results indicate that compounds containing an allyl-disulfide or allyl-sulfhydryl group are most likely responsible for the inhibition of cholesterol synthesis by garlic and that this inhibition is likely mediated at sterol 4a-methyl oxidase.
63 citations
TL;DR: The multiple amino acid sequence alignment of a conserved region suggests that the LAS of different eukaryotic lineages emerged from the ancestral CAS by convergent evolution.
Abstract: Sterols, essential eukaryotic constituents, are biosynthesized through either cyclic triterpenes, lanosterol (fungi and animals) or cycloartenol (plants). The cDNA for OSC7 of Lotus japonicus was shown to encode lanosterol synthase (LAS) by the complementation of a LAS-deficient mutant yeast and structural identification of the accumulated lanosterol. A double site-directed mutant of OSC7, in which amino acid residues crucial for the reaction specificity were changed to the cycloartenol synthase (CAS) type, produced parkeol and cycloartenol. The multiple amino acid sequence alignment of a conserved region suggests that the LAS of different eukaryotic lineages emerged from the ancestral CAS by convergent evolution.
62 citations
TL;DR: Geraniol has multiple effects on mevalonate and lipid metabolism in Hep G2 cells, affecting cell proliferation and cholesterogenesis, protein prenylation, and fatty-acid metabolism.
Abstract: Monoterpenes have multiple pharmacological effects on the metabolism of mevalonate. Geraniol, a dietary monoterpene, has in vitro and in vivo anti-tumor activity against several cell lines. We have studied the effects of geraniol on growth, fatty-acid metabolism, and mevalonate metabolism in the human hepatocarcinoma cell line Hep G2. Up to 100 micromol geraniol/L inhibited the growth rate and 3-hydroxymethylglutaryl coenzyme A reductase (HMG-CoA) reductase activity of these cells. At the same concentrations, it increased the incorporation of cholesterol from the medium in a dose-dependent manner. Geraniol-treated cells incorporated less 14C-acetate into nonsaponifiable lipids, inhibiting its incorporation into cholesterol but not into squalene and lanosterol. This is indicative of an inhibition in cholesterol synthesis at a step between lanosterol and cholesterol, a fact confirmed when cells were incubated with 3H-mevalonate. The incorporation of 3H-mevalonate into protein was also inhibited, whereas its incorporation into fatty acid increased. An inhibition of delta5 desaturase activity was demonstrated by the inhibition of the conversion of 14C-dihomo-gamma-linolenic acid into arachidonic acid. Geraniol has multiple effects on mevalonate and lipid metabolism in Hep G2 cells, affecting cell proliferation. Although mevalonate depletion is not responsible for cellular growth, it affects cholesterogenesis, protein prenylation, and fatty-acid metabolism.
58 citations
TL;DR: Effects of ostreolysin on membranes containing various steroids are presented, suggesting that the membrane lateral distribution and accessibility of the sterols are crucial for the activity of this new member of cholesterol-dependent cytolysins.
55 citations
TL;DR: The results suggest a primary role of C14SR in human cholesterol biosynthesis, whereas LBR role in the pathway remains unclear.
53 citations
TL;DR: Novel tetrahydroisoquinoline compounds were designed by coupling structure-based de novo design based on the structure of lanosterol 14alpha-demethylase (CYP51) showing potent antifungal activities, in which compounds 6 and 7 had equal or stronger antif fungus activities against five test fungi than that of fluconazole.
TL;DR: Repeated observation of multiple abortive and/or alternative cyclization/arrangement products from various ERG7(H234X) mutants demonstrated the catalytic plasticity of the enzyme.
Abstract: Site-saturated mutagenesis experiments were carried out on the His234 residue of Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase (ERG7) to characterize its functional role in ERG7 activity and to determine its effect on the oxidosqualene cyclization/rearrangement reaction. Two novel intermediates, (13alphaH)-isomalabarica-14(26),17E,21-trien-3beta-ol and protosta-20,24-dien-3beta-ol, isolated from ERG7(H234X) mutants, provided direct mechanistic evidence for formation of the chair-boat 6-6-5 tricyclic Markovnikov cation and protosteryl cation that were assigned provisionally to the ERG7-catalyzed biosynthetic pathway. In addition, we obtained mutants that showed a complete change in product specificity from lanosterol formation to either protosta-12,24-dien-3beta-ol or parkeol production. Finally, the repeated observation of multiple abortive and/or alternative cyclization/arrangement products from various ERG7(H234X) mutants demonstrated the catalytic plasticity of the enzyme. Specifically, subtle changes in the active site affect both the stability of the cation-pi interaction and generate product diversity.
01 Jan 2006
TL;DR: A detailed discussion of specific enzymatic reactions and the products so formed can be found in this article, with a focus on the reaction of the cytochrome P450 side-chain cleavage enzyme.
Abstract: Testosterone represents the major circulating androgen in the male and is synthesized by a sequence of enzymatic reactions that converts the substrate for all steroid biosynthesis, cholesterol, initially to the first steroid produced, pregnenolone, and then through a number of steroid intermediates to testosterone. This chapter discusses the specific enzymatic reactions and the products so formed. Cholesterol synthesis involves the formation of mevalonic acid, squalene, lanosterol, and finally cholesterol. The uptake of cholesterol from the serum requires the interaction of circulating lipoproteins with specific cell surface receptors designed to interact with these lipoproteins and internalize them either in whole or in part. The initial enzymatic reaction in the biosynthesis of all steroids in all steroidogenic tissues is the conversion of cholesterol to pregnenolone. This reaction occurs through the activity of the cytochrome P450 side-chain cleavage enzyme. In the testis, testosterone is the major androgen produced by the Leydig cells and is responsible for the normal maintenance of spermatogenesis. However, testosterone can also be converted to the more potent androgen, dihydrotestosterone (DHT), through the action of the enzyme 5α-reductase.
TL;DR: Overall, Trp232 plays a catalytic role in the influence of rearrangement process and determination of deprotonation position but does not involve intervention in the cyclization steps.
TL;DR: Replacement of animal/fungi-like Ile(105) in the B' helix of TC CYP51 with phenylalanine increases the ability of the enzyme to metabolize O, converting it into a more plant-like sterol 14alpha-demethylase, leading to different pathways for sterol production in TC versus TB.
Abstract: Sterol 14α-demethylases (CYP51) are metabolic cytochromes P450, found in each biological kingdom. They catalyse a single three-step reaction included in all sterol biosynthetic pathways. Plant CYP51s have strict preference towards their physiological substrate O (obtusifoliol), which is C-4-monomethylated. Natural substrates of animal/fungal CYP51 (lanosterol, 24,25-dihydrolanosterol or 24-methylenelanosterol) are C-4-dimethylated. CYP51 from the pathogenic protozoa TB ( Trypanosoma brucei ) is the first example of O -specific sterol 14α-demethylase in non-photosynthetic organisms. Surprisingly, at 83% amino acid identity to the TB orthologue, CYP51 from TC ( Trypanosoma cruzi ) clearly prefers C-4-dimethylated sterols. Replacement of animal/fungi-like Ile 105 in the B′ helix of TC CYP51 with phenylalanine, the residue found in this position in all plant and other trypanosome CYP51s, dramatically increases the ability of the enzyme to metabolize O , converting it into a more plant-like sterol 14α-demethylase. A more than 100-fold increase in binding and turnover is observed for the 24-desmethyl analogue of O [ N (norlanosterol)], which is found in vivo in procyclic forms of TB and is a good TB CYP51 substrate in vitro . We believe that (i) N is a non-conventional CYP51 substrate, preferred in TB and perhaps other Trypanosomatidae and (ii) functional similarity of TC CYP51 to animal/fungal orthologues is a result of evolutionary convergence (including F105I mutation), leading to different pathways for sterol production in TC versus TB.
TL;DR: Stereoselective synthesis of the potentially biologically valuable 5beta-lanosteroidal-type backbone was achieved via anionic cycloaddition and the two new bicyclic Nazarov intermediates 14 and 40 could lead to the total synthesis of new lanosterol-based inhibitors.
Abstract: Stereoselective synthesis of the potentially biologically valuable 5β-lanosteroidal-type backbone was achieved via anionic cycloaddition. Synthesis of the two new bicyclic Nazarov intermediates 14 and 40 and their cycloaddition with chiral cyclohexenone 25 and further functional group manipulations resulted in highly functionalized tetracyclic intermediates 28 and 44. These synthetic intermediates could lead to the total synthesis of new lanosterol-based inhibitors.
TL;DR: A CYP51 is cloned and characterized from MAC that functions as a lanosterol 14alpha-demethylase, and the direct interactions of azoles with purified MAC-CYP51 are shown by absorbance and electron paramagnetic resonance spectroscopy.
Abstract: Mycobacterium avium complex (MAC) causes chronic lung disease in immunocompetent people and disseminated infection in patients with AIDS. MAC is intrinsically resistant to many conventional antimycobacterial agents, it develops drug resistance rapidly to macrolide antibiotics, and patients with MAC infection experience frequent relapses or the inability to completely eradicate the infection with current treatment. Treatment regimens are prolonged and complicated by drug toxicity or intolerances. We sought to identify biochemical pathways in MAC that can serve as targets for novel antimycobacterial treatment. The cytochrome P450 enzyme, CYP51, catalyzes an essential early step in sterol metabolism, removing a methyl group from lanosterol in animals and fungi, or from obtusifoliol in plants. Azoles inhibit CYP51 function, leading to an accumulation of methylated sterol precursors. This perturbation of normal sterol metabolism compromises cell membrane integrity, resulting in growth inhibition or cell death. We have cloned and characterized a CYP51 from MAC that functions as a lanosterol 14α-demethylase. We show the direct interactions of azoles with purified MAC-CYP51 by absorbance and electron paramagnetic resonance spectroscopy, and determine the minimum inhibitory concentrations (MICs) of econazole, ketoconazole, itraconazole, fluconazole, and voriconazole against MAC. Furthermore, we demonstrate that econazole has a MIC of 4 μg/ml and a minimum bacteriocidal concentration of 4 μg/ml, whereas ketoconazole has a MIC of 8 μg/ml and a minimum bacteriocidal concentration of 16 μg/ml. Itraconazole, voriconazole, and fluconazole did not inhibit MAC growth to any significant extent.
TL;DR: The formation of the 24-methyl sterols seems to be catalyzed by the direct methylation of a common Delta24-acceptor sterol thereby bypassing the intermediacy of an isomerization step for rearrangement of the Delta24(28)-bond to Delta25(25)-position as operates in Ascomycetes fungi and all plants.
TL;DR: Immunochemistry analysis shows that leydig cells express the highest level of the CYP51 protein in testis, which indicates a stage- and cell type-specific expression of CYP 51 protein in bovine oogenesis.
Abstract: Meiosis activating sterol (MAS), the intermediate of cholesterol biosynthesis, is an important substance to stimulate oocytes maturation in FSH-induced signal transduction pathway. Lanosterol 14α-demethylase (CYP51) converts lanosterol to MAS. Although MAS is firstly isolated from bovine testis, the information about bovine CYP51 gene and its expression is little. In present studies, the cDNA cloning, genomic structure, chromosomal mapping, and expression patterns of bovine CYP51 were demonstrated. The cDNA coding bovine CYP51 contains a 1509 bp open reading frame and a 1119 bp 3′ untranslated region. And the bovine CYP51 genen includes 10 exons and spans about 17 kb. Screening the cattle RH5000 panel bovine CYP51 is mapped to chromosome 4 (0cR). The sequenced promoter region is TATA-less and contains several highly conserved regulatory elements, such as GC-box, cAMP-responsive elements (CRE), sterol regulatory element (SRE) which is important fragment for its transcription. No evidence of processed pseudogenes is found using long PCR and Southern blot. Northern blot analysis reveals that an approximately 2.7 kb mRNA is expressed in all the examined bovine tissues, while a 1.8 kb mRNA is found only in the mature bovine testis where the MAS is accumulated. Immunochemistry analysis shows that leydig cells express the highest level of the CYP51 protein in testis. Among different stages follicles it is localized primarily to the oocytes with the level varying slightly. Granulosa cells of primordial, primary and secondary follicles show background staining. While granulosa cells facing the antrum and cumulus granulosa cells of antral follicles show considerably heavier staining. The highest level is expressed in corpus lutea. These data indicate a stage- and cell type-specific expression of CYP51 protein in bovine oogenesis.
TL;DR: It was revealed that thermodynamic parameters were found to have overall significant correlationship with anti fungal activity and these studies provide an insight to design new molecules.
Abstract: A quantitative structure activity relationship, Hansch approach was applied on twenty compounds of chromene derivatives as Lanosterol 14α-demethylase inhibitory activity against eight fungal organisms. Various physicochemical descriptors and reported minimum inhibitory concentration values of different fungal organisms were used as independent variables and dependent variable respectively. The best models for eight different fungal organisms were first validated by leave-one-out cross validation procedure. It was revealed that thermodynamic parameters were found to have overall significant correlationship with anti fungal activity and these studies provide an insight to design new molecules.
Patent•
10 Sep 2006
TL;DR: In this article, an improved method for producing sterols - lanosterol and cholesterol from wooly fat that can be used in preparing medicinal and cosmetic preparations is carried out by alkaline hydrolysis of raw, extraction of unsaponifiable substances, removal of solvent and successive isolation of lanosterols and cholesterol.
Abstract: FIELD: medicinal industry, sterols. ^ SUBSTANCE: invention relates, in particular, to the improved method for producing sterols - lanosterol and cholesterol from wooly fat that can be used in preparing medicinal and cosmetic preparations. Method is carried out by alkaline hydrolysis of raw, extraction of unsaponifiable substances, removal of solvent and successive isolation of lanosterol and cholesterol. Alkaline hydrolysis of raw is carried out with a mixture of ethanol, sodium hydroxide, pyrogallol and water at temperature 70°C for 4 h at stirring in the following ratio of components: raw : ethanol : sodium hydroxide : pyrogallol : water = 100.0:(300.0-350.0):(30.0-35.0):(0.01-0.05):(7.5-12.0), respectively, with the indicated mixture with addition of toluene in the following ratio: raw : ethanol : sodium hydroxide : pyrogallol : toluene : water = 100.0:(220.0-255.0):(30.0-38.0):(0.05-0.12):(100.0-137.0):(2.5-7.0), respectively, and lanosterol is isolated by precipitation from mixture of methylene chloride and ethanol in the ratio = 1:1. Before removal of solvent unsaponifiable substances are extracted at temperature 50°C for 2-3 h at stirring. Invention provides increasing yield of the end product, enhancing qualitative indices and reducing cost of production. ^ EFFECT: improved producing method. ^ 2 cl, 3 ex
TL;DR: In this paper, the Hartree-Fock scheme was used to determine the importance of the 14α-demethylation of biosynthetic reactions by lanosta-8,24-dien-3β-ol (lanosterol), and the theoretical data were analyzed and the presence of HOMO on the region C8C9 and C14C141, a negative charge on the outgoing methyl C141.
Abstract: The 14α-demethylation of biosynthetic reactions is carried out exclusively by lanosta-8,24-dien-3β-ol (lanosterol). Theoretical calculations were done to determine the importance of this structure with the Hartree–Fock scheme. It was modeled on structures similar to lanosterol with variations on the endo between C8C9 (lanosta-7,24-dien-3β-ol and lanosta-6,24-dien-3β-ol) as compared with the exo between C24C25 (Lanosta-8-en-3β-ol) and the size of the side chain (27-norlanosta-8-en-3β-ol, 26,27-dinorlanosta-8-en-3β-ol, 25,26,27-trinorlanosta-8-en-3β-ol, 24,25,26,27-tetranorlanosta-8-en-3β-ol, 23,24,25,26,27-pentanorlanosta-8-en-3β-ol, 22,23,24,25,26,27-hexanorlanosta-8-en-3β-ol). Energetic, electronic, and orbital evidence was found. The theoretical data were analyzed and were found to be important for the 14α-demethylation, the presence of HOMO on the region C8C9 and C14C141, a negative charge on the outgoing methyl C141. This atomic charge varies with the size of the side chain, and with the modification of the endo and exo double bonds. The conformation of the structure of the steroid is also related to its reactivity. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
DOI•
01 Jan 2006
TL;DR: The results obtained imply that Diels–Alder Reactions can be tuned towards either a positive or a negative response depending on the underlying substance, such as adrenaline or carbon dioxide.
Abstract: ........................................................................................................................1 Chapter 1: Introduction ..............................................................................................3 1.1 Computational methods .......................................................................................7 Chapter 2: Stereoselectivity and Regioselectivity of Diels–Alder Reactions........11 2.
Journal Article•
TL;DR: Novel tetralin compounds were designed and synthesized on the three-dimensional model of lanosterol 14α-demethylase of Candida albicans and exhibited potent antifungal activities, especially compounds 16, 20.