A simple and effective preparation of quercetin pentamethyl ether from quercetin

Among the five hydroxy (OH) groups of quercetin (3,5,7,3',4'-pentahydroxyflavone), the OH group at 5 position is the most resistant to methylation due to its strong intramolecular hydrogen bonding with the carbonyl group at 4 position. Thus, it is generally difficult to synthesize the pentamethyl ether efficiently by conventional methylation. Here, we describe a simple and effective per-O-methylation of quercetin with dimethyl sulfate in potassium (or sodium) hydroxide/dimethyl sulfoxide at room temperature for about 2 hours, affording quercetin pentamethyl ether (QPE) quantitatively as a single product. When methyl iodide was used in place of dimethyl sulfate, the C-methylation product 6-methylquercetin pentamethyl ether was also formed. A computational study provided a rationale for the experimental results.

Structural basis of arginine asymmetrical dimethylation by PRMT6

PRMT6 is a type I protein arginine methyltransferase, generating the asymmetric dimethylarginine mark on proteins such as histone H3R2. Asymmetric dimethylation of histone H3R2 by PRMT6 acts as a repressive mark that antagonizes trimethylation of H3 lysine 4 by the MLL histone H3K4 methyltransferase. PRMT6 is overexpressed in several cancer types, including prostate, bladder and lung cancers; therefore, it is of great interest to develop potent and selective inhibitors for PRMT6. Here, we report the synthesis of a potent bisubstrate inhibitor GMS [6′-methyleneamine sinefungin, an analog of sinefungin (SNF)], and the crystal structures of human PRMT6 in complex, respectively, with S-adenosyl-L-homocysteine (SAH) and the bisubstrate inhibitor GMS that shed light on the significantly improved inhibition effect of GMS on methylation activity of PRMT6 compared with SAH and an S-adenosyl-L-methionine competitive methyltransferase inhibitor SNF. In addition, we also crystallized PRMT6 in complex with SAH and a short arginine-containing peptide. Based on the structural information here and available in the PDB database, we proposed a mechanism that can rationalize the distinctive arginine methylation product specificity of different types of arginine methyltransferases and pinpoint the structural determinant of such a specificity.

Synthesis and Heme Polymerization Inhibitory Activity (HPIA) Assay of Antiplasmodium of (1)-N-(3,4-Dimethoxybenzyl)-1,10-Phenanthrolinium Bromide from Vanillin

The synthesis of (1)-N-(3,4-dimethoxy-benzyl)-1,10-phenanthrolinium bromide had been conducted from vanillin. Heme polymerization inhibitory activity assay of the synthesized antiplasmodium has also been carried out. The first step of reaction was methylation of vanillin using dimethylsulfate and NaOH. The mixture was refluxed for 2 h to yield veratraldehyde in the form of light yellow solid (79% yield). Methylation product was reduced using sodium borohydride (NaBH4) with grinding method and yielded veratryl alcohol in the form of yellow liquid (98% yield). Veratryl alcohol was brominated using PBr3 to yield yellowish black liquid (85% yield). The final step was benzylation of 1,10-phenanthroline monohydrate with the synthesized veratryl bromide under reflux condition in acetone for 14 h to afford (1)-N-(3,4-dimethoxy-benzyl)-1,10-phenanthrolinium bromide (84%) as yellow solid with melting point of 166-177 °C. The structures of products were characterized by FT-IR, GC-MS and 1H-NMR spectrometers. The results of heme polymerization inhibitory activity assay of (1)-N-(3,4-dimethoxybenzyl)-1,10-phenanthrolinium bromide showed that it had IC50 HPIA of 3.63 mM, while chloroquine had IC50 of4.37 mM. These results indicated that (1)-N-(3,4-dimethoxybenzyl)-1,10-phenanthrolinium bromide was more potential antiplasmodium than chloroquine.

SYNTHESIS OF 6-NITRO VERATRYL ALCOHOL AND 6-NITRO VERATRALDOXIM FROM VANILIN AS INTERMEDIATES FOR THE PREPARATION OF C-9154 ANTIBIOTIC DERVATIVES

The synthesis of 6-nitro veratryl alcohol and 6-nitro veratraldoxim from vanilin which was required as intermediates for the preparation of C-9154 antibiotic derivatives was carried out. C-9154 antibiotic is a sufficiently potent antibiotic, but so far this is produced only in low yields through microbiological processes. The reaction steps performed were (1) methylation of vanilin, (2) nitration of the methylation product, (3) reduction of the corresponding nitro compound and (4) reaction of the nitration product with HO-NH2.HCl. Methylation of vanilin was conducted using dimethylsulfate and NaOH at 60 oC for 2 hours. Nitration of the methylation product was performed in 2 methods, i.e. using neat HNO3 and using a mixture of HNO3 and H2SO4 both at 5 oC for 2 hours. Reduction of the nitration product was conducted using NaBH4 either at room temperature and at reflux. Reaction of the nitration product with HO-NH2.HCl was carried out in ethanol 95% at 50 oC for 2 hours. The products were analyzed by means of TLC, GC, IR, 1H NMR and GC-MS spectrometers. The methylation of vanilin gave 87.7% yield of veratraldehyde which was found as a white crystal (m.p 43 oC). The nitration of veratraldehyde produced 6-nitro veratraldehyde observed as a yellow crystal having of m.p. 130 oC. Nitration using neat HNO3 gave a smaller yield (50.35%) of 6-nitro veratraldehyde than nitration with a mixture of HNO3 and H2SO4 (93.63%). Reduction of 6-nitro veratraldehyde using NaBH4 at room temperature and at reflux afforded 6-nitro veratryl alcohol which was found as brown crystal (m.p 123-127 oC) respectively in 13.47% and 56.61%. This reduction also produced 6-amino veratryl alcohol and 3,4-dimethoxy benzoic zcid as by products. 6-Nitro veratraldehyde reacts with HO-NH2.HCl to give 6-nitro veratraldoxim in 48.27% yield. Keywords: antibiotics, veratril alcohol, veratraldoxim vanilin

SINTESIS 6-NITRO VERATRALDEHID (3,4-DIMETOKSI-6-NITRO BENZALDEHID) DARI VANILIN DENGAN HNO3 DAN CAMPURAN HNO3-H2SO4

The synthesis of 6-nitro veratraldehyde from vanillin was used HNO3 and a mixture of HNO3 and H2SO4. The reaction steps were (I) methylation of vanillin and (2) nitration of the methylation product. Methylation of vanillin was conducted using dimetnylsulfate and NaOH at 60 0C for 2 hours. Nitration of the methylation product was performed in two methods, which using HN03 and using a mixture of HN03 and H2SO4 both at 5 0C for 2 hours. The products were analyzed by means of TLC, GC; IR, 1H-NMR and GC-MS spectrometers.The methylation of vanillin gave 87.7 % yield of veratraldehyde which was found as a white crystal (m.p 43 oC). The nitration of veratraldehyde produced 6-nitro veratraldehyde observed as a yellow crystal having of m.p. 1300C. Nitration using neat HNO3 gave a smaller yield (50.35%) of 6-nitro veratraldehyde than nitration with a mixture of HNO3 and H2SO4 (93.63 %).

Gene Encoding the Hydrolase for the Product of the meta-Cleavage Reaction in Testosterone Degradation by Comamonas testosteroni

ABSTRACT In a previous study we isolated the meta-cleavage enzyme gene, tesB, that encodes an enzyme that carries out a meta-cleavage reaction in the breakdown of testosterone by Comamonas testeroni TA441 (M. Horinouchi et al., Microbiology 147:3367-3375, 2001). Here we report the isolation of a gene, tesD, that encodes a hydrolase which acts on the product of the meta-cleavage reaction. We isolated tesD by using a Tn5 mutant of TA441 that showed limited growth on testosterone. TesD exhibited ca. 40% identity in amino acid sequence with BphDs, known hydrolases of biphenyl degradation in Pseudomonas spp. The TesD-disrupted mutant showed limited growth on testosterone, and the culture shows an intense yellow color. High-pressure liquid chromatography analysis of the culture of TesD-disrupted mutant incubated with testosterone detected five major intermediate compounds, one of which, showing yellow color under neutral conditions, was considered to be the product of the meta-cleavage reaction. The methylation product was analyzed and identified as methyl-4,5-9,10-diseco-3-methoxy-5,9,17-trioxoandrosta-1(10),2-dien-4-oate, indicating that the substrate of TesD in testosterone degradation is 4,5-9,10-diseco-3-hydroxy-5,9,17-trioxoandrosta-1(10),2-dien-4-oic acid. 4,5-9,10-Diseco-3-hydroxy-5,9,17-trioxoandrosta-1(10),2-dien-4-oic acid was transformed by Escherichia coli-expressed TesD. Downstream of tesD, we identified tesE, F, and G, which encode for enzymes that degrade one of the products of 4,5-9,10-diseco-3-hydroxy-5,9,17-trioxoandrosta-1(10),2-dien-4-oic acid converted by TesD.

The preparation of some fused isothiazole derivatives

The treatment of di(2-amino-5-methylphenyl)methane with N-sulfinylmethanesulfonamide gives two materials, 3-(2-amino-5-methylphenyl)-5-methyl-2,1-benzisothiazole and what appears to be its tautomer, a 2,1-benzisothiazolo[2,3-b]-2,1-benzisothiazole derivative. Reaction of the former with methyl iodide gives mono-, di-, and trimethyl derivatives. The second of these also possesses the symmetrical 2,1-benzisothiazolo[2,3-b]-2,1-benztsothiazole structure. The structure of the other methylation product and of the acetylation products are discussed. Some 1,2-dithiol-3-ylidene-2-pyridylmethanes were made by condensation of 3-alkylthio-1,2-dithiolium salts with methyl 2-pyridylacetate. These demonstrate little sulphur–nitrogen interaction. 3-Methylthio-4-phenyl-1,2-dithiolium iodide reacts anomalously with methyl 2-pyridylacetate to form a quinolizinethione. 1,2-Benzisothiazolo[2,3-a]pyridintum triiodide was made by iodine oxidation of 2-(2-mercaptophenylpyridine).