Microbial C-hydroxylation and β-4-O-methylglucosidation of methyl-benzamide 7-azanorbornane ethers with Beauveria bassiana

N-Substituted 7-azanorbornanes were prepared by acylation of easily accessible 7-azanorbornane hydrochloride. Derivatives possessing an electron-withdrawing docking/protecting group and bearing an aryl methylether were subjected to biotransformation with the fungus Beauveria bassiana ATCC 7159. O-Demethylation and β-4-O-methylglucosidation reactions were observed for the major metabolite in this biotransformation (isolation yields: 6, 30%; 11a, 44%; 11b, 47%; 11c, 14%). C-Hydroxylation on an unfunctionalized carbon was also observed in most of the cases.     

Biotransformation of p-, m-, and o-hydroxybenzoic acids by Panax ginseng hairy root cultures

The regioselective glycosylation of three isomers of hydroxybenzoic acids was observed in Panax ginseng hairy root cultures. p-Hydroxybenzoic acid (1) and m-hydroxybenzoic acid (2) were converted into their corresponding glycosides (1a and 2a) and glycosyl esters (1b and 2b) while no metabolite of o-hydroxybenzoic acid (3) was detected. A new compound, m-hydroxybenzoic acid β-d-xylopyranosyl (1 → 6)-β-d-glycopyranosyl ester (2c) was identified as a biotransformation product of 2. Further time-course studies of the biotransformation reactions showed that the glycosides were major products in the latter stage. The addition of carbohydrates or antioxidants increased glycosyl esters formation.     

Synthesis of Pyrrolo[2′,3′:4,5]Furo[3,2-c]Pyridine-2-Carboxylic Acids

1H-Pyrrolo[2′,3′:4,5]furo[3,2-c]pyridine-2-carboxylic acid (6a) and its 1-methyl (6b) and 1-benzyl (6c) derivatives were synthesized. 3-(5-Methoxycarbonyl-4H-furo[3,2-b]-pyrrole-2-yl)propenoic acid (1) was converted to the corresponding azide 2, which in turn was cyclized to give 3 by heating in diphenylether. The pyridone 3 obtained was aromatized with phosphorus oxychloride, then reduced with zinc in acetic acid to give methyl 1H-pyrrolo[2′,3′:4,5]furo[3,2-c]pyridine-2-carboxylate (5), which by hydrolysis gave the corresponding carboxylic acid 6a.     

Oxidation of 1,4-alkanediols into γ-lactones via γ-lactols using Rhodococcus erythropolis as biocatalyst

Whole cells of Rhodococcus erythropolis DSM 44534 grown on ethanol, (R)- and (S)-1,2-propanediol were used for biotransformation of racemic 1,4-alkanediols into γ-lactones. The cells oxidized 1,4-decanediol (1a) and 1,4-nonanediol (2a) into the corresponding γ-lactones 5-hexyl-dihydro-2(3H)-furanone (γ-decalactone, 1c) and 5-pentyl-dihydro-2(3H)-furanone (γ-nonalactone, 2c), respectively, with an EE(R) of 40–75%. The transient formation of the γ-lactols 5-hexyl-tetrahydro-2-furanol (γ-decalactol, 1b) and 5-pentyl-tetrahydro-2-furanol (γ-nonalactol, 2b) as intermediates was observed by GC–MS. 1,4-Pentanediol (3a) was transformed into 5-methyl-dihydro-2(3H)-furanone (γ-valerolactone, 3c) whereas (R)- and (S)-2-methyl-1,4-butanediol (4a) was converted to the methyl-substituted γ-butyrolactones 4-methyl-dihydro-2(3H)-furanone (4c₁) and 3-methyl-dihydro-2(3H)-furanone (4c₂) in a ratio of 80:20 with a yield of 55%. Also cis-2-buten-1,4-diol (5a) was transformed resulting in the formation of 2(5H)-furanone (γ-crotonolactone, 5c). At the higher pH values of 8.8 the yield of lactone formed was improved; however, the enatiomeric excesses were slightly higher at the lower pH of 5.2.     

Asymmetric synthesis and biological evaluation of Danshensu derivatives as anti-myocardial ischemia drug candidates

The synthesis and bioactivities of Danshensu derivatives (R)-methyl 2-acetoxy-3-(3,4-diacetoxyphenyl)propanoate (1a), (R)-methyl 2-acetoxy-3-(3,4-methylenedioxyphenyl)propanoate (1b) and their racemates 7 and 10 were reported in this paper. These derivatives were designed to improve their chemical stability and liposolubility by protecting Danshensu’s phenolic hydroxyl groups with acetyl or methylene which could be readily hydrolyzed to release bioactive Danshensu. The asymmetric synthesis of 1a and 1b were achieved by catalytic hydrogenation of (Z)-methyl 2-acetoxy-3-(3,4-diacetoxyphenyl)-2-propenoate (6a) and (Z)-methyl 2-acetoxy-3-(3,4-methylenedioxyphenyl)-2-propenoate (6b) in excellent enantiomeric excesses (92% ee and 98% ee, respectively) and good yields (>89%). An unexpected intermediate product, (Z)-2-acetoxy-3-(3,4-dihydroxyphenyl)acrylic acid (4c) was obtained with high chemoselectivity in 86% yield by keeping the reaction temperature at 60 °C and its structure was identified by X-ray single crystal diffraction analysis. 1a, 1b and their racemates 7, 10 as well as 4c exhibited potent protective activities against hypoxia-induced cellular damage. The in vitro test showed that all these compounds could increase cell viability, and inhibit lipid hyperoxidation. Furthermore, 1a and 4c could inhibit apoptosis by regulating the expression of apoptosis-related molecule in gene and protein levels, up-regulating the expression of bcl-2 and down-regulating bax and caspase-3. The in vivo test indicated that 4c exhibited anti-myocardial ischemic effects featured by reducing infarction size and increasing the level of the intracellular enzymes detectable in serum. Therefore, these Danshensu derivatives may be good drug candidates for anti-myocardial ischemia therapy and merit further investigation.     

Synthesis and evaluation of triazole linked glycosylated 18β-glycyrrhetinic acid derivatives as anticancer agents

A series of glycosyl triazol linked 18β-glycyrrhetinic acid (GA) derivatives have been synthesized using 1,3-dipolar cycloaddition reaction of per-O-acetylated glycosyl azide derivatives (4a–h) with propargyl ester of 18β-glycyrrhetinic acid (GA) (2 and 3) following the concept of ‘Click chemistry’. The synthesized triazole derivatives were de-O-acetylated to furnish compounds (7a–h and 8a–c) with free hydroxyl groups in the carbohydrate moieties, which were evaluated for their anticancer potential against human cervical cancer cells (HeLa) and normal kidney epithelial (NKE) cells. GA (1), compound 7d, compound 7g and compound 8c showed promising anticancer activities.     

Methylation of the ß-positions of the furan ring in F-acids

Major incubation products in feeding experiments with the sodium salt of 7-(5-butyl-furan-2-yl)heptanoic acid (3) on suspension cultures of Saccharum spec. are the unusual F-acids (4a) and (4b). They possess in contrast to natural monomethyl substituted F-acids a methyl substituent in the 4-position of the furan ring. Unexpectedly, the dimethyl substituted F-acids (4c) and (4d) were found only in very small amounts. The detection and structure elucidation of the methylation products (4a)–(4d) was achieved predominantly by GC-MS analysis of the corresponding tetrahydrofuran derivatives (5a)–(5d).     

Novel biotransformation processes of dihydroartemisinic acid and artemisinic acid to their hydroxylated derivatives by two plant cell culture systems

Novel biotransformation processes of dihydroartemisinic acid (1) and artemisinic acid (2) to their hydroxylated derivatives were investigated using the cell suspension cultures of Catharanthus roseus and Panax quinquefolium crown galls as two biocatalyst systems. Five biotransformation products, 3-α-hydroxydihydroartemisinic acid (3), 3-β-hydroxydihydroartemisinic acid (4), 15-hydroxy-cadin-4-en-12-oic acid (5), 3-α-hydroxyartemisinic acid (6) and 3-β-hydroxyartemisinic acid (7), were isolated by chromatograph methods and identified by the analysis of ¹H NMR, ¹³C NMR, and ESI-MS spectra. Compounds 3–5 were obtained for the first time by biotransformation process. It was also the first time to transform artemisinic acid to yield epimeric 3-hydroxy artemisinic acids in plant cell culture system. The biocatalyst system of C. roseus cell cultures showed a great capacity of regio- and stereo-selective hydroxylation in allyl group of the exogenous substrates. The results also showed that the biocatalyst system of P. quinquefolium crown galls possessed the ability to hydroxylate propenyl group of exogenous substrates in a regio- and substrate-selective manner. Furthermore, the in vitro antitumor activity of the hydroxyl products was evaluated by MTT assay. The result indicated that α-hydroxyl products possessed stronger antitumor activity than β-hydroxyl products against the HepG2 and GLC-82 cell lines.     

Dinitroglyceryl and diazen-1-ium-1,2-diolated nitric oxide donor ester prodrugs of aspirin,indomethacin and ibuprofen: Synthesis,biological evaluation and nitric oxide release studies

A new group of hybrid nitric oxide (NO) releasing anti-inflammatory (AI) ester prodrugs (NONO-NSAIDs) wherein a 1,3-dinitrooxy-2-propyl (12a–c), or O²-acetoxymethyl-1-[2-(methyl)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate (14a–c), NO-donor moiety is directly attached to the carboxylic acid group of aspirin, indomethacin or ibuprofen were synthesized. NO release from the dinitrooxypropyl, or diazen-1-ium-1,2-diolate, ester prodrugs was increased substantially upon incubation in the presence of l-cysteine (12a–c) or rat serum (14a–c). The ester prodrugs (12a–c, 14a–c), which did not inhibit the COX-1 isozyme, exhibited modest inhibitory activity against the COX-2 isozyme. The NONO-NSAIDs 12a–c and 14a–c exhibited in vivo AI activity that was similar to that exhibited by the parent drug aspirin, indomethacin or ibuprofen when the same oral dose (μmol/kg) was administered. These similarities in oral potency profiles suggest these NONO-NSAIDs act as classical prodrugs that require metabolic activation by esterase-mediated hydrolysis. Hybrid NO-donor/anti-inflammatory prodrugs of this type (NONO-NSAIDs) offer a potential drug design concept targeted toward the development of anti-inflammatory drugs with reduced adverse gastrointestinal effects.     

Microbial transformation of glycyrrhetinic acid derivatives by Bacillus subtilis ATCC 6633 and Bacillus megaterium CGMCC 1.1741

Glycyrrhetinic acid (GA), the major bioactive pentacyclic triterpene aglycone of licorice root, was known to play a vital role in anti-ulcer, anti-depressant, anti-inflammatory, and anti-allergic. In this study, we semi-synthesized five GA derivatives by a series of chemical reactions. They were selected as substrates for the biotransformation and yielded thirteen metabolites by Bacillus subtilis ATCC 6633 and Bacillus megaterium CGMCC 1.1741. Their structures were identified on the basis of extensive spectroscopic methods and nine of them were found for the first time. Two main types of reactions, regio- and stereo-selective hydroxylation and glycosylation, especially in the unactivated C-H bonds including C-11, C-19 and C-27, were observed in the biotransformation process, which greatly expand the chemical diversities of GA derivatives. All compounds were tested for their inhibitory effects on nitric oxide (NO) generation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Among them, olean-12-ene-3β,7β,15α,19α,30-pentol (16) and olean-12-ene-3β,7β,15α,27,30-pentol (17) showed significant inhibitory effect with IC₅₀ values of 0.64 and 0.07 μM, respectively.     

Lactones 26 : Stereoselective microbial epoxidation of unsaturated bicyclic γ-lactones with the alkylsubstituted cyclohexane system

The strain Absidia cylindrospora was chosen among eight fungal strains for the biotransformation of unsaturated lactones 1a–c. The processes were carried out by means of shaken cultures. The compounds 1a and 1b were efficiently converted into the corresponding trans-epoxylactones (2a and 2b), whereas the transformation of 1c gave the unsaturated hydroxylactone 3, with the tertiary hydroxy group introduced in the allylic position. The compound 2b was obtained with 100% ee. The structures of compounds 2a and 2b were fully confirmed by the X-ray analysis, which showed the half boat and half chair conformation of cyclohexane ring in these molecules, respectively. All the products were not reported previously in the literature.     

Antioxidant,anti-tyrosinase and anti-melanogenic effects of (E)-2,3-diphenylacrylic acid derivatives

During our continued search for strong skin whitening agents over the past ten years, we have investigated the efficacies of many tyrosinase inhibitors containing a common (E)-β-phenyl-α,β-unsaturated carbonyl scaffold, which we found to be essential for the effective inhibition of mushroom and mammalian tyrosinases. In this study, we explored the tyrosinase inhibitory effects of 2,3-diphenylacrylic acid (2,3-DPA) derivatives, which also possess the (E)-β-phenyl-α,β-unsaturated carbonyl motif. We synthesized fourteen (E)-2,3-DPA derivatives 1a–1n and one (Z)-2,3-DPA-derivative 1l′ using a Perkin reaction with phenylacetic acid and appropriate substituted benzaldehydes. In our mushroom tyrosinase assay, 1c showed higher tyrosinase inhibitory activity (76.43 ± 3.53%, IC₅₀ = 20.04 ± 1.91 µM) with than the other 2,3-DPA derivatives or kojic acid (21.56 ± 2.93%, IC₅₀ = 30.64 ± 1.27 μM). Our mushroom tyrosinase inhibitory results were supported by our docking study, which showed compound 1c (−7.2 kcal/mole) exhibited stronger binding affinity for mushroom tyrosinase than kojic acid (−5.7 kcal/mole). In B16F10 melanoma cells (a murine cell-line), 1c showed no cytotoxic effect up to a concentration of 25 μM and exhibited greater tyrosinase inhibitory activity (68.83%) than kojic acid (49.39%). In these cells, arbutin (a well-known tyrosinase inhibitor used as the positive control) only inhibited tyrosinase by 42.67% even at a concentration of 400 μM. Furthermore, at 25 µM, 1c reduced melanin contents in B16F10 melanoma cells by 24.3% more than kojic acid (62.77% vs. 38.52%). These results indicate 1c is a promising candidate treatment for pigmentation-related diseases and potential skin whitening agents.     

Synthesis and antiproliferative evaluation of certain indolo[3,2-c]quinoline derivatives

The present report describes the synthesis and antiproliferative evaluation of certain indolo[3,2-c]quinoline derivatives. For the C₆ anilino-substituted derivatives, (11H-indolo[3,2-c]quinolin-6-yl)phenylamine (6a) was inactive. Structural optimization of 6a by the introduction of a hydroxyl group at the anilino-moiety resulted in the enhancement of antiproliferative activity in which the activity decreased in an order of para-OH, 7a > meta-OH, 8a > ortho-OH, 9a. For the C₆ alkylamino-substituted derivatives, 11a, 12a, 13a, 14a, and 15a exhibited comparable antiproliferative activities against all cancer cells tested and the skin Detroit 551 normal fibroblast cells. Three cancer cells, HeLa, A549, and SKHep, are very susceptible with IC₅₀ of less than 2.17 μM while PC-3 is relatively resistant to this group of indolo[3,2-c]quinolines. For the 2-phenylethylamino derivatives, compound 20a is active against the growth of HeLa with an IC₅₀ of 0.52 μM, but is less effective against the growth of Detroit 551 with an IC₅₀ of 19.32 μM. For the bis-indolo[3,2-c]quinolines, N,N-bis-[3-(11H-indolo[3,2-c]quinolin-6-yl)aminopropyl]amine hydrochloride (25) is more active than its N-methyl derivative 26 and the positive Doxorubicin. Mechanism studies indicated 25 can induce caspase-3 activation, γ-H2AX phosphorylation, cleavage of poly(ADP-ribose)polymerase and DNA fragmentation. These results provide evidence that DNA, topo I, and topo II are the primary targets of indolo[3,2-c]quinoline derivatives and that consequently inhibits proliferation and causes apoptosis in cancer cells.     

Synthesis and anti-Candidal activity of N-(4-aryl/cyclohexyl)-2-(pyridine-4-yl carbonyl) hydrazinecarbothioamide

Eighteen N-(4-aryl/cyclohexyl)-2-(pyridine-4-yl carbonyl) hydrazinecarbothioamide derivatives were synthesized, evaluated against ten clinical isolates of Candida spp. and compared with itraconazole. Introduction of p-chloro (2c), p-iodo (2q), m-chloro (2l) and o-nitro (2r) substitution at phenyl ring of thiosemicarbazide enhanced the anti-Candida activity. Compound (2c) bearing p-cholorophenyl ring was found to be the most effective against Candida albicans ATCC 66027, Candida spp. 12810 (blood) and Candida spp. 178 (HVS) with MIC value of 0.09–0.78 μg/mL, whereas itraconazole exhibits the inhibitory activity with MIC value of 0.04–1.56 μg/mL against all tested strains. There is a correlation between anti-Candidal activity and p-chloro substitution at phenyl ring of thiosemicarbazide. All synthesized compounds were investigated for their potential cytotoxicity against non cancer cell line MCF-10A. The active compounds 2c, 2r and 2a were further investigated for their cytotoxic effects on three cancer cell lines; HT1080 (skin), HepG2 (liver) and A549 (lung). The active compounds showed minimal cytotoxic activity against non cancer cell line and all three cancer cell lines. Moreover, compound 2c displaying better activity against C. albicans ATCC66027 and Candida spp. [blood] compared to reference drug (itraconazole), represents a good lead for the development of newer, potent and broad spectrum anti-Candidal agents.     

Dopamine release and molecular modeling study of some coumarin derivatives

4-aryl-2-amino-6-(4-hydroxy-2-oxo-2H-chromen-3-yl)-pyridin-3-carbonitrile (1), 4-aryl-2-oxo-6-(4-hydroxy-2-oxo-2H-chromen-3-yl)-pyridin-3-carbonitriles (2a-2c), 3-(6-aryl-1,2,5,6- tetrahydro-2-thioxopyrimidin-4-yl)-4-hydroxy-2H-chromen-2-one (3a, 3b) and pyrazol-3-yl-4-hydroxycoumarin derivatives (4a-4c, 5, 6a, 6b, 7a, 7b, and 8a-8c) were prepared in order to measure their % change dopamine release in comparison to amphetamine as reference, using PC-12 cells in different concentrations. In addition, the molecular modeling study of the compounds into 3BHH receptor was also demonstrated. The calculated inhibition constant (k_i) implemented in the AutoDock program revealed identical correlation with the experimental results to that obtained binding free energy (ΔG_b) as both parameters revealed reasonable correlation coefficients (R²) being 0.51 involving 10 compounds; (1, 2b, 2c, 3a, 3b, 4a, 4b, 6a, and 8c).     

Synthesis of new 1-(4-methane(amino)sulfonylphenyl)-5-(4-substituted-aminomethylphenyl)-3-trifluoromethyl-1H-pyrazoles: A search for novel nitric oxide donor anti-inflammatory agents

A group of 1-(4-methane(amino)sulfonylphenyl)-5-(4-substituted-aminomethylphenyl)-3-trifluoromethyl-1H-pyrazoles (12a–f) was synthesized and evaluated as anti-inflammatory agents. While all the compounds (20 mg/kg) showed significant anti-inflammatory activity after 3 h of inflammation induction (69–89%) as compared to celecoxib (80%), 1-(4-methanesulfonylphenyl)-5-(4-methylaminomethylphenyl)-3-trifluoromethyl-1H-pyrazole (12a) was found to be the most effective one (89%). The synthesis of model hybrid nitric oxide donor N-diazen-1-ium-1,2-diolate derivatives of 1-(4-methanesulfonylphenyl)-5-(4-substituted-aminomethylphenyl)-3-trifluoromethyl-1H-pyrazoles (10a–f) requires further investigation since the reaction of N-(4-(1-(4-(methylsulfonyl)phenyl)-3-(trifluoromethyl)-1H-pyrazol-5-yl)benzyl)ethanamine (12b) or 1-(4-(1-(4-(methylsulfonyl)phenyl)-3-(trifluoromethyl)-1H-pyrazol-5-yl)benzyl)piperazine (12c) with nitric oxide furnished N-nitroso derivatives (13 and 14), respectively, rather than the desired N-diazen-1-ium-1,2-diolate derivatives (10b and 10c).     

Novel benzyl-substituted molybdocene anticancer drugs

From the reaction of 6-(p-methoxyphenyl) fulvene (1a), 6-(3,4-dimethoxyphenyl) fulvene (1b) and 6-(3,4,5-trimethoxyphenyl) fulvene (1c) with LiBEt₃H, lithiated cyclopentadienide intermediates (2a-c) were synthesised. These intermediates were then transmetallated to molybdocene using MoCl₄ (synthesized in situ) to yield the benzyl-substituted molybdocenes bis-[(p-methoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3a), bis-[(3,4-dimethoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3b), and bis-[(3,4,5-trimethoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3c). The molybdocene 3a was characterised by single crystal X-ray diffraction. All three molybdocenes had their cytotoxicity investigated through MTT based preliminary in vitro testing on the human renal cell line Caki-1 in order to determine their IC50 values and compare them with the corresponding titanocene and vanadocene dichloride derivatives. Molybdocenes 3b-c were found to have the same IC50 values of 290 μM, while 3a yielded a value of 84 μM, respectively     

2-(1-(Dimethylamino)ethyl)phenylpalladium(II) complexes 5-functionalized with fluorous silyl tails

New fluorous-organometallics based on the chiral ligand α-methyl-N,N-dimethylbenzylamine (TMBA) were prepared by treatment of fluorous silyl bromide reagents with in situ 4-lithiated TMBA to give fluorous N,N-dimethyl(α-methyl-4-trialkylsilylbenzyl)amine ligands 1a-1c that vary in the number of fluorous tails attached to the Si atom. Ligands 1a-1c were successfully cyclo-palladated by treatment with Pd(OAc)₂/LiCl in methanol to furnish the corresponding chloride-bridged dimeric arylpalladium(II) complexes 2a-2c in good yields. The latter derivatives could be converted into monomeric Lewis-base adducts by complexation with pyridine (3a-3c), or triphenylphosphine (4a-4c). The crystal structure of triphenylphosphine complex 4a has been elucidated. To probe their fluorophilicity, the partition coefficient of each of the derivatives in the fluorous biphasic solvent (FBS) system perfluoromethylcyclohexane/n-octane has been determined.     

α-Glucosidase-inhibitory iminosugars from the leaves of Suregada glomerulata

A water extract of the leaves of Suregada glomerulata (Euphorbiaceae) was found to inhibit rat small intestinal α-glucosidase. An examination of the extract afforded 20 iminosugars including one pyrrolidine and 19 piperidines. The structures of the 10 new compounds (11–20) were determined by NMR, and MS spectroscopic data analyses, and chemical correlations. The novelty of the identified compounds mainly stems from the loss of a hydroxy at C-4 and the presence of an 8-hydroxyoctyl side chain. Nine N-alkyl derivatives including N-methyl (1a, 8a, and 13a), N-butyl (1b, 2b, and 9b) and N,N-dimethyl (1c, 2c, and 9c) were synthesized. The compounds were tested for rat small intestinal α-glucosidase inhibitory activity. In total, 15 compounds, including compounds 11, 12, 15, and 19 and the three derivatives 8a, 9b, and 13a, showed inhibitory activity with IC₅₀ values less than 40 μM. In vivo results showed that total alkaloids of S. glomerulata (10 mg/kg) and four major iminosugars 1, 2, 3, and 9 (10 mg/kg) can lower the postprandial blood glucose level after sucrose and starch load in healthy male ICR mice.