Rational design, synthesis and preliminary antitumor activity evaluation of a chlorambucil derivative with potent DNA/HDAC dual-targeting inhibitory activity.

Histone deacetylases (HDACs) play a pivotal role not only in gene expression but also in DNA repair. Herein, we report the successful design, synthesis and evaluation of a chlorambucil derivative named vorambucil with a hydroxamic acid tail as a DNA/HDAC dual-targeting inhibitor. Vorambucil obtained both potent DNA and HDACs inhibitory activities. Molecular docking results supported the initial pharmacophoric hypothesis and rationalized the potent inhibitory activity of vorambucil against HDAC1, HDAC2 and HDAC6. Vorambucil showed potent antiproliferative activity against all the test four cancer cell lines with IC50 values of as low as 3.2-6.2µM and exhibited 5.0-18.3-fold enhanced antiproliferative activity than chlorambucil. Vorambucil also significantly inhibits colony formation of A375 cancer cells. Further investigation showed that vorambucil remarkably induced apoptosis and arrested the cell cycle of A375 cells at G2/M phase. Vorambucil could be a promising candidate and a useful tool to elucidate the role of those DNA/HDAC dual-targeting inhibitors for cancer therapy.

Metabolic responses in Candida tropicalis to complex inhibitors during xylitol bioconversion.

During xylitol fermentation, Candida tropicalis is often inhibited by inhibitors in hemicellulose hydrolysate. The mechanisms involved in the metabolic responses to inhibitor stress and the resistances to inhibitors are still not clear. To understand the inhibition mechanisms and the metabolic responses to inhibitors, a GC/MS-based metabolomics approach was performed on C. tropicalis treated with and without complex inhibitors (CI, including furfural, phenol and acetic acid). Partial least squares discriminant analysis was used to determine the metabolic variability between CI-treated groups and control groups, and 25 metabolites were identified as possible entities responsible for the discrimination caused by inhibitors. We found that xylose uptake rate and xylitol oxidation rate were promoted by CI treatment. Metabolomics analysis showed that the flux from xylulose to pentose phosphate pathway increased, and tricarboxylic acid cycle was disturbed by CI. Moreover, the changes in levels of 1,3-propanediol, trehalose, saturated fatty acids and amino acids showed different mechanisms involved in metabolic responses to inhibitor stress. The increase of 1,3-propanediol was considered to be correlated with regulating redox balance and osmoregulation. The increase of trehalose might play a role in protein stabilization and cellular membranes protection. Saturated fatty acids could cause the decrease of membrane fluidity and make the plasma membrane rigid to maintain the integrity of plasma membrane. The deeper understanding of the inhibition mechanisms and the metabolic responses to inhibitors will provide us with more information on the metabolism regulation during xylitol bioconversion and the construction of industrial strains with inhibitor tolerance for better utilization of bioresource.

GC-MS-based metabolomics study of the responses to arachidonic acid in Blakeslea trispora.

The potential use of arachidonic acid (AA) to enhance the production of ß-carotene in Blakeslea trispora was investigated in this work. To study the mechanism of the B. trispora response to AA, we used a systematic analytical approach to investigate the changes in the B. trispora cell metabolome at different time points after AA treatment. A maximum of ß-carotene production was obtained when 0.4g/l AA was added after 36h of cultivation. Gas chromatography-mass spectrometry (GC-MS)-based metabolomics approach and a multivariate analysis were used to investigate the intracellular biochemical changes in B. trispora. With the aid of principal component analysis (PCA), the intracellular metabolite profiles of all the groups were distinguished. Moreover, a group classification and pairwise discrimination between the control and AA-treated groups were obtained through partial least-squares-discriminant analysis (PLS-DA), and 27 differential metabolites with variable importance in the projection (VIP) value higher than 1 were identified, which was also confirmed by the subsequent hierarchical cluster analysis (HCA). Separation of the control and AA-treated groups was mainly due to the compounds of the Krebs cycle, fatty acids and amino acids. With the treatment of AA, the glycolysis was enhanced and the use of glucose for fermentation was increased. The increased levels of some fatty acids and decreased levels of amino acids in the AA-treated cells could also be the responses to the addition of AA. Metabolomics provided a powerful methodology to gain insight in metabolic changes induced by metabolic stimulators in microorganisms.

Biosynthesis of nucleoside analogues via thermostable nucleoside phosphorylase.

Biocatalyzed synthesis of nucleoside analogues was carried out using two thermostable nucleoside phosphorylases from the hyperthermophilic aerobic crenarchaeon Aeropyrum pernix K1. The synthesis of the 2,6-diaminopurine nucleoside and 5-methyluridine was used as a reaction model to test the process. Both the purine nucleoside phosphorylase (apPNP) and uridine phosphorylase (apUP) were functionally expressed in Escherichia coli. The recombinant enzymes were characterized after purification, and both enzymes showed high thermostability and broad substrate specificity. Both enzymes retained 100 % of their activity after 60 min at high temperature, and the optimum temperature for the enzymes was 90-100 °C. The nucleoside phosphorylases obtained from A. pernix are valuable industrial biocatalysts for high-temperature reactions that produce nucleoside drugs in high yields.

Improved ß-carotene production by oxidative stress in Blakeslea trispora induced by liquid paraffin.

When 3 % (v/v) liquid paraffin was added to the medium, ß-carotene production increased from 397 to 715 mg l(-1) in mated cultures of Blakeslea trispora. Liquid paraffin also enhanced the oxygen concentration and induce high oxidative stress, as observed by the increase in activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). After 84 h of cultivation in the presence of liquid paraffin, the activities of SOD, CAT and POD in B. trispora increased 77, 52.5 and 76.6 %, respectively.

Effect of organic acids found in cottonseed hull hydrolysate on the xylitol fermentation by Candida tropicalis.

Five organic acids (acetic, ferulic, 4-hydroxybenzoic, formic and levulinic acids) typically associated in the hemicellulose hydrolysate were selected to study their effects on the xylitol fermentation. The effects of individual and combined additions were independently evaluated on the following parameters: inhibitory concentration; initial cell concentration; pH value; and membrane integrity. The results showed that the toxicities of organic acids were related to their hydrophobility and significantly affected by the fermentative pH value. In addition, it was revealed that the paired combinations of organic acids did not impose synergetic inhibition. Moreover, it was found that the fermentation inhibition could be alleviated with the simple manipulations by increasing the initial cell concentration, raising the initial pH value and minimizing furfural levels by evaporation during the concentration of hydrolysates. The proposed strategies for minimizing the negative effects could be adopted to improve the xylitol fermentation in the industrial applications.

Two-step efficient synthesis of 5-methyluridine via two thermostable nucleoside phosphorylase from Aeropyrum pernix.

5-Methyluridine has been synthesized in high yield using guanosine and thymine as starting materials in the presence of highly thermostable recombinant purine nucleoside phosphorylase (PNP) and uridine phosphorylase (UP) obtained from hyperthermophilic aerobic crenarchaeon Aeropyrum pernix. Key reaction parameters such as pH, temperature, concentration of buffer and substrates were investigated. At the optimal conditions, 5-methyluridine was achieved in yield 85% with a guanosine conversion of 96% in 10ml scale. The process can be performed at high temperature, which will highly increase the solubility of substrates, therefore, this process is suitable for the industry application.

Molecular cloning and functional expression of two key carotene synthetic genes derived from Blakeslea trispora into E. coli for increased ß-carotene production.

Blakeslea trispora is used commercially to produce ß-carotene. Isopentenyl pyrophosphate isomerase (IPI) and geranylgeranyl pyrophosphate synthase (GGPS) are key enzymes in the biosynthesis of carotenoids. The cDNAs of genes ipi and carG were cloned from the fungus and expressed in Escherichia coli. Greater GGPS activity was needed in the engineered E. coli when IPP activity was increased. The introduction of GGPS and IPI increased the ß-carotene content in E. coli from 0.5 to 0.95 mg/g dry wt.

Rational design and characterization of a DNA/HDAC dual-targeting inhibitor containing nitrogen mustard and 2-aminobenzamide moieties.

Histone deacetylases (HDACs) play a key role not only in gene expression but also in DNA repair. Herein, we report the rational design and characterization of a compound named chlordinaline containing nitrogen mustard and 2-aminobenzamide moieties as a DNA/HDAC dual-targeting inhibitor. Chlordinaline exhibited moderate total HDAC inhibitory activity. The HDAC isoform selectivity assay indicated that chlordinaline mostly inhibits HDAC3. Chlordinaline exhibited both DNA and HDAC inhibitory activities and showed potent antiproliferative activity against all the six test cancer cell lines with IC50 values of as low as 3.1-14.2 µM, which is significantly more potent than reference drugs chlorambucil and tacedinaline. Chlordinaline could induce the apoptosis and G2/M phase cell cycle arrest of A375 cancer cells. This study demonstrates that combining nitrogen mustard and 2-aminobenzamide moieties into one molecule is an effective method to obtain DNA/HDAC dual-targeting inhibitors as potent antitumor agents. Chlordinaline as the first example of such DNA/HDAC dual-targeting inhibitors could be a promising candidate for cancer therapy and could also be a lead compound for further optimization.

Design, synthesis and biological evaluation of novel 2-aminobenzamides containing dithiocarbamate moiety as histone deacetylase inhibitors and potent antitumor agents.

A novel series of 2-aminobenzamides with dithiocarbamate as cap group were designed and synthesized as histone deacetylase (HDAC) inhibitors. Most newly synthesized compounds displayed potent antiproliferative activity against diverse human tumor cell lines. The most potent compounds, M101, M122 and M133 exhibited remarkably enhanced anticancer potency against 6 kinds of cancer cell lines with IC50 values of as low as 0.54-2.49 µM compared with CS055 (2.28∼ >26 µM) and MS275 (0.47-6.74 µM). HDAC isoform selectivity assay indicated that M101, M122 and M133 are HDAC1 and HDAC2 selective inhibitors. We also rationalize the high potency and selectivity of compound M122 by molecular docking. Further investigation showed that M101, M122 and M133 could inhibit colony formation of human hepatocellular carcinoma cell line SMMC7721. Furthermore, M101, M122 and M133 remarkably induced apoptosis in SMMC7721 cancer cells. M101 and M133 were found to potently induce SMMC7721 cancer cell cycle arrest at G2/M phase. This study demonstrated that introducing dithiocarbamate as the capping group of 2-aminobenzamide is effective for improving both HDAC inhibitory activity and antitumor activity. The most potent compounds, M101, M122 and M133 could be promising candidates for cancer therapy.

Design, synthesis and biological evaluation of novel carbamodithioates as anti-proliferative agents against human cancer cells.

A series of new carbamodithioates compounds has been successfully synthesized. All the carbamodithioate derivatives of SFE and SFA with benzenethiols (substituted or unsubstituted) exhibited, in general, higher percentages of inhibition than their parent compounds: SFE and SFA. A number of carbamodithioate derivatives with benzenethiols (substituted or unsubstituted) (1l, 1m, 1n, 1o, 1q, 1s, 2l, 2n, 2p, 2q, 2r and 2s) were investigated for in vitro anti-proliferative activities against five cancer cell lines: SMMC-7721, A549, A375, HCT 116 and Hela. The carbamodithioate compounds (1l, 1m, 1n, 1o, 1q and 1s) derived from SFE and the carbamodithioate compounds (2l, 2n, 2p, 2q, 2r and 2s) derived from SFA are more sensitive toward SMMC-7721and A549 cancer cells than toward other cancer cells in that their IC50 values are appreciably lower. Moreover, they exhibited stronger inhibitory activities than their parent compound SFE and SFE. Further investigation indicated that these carbamodithioate derivatives inhibited colony formation of SMMC-7721 and remarkably induced the G2/M or G0/G1 phase cell cycle arrest and apoptosis in SMMC-7721 cancer cells. More important, these carbamodithioate derivatives are stable in protic solvent media than their parent compounds. By virtue of the simplicity of the preparation of these carbamodithioate derivatives and their stability, compounds 1m and 2s could be the promising candidates for replacement for their parent SFE and SFA for cancer prevention agents.

Design, synthesis and biological evaluation of novel hydroxamates and 2-aminobenzamides as potent histone deacetylase inhibitors and antitumor agents.

Many studies have indicated that histone deacetylase (HDAC) inhibitors are promising agents for the treatment of cancer. With the aim to search for novel potent HDAC inhibitors, we designed and synthesized two series of hydroxamates and 2-aminobenzamides compounds as HDAC inhibitors and antitumor agents. Those compounds were investigated for their HDAC enzymatic inhibitory activities and in vitro anti-proliferation activities against diverse cancer cell line (A549, HepG2, MGC80-3 and HCT116). Most of the synthesized compounds displayed potent HDAC inhibitory activity and antiproliferative activity. In particular, Compound 12a, N-(2-aminophenyl)-4-[(4-fluorophenoxy)methyl]benzamide, was shown to have the most HDAC inhibitory activity (70.6% inhibition at 5 µM) and antitumor activity with IC50 value of as low as 3.84 µM against HepG2 human liver hepatocellular carcinoma cell line, more than 4.8-fold lower than CS055 and 5.9-fold lower than CI994. HDAC isoform selectivity assay indicated 12a is a potent HDAC2 inhibitor. Docking study of 12a suggested that it bound tightly to the binding pocket of HDAC2. Further investigation showed that 12a could inhibit the migration and colony formation of A549 cancer cells. Furthermore, 12a remarkably induced apoptosis and G2/M phase cell cycle arrest in A549 cancer cells. Those results indicated that compound 12a could be a promising candidate for treatment of cancer.

The stability and degradation mechanism of sulforaphene in solvents.

Sulforaphene, a natural compound, has been investigated as a potential anticancer agent. However, the stability of sulforaphene, in various solvents, and its degradation pathway have not been appropriately reported. This instability impairs the preparation process, the biological evaluation experiments, and the applications of sulforaphene. In this study, the stability of sulforaphene stored at 26°C was investigated in each of the following six solvents: two kinds of protic solvents (methanol and ethanol) and four kinds of aprotic solvents (acetonitrile, dichloromethane, ethyl acetate and acetone). Sulforaphene was found to be stable in aprotic solvents and unstable in the protic solvents. The degradation products of sulforaphene in protic solvents (methanol and ethanol) were purified by the preparative HPLC and identified by ESI/MS and NMR ((1)H NMR). The degradation pathways of sulforaphene in methanol and ethanol were proposed. It was found that sulforaphene was degraded into two kinds of structural isomer in alcohols.

The mechanism of sulforaphene degradation to different water contents.

Sulforaphene extracted from radish seeds was strongly associated with cancer prevention. However, sulforaphene was unstable in aqueous medium and at high temperature. This instability impairs many useful applications of sulforaphene. In this paper, the stability of sulforaphene (purity above 95%) during storage at -20°C, 4°C and 26°C was studied. The degradation product was purified by preparative HPLC and identified by ESI/MS, NMR ((1)H and (13)C NMR) and FTIR spectroscopy. The degradation pathway of sulforaphene was presented. Furthermore, we found that the degradation rate of sulforaphene was closely related to the water content of sulforaphene sample. The higher the water content was, the faster the sulforaphene sample degraded. A mathematical model was developed to predict the degradation constant at various water contents. It provided a guideline for industry to improve the stability of sulforaphene during preparation, application and storage.

Synergistic Effect of the Combination of Novel Suberoylanilide Hydroxamic Acid Derivatives with Cisplatin on Anti-proliferation of Human Cancer Cells.

A novel, green, and atom-economical boric acid catalyzed direct amidation without the use of any coupling agents for the preparation of suberoylanilide hydroxamic acid (SAHA) and SAHA-based inhibitors targeting anti-proliferation of cancer cells is provided. The new SAHA-based inhibitor B123, when used alone, exhibited higher anti-proliferative activities than SAHA or Cisplatin against a number of human cancer cells. We have examined the effect of combination of these SAHA-based inhibitors with Cisplatin. We found synergistic effects of the combination of SAHA-based inhibitors with Cisplatin over a wide range of concentrations against human liver cancer cells HepG2 and two human lung cancer cell lines H1299 and H460. This synergism leads up to 8-fold of dose reduction for Cisplatin in the combination with our synthesized inhibitor B123 against H1299.

Synthesis and Anti-tumor Activities of Novel Phenyl Substituted Suberoylanilide Hydroxamic Acid Derivatives Against Human Cancer Cells.

A facile and atom-economical boric acid catalyzed direct amidation without any coupling agents for the preparation of Suberoylanilide Hydroxamic Acid (SAHA) and SAHA-based inhibitors targeting anti-proliferation of cancer cells is described. It is applicable to the preparation of SAHA-based inhibitors having an unprotected hydroxyl group in the phenyl ring without the need of the protection. The in-vitro assays data indicate that the nature and the position of the substituents (activating and/or deactivating) in the capping group (phenyl ring) of SAHA-based inhibitors synthesized in this study have a vital impact on the potency of anti-proliferative activity against cancer cells. With low toxicity toward the normal cells, a number of synthesized SAHA-based inhibitors with two substituents in the phenyl ring possess higher antiproliferative activity than SAHA and Cisplatin toward six studied cancer cell lines: A375 human skin cancer cells, A549 human lung cancer cells, MGC80-3 human gastric cancer cells, H460 human lung cancer cells, H1299 human lung cancer cells, and HepG2 human liver cancer cells. Cisplatin is a common chemotherapeutic drug with high cytotoxicity for a variety of cancer treatments. The inhibitors provided in this study might signify future therapeutic drugs for cancer treatment.

The stability and degradation kinetics of Sulforaphene in microcapsules based on several biopolymers via spray drying.

Sulforaphene (SFE) was extracted from the radish seeds and the purity of SFE extracted by our laboratory was 95%. It is well known that SFE can prevent cancers. It is also known that SFE is unstable to heat. To overcome the problem, SFE microcapsules using natural biopolymers were prepared by spray drying. The results indicated that SFE microcapsules using hydroxypropyl-ß-cyclodextrin (HP-ß-CD), maltodextrin (MD) and isolated soybean protein (SPI) as wall materials could effectively improve its stability against heat, especially SFE-loaded HP-ß-CD and MD microcapsules. The amount of SFE in the microcapsules was found 20% higher than that of the non-encapsulated SFE under 90 °C in 168 h. Our finding suggested that the rate of degradation of the non-encapsulated and encapsulated SFE with HP-ß-CD, MD and SPI followed the first-order kinetics. The speed of the degradation of the encapsulated SFE in biopolymers increased from SFE with HP-ß-CD, to SFE with MD, and to SFE-SPI. The non-encapsulated SFE degrades fastest.

Effect of selected aldehydes found in the corncob hemicellulose hydrolysate on the growth and xylitol fermentation of Candida tropicalis.

The effects of four aldehydes (furfural, 5-hydroxymethylfurfural, vanillin and syringaldehyde), which were found in the corncob hemicellulose hydrolysate, on the growth and xylitol fermentation of Candida tropicalis were investigated. The results showed that vanillin was the most toxic aldehyde for the xylitol fermentation, followed by syringaldehyde, furfural and 5-hydroxymethylfurfural. Moreover, the binary combination tests revealed that furfural amplified the toxicity of other aldehydes and the toxicities of other binary combinations without furfural were simply additive. Based on the fermentation experiments, it was demonstrated that the inhibition of aldehydes could be alleviated by prolonging the fermentation incubation, increasing the initial cell concentration, enhancing the initial pH value and minimizing the furfural levels in the hydrolysate evaporation process. The strategies that we proposed to suppress the inhibitory effects of the aldehydes successfully avoided the complicated and costly detoxifications. Our findings could be potentially adopted for the industrial xylitol fermentation from hydrolysates.

Instability and Structural Change of 4-Methylsulfinyl-3-butenyl Isothiocyanate in the Hydrolytic Process.

Sulforaphene (4-methylsulfinyl-3-butenyl isothiocyanate), which has significant chemopreventive activities, is an important phytochemical ingredient produced by myrosinase hydrolysis of glucoraphenin (4-methylsulfinyl-3-butenyl glucosinolate) found in radish seeds. In this research, we found that sulforaphene was unstable and converted rapidly to a water-soluble degradation product in the hydrolytic process. The degradation product was successfully purified by preparative high-performance liquid chromatography on a C18 column using 10% methanol in water as the mobile phase. On the basis of MS and NMR spectroscopy data, the degradation product was identified to be 6-[(methylsulfinyl)methyl]-1,3-thiazinan-2-thione. The degradation pathway of sulforaphene was proposed in our study. Furthermore, low pH and metal ions were also found to have an effective inhibition to the degradation reaction of sulforaphene. Through adjusting the pH value of the system or adding metal ions after the content of sulforaphene has reached its maximum, the yield of sulforaphene increased significantly compared with that of the control.

Xylitol production from corncob hydrolysate using polyurethane foam with immobilized Candida tropicalis.

Polyurethane foam (PUF) was used as a carrier for Candida tropicalis (C. tropicalis) in the multi-batches fermentation of xylitol from xylose-containing corncob hemicellulose hydrolysate. After washing and sterilization, PUF (density of 320 kgm(-3), specific surface area of 1.5-2.0 × 10(5) m(2) m(-3), average porosity of 95%, pore diameter of 0.03 mm and cubic length of 5mm) was mixed with the culture medium at appropriate proportion followed by the inoculation. The fermentation parameters such as initial cell concentration, PUF dosage, pH value and temperature were controlled to study the effects on xylitol fermentation. In the 21-day durability tests, the optimal xylitol yield and volumetric productivity reached to 71.2% and 2.10 gL(-1)h(-1) respectively. Moreover, the average xylitol yield and volumetric productivity were 66.3% and 1.90 gL(-1)h(-1) for ten batchwise operations. The current research demonstrated that the PUF immobilization could serve as an efficient method for improving the cells vitality and enzyme reactivity in the continuous operation of fermentation.