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Hypercholesterolemia Is Recognized As a Risk Factor for Atherosclerotic Disease, Such As Coronary Heart Disease. Moderate Exerci VOL. 56 NO. 10, OCT. 2003 THE JOURNAL OF ANTIBIOTICS pp. 817-826 Lanopylins A1, B1, A2 and B2, Novel Lanosterol Synthase Inhibitors from Streptomyces sp. K99-5041 YUICHI SAKANOa, MASAAKI SHIBUYAa, ATSUKO MATSUMOTOb,YOKO TAKAHASHIb, HIROSHI TOMODAb, SATOSHI OMURAb and YUTAKA EBIZUKAa,* a Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan b Kitasato Institute for Life Sciences, Kitasato University, and The Kitasato Institute, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan (Received for publication June 25, 2003) From an actinomycete strain, Streptomyces sp. K99-5041, lanopylins A1, B1, A2 and B2 were isolated as new natural products that inhibited the reaction of recombinant human lanosterol synthase. The crude extract from the whole broth of this strain was fractionated by silica gel column chromatography to afford an active fraction that showed a single spot on TLC. Detailed analyses of this fraction with liquid chromatography-atmospheric pressure chemical ionization mass spectrometry revealed that it contained 20 homologous compounds with differing side chain lengths. The fraction was separated by preparative HPLC to afford four of these homologues, lanopylins A1, B1, A2 and B2. Detailed spectroscopic analyses of these isolated compounds led to the identification of their structures. Lanopylins A1 and B1 were (3E)-isohexadecylmethylidene-2-methyl-1-pyrroline and (3E)-hexadecylmethylidene-2-methyl- 1-pyrroline, respectively, and lanopylins A2 and B2 were homologues with the insertion of one cis-ethylenylidene in the side chain of lanopylins A1 and B1, respectively. These compounds inhibited recombinant human lanosterol synthase with IC50 values of 15, 18, 33, and 41μM, respectively. Hypercholesterolemia is recognized as a risk factor for effects. atherosclerotic disease, such as coronary heart disease. Lanosterol synthase (EC 5.4.99.7) is viewed as more Moderate exercise and/or diets containing low cholesterol selective target for suppression of cholesterol biosynthesis2,3) or which suppress cholesterol biosynthesis may prevent since it is located downstream of HMG-CoA reductase in the development of hypercholesterolemia. 3-Hydroxy-3- the pathway. Reported lanosterol synthase inhibitors are methylglutaryl coenzyme A (HMG-CoA) reductase (EC lauryldimethylamine N-oxide (LDAO)4), 29-methylidene- 1.1.1.34) is a clinically validated target for suppressing 2,3-oxidosqualene (29-MOS)5), BIBX 796), Ro 48-80717), cholesterol biosynthesis. Inhibitors of this enzyme, for BIBB 5158) etc., although no natural compounds have so example, pravastatin and lovastatin, are the first choice far been reported to be lanosterol synthase inhibitors. Using for pharmaceutical treatment of hypercholesterolemia1). But recombinant human enzymes, screening of inhibitors of since HMG-CoA reductase is located upstream in the natural origin has been carried out with fermentation broths cholesterol biosynthetic pathway, inhibition of this enzyme of 1,031 actinomycete strains. Four inhibitors, lanopylin may cause a simultaneous reduction in the physiologically A1, B1, A2 and B2, have been isolated as new natural essential non-sterol isoprenoid metabolites such as products from the actinomycete strain Streptomyces sp. dolichol, ubiquinone, and prenylated proteins. On the other K99-5041 and their structures elucidated using spectroscopic hand, inhibition of the enzymes along the pathway from methods. In this paper, we describe the taxonomy and lanosterol through cholesterol will cause accumulation of fermentation of the producing strain, and isolation, steroidal intermediates or metabolites, with unexpected side biological properties, and structure elucidation of these * Corresponding author:[email protected] 818 THE JOURNAL OF ANTIBIOTICS OCT. 2003 compounds. In Vitro Assay for Human Lanosterol Synthase The details of procedures for the preparation of cell-free extracts from recombinant Saccharomyces cerevisiae Materials and Methods expressing human lanosterol synthase, the preparation of [14C] (3S)-2,3-oxidosqualene and the in vitro assay for General human lanosterol synthase will be described elsewhere. The The actinomycete strain K99-5041 was isolated from a cDNA of human lanosterol synthase16) was expressed in the soil sample. The International Streptomyces Project (ISP) mutant S. cerevisiae GIL77 (gal2 hem3-6 erg7 ura3-167)17), media recommended by SHIRLING and GOTTLIES9), and and the cells from this recombinant yeast were collected media recommended by WAKSMAN10) were used to and homogenized in a Waring blender with acid-washed investigate the cultural and physiological characteristics. glass beads in 0.1M potassium-phosphate buffer (pH Cultures were routinely observed after incubation for two 7.4, containing 0.45M sucrose, 1mM EDTA and 1mM weeks at 27℃. Color names and hue numbers were dithiothreitol). The lysate was centrifuged at 8,600×g for determined according to the Color Harmony Manual11). The 30 minutes and the resultant supernatant was adjusted to utilization of carbon sources was tested by growth on ca. 10mg protein/ml with the same buffer. The amount of PRIDHAMand GOTTLIEB'smedium containing 1% carbon protein was estimated using the Protein Assay (Bio-Rad). at 27℃12). The morphological properties were observed The substrate [14C] (3S)-2,3-oxidosqualene was prepared with a scanning electron microscope (model JSM-5600, by feeding the mutant yeast strain GL7 (MATa gal2 JEOL). The isomers of diaminopimelic acid (DAP) hem3-6 erg7)18)with [1-14C] sodium acetate. The in vitro isomers were determined by the method of BECKER et enzyme reaction was performed as follows: The cell-free al.13). Menaquinones were extracted and purified after extract (1mg protein) was incubated with [14C] (3S)-2,3- COLLINSet al.14) then analyzed by high performance liquid oxidosqualene (0.17nmol, 4.5nCi dissolved in 5μl of 2- chromatography (HPLC) equipped with a CAPCELL PAK methoxyethanol) and testing samples (dissolved in 120μl C18 column (Shiseido)15). of 50% aqueous ethanol) in 1ml of 0.1M potassium NMR spectra were recorded using a JEOL JNM-alpha phosphate buffer (pH 7.4, containing 0.1% Triton X-100) 500 spectrometer. Mass spectrometry analysis utilized a at 37℃ for 1 hour. After incubation, the reaction was JEOL JMS-SX102A spectrometer. UV and IR spectra were stopped by adding 6% KOH/EtOH followed by 10-minute measured with a Hitachi U-2000 spectrophotometer and a incubation at 37℃. After extraction with cyclohexane, Horiba FT-210 infrared spectrometer, respectively. Optical the lipids were concentrated and applied to a TLC plate rotations were obtained with a JASCO P-1010 polarimeter. (Merck), which was developed with benzene-acetone Liquid chromatography-atmospheric pressure chemical (19:1). The resultant TLC plates were exposed to an ionization mass spectrometry (LC-APCIMS) analysis was imaging plate and analyzed with a Photo Image Analyzer carried out using a Thermo Quest LCQ equipped with a BAS-1500 (Fujifilm). Hewlett Packard HP1100 series LC system under the following conditions: column, TSK gel ODS-80TM Results and Discussion (4.6×150mm, Tosoh); eluent, 98% MeOH; flow rate, 0.8ml/minute; and photodiode array detector, APCI Taxonomy of the Producing Organism (positive). The vegetative mycelia grew abundantly on yeast extract- Fermentation Media malt extract agar and oatmeal agar, and did not show The seed medium was composed of starch 2.4%, glucose fragmentation into coccoid forms or bacillary elements. 0.1%, peptone 0.3%, meat extract 0.3%, yeast extract 0.5% The aerial mycelia grew abundantly on yeast extract-malt and CaCO3 0.4% in deionized water (pH 7.0 prior to extract agar. The spore chains were open loops and each sterilization). The production medium was composed of had more than 20 spores per chain. The spores were glucose 0.5%, corn steep powder 1.0%, oatmeal 1.0%, cylindrical in shape, 0.9-1.1×0.6-0.7μm in size and had Pharmamedia 1.0%, K2HPO4 0.1%, MgSO4・7H2O 0.1%, a smooth surface (Fig. 1). Whirls, sclerotic granules, Sekado (Kanto Chemicals, Co. Ltd.) 0.5% and trace sporangia or flagellate spores were not observed. elements (each 0.0001%: FeSO4・7H2O, MnCl2・4H2O, The isomer of DAP in whole-cell hydrolysates of strain ZnSO4・7H2O, CuSO4・5H2O and CoCl2・6H2O) in tap water K99-5041 was determined to be LL-form. Major (pH 7.0 prior to sterilization). menaquinones were MK-9(H6) and MK-9(H8). VOL. 56 NO. 10 THE JOURNAL OF ANTIBIOTICS 819 Table 1. Cultural characteristics of strain K99-5041. a; Medium recommended by ISP b; Medium recommended by S. A. Waksman. Abbreviations: G, growth of vegetative mycelium; R, reverse side color; AM, aerial mycelium; SP, soluble pigment. Fig. 1. Scanning electron micrograph of Table 2. Physiological properties of strain Streptomyices sp. K99-5041. K99-5041. Table 3. Utilization of carbon sources by strain K99-5041. 820 THE JOURNAL OF ANTIBIOTICS OCT. 2003 The cultural characteristics, the physiological properties analyses revealed that they were mixtures because the and the utilization of carbon sources are shown in Tables signals δH 5.35, 2.01 and δC 129.9, 27.2 were observed at 1-3. The color of vegetative mycelia was yellow to decimal intensities (data not shown). brown and the aerial mass was white to gray. Melanoid Next, we performed detailed LC-APCIMS analysis of pigment was not produced but yellowish pigment was fraction N. For example, in the mass spectra of peaks A and produced. B, a signal was observed at m/z 320 (26 mass units smaller Based on the taxonomic properties described above, than the molecular mass m/z 346) and further investigation strain K99-5041 is considered to belong to the genus of the mass chromatograms at m/z 320 and 346 revealed a Streptomyces19). ca. 0.1-minute time lag in the retention time (Fig. 2-(B)). A similar time lag was observed in other HPLC peaks (data not shown). These findings led us to consider that each of Fermentation the above-mentioned ten peaks (from A to J) was composed A slant culture of strain K99-5041 was inoculated into a of two compounds, differing in molecular mass by 26 mass 500-ml Erlenmeyer flask containing 100ml of the seed units, and thus that fraction N contained 20 types of medium.
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