Production of (R)‐1‐phenylethanols through bioreduction of acetophenones by a new fungus isolate Trichothecium roseum

A total of 120 fungal strains were isolated from soil samples and evaluated in the bioreduction of substituted acetophenones to the corresponding (R)‐alcohols. Among these strains, isolate Trichothecium roseum EBK‐18 was highly effective in the production of (R)‐alcohols with excellent enantioselectivity (ee > 99%). Gram scale preparation of (R)‐1‐phenylethanol is reported. Chirality 2010. © 2009 Wiley‐Liss, Inc.     

Ketone bodies and two-compartment tumor metabolism: Stromal ketone production fuels mitochondrial biogenesis in epithelial cancer cells

We have previously suggested that ketone body metabolism is critical for tumor progression and metastasis. Here, using a co-culture system employing human breast cancer cells (MCF7) and hTERT-immortalized fibroblasts, we provide new evidence to directly support this hypothesis. More specifically, we show that the enzymes required for ketone body production are highly upregulated within cancer-associated fibroblasts. This appears to be mechanistically controlled by the stromal expression of caveolin-1 (Cav-1) and/or serum starvation. In addition, treatment with ketone bodies (such as 3-hydroxy-butyrate, and/or butanediol) is sufficient to drive mitochondrial biogenesis in human breast cancer cells. This observation was also validated by unbiased proteomic analysis. Interestingly, an MCT1 inhibitor was sufficient to block the onset of mitochondrial biogenesis in human breast cancer cells, suggesting a possible avenue for anticancer therapy. Finally, using human breast cancer tumor samples, we directly confirmed that the enzymes associated with ketone body production (HMGCS2, HMGCL and BDH1) were preferentially expressed in the tumor stroma. Conversely, enzymes associated with ketone re-utilization (ACAT1) and mitochondrial biogenesis (HSP60) were selectively associated with the epithelial tumor cell compartment. Our current findings are consistent with the “two-compartment tumor metabolism” model. Furthermore, they suggest that we should target ketone body metabolism as a new area for drug discovery, for the prevention and treatment of human cancers.     

Niacin deficiency modulates genes involved in cancer: Are smokers at higher risk?

The role of niacin’s metabolite, nicotinamide adenine dinucleotide (NAD), in DNA repair via base-excision repair pathway is well documented. We evaluated if niacin deficiency results in genetic instability in normal human fetal lung fibroblasts (MRC-5), and further, does it leads to enhanced accumulation of cigarette smoke–induced genetic damage? MRC-5 cells were grown discretely in niacin-proficient/deficient media, and exposed to nicotine-derived nitrosamine ketone (NNK, a cigarette smoke carcinogen). Niacin deficiency abated the NAD polymerization, augmented the spontaneous induction of micronuclei (MN) and chromosomal aberrations (CA) and raised the expression of 10 genes and suppressed 12 genes involved in different biological functions. NNK exposure resulted in genetic damage as measured by the induction of MN and CA in cells grown in niacin-proficient medium, but the damage became practically marked when niacin-deficient cells were exposed to NNK. NNK exposure raised the expression of 16 genes and suppressed the expression of 56 genes in cells grown in niacin-proficient medium. NNK exposure to niacin-deficient cells raised the expression of eight genes including genes crucial in promoting cancer such as FGFR3 and DUSP1 and suppressed the expression of 33 genes, including genes crucial in preventing the onset and progression of cancer like RASSF2, JUP, and IL24, in comparison with the cells grown in niacin-proficient medium. Overall, niacin deficiency interferes with the DNA damage repair process induced by chemical carcinogens like NNK, and niacin-deficient population are at the higher risk of genetic instability caused by cigarette smoke carcinogen NNK.     

Exploring antidiabetic potential of adamantyl-thiosemicarbazones via aldose reductase (ALR2) inhibition

The role of aldose reductase (ALR2) in diabetes mellitus is well-established. Our interest in finding ALR2 inhibitors led us to explore the inhibitory potential of new thiosemicarbazones. In this study, we have synthesized adamantyl-thiosemicarbazones and screened them as aldehyde reductase (ALR1) and aldose reductase (ALR2) inhibitors. The compounds bearing phenyl 3a, 2-methylphenyl 3g and 2,6-dimethylphenyl 3m have been identified as most potent ALR2 inhibitors with IC₅₀ values of 3.99 ± 0.38, 3.55 ± 0.26 and 1.37 ± 0.92 µM, respectively, compared with sorbinil (IC₅₀ = 3.14 ± 0.02 μM). The compounds 3a, 3g, and 3m also inhibit ALR1 with IC₅₀ value of 7.75 ± 0.28, 7.26 ± 0.39 and 7.04 ± 2.23 µM, respectively. Molecular docking was also performed for putative binding of potent inhibitors with target enzyme ALR2. The most potent 2,6-dimethylphenyl bearing thiosemicarbazone 3m (IC₅₀ = 1.37 ± 0.92 µM for ALR2) and other two compound 3a and 3g could potentially lead for the development of new therapeutic agents.     

Asymmetric reduction of alpha, beta-unsaturated ketone to (R) allylic alcohol by Candida chilensis

A pilot scale whole cell process was developed for the enantioselective 1,2-reduction of prochiral alpha,beta-unsaturated ketone to (R) allylic alcohol using Candida chilensis. Initial development showed high enantiomeric excess (EE > 95%) but low product yield (10%). Process development, using a combination of statistically designed screening and optimization experiments, improved the desired alcohol yield to 90%. The fermentation growth stage, particularly medium composition and growth pH, had a significant impact on the bioconversion while process characterization identified diverse challenges including the presence of multiple enzymes, substrate/product toxicity, and biphasic cellular morphology. Manipulating the fermentation media allowed control of the whole cell morphology to a predominantly unicellular broth, away from the viscous pseudohyphae, which were detrimental to the bioconversion. The activity of a competing enzyme, which produced the undesired saturated ketone and (R) saturated alcohol, was minimized to < or =5% by controlling the reaction pH, temperature, substrate concentration, and biomass level. Despite the toxicity effects limiting the volumetric productivity, a reproducible and scaleable process was demonstrated at pilot scale with high enantioselectivity (EE > 95%) and overall yield greater than 80%. This was the preferred route compared to a partially purified process using ultra centrifugation, which led to improved volumetric productivity but reduced yield (g/day). The whole cell approach proved to be a valuable alternative to chemical reduction routes, as an intermediate step for the asymmetric synthesis of an integrin receptor antagonist for the inhibition of bone resorption and treatment of osteoporosis.     

Syntheses of Four Methyl-branched Secondary Acetates and a Methyl-branched Ketone as Possible Candidates for the Female Pheromone of the Screwworm Fly,Cochliomyia hominivorax

6-Acetoxy-19-methylnonacosane (1), 7-acetoxy-19-methylnonacosane (2), 8-acetoxy-19-methylnonacosane (3), 7-acetoxy-15-methylnonacosane (4), and 21-methyl-7-hentriacontanone (5) were synthesized as racemic and diastereomeric mixtures. These are new compounds isolated from an HPLC fraction of the female hexane extract which elicited mating responses in the male screwworm fly, Cochliomyia hominivorax.     

Lipophilic 9,10‐Dehydrofukinone Action on Pathogenic and Non‐Pathogenic Bacterial Biofilms. Why Is This Main Volatile Metabolite in Senecio?

The effect of a natural sesquiterpene ketone, 9,10‐dehydrofukinone (DHF), on pathogenic Staphylococcus aureus and Pseudomonas aeruginosa strains isolated from chronic infectious processes, was the focus of the present study. Lipophilic DHF produced important antibacterial synergistic effects in association with ciprofloxacin (CPX) against two biofilm‐forming strains of S. aureus HT1 (FIC=0.21) and P. aeruginosa HT5 (FIC=0.05). Hence, this mixture constitutes an excellent strategy to combat these biofilm‐producing bacteria that overexpress drug efflux pumps as a resistance mechanism. Additionally, a substantial rise in beneficial Lactobacillus biofilm biomass was determined as a very significant finding of this association. Particularly, a non‐pathogenic biofilm increment of 119 % was quantified when the mixture was added to a probiotic L. acidophilus ATCC SD‐5212 culture. A surface activity enhanced in 71 % with respect to untreated L. acidophilus culture was also generated by the DHF and CPX association, and therefore, a glycoprotein synthesis induction mediated by the mixture is discussed. The results obtained could help in the development of new selective antibiotics. From an ecological standpoint, the present study strongly suggests that DHF is a polyfunctional organic molecule produced with a high yield in Senecio punae that exerts a positive impact on a non‐pathogenic plant bacterium L. plantarum CE105.     

Highly selective anti-Prelog synthesis of optically active aryl alcohols by recombinant Escherichia coli expressing stereospecific alcohol dehydrogenase

Biocatalytic asymmetric synthesis has been widely used for preparation of optically active chiral alcohols as the important intermediates and precursors of active pharmaceutical ingredients. However, the available whole-cell system involving anti-Prelog specific alcohol dehydrogenase is yet limited. A recombinant Escherichia coli system expressing anti-Prelog stereospecific alcohol dehydrogenase from Candida parapsilosis was established as a whole-cell system for catalyzing asymmetric reduction of aryl ketones to anti-Prelog configured alcohols. Using 2-hydroxyacetophenone as the substrate, reaction factors including pH, cell status, and substrate concentration had obvious impacts on the outcome of whole-cell biocatalysis, and xylose was found to be an available auxiliary substrate for intracellular cofactor regeneration, by which (S)-1-phenyl-1,2-ethanediol was achieved with an optical purity of 97%e.e. and yield of 89% under the substrate concentration of 5 g/L. Additionally, the feasibility of the recombinant cells toward different aryl ketones was investigated, and most of the corresponding chiral alcohol products were obtained with an optical purity over 95%e.e. Therefore, the whole-cell system involving recombinant stereospecific alcohol dehydrogenase was constructed as an efficient biocatalyst for highly enantioselective anti-Prelog synthesis of optically active aryl alcohols and would be promising in the pharmaceutical industry.     

Chemical constituents from Alismatis Rhizoma and their anti-inflammatory activities in vitro and in vivo

Six new compounds, including a new compound with an unusual 2, 4, 6-cycloheptatrien ketone skeleton (1), two new diphenylpropanoid ethers (2, 3), a new protostane-type triterpenoid (4), two new norsesquiterpene (5a, 5b), and two new natural products (6, 7), together with eleven known compounds (8–18) were isolated from the aqueous extract of Alismatis Rhizoma (AR). Their structures were elucidated by a combination of 1D and 2D NMR (¹H and ¹³C NMR, COSY, HSQC, HMBC, and NOESY), HRESIMS spectroscopic data, experimental and calculated electronic circular dichroism (ECD) spectra. Some of the compounds were evaluated for their inhibitory effects on nitric oxide (NO) production in LPS-induced RAW 264.7 cells. Two protostane-type triterpenoids, compounds 4 and 17, exhibited potent inhibitory activities with the IC₅₀ values of 39.3 and 63.9 μM compared with indomethacin. In the meanwhile, their anti-inflammatory effects were also confirmed by acute inflammation model induced by CuSO₄ in zebrafish.